Biodegradable polyester resin composition, and biodegradable polyester molded article containing the same

Abstract

The present invention provides a biodegradable polyester resin composition containing a polyester resin including a diol, an aromatic dicarboxylic acid, and an aliphatic dicarboxylic acid; and a hydrophilicity regulator having a molecular weight of 400 to 1300 in an amount of 5000 ppm to 20000 ppm. The hydrophilicity regulator may contain an oligomer formed by reacting at least two or more of the diol, the aromatic dicarboxylic acid, and the aliphatic dicarboxylic acid.

Description

[Technical Field]

[0001] The examples relate to a biodegradable polyester resin composition, a biodegradable polyester film containing the same, and a biodegradable molded article containing the same. [Background technology]

[0002] In recent years, as concerns about environmental problems have increased, 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 in the manufacture of various products such as films, fibers, packaging materials, bottles, and containers. However, when the lifespan of the product reaches the end of its life, incineration releases harmful substances, and depending on the type, it can take several hundred years for it to decompose completely in nature.

[0003] To overcome the limitations of these polymers, research into biodegradable polymers that decompose quickly is actively being conducted. Examples of biodegradable polymers used include polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), and polybutylene succinate (PBS).

[0004] These biodegradable resin compositions are disclosed in publications such as Korean Patent No. 2012-0103158. [Overview of the project] [Problems that the invention aims to solve]

[0005] The examples aim to provide a biodegradable polyester resin composition that has an appropriate initial degree of hydrolysis and an appropriate degree of biodegradation, and that exhibits a high degree of hydrolysis not only in soil but also in water when disposed of, as well as a biodegradable polyester film containing the same. [Means for solving the problem]

[0006] The biodegradable polyester resin composition according to the examples contains a polyester resin comprising a diol, an aromatic dicarboxylic acid, and an aliphatic dicarboxylic acid; and a hydrophilicity regulator with a molecular weight of 400 to 1300 in an amount of 5000 ppm to 20000 ppm.

[0007] In one embodiment, the hydrophilicity regulator includes an oligomer formed by the reaction of at least two of the diol, the aromatic dicarboxylic acid, and the aliphatic dicarboxylic acid.

[0008] In one embodiment of the biodegradable polyester resin composition, the degree of hydrolysis after one week is 35% to 60%, and the degree of hydrolysis after three weeks is 85% or more. The degree of hydrolysis after one week and the degree of hydrolysis after three weeks are measured by the following measurement method.

[0009] [Measurement method] The degree of hydrolysis after one week is the rate of decrease in the number average molecular weight of the biodegradable polyester resin composition relative to its initial state when the biodegradable polyester film is left for one week under high temperature and high humidity conditions of 80°C and 100% humidity, and the degree of hydrolysis after three weeks is the rate of decrease in the number average molecular weight of the biodegradable polyester resin composition relative to its initial state when the biodegradable polyester film is left for three weeks under high temperature and high humidity conditions of 80°C and 100% humidity.

[0010] In one embodiment, the hydrophilicity regulator may include a first oligomer having a molecular weight between 415 and 425, a second oligomer having a molecular weight between 620 and 630, a third oligomer having a molecular weight between 640 and 650, and a fourth oligomer having a molecular weight between 840 and 850.

[0011] In one embodiment, the content of the first oligomer may be 3000 to 5000 ppm based on the polyester resin, the content of the second oligomer may be 2000 to 4000 ppm based on the polyester resin, the content of the third oligomer may be 500 to 2000 ppm based on the polyester resin, and the content of the fourth oligomer may be 700 to 2500 ppm based on the polyester resin.

[0012] In one embodiment, the hydrophilicity regulator may include a first oligomer, the first oligomer may contain one first unit represented by the following chemical formula 8 and one second unit represented by the following chemical formula 9.

[0013] [ka]

[0014] [ka]

[0015] In one embodiment, the hydrophilicity regulator comprises a second oligomer and a third oligomer, wherein the second oligomer contains one first unit and two second units, and the third oligomer contains two first units and one second unit, and the second oligomer may be included in the hydrophilicity regulator in an even higher content than the third oligomer.

[0016] In one embodiment, the hydrophilicity regulator further comprises a fourth oligomer, the fourth oligomer comprising two first units and two second units.

[0017] In one embodiment of the biodegradable polyester resin composition, the water contact angle measured by the following measurement method may be 65° to 90°, and the polarity measured by the following measurement method may be 4mN / m to 7mN / m.

[0018] [Measurement Method] The biodegradable polyester resin composition is dried at a temperature of 80°C, placed in a stainless-steel frame, compressed at a temperature of 210°C and a pressure of 10 MPa for 3 minutes to produce a polyester sheet having a thickness of 300 μm, and the water contact angle and the polarity degree on the surface of the polyester sheet are measured.

[0019] In the biodegradable polyester resin composition according to an embodiment, the biodegradation degree after 1 week is 45% to 65%, and the biodegradation degree after 9 weeks is 85% or more. The biodegradation degree after 1 week and the biodegradation degree after 9 weeks can be measured by the following measurement method. <0>

[0020] [Measurement Method] The biodegradation degree after 1 week is the reduction rate of the molecular weight of the polyester resin composition with respect to the initial value when the biodegradable polyester resin composition is placed for 1 week under composting conditions, a temperature of 60°C and a humidity of 90%. The biodegradation degree after 9 weeks is the reduction rate of the molecular weight of the polyester resin composition with respect to the initial value when the biodegradable polyester resin composition is placed for 9 weeks under composting conditions, a temperature of 60°C and a humidity of 90%.

[0021] The biodegradable polyester resin composition according to the embodiment contains a polyester resin containing a diol, an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid. The degree of hydrolysis after 1 week is 35% to 60%, and the degree of hydrolysis after 3 weeks is 85% or more. The degree of hydrolysis after 1 week and the degree of hydrolysis after 3 weeks are measured by the following measurement method.

[0022] [Measurement Method] The degree of hydrolysis after 1 week is the reduction rate of the number-average molecular weight of the biodegradable polyester resin composition with respect to the initial value when the biodegradable polyester resin composition is placed for 1 week under high-temperature and high-humidity conditions of a temperature of 80°C and a humidity of 100%. The degree of hydrolysis after 3 weeks is the reduction rate of the number-average molecular weight of the biodegradable polyester resin composition with respect to the initial value when the biodegradable polyester resin composition is placed for 3 weeks under high-temperature and high-humidity conditions of a temperature of 80°C and a humidity of 100%.

[0023] In the biodegradable polyester resin composition according to one embodiment, the biodegradation degree after 9 weeks is 85% or more, and the biodegradation degree after 9 weeks may be the reduction rate of the molecular weight of the biodegradable polyester resin composition with respect to the initial value when the biodegradable polyester resin composition is placed for 9 weeks under composting conditions, a temperature of 60°C and a humidity of 90%.

[0024] In the biodegradable polyester resin composition according to one embodiment, the biodegradation degree after 1 week is 45% to 75%, and the biodegradation degree after 1 week may be the reduction rate of the molecular weight of the biodegradable polyester resin composition with respect to the initial value when the biodegradable polyester resin composition is placed for 1 week under composting conditions, a temperature of 60°C and a humidity of 90%.

[0025] In the biodegradable polyester resin composition according to one embodiment, the degree of hydrolysis after 2 weeks is 80% to 95%, and the degree of hydrolysis after 2 weeks may be the reduction rate of the number average molecular weight of the biodegradable polyester resin composition with respect to the initial value when the biodegradable polyester resin composition is placed for 2 weeks under high temperature and high humidity conditions of a temperature of 80°C and a humidity of 100%.

[0026] In the biodegradable polyester resin composition according to one embodiment, the degree of hydrolysis after 4 weeks is 85% or more, and the degree of hydrolysis after 4 weeks is the reduction rate of the number average molecular weight of the biodegradable polyester resin composition with respect to the initial value when the biodegradable polyester resin composition is placed for 4 weeks under high temperature and high humidity conditions of a temperature of 80°C and a humidity of 100%. The increase rate of the degree of hydrolysis from 1 week to 2 weeks may be 29% / week to 50% / week, and the increase rate of the degree of hydrolysis from 3 weeks to 4 weeks may be 0.01% / week to 3% / week.

[0027] In one embodiment of the biodegradable polyester resin composition, the degree of biodegradation after 4 weeks is 73% to 85%. The degree of biodegradation after 4 weeks is the rate of decrease in the number-average molecular weight of the biodegradable polyester resin composition compared to its initial state, when the biodegradable polyester resin composition is left for 4 weeks under high temperature and high humidity conditions of 80°C and 100% humidity. The rate of increase in the degree of biodegradation from 1 to 4 weeks may be 3.5% / week to 8% / week.

[0028] In the biodegradable polyester resin composition according to one example, the acid value may be 2.0 mg KOH / g or less.

[0029] In one embodiment, the biodegradable polyester resin composition may contain oligomers with a molecular weight of 400 to 1300 at a concentration of 5000 ppm to 20000 ppm relative to the overall composition.

[0030] In the biodegradable polyester resin composition according to one embodiment, the oligomer may include the diol, the aromatic dicarboxylic acid, and the aliphatic dicarboxylic acid.

[0031] The biodegradable molded articles according to the examples may contain a polyester resin containing a diol, an aromatic dicarboxylic acid, and an aliphatic dicarboxylic acid; and a hydrophilicity regulator with a molecular weight of 400 to 1300 in an amount of 5000 ppm to 20000 ppm. [Effects of the Invention]

[0032] The biodegradable polyester resin composition according to the examples contains a hydrophilicity modifier having a molecular weight of approximately 400 to approximately 1300. Furthermore, the hydrophilicity modifier can adjust the hydrophilicity and / or hydrophobicity of the biodegradable polyester resin composition according to the examples. Thus, the hydrophilicity modifier can adjust the degree of hydrolysis of the biodegradable polyester resin composition according to the examples.

[0033] The biodegradable polyester resin composition according to the example may have the aforementioned appropriate degree of hydrolysis and appropriate degree of biodegradation due to the hydrophilicity modifier and manufacturing process.

[0034] In particular, the biodegradable polyester resin compositions according to the examples have a low initial degree of hydrolysis and a high late-stage degree of hydrolysis. Furthermore, the biodegradable polyester resin compositions according to the examples may have a biodegradation rate at an appropriate degree of hydrolysis.

[0035] As a result, the biodegradable polyester resin composition according to the examples can be efficiently applied to packaging films and the like. In other words, films made from the biodegradable polyester resin composition according to the examples can be used for ordinary purposes such as packaging. In this case, since the biodegradable polyester resin composition according to the examples has a low degree of hydrolysis initially, the biodegradable polyester film can maintain a certain level of mechanical and chemical properties within the typical usage period of the user.

[0036] Furthermore, since the biodegradable polyester resin composition according to the examples has a high degree of late hydrolysis, the film produced using the biodegradable polyester resin composition according to the examples may decompose easily when discarded after use. In particular, because the biodegradable polyester resin composition according to the examples has a high degree of late hydrolysis, the decomposition by ambient moisture and the decomposition by microorganisms in the biodegradable polyester resin composition according to the examples can complement each other. As a result, the biodegradable polyester resin composition according to the examples may have a low degree of early hydrolysis and a high degree of biodegradation.

[0037] Furthermore, the biodegradable polyester resin compositions according to the examples may have a biodegradability of 1.5 or more per aliphatic carboxylic acid. That is, the biodegradable polyester resin compositions according to the examples have a low aliphatic carboxylic acid content and a high biodegradability.

[0038] As a result, the biodegradable polyester resin composition according to the examples may have a relatively high aromatic carboxylic acid content, and therefore may exhibit high hydrolysis resistance in the initial stages and a high degree of biodegradation in the later stages.

[0039] The biodegradable polyester resin compositions according to the examples can maintain a certain level of mechanical and chemical properties within the user's service life. Furthermore, because the biodegradable polyester resin compositions according to the examples have a high degree of late-stage hydrolysis, they may decompose easily in rivers or the sea. In other words, the biodegradable polyester resin compositions according to the examples can solve environmental problems such as marine plastic pollution. [Brief explanation of the drawing]

[0040] [Figure 1] This is a schematic diagram showing the apparatus for producing the polyester resin composition according to the examples. [Figure 2] This figure shows an example of a biodegradable molded article formed by the polyester resin composition according to the examples. [Modes for carrying out the invention]

[0041] The invention will be described in detail below with concrete examples. The concrete examples are not limited to those disclosed below and can be modified in various forms as long as the gist of the invention remains unchanged.

[0042] In this specification, when a part is said to "include" a component, unless otherwise stated, this does not mean that it excludes other components, but rather that it may further include other components.

[0043] Furthermore, it should be understood that all numerical ranges indicating physical properties, dimensions, etc., of the components described herein are modified by the term "approximately" unless otherwise specified.

[0044] The terms first, second, primary, secondary, etc., used herein are used to describe various components, and such components are not limited by these terms. The terms are used solely for the purpose of distinguishing one component from another.

[0045] The biodegradable polyester resin compositions according to the examples contain a biodegradable polyester resin. The biodegradable polyester resin compositions according to the examples may contain the biodegradable polyester resin alone or together with other resins or additives.

[0046] The biodegradable polyester resin comprises a diol, an aromatic dicarboxylic acid, and an aliphatic dicarboxylic acid. The biodegradable polyester resin comprises a diol residue, an aromatic dicarboxylic acid residue, and an aliphatic dicarboxylic acid residue. The diol residue is derived from the diol, the aromatic dicarboxylic acid residue is derived from the aromatic dicarboxylic acid, and the aliphatic dicarboxylic acid residue is derived from the aliphatic dicarboxylic acid. The biodegradable polyester resin comprises a diol component, an aromatic dicarboxylic acid component, and an aliphatic dicarboxylic acid component. Similarly, the diol component may be derived from the diol, the aromatic dicarboxylic acid component may be derived from the aromatic dicarboxylic acid, and the aliphatic dicarboxylic acid component may be derived from the aliphatic dicarboxylic acid.

[0047] In the description of the biodegradable polyester resin composition by example, the diol residue may also be represented as a diol. In the biodegradable polyester resin, the dicarboxylic acid residue may also be represented as a dicarboxylic acid. Furthermore, the residue can be represented as the component.

[0048] The diol may be an aliphatic diol. The diol may be ethanediol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1, At least one of the following groups may be selected: 3-pentanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 2,4-dimethyl-2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-octadecanediol, or derivatives thereof.

[0049] The diol may be selected from the group consisting of 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, diethylene glycol, neopentyl glycol, or derivatives thereof, with at least one of these being selected.

[0050] The diol may be selected from the group consisting of 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or derivatives thereof, with at least one selected from these.

[0051] The diol may include 1,4-butanediol or a derivative thereof.

[0052] The aromatic dicarboxylic acid may be at least one selected from the group consisting of phthalic acid, terephthalic acid, isophthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, anthracenedicarboxylic acid, phenantradicarboxylic acid, or derivatives thereof.

[0053] The aromatic dicarboxylic acid may be selected from at least one of the group consisting of terephthalic acid, dimethyl terephthalate, 2,6-naphthalenedicarboxylic acid, isophthalic acid, or derivatives thereof.

[0054] The aromatic dicarboxylic acid may include terephthalic acid, dimethyl terephthalate, or derivatives thereof.

[0055] The aliphatic dicarboxylic acid may be at least one selected from the group consisting of oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, or derivatives thereof.

[0056] The aliphatic dicarboxylic acid may be selected from the group consisting of adipic acid, succinic acid, sebacic acid, or derivatives thereof, with at least one of these being selected.

[0057] The aliphatic dicarboxylic acid may include adipic acid or a derivative thereof.

[0058] In the biodegradable polyester resin, the molar ratio of the total diol residues including the diol to the total dicarboxylic acid residues including the aromatic dicarboxylic acid and the aliphatic dicarboxylic acid may be about 1:0.9 to about 1:1.1. The molar ratio of the total diol residues to the total dicarboxylic acid residues may be about 1:0.95 to about 1:1.05.

[0059] In the biodegradable polyester resin, the molar ratio of the aromatic dicarboxylic acid residue to the aliphatic dicarboxylic acid residue may be about 3:7 to about 7:3. In the biodegradable polyester resin, the molar ratio of the aromatic dicarboxylic acid residue to the aliphatic dicarboxylic acid residue may be about 3.3:6.7 to about 6.7:3.3. In the biodegradable polyester resin, the molar ratio of the aromatic dicarboxylic acid residue to the aliphatic dicarboxylic acid residue may be about 4:6 to about 6:4. In the biodegradable polyester resin, the molar ratio of the aromatic dicarboxylic acid residue to the aliphatic dicarboxylic acid residue may be about 4.2:5.8 to about 5:5.

[0060] The biodegradable polyester resin may contain diol residues derived from 1,4-butanediol in a content of approximately 90 mol% or more, based on the total diol content. The biodegradable polyester resin may contain diol residues derived from 1,4-butanediol in a content of approximately 95 mol% or more, based on the total diol content. The biodegradable polyester resin may contain diol residues derived from 1,4-butanediol in a content of approximately 98 mol% or more, based on the total diol content.

[0061] The biodegradable polyester resin may contain aromatic dicarboxylic acid residues derived from terephthalic acid or dimethyl terephthalate in a content of approximately 30 mol% to approximately 70 mol%, based on the total dicarboxylic acid content. The biodegradable polyester resin may contain aromatic dicarboxylic acid residues derived from terephthalic acid or dimethyl terephthalate in a content of approximately 35 mol% to approximately 65 mol%, based on the total dicarboxylic acid content. The biodegradable polyester resin may contain dicarboxylic acid residues derived from terephthalic acid or dimethyl terephthalate in a content of approximately 40 mol% to approximately 60 mol%, based on the total dicarboxylic acid content. The biodegradable polyester resin may contain aromatic dicarboxylic acid residues derived from terephthalic acid or dimethyl terephthalate in a content of approximately 43 mol% to approximately 55 mol%, based on the total dicarboxylic acid content.

[0062] The biodegradable polyester resin may contain aliphatic dicarboxylic acid residues derived from adipic acid in a content of approximately 30 mol% to approximately 70 mol%, based on the total dicarboxylic acid. The biodegradable polyester resin may contain aliphatic dicarboxylic acid residues derived from adipic acid in a content of approximately 35 mol% to approximately 65 mol%, based on the total dicarboxylic acid. The biodegradable polyester resin may contain aliphatic dicarboxylic acid residues derived from adipic acid in a content of approximately 40 mol% to approximately 60 mol%, based on the total dicarboxylic acid. The biodegradable polyester resin may contain aliphatic dicarboxylic acid residues derived from adipic acid in a content of approximately 47 mol% to approximately 57 mol%, based on the total dicarboxylic acid.

[0063] Furthermore, the biodegradable polyester resin may include a first block and a second block. The biodegradable polyester resin may have a molecular structure in which the first block and the second block are alternately bonded.

[0064] The first block may include the diol residue and the aromatic dicarboxylic acid residue. The first block may be formed by the esterification reaction of the diol and the aromatic dicarboxylic acid. The first block may include only the diol residue and the aromatic dicarboxylic acid residue. The first block may include only the repeating units formed by the esterification reaction of the diol and the aromatic dicarboxylic acid. That is, the first block may represent the sum of the repeating units of the diol and the aromatic dicarboxylic acid before the aliphatic dicarboxylic acid is attached.

[0065] The second block may include the diol residue and the aliphatic dicarboxylic acid residue. The second block may be formed by the esterification reaction of the diol and the aliphatic dicarboxylic acid. The second block may include only the diol residue and the aliphatic dicarboxylic acid residue. The second block may include only the repeating units formed by the esterification reaction of the diol and the aliphatic dicarboxylic acid. That is, the second block may represent the sum of the repeating units of the diol and the aliphatic dicarboxylic acid before the aromatic dicarboxylic acid is bonded to them.

[0066] In the biodegradable polyester resin, the ratio (X / Y) of the number of first blocks (X) to the number of second blocks (Y) may be about 0.5 to about 1.5. In the biodegradable polyester resin, the ratio (X / Y) of the number of first blocks (X) to the number of second blocks (Y) may be about 0.6 to about 1.4. In the biodegradable polyester resin, the ratio (X / Y) of the number of first blocks (X) to the number of second blocks (Y) may be about 0.7 to about 1.3. In the biodegradable polyester resin, the ratio (X / Y) of the number of first blocks (X) to the number of second blocks (Y) may be about 0.75 to about 1.2. Also, in the biodegradable polyester resin, the ratio (X / Y) of the number of first blocks (X) to the number of second blocks (Y) may be 0.8 to 1.1. The number of the first blocks may be even smaller than the number of the second blocks.

[0067] The number of the first blocks may be approximately 30 to approximately 300. The number of the first blocks may be approximately 40 to approximately 250. The number of the first blocks may be approximately 50 to approximately 220. The number of the first blocks may be approximately 60 to approximately 200. The number of the first blocks may be approximately 70 to approximately 200. The number of the first blocks may be approximately 75 to approximately 200.

[0068] The number of the first blocks may vary depending on the content of the aromatic dicarboxylic acid, the molecular weight of the biodegradable polyester resin, and the polymerization process described later. In other words, the number of the first blocks may increase as the molar ratio of the aromatic dicarboxylic acid increases and the molecular weight of the biodegradable polyester resin increases.

[0069] The number of the second blocks may be approximately 30 to approximately 300. The number of the second blocks may be approximately 40 to approximately 250. The number of the second blocks may be approximately 50 to approximately 220. The number of the second blocks may be approximately 60 to approximately 200. The number of the second blocks may be approximately 70 to approximately 200. The number of the second blocks may be approximately 75 to approximately 200.

[0070] The number of the second block may vary depending on the content of the aliphatic dicarboxylic acid, the molecular weight of the biodegradable polyester resin, and the polymerization process described later. Specifically, the number of the first block may increase as the molar ratio of the aliphatic dicarboxylic acid increases and the molecular weight of the biodegradable polyester resin increases.

[0071] When the biodegradable polyester resin includes the first block and the second block within the above range, the biodegradable polyester resin composition according to the example may have appropriate mechanical strength and appropriate biodegradability. Furthermore, when the biodegradable polyester resin includes the first block and the second block within the above range, the biodegradable polyester resin composition according to the example may have improved flexibility and improved rigidity. This allows the biodegradable polyester resin composition according to the example to be easily used in injection molded products and the like. Furthermore, when the biodegradable polyester resin includes the first block and the second block within the above range, the biodegradable polyester resin composition according to the example may have appropriate resistance to ultraviolet light and appropriate biodegradability.

[0072] The first block may be represented by the following formula 1.

[0073] [ka]

[0074] Here, R1 is a substituted or unsubstituted allylene group having 6 to 20 carbon atoms, R2 is a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms, and m may be 1 to 20.

[0075] R1 may be a substituted or unsubstituted phenylene group, and R2 may be a butylene group.

[0076] The second block may be represented by the formula shown in 2 below.

[0077] [ka]

[0078] Here, R3 and R4 are each independently substituted or unsubstituted alkylene groups having 1 to 20 carbon atoms, and n may be 1 to 20.

[0079] R3 and R4 may be butylene groups.

[0080] The biodegradable polyester resin may have a structure in which the first block and the second block are alternately bonded to each other. The biodegradable polyester resin may also be represented by the following chemical formula 3.

[0081] [ka]

[0082] Here, R1 is a substituted or unsubstituted allylene group having 6 to 20 carbon atoms, R2 is a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms, and m may be 1 to 20. Also, R3 and R4 are each independently substituted or unsubstituted alkylene groups having 1 to 20 carbon atoms, and n may be 1 to 20.

[0083] The diol residue may include a residue of 1,4-butanediol or a derivative thereof, the aromatic dicarboxylic acid residue may include a residue of terephthalic acid or a derivative thereof, and the aliphatic dicarboxylic acid residue may include a residue of adipic acid or a derivative thereof.

[0084] For example, the biodegradable polyester resin may include a first block comprising a residue of 1,4-butanediol or a derivative thereof, and a residue of terephthalic acid or a derivative thereof.

[0085] Alternatively, the biodegradable polyester resin may include a first block comprising a residue of 1,4-butanediol or a derivative thereof, and a residue of dimethyl terephthalate or a derivative thereof.

[0086] The biodegradable polyester resin may also include a second block comprising a residue of 1,4-butanediol or a derivative thereof, and a residue of adipic acid or a derivative thereof.

[0087] Alternatively, the biodegradable polyester resin may include a second block comprising a residue of 1,4-butanediol or a derivative thereof, and a residue of succinic acid or a derivative thereof.

[0088] A biodegradable polyester resin according to an embodiment of the present invention may comprise a first block comprising a residue of 1,4-butanediol or a derivative thereof and a residue of terephthalic acid or a derivative thereof, and a second block comprising a residue of 1,4-butanediol or a derivative thereof and a residue of adipic acid or a derivative thereof.

[0089] The first block may be represented by the following formula 4, and the second block may be represented by the following formula 5.

[0090] [ka]

[0091] Here, m may be between 1 and 20.

[0092] [ka]

[0093] Here, n may range from 1 to 20.

[0094] The biodegradable polyester resin may be represented by the following chemical formula 6.

[0095] [ka]

[0096] Here, m is between 1 and 20, and n may also be between 1 and 20.

[0097] When the first and second blocks satisfy the above configuration, it may be even more advantageous in providing a biodegradable polyester sheet, film, or molded article that is excellent in biodegradability and water degradability, and has improved physical properties.

[0098] Furthermore, when the biodegradable polyester resin includes the first block and the second block within the above range, the biodegradable polyester resin composition according to the example may have appropriate mechanical properties and appropriate UV resistance characteristics.

[0099] Because the first and second blocks have the above-described characteristics, the mechanical properties of the biodegradable polyester resin composition according to the examples can be improved.

[0100] Since the first and second blocks have the characteristics described above, the biodegradable polyester resin composition according to the example may have appropriate UV resistance properties.

[0101] Since the first and second blocks have the characteristics described above, the biodegradable polyester resin composition according to the example may have an appropriate biodegradation rate.

[0102] Since the first and second blocks have the characteristics described above, the biodegradable polyester resin composition according to the example may have an appropriate hydrolysis rate.

[0103] The biodegradable polyester resin may further contain a branching agent. The branching agent may contain a trivalent or higher alcohol and / or a trivalent or higher carboxylic acid. The branching agent can react with the diol, the aromatic dicarboxylic acid, and the aliphatic dicarboxylic acid. As a result, the branching agent may be included in the biodegradable polyester resin as part of its molecular structure.

[0104] The aforementioned trivalent or higher alcohol may be selected from at least one of the group consisting of glycerol, pentaerythritol, or trimethylolpropane.

[0105] The aforementioned trivalent or higher carboxylic acids include methane tricarboxylic acid, ethane tricarboxylic acid, citric acid, benzene-1,3,5-tricarboxylic acid, 5-sulfo-1,2,4-benzenetricarboxylic acid, ethane-1,1,2,2-tetracarboxylic acid, propane-1,1,2,3-tetracarboxylic acid, butane-1,2,3,4-tetracarboxylic acid, cyclopentane-1,2,3,4-tetracarboxylic acid, or benzene-1,2,4,5-tetracarboxylic acid At least one of the group consisting of (acid) may be selected.

[0106] The branching agent may be included in the biodegradable polyester resin in an amount of approximately 0.1 wt% to approximately 5 wt% based on the total biodegradable polyester resin. The branching agent may be included in the biodegradable polyester resin in an amount of approximately 0.1 wt% to approximately 3 wt% based on the total biodegradable polyester resin. The branching agent may be included in the biodegradable polyester resin in an amount of approximately 0.1 wt% to approximately 1 wt% based on the total biodegradable polyester resin.

[0107] Since the biodegradable polyester resin contains the branching agent within the above range, the biodegradable polyester resin composition according to the example may have appropriate mechanical properties and appropriate biodegradability.

[0108] The biodegradable polyester resin composition according to the examples may contain the biodegradable resin in an amount of approximately 30 wt% or more based on the weight of the total composition. The biodegradable polyester resin composition according to the examples may contain the biodegradable resin in an amount of approximately 50 wt% or more based on the weight of the total composition. The biodegradable polyester resin composition according to the examples may contain the biodegradable resin in an amount of approximately 70 wt% or more based on the weight of the total composition. The biodegradable polyester resin composition according to the examples may contain the biodegradable resin in an amount of approximately 80 wt% or more based on the weight of the total composition. The biodegradable polyester resin composition according to the examples may contain the biodegradable resin in an amount of approximately 90 wt% or more based on the weight of the total composition. The biodegradable polyester resin composition according to the examples may contain the biodegradable resin in an amount of approximately 95 wt% or more based on the weight of the total composition. The biodegradable polyester resin composition according to the examples may contain the biodegradable resin in an amount of approximately 99 wt% or more based on the weight of the total composition. The maximum content of the biodegradable resin in the biodegradable polyester resin composition according to the examples may be approximately 100 wt% based on the weight of the total composition.

[0109] The biodegradable polyester resin composition according to the examples may further contain a reinforcing material. The reinforcing material can improve the mechanical properties of the biodegradable polyester resin composition according to the examples and the film or molded article produced therefrom. The reinforcing material can also adjust the ultraviolet deformation characteristics of the biodegradable polyester resin composition according to the examples. The reinforcing material can also adjust the hydrolysis characteristics of the biodegradable polyester resin composition according to the examples. The reinforcing material can also adjust the biodegradability of the biodegradable polyester resin according to the examples.

[0110] The reinforcing material may be derived from biomass. The reinforcing material may be a fiber made of organic material. The reinforcing material may be nanocellulose.

[0111] The nanocellulose may be one or more selected from the group consisting of nanocrystalline cellulose, cellulose nanofiber, microfibrillated cellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, cellulose acetate, methylcellulose, ethylcellulose, propylcellulose, butylcellulose, pentylcellulose, hexylcellulose, or cyclohexylcellulose.

[0112] The nanocellulose may contain ionically bonded metals. The nanocrystalline cellulose may contain the element sodium. The nanocrystalline cellulose may also contain sulfate. The nanocrystalline cellulose may also contain carboxylates. The nanocrystalline cellulose may be cellulose hydrogen sulphate sodium salt.

[0113] The nanocellulose may be represented by the following chemical formula 7.

[0114] [ka]

[0115] Here, x may be between 1 and 35, and y may be between 1 and 10. Alternatively, x may be between 15 and 35, and y may be between 1 and 10.

[0116] The aforementioned nanocellulose is approximately 200 m 2 / g~about 600m 2 It may also have a specific surface area of ​​250 m / g. The nanocellulose is approximately 250 m 2 / g~about 500m 2 It may also have a specific surface area of ​​ / g.

[0117] The weight-average molecular weight of the nanocellulose may be approximately 10,000 g / mol to approximately 40,000 g / mol. The weight-average molecular weight of the nanocrystalline cellulose may be approximately 11,000 g / mol to approximately 35,000 g / mol.

[0118] The moisture content of the nanocrystalline cellulose may be approximately 2 wt% to approximately 8 wt%. The moisture content of the nanocrystalline cellulose may be approximately 4 wt% to approximately 6 wt%.

[0119] The average diameter of the nanocellulose may be about 0.5 nm to about 10 nm. The average diameter of the nanocellulose may be about 1 nm to about 8 nm. The average diameter of the nanocellulose may be about 1.5 nm to about 7 nm.

[0120] The average length of the nanocellulose may be approximately 20 nm to approximately 300 nm. The average length of the nanocellulose may be approximately 30 nm to approximately 180 nm. The average length of the nanocellulose may be approximately 35 nm to approximately 150 nm.

[0121] By ensuring that the diameter and length of the nanocellulose satisfy the above range, the biodegradability and physical properties of the biodegradable polyester resin, or the biodegradable polyester sheets, films, and molded articles obtained using it, can be further improved.

[0122] The diameter and length of the nanocellulose can be measured by atomic force microscopy while it is dispersed in water.

[0123] The sulfur content of the nanocellulose may be about 0.1 wt% to about 1.2 wt% based on the total nanocrystalline cellulose. The sulfur content of the nanocrystalline cellulose may be about 0.75 wt% to about 1.1 wt% based on the total nanocrystalline cellulose.

[0124] The pH of the nanocellulose may be 5 to 7. The pH of the nanocellulose may be 6 to 7.

[0125] The zeta potential of the nanocellulose may be approximately -25mV to approximately -50mV. The zeta potential of the nanocellulose may also be approximately -30mV to approximately -45mV.

[0126] The nanocellulose may be included in the biodegradable polyester resin composition according to the examples in an amount of about 0.01 parts by weight to about 2 parts by weight based on 100 parts by weight of the biodegradable polyester resin. The nanocellulose may be included in the biodegradable polyester resin composition according to the examples in an amount of about 0.03 parts by weight to about 1.5 parts by weight based on 100 parts by weight of the biodegradable polyester resin. The nanocellulose may be included in the biodegradable polyester resin composition according to the examples in an amount of about 0.04 parts by weight to about 1.2 parts by weight based on 100 parts by weight of the biodegradable polyester resin. The nanocellulose may be included in the biodegradable polyester resin composition according to the examples in an amount of about 0.05 parts by weight to about 1 part by weight based on 100 parts by weight of the biodegradable polyester resin.

[0127] Because the nanocellulose has the characteristics described above, it may be uniformly dispersed in the biodegradable polyester resin composition according to the examples.

[0128] Because the nanocellulose has the characteristics described above, it can improve the mechanical properties of the biodegradable polyester resin composition according to the examples.

[0129] Furthermore, the nanocellulose functions as a crystal nucleating agent, improving the crystallization rate of the biodegradable polyester resin composition according to the examples. This allows the nanocellulose to increase the crystallization temperature of the biodegradable polyester resin composition according to the examples.

[0130] Since the nanocellulose has the characteristics described above, the biodegradable polyester resin composition according to the examples may have appropriate UV resistance properties.

[0131] Since the nanocellulose has the characteristics described above, the biodegradable polyester resin composition according to the examples may have an appropriate biodegradation rate.

[0132] Since the nanocellulose has the characteristics described above, the biodegradable polyester resin composition according to the examples may have an appropriate hydrolysis rate.

[0133] The biodegradable polyester resin compositions according to the examples may also contain metal salts.

[0134] The metal salt may be present in a content of approximately 0.1 ppm to approximately 1000 ppm based on the total weight of the biodegradable polyester resin composition according to the examples. The metal salt may be present in a content of approximately 1 ppm to approximately 500 ppm based on the total weight of the biodegradable polyester resin composition according to the examples. The metal salt may be present in a content of approximately 1 ppm to approximately 100 ppm based on the total weight of the biodegradable polyester resin composition according to the examples. The metal salt may be present in a content of approximately 1 ppm to approximately 50 ppm based on the total weight of the biodegradable polyester resin composition according to the examples.

[0135] The metal salt may be selected from the group consisting of nitrates, sulfates, hydrochlorides, or carboxylates. The metal salt may be selected from the group consisting of titanium salts, silicon salts, sodium salts, calcium salts, potassium salts, magnesium salts, copper salts, iron salts, aluminum salts, or silver salts. The metal salt may be selected from the group consisting of magnesium acetate, calcium acetate, potassium acetate, copper nitrate, silver nitrate, or sodium nitrate.

[0136] The aforementioned metal salt may contain one or more elements selected from the group consisting of iron (Fe), magnesium (Mg), nickel (Ni), cobalt (Co), copper (Cu), palladium (Pd), zinc (Zn), vanadium (V), titanium (Ti), indium (In), manganese (Mn), silicon (Si), and tin (Sn).

[0137] Furthermore, the metal salt may be selected from the group consisting of acetate, nitrate, nitride, sulfide, sulfate, sulfoxide, hydrooxide, hydrate, chloride, chlorinate, and bromide.

[0138] Since the biodegradable polyester resin composition according to the examples contains the metal salt in the above-mentioned amounts, the hydrolysis rate and biodegradation rate can be appropriately adjusted.

[0139] The biodegradable polyester resin composition according to the examples may further contain a hydrolysis-resistant agent.

[0140] The hydrolysis-resistant agent may be selected from at least one silicon-based compound such as silane, silazane, or siloxane.

[0141] The hydrolysis-resistant agent may contain an alkoxysilane. The hydrolysis-resistant agent may contain trimethoxysilane and / or triethoxysilane. The hydrolysis-resistant agent may contain an alkoxysilane containing an epoxy group. The hydrolysis-resistant agent may contain at least one from the group consisting of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-Glycidoxypropyl methyldimethoxysilane, 3-Glycidoxypropyl trimethoxysilane, 3-Glycidoxypropyl methyldiethoxysilane, or 3-Glycidoxypropyl triethoxysilane.

[0142] The hydrolysis-resistant agent may be included in the biodegradable polyester resin composition according to the examples in a content of about 1 ppm to about 10,000 ppm. The hydrolysis-resistant agent may be included in the biodegradable polyester resin composition according to the examples in a content of about 1 ppm to about 1,000 ppm. The hydrolysis-resistant agent may be included in the biodegradable polyester resin composition according to the examples in a content of about 5 ppm to 500 ppm. The hydrolysis-resistant agent may be included in the biodegradable polyester resin composition according to the examples in a content of about 10 ppm to 300 ppm.

[0143] The hydrolysis-resistant agent may bond to the biodegradable polyester resin. The hydrolysis-resistant agent may chemically bond to the biodegradable polyester resin. The hydrolysis-resistant agent may chemically bond to the polymer contained in the biodegradable polyester resin. The hydrolysis-resistant agent can couple the polymers contained in the biodegradable polyester resin with each other.

[0144] The biodegradable polyester resin compositions according to the examples contain the hydrolysis-resistant agent within the range described above, and therefore may have appropriate hydrolysis resistance properties. In particular, the biodegradable polyester resins according to the examples contain the hydrolysis-resistant agent within the range described above, and therefore may have appropriate initial hydrolysis properties and improved biodegradability.

[0145] Therefore, the biodegradable polyester resin composition according to the examples may contain silicon. The biodegradable polyester resin composition according to the examples may contain silicon in a content of about 0.1 ppm to about 100 ppm. The biodegradable polyester resin composition according to the examples may contain silicon in a content of about 0.1 ppm to about 50 ppm. The biodegradable polyester resin composition according to the examples may contain silicon in a content of about 0.1 ppm to about 20 ppm.

[0146] Furthermore, the hydrolysis-resistant agent can also react with terminal carboxyl groups or unreacted carboxyl groups. As a result, the biodegradable polyester resin composition according to the examples may have a low acid value.

[0147] Furthermore, the hydrolysis-resistant agent can couple the polymers contained in the biodegradable polyester resin, thereby increasing the proportion of high molecular weight polymers in the biodegradable polyester resin composition according to the examples. This can improve the mechanical properties of the biodegradable polyester resin composition according to the examples.

[0148] The biodegradable polyester resin composition according to the examples may further contain a chain extender.

[0149] The chain extender may contain an isocyanate.

[0150] The chain extender may be selected from the group consisting of monofunctional isocyanates or polyfunctional isocyanates, with at least one selected from this group.

[0151] The chain extender may be selected from at least one of the group consisting of toylene 2,4-diisocyanate, toylene 2,6-diisocyanate, diphenylmethane 4,4'-diisocyanate, and 2,4'-diisocyanate, naphthalene 1,5-diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, isophorone diisocyanate, and methylenebis(4-isocyanatokilohexane).

[0152] The chain extender may contain triisocyanate. The chain extender may also contain tri(4-isocyanatophenyl)methane.

[0153] The chain extender may contain an acrylic polymer. The acrylic polymer may contain acrylic groups. The acrylic groups may be bonded to the main chain as side chains. The acrylic polymer may contain epoxy groups. The epoxy groups may be bonded to the main chain as side chains.

[0154] The chain extender may include a styrene copolymer. The chain extender may also include a styrene glycidyl acrylate.

[0155] The chain extender may be chemically bonded to the biodegradable polyester resin. The chain extender may be chemically bonded to the polymer contained in the biodegradable polyester resin. The chain extender may be bonded to the ends of the polymer contained in the biodegradable polyester resin. Alternatively, the chain extender may be bonded to the ends of three polymers contained in the biodegradable polyester resin.

[0156] The chain extender may be an end-capping agent that caps the ends of the polymer.

[0157] The chain extender may be included in the biodegradable polyester resin composition according to the examples in a content of about 0.1 wt% to about 10 wt%. The chain extender may be included in the biodegradable polyester resin composition according to the examples in a content of about 0.2 wt% to about 8 wt%. The chain extender may be included in the biodegradable polyester resin composition according to the examples in a content of about 0.3 wt% to about 7 wt%.

[0158] The biodegradable polyester resin compositions according to the examples may have appropriate hydrolysis resistance and appropriate biodegradability when they contain the chain extender within the range described above.

[0159] Furthermore, the chain extender can react with terminal carboxyl groups or unreacted carboxyl groups. As a result, the biodegradable polyester resin composition according to the examples may have a low acid value.

[0160] Furthermore, the chain extender couples the polymer contained in the biodegradable polyester resin, thereby increasing the proportion of high molecular weight polymers in the biodegradable polyester resin composition according to the examples. This can improve the mechanical properties of the biodegradable polyester resin composition according to the examples.

[0161] The biodegradable polyester resin composition according to the examples may contain an oligomer. The molecular weight of the oligomer may be about 400 to about 1300.

[0162] The oligomer may be present in the biodegradable polyester resin composition according to the examples in an amount of approximately 3,000 ppm to approximately 30,000 ppm based on the overall resin composition. The oligomer may be present in the biodegradable polyester resin composition according to the examples in an amount of approximately 5,000 ppm to approximately 20,000 ppm based on the overall resin composition. The oligomer may be present in the biodegradable polyester resin composition according to the examples in an amount of approximately 5,000 ppm to approximately 15,000 ppm based on the overall resin composition. The oligomer may be present in the biodegradable polyester resin composition according to the examples in an amount of approximately 7,000 ppm to approximately 15,000 ppm based on the overall resin composition.

[0163] The oligomer may be a reaction product of at least two of the diol, the aromatic dicarboxylic acid, and the aliphatic dicarboxylic acid. The oligomer may also be a reaction product of 1,4-butanediol, terephthalic acid, and adipic acid.

[0164] The oligomer may include oligomers in which the molar ratio of the aliphatic dicarboxylic acid is even higher than the molar ratio of the aromatic dicarboxylic acid. Of the oligomers, the proportion of oligomers containing a relatively higher amount of the aliphatic dicarboxylic acid may be even higher than the proportion of oligomers containing a relatively higher amount of the aromatic dicarboxylic acid.

[0165] The oligomer may include a first oligomer, a second oligomer, a third oligomer, and a fourth oligomer.

[0166] The first oligomer may have a molecular weight between 415 and 425. The first oligomer may have a molecular weight between 419 and 424.

[0167] The first oligomer may be a reaction product formed by the reaction of two molecules of 1,4-butanediol, one molecule of terephthalic acid, and one molecule of adipic acid. That is, the first oligomer may contain the 1,4-butanediol, terephthalic acid, and adipic acid in a molar ratio of 2:1:1. The first oligomer may also have four ester bonds. The first oligomer may also have a ring structure.

[0168] Furthermore, the first oligomer may contain one first unit represented by the following chemical formula 8 and one second unit represented by the following chemical formula 9.

[0169] [ka]

[0170] [ka]

[0171] The first oligomer may have a ring structure. The first oligomer may include the first unit and the second unit and have a ring structure.

[0172] The first oligomer may be represented by the following chemical formula 10.

[0173] [ka]

[0174] The content of the first oligomer may be about 1000 ppm to about 6000 ppm based on the total biodegradable polyester resin composition according to the examples. The content of the first oligomer may be about 1500 ppm to about 5000 ppm based on the total biodegradable polyester resin composition according to the examples. The content of the first oligomer may be about 2000 ppm to about 4500 ppm based on the total biodegradable polyester resin composition according to the examples. The content of the first oligomer may be about 2500 ppm to about 5000 ppm based on the total biodegradable polyester resin composition according to the examples.

[0175] The second oligomer may have a molecular weight between 620 and 630. The second oligomer may have a molecular weight between 621 and 626.

[0176] The second oligomer may be a reaction product formed by the reaction of three molecules of 1,4-butanediol, one molecule of terephthalic acid, and two molecules of adipic acid. That is, the second oligomer may contain 1,4-butanediol, terephthalic acid, and adipic acid in a molar ratio of 3:1:2. Furthermore, the second oligomer may have six ester bonds.

[0177] The second oligomer may contain one first unit represented by formula 6 and two second units represented by formula 7.

[0178] The second oligomer may be selected from at least one of the groups consisting of the following chemical formulas 11, 12, or 13.

[0179] [ka]

[0180] [ka]

[0181] [ka]

[0182] The content of the second oligomer may be about 1000 ppm to about 5000 ppm based on the total biodegradable polyester resin composition according to the examples. The content of the second oligomer may be about 1200 ppm to about 4500 ppm based on the total biodegradable polyester resin composition according to the examples. The content of the second oligomer may be about 1500 ppm to about 4000 ppm based on the total biodegradable polyester resin composition according to the examples. The content of the second oligomer may be about 2000 ppm to about 3800 ppm based on the total biodegradable polyester resin composition according to the examples.

[0183] The third oligomer may have a molecular weight between 640 and 650. The third oligomer may have a molecular weight between 641 and 645.

[0184] The third oligomer may be a reaction product formed by the reaction of three molecules of 1,4-butanediol, two molecules of terephthalic acid, and one molecule of adipic acid. That is, the third oligomer may contain 1,4-butanediol, terephthalic acid, and adipic acid in a molar ratio of 3:2:1. Furthermore, the third oligomer may have six ester bonds.

[0185] The third oligomer may contain two first units represented by formula 6 and one second unit represented by formula 7.

[0186] The third oligomer may be selected from at least one of the groups consisting of the following chemical formulas 14, 15, or 16.

[0187] [ka]

[0188] [ka]

[0189] [ka]

[0190] The content of the third oligomer may be about 300 ppm to about 3000 ppm based on the total biodegradable polyester resin composition according to the examples. The content of the third oligomer may be about 500 ppm to about 2500 ppm based on the total biodegradable polyester resin composition according to the examples. The content of the third oligomer may be about 700 ppm to about 2000 ppm based on the total biodegradable polyester resin composition according to the examples. The content of the third oligomer may be about 800 ppm to about 1800 ppm based on the total biodegradable polyester resin composition according to the examples.

[0191] The fourth oligomer may have a molecular weight between 840 and 850. The fourth oligomer may have a molecular weight between 841 and 845.

[0192] The fourth oligomer may contain a reaction product formed by the reaction of four molecules of 1,4-butanediol, two molecules of terephthalic acid, and two molecules of adipic acid. That is, the fourth oligomer may contain the 1,4-butanediol, terephthalic acid, and adipic acid in a molar ratio of 4:2:2. Furthermore, the fourth oligomer may have eight ester bonds.

[0193] The fourth oligomer may contain two first units represented by formula 6 and two second units represented by formula 7.

[0194] Furthermore, the fourth oligomer may contain at least one of the following binding structures.

[0195] 1) Unit 1 - Unit 1 - Unit 2 - Unit 2 2) Unit 1 - Unit 2 - Unit 1 - Unit 2 3) Unit 1 - Unit 2 - Unit 2 - Unit 1 4) Unit 2 - Unit 1 - Unit 1 - Unit 2

[0196] The content of the fourth oligomer may be about 300 ppm to about 3500 ppm based on the total biodegradable polyester resin composition according to the examples. The content of the fourth oligomer may be about 500 ppm to about 3000 ppm based on the total biodegradable polyester resin composition according to the examples. The content of the fourth oligomer may be about 700 ppm to about 2500 ppm based on the total biodegradable polyester resin composition according to the examples. The content of the fourth oligomer may be about 800 ppm to about 2000 ppm based on the total biodegradable polyester resin composition according to the examples.

[0197] Based on the total oligomer, the proportion of the first oligomer (content of the first oligomer / total content of oligomers) may be approximately 0.20 to approximately 0.5. Based on the total oligomer, the proportion of the first oligomer may be approximately 0.25 to approximately 0.45. Based on the total oligomer, the proportion of the first oligomer may be approximately 0.30 to approximately 0.45. Based on the total oligomer, the proportion of the first oligomer may be approximately 0.32 to approximately 0.43.

[0198] Based on the total oligomer, the proportion of the second oligomer (content of the second oligomer / total content of the oligomer) may be approximately 0.15 to approximately 0.45. Based on the total oligomer, the proportion of the second oligomer may be approximately 0.20 to 0.40. Based on the total oligomer, the proportion of the second oligomer may be approximately 0.23 to 0.37. Based on the total oligomer, the proportion of the second oligomer may be approximately 0.25 to 0.36.

[0199] Based on the total oligomer, the proportion of the third oligomer (content of the third oligomer / total content of oligomers) may be approximately 0.05 to approximately 0.25. Based on the total oligomer, the proportion of the third oligomer may be approximately 0.07 to 0.20. Based on the total oligomer, the proportion of the third oligomer may be approximately 0.08 to 0.17. Based on the total oligomer, the proportion of the third oligomer may be approximately 0.09 to 0.16.

[0200] Based on the total oligomer, the proportion of the fourth oligomer (content of the fourth oligomer / total content of oligomers) may be approximately 0.05 to approximately 0.30. Based on the total oligomer, the proportion of the fourth oligomer may be approximately 0.07 to 0.25. Based on the total oligomer, the proportion of the fourth oligomer may be approximately 0.08 to 0.22. Based on the total oligomer, the proportion of the fourth oligomer may be approximately 0.09 to 0.19.

[0201] Based on the first oligomer, the ratio of the second oligomer (content of the second oligomer / content of the first oligomer) may be approximately 0.5 to approximately 1.2. Based on the first oligomer, the ratio of the second oligomer may be approximately 0.55 to approximately 1.0. Based on the first oligomer, the ratio of the second oligomer may be approximately 0.6 to approximately 0.95. Based on the first oligomer, the ratio of the second oligomer may be approximately 0.7 to approximately 0.9.

[0202] Based on the first oligomer, the ratio of the third oligomer (content of the third oligomer / content of the first oligomer) may be approximately 0.2 to approximately 0.6. Based on the first oligomer, the ratio of the third oligomer may be approximately 0.22 to approximately 0.50. Based on the first oligomer, the ratio of the third oligomer may be approximately 0.23 to approximately 0.45. Based on the first oligomer, the ratio of the third oligomer may be approximately 0.25 to approximately 0.42.

[0203] Based on the first oligomer, the proportion of the fourth oligomer (content of the fourth oligomer / content of the first oligomer) may be approximately 0.25 to approximately 0.65. Based on the first oligomer, the proportion of the fourth oligomer may be approximately 0.27 to approximately 0.55. Based on the first oligomer, the proportion of the fourth oligomer may be approximately 0.30 to approximately 0.50. Based on the first oligomer, the proportion of the fourth oligomer may be approximately 0.30 to approximately 0.48.

[0204] The second oligomer may be present in the oligomer in an even higher concentration than the third oligomer.

[0205] Based on the second oligomer, the ratio of the third oligomer (content of the third oligomer / content of the second oligomer) may be approximately 0.2 to approximately 0.6. Based on the second oligomer, the ratio of the third oligomer (content of the third oligomer / content of the second oligomer) may be approximately 0.24 to approximately 0.5. Based on the second oligomer, the ratio of the third oligomer (content of the third oligomer / content of the second oligomer) may be approximately 0.27 to approximately 0.45.

[0206] The molecular weight and content of the oligomer can be measured by liquid chromatography-mass spectrometry.

[0207] First, the biodegradable polyester resin composition or biodegradable polyester film according to the examples is crushed and classified to produce a powder having an average particle size (D50) of approximately 50 μm. The powder is then immersed in an organic solvent such as acetonitrile at room temperature for approximately 24 hours. After sampling the upper solution of the organic solvent, the molecular weight and content of the oligomer can be measured by liquid chromatography-mass spectrometry. Furthermore, a black curve is obtained by using dibutyl phthalate as a standard substance to measure the oligomer content.

[0208] The oligomer may also be a hydrophilicity regulator capable of adjusting the hydrophilicity and / or hydrophobicity of the biodegradable polyester resin composition according to the examples. This allows the oligomer to appropriately adjust the degree of hydrolysis of the biodegradable resin composition according to the examples. The oligomer may also be a hydrolysis regulator that appropriately adjusts the degree of hydrolysis of the biodegradable resin composition according to the examples.

[0209] Furthermore, the oligomer can appropriately adjust the degree of biodegradation of the biodegradable resin composition according to the examples. The oligomer may also be a biodegradation regulator that appropriately adjusts the degree of biodegradation of the biodegradable resin composition according to the examples.

[0210] The biodegradable resin compositions according to the examples contain the oligomers within the above range and may therefore have an appropriate degree of hydrolysis and an appropriate degree of biodegradation. In particular, the biodegradable resin compositions according to the examples contain the first oligomer, the second oligomer, the third oligomer, and the fourth oligomer within the above range and may therefore have an appropriate degree of hydrolysis and an appropriate degree of biodegradation.

[0211] As described above, the oligomer can adjust the degree of biodegradation of the biodegradable polyester resin composition according to the examples. As a result, the biodegradable polyester resin composition according to the examples may have an appropriate degree of hydrolysis and an appropriate degree of biodegradation.

[0212] The biodegradable polyester resin compositions according to the examples contain oligomers having the above-described characteristics, and therefore may have a low initial degree of hydrolysis, a high late-stage degree of hydrolysis, and a high late-stage biodegradation.

[0213] As a result, the biodegradable polyester resin composition according to the examples can be efficiently applied to packaging films and the like. In other words, films made from the biodegradable polyester resin composition according to the examples can be used for ordinary purposes such as packaging. At this time, since the biodegradable polyester resin composition according to the examples has a low degree of hydrolysis initially, the biodegradable polyester film can maintain a certain level of mechanical and chemical properties within the user's normal usage period.

[0214] Furthermore, the biodegradable polyester resin compositions according to the examples may have a high degree of late hydrolysis because they contain oligomers having the characteristics described above. As a result, films produced using the biodegradable polyester resin compositions according to the examples may decompose easily when discarded after use.

[0215] Furthermore, since the biodegradable polyester resin composition according to the examples contains oligomers having the above-mentioned characteristics, decomposition by ambient moisture and decomposition by microorganisms can complement each other. As a result, the biodegradable polyester resin composition according to the examples may have a low initial degree of hydrolysis and a high degree of biodegradation.

[0216] Furthermore, since the biodegradable polyester resin composition according to the examples contains oligomers having the above-mentioned characteristics, it may have a biodegradability of about 1.5 or more per aliphatic carboxylic acid. That is, the biodegradable polyester resin composition according to the examples has a low aliphatic carboxylic acid content and a high biodegradability. As a result, the biodegradable polyester resin composition according to the examples has a relatively high aromatic carboxylic acid content, and may have high hydrolysis resistance in the initial stages and a high biodegradability in the later stages.

[0217] The biodegradable polyester resin compositions according to the examples can maintain a certain level of mechanical and chemical properties within the user's service life. Furthermore, because the biodegradable polyester resin compositions according to the examples have a high degree of late-stage hydrolysis, they may decompose easily in rivers or the sea. In other words, the biodegradable polyester resin compositions according to the examples can solve environmental problems such as marine plastic pollution.

[0218] The biodegradable polyester resin composition according to the examples may contain a heat stabilizer. The heat stabilizer may be a phosphorus-based heat stabilizer.

[0219] The heat stabilizer may be at least one selected from the group consisting of amine-based high-temperature heat stabilizers such as tetraethylenepentaamine, triethylphosphonoacetate, phosphoric acid, phosphorous acid, polyphosphoric acid, trimethyl phosphate (TMP), triethyl phosphate, trimethyl phosphine, or triphenyl phosphine.

[0220] Furthermore, the heat stabilizer may be an antioxidant having an antioxidant function.

[0221] The content of the heat stabilizer may be approximately 3,000 ppm or less based on the total weight of the biodegradable polyester resin. The content of the heat stabilizer may be, for example, 10 ppm to 3,000 ppm, 20 ppm to 2,000 ppm, 20 ppm to 1,500 ppm, or 20 ppm to 200 ppm based on the total weight of the biodegradable polyester resin. By satisfying the above range for the content of the heat stabilizer, it is possible to control the degradation of the polymer due to high temperatures during the reaction process, reduce the end groups of the polymer, and improve the color. In addition, the heat stabilizer can suppress the activation of titanium-based catalysts and adjust the reaction rate.

[0222] The biodegradable polyester resin compositions according to the examples may contain an elongation improver. Examples of the elongation improver include oils such as paraffin oil, naphthenic oil, or aromatic oil, or adipates such as dibutyl adipate, diethylhexyl adipate, dioctyl adipate, or diisopropyl adipate.

[0223] The elongation improver may be included in the biodegradable polyester resin composition according to the examples in an amount of about 0.001 parts by weight to about 1 part by weight, based on 100 parts by weight of the biodegradable polyester resin. The elongation improver may be included in the biodegradable polyester resin composition according to the examples in an amount of about 0.01 parts by weight to about 1 part by weight, based on 100 parts by weight of the biodegradable polyester resin.

[0224] Since the elongation improver is included within the range described above, the biodegradable polyester resin composition according to the examples may have improved mechanical properties.

[0225] The biodegradable polyester resin composition according to the embodiment may contain an inorganic filler. The inorganic filler may be at least one selected from the group consisting of calcium sulfate, barium sulfate, talc, talcum powder, bentonite, kaolin, chalk powder, calcium carbonate, graphite, gypsum, electrically conductive carbon black, calcium chloride, iron oxide, aluminum oxide, potassium oxide, dolomite, silicon dioxide, wollastonite, titanium dioxide, silicate, mica, glass fiber, or mineral fiber.

[0226] Regarding the inorganic filler, based on the volume in the particle size distribution obtained by the laser diffraction method, the cumulative 50% particle size (D 50 ) may be about 100 μm or less, about 85 μm or less, about 70 μm or less, about 50 μm or less, about 25 μm or less, about 10 μm or less, about 5 μm or less, about 3 μm or less, or about 1 μm or less.

[0227] Also, the specific surface area of the inorganic filler may be about 100 m 2 / g or more. For example, the specific surface area of the inorganic filler may be about 100 m 2 / g or more, about 105 m 2 / g or more, or about 110 m 2 / g or more.

[0228] The inorganic filler may be contained in the biodegradable polyester resin composition according to the embodiment at a content of about 3 parts by weight to about 50 parts by weight based on 100 parts by weight of the biodegradable polyester resin. The inorganic filler may be contained in the biodegradable polyester resin composition according to the embodiment at a content of about 5 parts by weight to about 30 parts by weight based on 100 parts by weight of the biodegradable polyester resin.

[0229] The inorganic filler may be included in a content of approximately 3,000 ppm or less based on the total weight of the biodegradable polyester resin composition according to the examples. For example, the content of the inorganic filler may be approximately 3,000 ppm or less, approximately 1,500 ppm or less, approximately 1,200 ppm or less, approximately 800 ppm or less, or approximately 600 ppm or less based on the total weight of the biodegradable polyester resin composition according to the examples, or approximately 50 ppm or more, approximately 100 ppm or more, approximately 130 ppm or more, approximately 150 ppm or more, or approximately 180 ppm or more.

[0230] Since the biodegradable polyester resin composition according to the examples contains the inorganic filler in the above-mentioned amounts, it may have the mechanical properties, appropriate UV resistance, appropriate biodegradation rate, and appropriate hydrolysis rate of the biodegradable polyester resin composition according to the examples.

[0231] The biodegradable polyester resin composition according to the examples may further contain two types of biodegradable resins. The biodegradable polyester resin composition according to the examples may also be a composite resin composition containing two or more types of resins, fillers, and additives.

[0232] The two biodegradable resins mentioned above may be selected from at least one of the groups consisting of polybutylene azelate terephthalate (PBAzT), polybutylene sebacate terephthalate (PBSeT), polybutylene succinate terephthalate (PBST), polyhydroxyalkanoate (PHA), or polylactic acid (PLA).

[0233] The two types of biodegradable resins may be included in the biodegradable polyester resin composition according to the examples in an amount of about 10 to about 100 parts by weight, based on 100 parts by weight of the biodegradable polyester resin. The two types of biodegradable resins may be included in the biodegradable polyester resin composition according to the examples in an amount of about 10 to about 60 parts by weight, based on 100 parts by weight of the biodegradable polyester resin. The two types of biodegradable resins may be included in the biodegradable polyester resin composition according to the examples in an amount of about 20 to about 50 parts by weight, based on 100 parts by weight of the biodegradable polyester resin.

[0234] The two biodegradable resins can complement the mechanical, optical, and chemical properties of the biodegradable polyester resin. The biodegradable polyester resin composition according to the examples contains the two biodegradable resins in the above-mentioned amounts and may therefore have the mechanical properties, appropriate UV resistance, appropriate biodegradation rate, and appropriate hydrolysis rate of the biodegradable polyester resin composition according to the examples.

[0235] Furthermore, the number of carboxyl end groups in the biodegradable polyester resin composition according to the examples may be about 50 eq / ton or less. For example, the number of carboxyl end groups in the biodegradable polyester resin according to the examples may be about 50 eq / ton or less, about 48 eq / ton or less, about 45 eq / ton or less, or about 42 eq / ton or less. By adjusting the number of carboxyl end groups within the above range, when the biodegradable polyester resin composition according to the examples is extruded to form a molded product, degradation can be prevented and improved mechanical properties can be achieved.

[0236] Furthermore, the intrinsic viscosity (IV) of the biodegradable polyester resin composition according to the examples may be about 0.9 dl / g or higher. The intrinsic viscosity of other biodegradable polyester resin compositions according to the examples may be about 0.95 dl / g or higher, about 1.0 dl / g or higher, about 1.1 dl / g or higher, about 1.2 dl / g or higher, or about 1.3 dl / g or higher. The intrinsic viscosity of the biodegradable polyester resin composition according to the examples may be about 0.95 dl / g to about 1.7 dl / g. The intrinsic viscosity of the biodegradable polyester resin composition according to the examples may be about 1.3 dl / g to about 1.7 dl / g. The intrinsic viscosity of the biodegradable polyester resin composition according to the examples may be about 1.4 dl / g to about 1.7 dl / g.

[0237] The process for producing the biodegradable polyester resin composition according to the examples is as follows:

[0238] Referring to Figure 1, the biodegradable polyester resin manufacturing apparatus includes a slurry stirrer 100, an esterification reaction section 200, a condensation polymerization reaction section 300, a post-processing section 400, a first recovery section 510, and a second recovery section 520.

[0239] The method for producing the biodegradable polyester resin includes the step of producing a slurry containing the diol and the aromatic dicarboxylic acid.

[0240] The step of producing the slurry includes a step of mixing and treating the diol and the aromatic dicarboxylic acid. That is, the step of producing the slurry may be a pretreatment step before the esterification reaction, and may be a step of mixing the diol and the aromatic dicarboxylic acid to form a slurry.

[0241] The temperature of the slurry of the diol and the aromatic dicarboxylic acid may be about 5°C to 15°C higher than the melting point of the diol. For example, if the diol is 1,4-butanediol, the temperature of the slurry may be about 35°C to 45°C.

[0242] The diol and the aromatic dicarboxylic acid can be added to the slurry stirrer 100 and stirred to produce the slurry.

[0243] By pre-treating the mixture of the diol and the aromatic dicarboxylic acid to form a slurry, the diol and aromatic dicarboxylic acid can be reacted uniformly, and the esterification reaction can be accelerated, thereby increasing the reaction efficiency.

[0244] In particular, when aromatic dicarboxylic acids, such as terephthalic acid, are perfectly crystalline and in powder form, their solubility in the diol can be very low, making homogeneous reactions difficult. Therefore, the slurry pretreatment process can play a very important role in increasing reaction efficiency and providing biodegradable polyester resins, sheets, films, and molded articles with excellent physical properties as embodied in the present invention.

[0245] When the aromatic dicarboxylic acid is terephthalic acid, the terephthalic acid is perfectly crystalline, has no melting point, is a white crystal that sublimes at around 300°C at atmospheric pressure, and has very low solubility in the diol, making homogeneous reactions difficult. Therefore, if a pretreatment step is performed before the esterification reaction, the reaction with the diol occurs within the solid matrix of terephthalic acid, increasing the surface area and inducing a homogeneous reaction.

[0246] Furthermore, if the aromatic dicarboxylic acid is dimethyl terephthalate, the pretreatment process can create a molten state of the dimethyl terephthalate at approximately 142°C to 170°C, allowing it to react with the diol, thus enabling a faster and more efficient esterification reaction.

[0247] On the other hand, in the pretreatment step for producing the slurry, the structure and physical properties of the biodegradable polyester resin may differ depending on the particle size, particle size distribution, and pretreatment reaction conditions of the aromatic dicarboxylic acid.

[0248] For example, the aromatic dicarboxylic acid includes terephthalic acid, wherein the terephthalic acid has an average particle size (D50) of 10 μm to 400 μm as measured by a Microtrac S3500 particle size analyzer in the particle size distribution (PSD), and the standard deviation of the average particle size (D50) is 100 or less. The standard deviation means the square root of the variance. The average particle size (D50) of the terephthalic acid may be 20 μm to 200 μm, for example, 30 μm to 200 μm, or for example, 100 μm to 160 μm. When the average particle size (D50) of the terephthalic acid satisfies the above range, it may be even more advantageous in terms of improved solubility in the diol and reaction rate.

[0249] In the aforementioned pretreatment step, the diol and the aromatic dicarboxylic acid can be mixed and put into the slurry agitator 100 (tank).

[0250] The slurry agitator 100 may be more advantageous in achieving efficient agitation if, for example, its lowest part is of the anchor type, the height to the agitator is 20 mm or more, and it is equipped with two or more rotating blades.

[0251] For example, the slurry agitator 100 may have a height of 20 mm or more from the agitator, meaning that there is almost no contact between the reactor and the bottom of the agitator. In this case, slurry can be obtained without sedimentation. If the pattern, shape, and blades of the agitator do not satisfy the above conditions, when the diol and aromatic dicarboxylic acid are initially mixed, the aromatic dicarboxylic acid may settle at the bottom, and in this case, phase separation may occur.

[0252] The pretreatment step for producing the slurry may include a step of mixing the diol and the aromatic dicarboxylic acid and stirring them at a temperature of about 30°C to about 100°C at a speed of about 50 rpm to about 200 rpm for 10 minutes or more, for example, 10 minutes to 200 minutes.

[0253] The aforementioned diol may have the same characteristics as described above.

[0254] The diol can be added all at once or in portions. For example, the diol can be added separately, sometimes mixed with an aromatic dicarboxylic acid and sometimes mixed with an aliphatic dicarboxylic acid.

[0255] The aforementioned aromatic dicarboxylic acid may have the same characteristics as described above.

[0256] In the pretreatment step for producing the slurry, the molar ratio of the diol to the aromatic dicarboxylic acid may be about 0.8:1 to about 2:1. In the pretreatment step for producing the slurry, the molar ratio of the diol to the aromatic dicarboxylic acid may be about 1.1:1 to about 1.5:1. In the pretreatment step for producing the slurry, the molar ratio of the diol to the aromatic dicarboxylic acid may be about 1.2:1 to about 1.5:1.

[0257] If the diol is added in an even larger amount than the aromatic dicarboxylic acid, the aromatic dicarboxylic acid can be easily dispersed.

[0258] Furthermore, additives may be added to the slurry. The nanocellulose and / or the metal salt may be added to the slurry in the form of a dispersion or solution.

[0259] The method for producing the biodegradable polyester resin involves mixing a diol and an aromatic dicarboxylic acid, pre-treating the mixture to obtain a slurry which is then subjected to an esterification reaction to obtain a prepolymer. By subjecting this prepolymer to a condensation polymerization reaction, the desired structure and physical properties of the biodegradable polyester resin can be efficiently achieved through the embodiment of the present invention.

[0260] The method for producing the biodegradable polyester resin includes a step of subjecting the slurry and the aliphatic dicarboxylic acid to an esterification reaction to produce a prepolymer. The slurry and the aliphatic dicarboxylic acid can react in the ester reaction section.

[0261] In the esterification reaction, by using the slurry, the reaction time can be shortened. For example, the slurry obtained in the pretreatment step can shorten the reaction time of the ester reaction by 1.5 times or more.

[0262] The esterification reaction can be carried out at least once or more.

[0263] In one embodiment, the esterification reaction can be carried out once after adding an aliphatic dicarboxylic acid, or a diol and an aliphatic dicarboxylic acid to the slurry. That is, the slurry is charged into the esterification reactor, and the esterification reaction can be carried out by charging the aliphatic dicarboxylic acid alone, or the aliphatic dicarboxylic acid and the diol into the esterification reactor.

[0264] The diol and the aliphatic dicarboxylic acid may be added to the slurry containing the aromatic dicarboxylic acid in a slurry state.

[0265] The esterification reaction can be carried out at about 250 °C or lower for about 0.5 hour to about 6 hours. Specifically, the esterification reaction can be carried out at about 180 °C to about 250 °C, about 185 °C to about 240 °C or about 200 °C to about 240 °C under normal pressure or reduced pressure until the by-product water theoretically reaches 95%. For example, the esterification reaction can be carried out for 0.5 hour to 5.5 hours, 0.5 hour to 4.5 hours or 1 hour to 4 hours, but is not limited thereto.

[0266] In the esterification reaction, the total number of moles of diol charged may be about 1.0 to about 1.8 relative to the total number of moles of the aromatic dicarboxylic acid and the aliphatic dicarboxylic acid. In the esterification reaction, the total number of moles of diol charged may be about 1.1 to about 1.6 relative to the total number of moles of the aromatic dicarboxylic acid and the aliphatic dicarboxylic acid.

[0267] Also, the temperature of the slurry of the diol and the aliphatic dicarboxylic acid may be about 5 °C to about 15 °C higher than the melting point of the diol.

[0268] Also, various additives such as the nanocellulose may be added to the slurry of the diol and the aliphatic dicarboxylic acid.

[0269] In one embodiment, the first esterification reaction can be carried out with the slurry itself or after the diol is added to the slurry. Also, after the first ester reaction, the aliphatic dicarboxylic acid or a mixture of the aliphatic dicarboxylic acid and the diol is charged into the ester reaction section, and a second ester reaction can be carried out together with the first ester reaction product.

[0270] The first esterification reaction can be carried out at 250 °C or lower for 0.25 hours to 4 hours. Specifically, the first esterification reaction can be carried out at 180 °C to 250 °C, 185 °C to 240 °C or 200 °C to 240 °C under normal pressure or reduced pressure until the by-product water theoretically reaches 95%. For example, the first esterification reaction can be carried out for 0.25 hours to 4 hours, 0.25 hours to 3.5 hours or 1.5 hours to 3 hours, but is not limited thereto.

[0271] The second esterification reaction can be carried out at approximately 250°C or below for 0.25 to 3.5 hours. Specifically, the second esterification reaction can be carried out at 180°C to 250°C, 185°C to 240°C, or 200°C to 240°C under atmospheric or reduced pressure until the by-product water theoretically accounts for 95%. For example, the second esterification reaction can be carried out for 0.5 to 3 hours, 1 to 2.5 hours, or 1.5 to 3 hours, but is not limited to these.

[0272] In the first and second esterification reactions, the reaction temperature and reaction time may be adjusted, respectively, to control the number ratio of the first and second blocks. Furthermore, when the esterification reaction is carried out separately as the first and second esterification reactions, the overall esterification reaction can be precisely controlled. This can improve the reaction stability and reaction uniformity of the esterification reaction.

[0273] After the second esterification reaction is completed, a third esterification reaction can be carried out. At this time, a monomer composition containing at least one of the diol, the aromatic dicarboxylic acid, and the aliphatic dicarboxylic acid is added to the product of the second esterification reaction to carry out the third esterification reaction.

[0274] The monomer composition may be added to the second ester reaction product in an amount of about 0.5 parts by weight to about 5 parts by weight, based on 100 parts by weight of the second ester reaction product.

[0275] Furthermore, in the monomer composition, the molar ratio of the aromatic dicarboxylic acid to the aliphatic dicarboxylic acid may be about 1:1 to about 1:3.

[0276] Furthermore, in the monomer composition, the molar ratio of the diol to the total dicarboxylic acid may be about 0.8:1 to 1:1.2.

[0277] The third esterification reaction can be carried out at approximately 250°C or below for 0.1 to 0.5 hours. Specifically, the third esterification reaction can be carried out at 180°C to 250°C, 185°C to 240°C, or 200°C to 240°C under atmospheric pressure or reduced pressure. For example, the third esterification reaction can be carried out for 5 to 40 minutes, 10 to 30 minutes, or 10 to 20 minutes, but is not limited to these times.

[0278] A prepolymer can be formed by the third esterification reaction described above.

[0279] When the third esterification reaction is carried out under the above-described process conditions using the monomer composition described above, the content of the oligomer can be adjusted as appropriate.

[0280] In contrast, the oligomer can be manufactured separately and added to the second ester reaction product to produce the prepolymer.

[0281] In the third esterification reaction, the second esterification reaction product does not necessarily have to be used. That is, the third esterification reaction can be carried out using the monomer composition and other additives such as a catalyst. Subsequently, the second esterification reaction product and the third esterification reaction product can be mixed with each other to produce the prepolymer. In this case, the third esterification reaction product can be mixed with the second esterification reaction product in an amount of about 0.1 parts by weight to about 5 parts by weight, based on 100 parts by weight of the second esterification reaction product, to produce the prepolymer.

[0282] The average water molecular weight of the prepolymer may be approximately 500 to approximately 10,000 g / mol. For example, the average water molecular weight of the prepolymer may be approximately 500 to approximately 8,500 g / mol, approximately 500 to approximately 8,000 g / mol, approximately 500 to approximately 7,000 g / mol, approximately 500 g / mol to approximately 5,000 g / mol, or approximately 1,500 g / mol to approximately 4,000 g / mol. By ensuring that the average water molecular weight of the prepolymer satisfies the above range, the molecular weight of the polymer in the condensation polymerization reaction can be efficiently increased.

[0283] The water-average molecular weight can be measured using gel permeation chromatography (GPC). Specifically, the data calculated by gel permeation chromatography includes various parameters such as Mn, Mw, and Mp, and the molecular weight can be measured using the water-average molecular weight (Mn) as the reference.

[0284] The reinforcing material, the branching agent, and / or the metal salt may be added together with the slurry before the esterification reaction. The reinforcing material, the branching agent, and / or the metal salt may also be added to the esterification reaction section 200 during the esterification reaction. The reinforcing material, the branching agent, and / or the metal salt may also be added to the esterification reaction product after the esterification reaction. Furthermore, the reinforcing material, the branching agent, and / or the metal salt may be added together with the aliphatic dicarboxylic acid. Furthermore, the reinforcing material, the branching agent, and / or the metal salt may be added to the esterification reaction section 200 after the first esterification reaction and before the second esterification reaction.

[0285] Since the reinforcing material and / or the metal salt are introduced into the esterification reaction, the reinforcing material and / or the metal salt may be uniformly dispersed within the biodegradable polyester resin.

[0286] The reinforcing material may have the characteristics described above. In particular, nanocellulose can be used as the reinforcing material.

[0287] The nano-cellulose may be pretreated by a bead mill, by ultrasonic waves, or by high-speed dispersion at about 1000 rpm to about 1500 rpm before being introduced. Specifically, the nano-cellulose may be bead mill-pretreated or ultrasonically pre-treated with water-dispersed nano-cellulose.

[0288] First, the bead mill pretreatment can be performed with a vertical mill or a horizontal mill as a wet milling device. Although the horizontal mill is preferable in that it can hold a larger amount of beads inside the chamber, reduces uneven wear of the machine, reduces wear of the beads, and is easy to maintain, it is not limited thereto.

[0289] The bead mill pretreatment can be performed using one or more types of beads selected from the group consisting of zirconium, zircon, zirconia, quartz, and aluminum oxide.

[0290] Specifically, the bead mill pretreatment can be performed using beads having a diameter of about 0.3 mm to about 1 mm. For example, the diameter of the beads may be about 0.3 mm to about 0.9 mm, about 0.4 mm to about 0.8 mm, about 0.45 mm to about 0.7 mm, or about 0.45 mm to about 0.6 mm.

[0291] By satisfying the above range of the bead diameter, the dispersibility of the nano-cellulose can be further improved. If the bead diameter exceeds the above range, the average particle size and particle size deviation of the nano-cellulose may increase, resulting in low dispersibility.

[0292] Furthermore, the bead mill pretreatment is preferable in that it uses beads with a specific gravity higher than that of nanocellulose, as this allows for sufficient energy transfer. For example, the beads may be 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 are preferred, but are not limited to this.

[0293] Furthermore, the ultrasonic pretreatment is a method of physically sealing or pulverizing nanoparticles by generating waves through the emission of 20 kHz ultrasonic waves into a solution.

[0294] The ultrasonic pretreatment can be performed at an output of 30,000 J / s or less for less than 30 minutes. For example, the ultrasonic pretreatment can be performed at an output of 25,000 J / s or less or 22,000 J / s or less for 25 minutes or less, 20 minutes or less, or 18 minutes or less. By keeping the output and execution time within the above range, the effect of the ultrasonic pretreatment, i.e., the improvement in dispersibility, can be maximized. If the energy amount exceeds the above range, the nanoparticles may re-aggregate, resulting in lower dispersibility.

[0295] The nanocellulose in the embodiment may be pre-treated with a bead mill or ultrasonic pre-treatment. Alternatively, the nanocellulose in the embodiment may be pre-treated with both a bead mill and ultrasonic pre-treatment. In this case, it is preferable to perform ultrasonic pre-treatment after bead mill pre-treatment in order to prevent re-aggregation and improve dispersibility.

[0296] Because the nanocellulose contains ionically bonded metals, it exhibits very high dispersibility in water. Furthermore, the bead mill pretreatment and / or ultrasonic pretreatment yield an aqueous dispersion of the nanocellulose with a very high degree of dispersion. In the nanocellulose aqueous dispersion, the content of the nanocellulose may be about 1 wt% to about 50 wt%.

[0297] A titanium-based catalyst and / or a germanium-based catalyst can be used in the esterification reaction. Specifically, the titanium-based catalyst and / or the germanium-based catalyst can be added to the slurry to carry out the esterification reaction.

[0298] Furthermore, the titanium-based catalyst and / or the germanium-based catalyst may be added to the slurry before the first esterification reaction, and the titanium-based catalyst and / or the germanium-based catalyst may be further added to the product of the first esterification reaction.

[0299] The biodegradable polyester resin may contain one or more titanium-based catalysts selected from the group consisting of titanium isopropoxide, antimony trioxide, dibutyltin oxaside, tetrapropyl titanate, tetrabutyl titanate, tetraisopropyl titanate, antimony acetate, calcium acetate, and magnesium acetate, or one or more germanium-based catalysts selected from the group consisting of germanium oxide, germanium methoxide, germanium ethoxide, tetramethylgermanium, tetraethylgermanium, and germanium sulfide.

[0300] Furthermore, the content of the catalyst may be approximately 100 ppm to 1000 ppm, based on the total weight of the diol, aromatic dicarboxylic acid, and aliphatic dicarboxylic acid. For example, it may contain titanium-based or germanium-based catalysts in amounts of approximately 100 ppm to 800 ppm, approximately 150 ppm to 700 ppm, approximately 200 ppm to 600 ppm, or approximately 250 ppm to 950 ppm. By satisfying the above ranges for catalyst content, the physical properties can be further improved.

[0301] Furthermore, the heat stabilizer may be added together with the slurry before the esterification reaction. The heat stabilizer may be added to the esterification reaction section 200 during the esterification reaction. The heat stabilizer may be added to the esterification reaction product after the esterification reaction. Furthermore, the heat stabilizer may be added together with the aliphatic dicarboxylic acid. Furthermore, the heat stabilizer may be added to the esterification reaction section 200 after the first esterification reaction and before the second esterification reaction.

[0302] The characteristics of the heat stabilizer may be the same as those described above.

[0303] The content of the heat stabilizer may be 3,000 ppm or less based on the total weight of the diol, aromatic dicarboxylic acid, and aliphatic dicarboxylic acid. Specifically, the content of the heat stabilizer may be, for example, 10 ppm to 3,000 ppm, 20 ppm to 2,000 ppm, 20 ppm to 1,500 ppm, or 20 ppm to 200 ppm based on the total weight of the diol, aromatic dicarboxylic acid, and aliphatic dicarboxylic acid. By satisfying the above range for the content of the heat stabilizer, it is possible to control the degradation of the polymer due to high temperatures during the reaction process, reduce the end groups of the polymer, and improve the color.

[0304] After the esterification reaction is completed, one or more additives selected from the group consisting of silica, potassium, or magnesium, and a color corrector such as cobalt acetate may be further added to the esterification reaction product. That is, after the esterification reaction is completed, the additives and / or color correctors may be added and stabilized before the polymerization condensation reaction can be carried out. The additives and / or color correctors may be added after the esterification reaction is completed and introduced into the polymerization condensation reaction section 300 together with the prepolymer. In this way, the additives and / or color correctors may be uniformly dispersed in the biodegradable polyester resin.

[0305] Furthermore, the inorganic filler may be added to the esterification reaction product after the esterification reaction is completed. That is, after the esterification reaction is completed, the inorganic filler may be added and stabilized before the polymerization condensation reaction can be carried out. The characteristics of the inorganic filler are as described above. The inorganic filler may be added to the polymerization condensation reaction section 300 together with the prepolymer to carry out the polymerization condensation step. In this way, the inorganic filler may be uniformly dispersed in the biodegradable polyester resin.

[0306] Furthermore, the first recovery unit 510 recovers reaction by-products such as water from the esterification reaction unit 200. The first recovery unit 510 can recover by-products generated in the esterification reaction by applying vacuum pressure or refluxing to the esterification reaction unit 200.

[0307] The method for producing the biodegradable polyester resin includes a step of undergoing a condensation polymerization reaction of the prepolymer. The condensation polymerization reaction can be carried out as follows.

[0308] The prepolymer is introduced into the polymerization condensation reaction section 300. Alternatively, at least one of the reinforcing material, the heat stabilizer, the color corrector, the inorganic filler, the metal salt, or other additives may be introduced into the polymerization condensation reaction section 300 together with the prepolymer.

[0309] Furthermore, the prepolymer and oligomer composition can be introduced into the polymerization reaction section to carry out the polymerization reaction of the prepolymer and the oligomer.

[0310] The oligomer composition may be manufactured by the following method.

[0311] The oligomer composition can be produced by an esterification reaction of the diol, the aromatic dicarboxylic acid, and the aliphatic dicarboxylic acid. In this case, the oligomer composition may be produced so as to mainly contain oligomers with a molecular weight of 400 to 1300.

[0312] The temperature of the esterification reaction for producing the oligomer composition may be about 200°C to about 250°C. The esterification reaction time for producing the oligomer composition may be about 5 minutes to about 20 minutes.

[0313] Furthermore, the content of the oligomer composition introduced into the polymerization reaction may be approximately 0.5 wt% to approximately 10 wt% based on the total weight introduced into the polymerization reaction. The content of the oligomer composition introduced into the polymerization reaction may be approximately 1 wt% to approximately 7 wt% based on the total weight introduced into the polymerization reaction.

[0314] Since the characteristics and content of the oligomer composition are as described above, the biodegradable polyester resin composition according to the examples may contain oligomers with a molecular weight of 400 to 1300 in an appropriate amount.

[0315] Subsequently, the condensation polymerization reaction can be carried out at approximately 180°C to approximately 280°C and at approximately 10 torr or less for approximately 1 to 5 hours. For example, the condensation polymerization reaction can be carried out at approximately 190°C to approximately 270°C, approximately 210°C to approximately 260°C, or approximately 230°C to approximately 255°C, at approximately 0.9 torr or less, approximately 0.7 torr or less, approximately 0.2 torr to approximately 10 torr, approximately 0.2 torr to approximately 0.9 torr, or approximately 0.2 torr to approximately 0.6 torr, for approximately 1.5 hours to approximately 5 hours, approximately 2 hours to approximately 5 hours, or approximately 2.5 hours to approximately 4.5 hours.

[0316] Furthermore, the condensation polymerization reaction may include primary and secondary condensation polymerization.

[0317] For example, the primary condensation polymerization can be carried out at a temperature of approximately 260°C or lower, approximately 250°C or lower, approximately 215°C to approximately 250°C, approximately 215°C to approximately 245°C, or approximately 230°C to approximately 245°C, for a duration of approximately 1 torr to approximately 200 torr, approximately 2 torr to approximately 100 torr, approximately 4 torr to approximately 50 torr, approximately 5 torr to approximately 45 torr, or approximately 8 torr to approximately 32 torr, for a duration of approximately 0.5 hours to approximately 3.5 hours, approximately 0.5 hours to approximately 3.0 hours, or approximately 0.5 hours to approximately 2.8 hours.

[0318] Furthermore, the secondary polymerization can be carried out at approximately 220°C to approximately 265°C, approximately 230°C to approximately 260°C, or approximately 235°C to approximately 255°C, with a condensation rate of approximately 1 torr or less, approximately 0.8 torr or less, approximately 0.6 torr or less, approximately 0.1 torr to approximately 1 torr, approximately 0.2 torr to approximately 0.8 torr, or approximately 0.2 torr to approximately 0.6 torr, for approximately 0.5 hours to approximately 4 hours, approximately 1 hour to approximately 3.5 hours, or approximately 1.5 hours to approximately 3.5 hours.

[0319] Furthermore, a titanium-based catalyst or a germanium-based catalyst may be added to the prepolymer before the condensation polymerization reaction. Also, before the condensation polymerization reaction, one or more additives selected from the group consisting of silica, potassium, or magnesium; amine-based stabilizers such as trimethyl phosphate, triphenyl phosphate, trimethylphosphine, phosphoric acid, phosphorous acid, or tetraethylenepentaamine; and polymerization catalysts such as antimonitor trioxide, antimony trioxide, or tetrabutyl titanate may be added to the prepolymer.

[0320] The average water molecular weight of the polymer may be about 30,000 g / mol or more. For example, the average water molecular weight of the polymer may be about 33,000 g / mol or more, about 45,000 g / mol or more, or about 30,000 g / mol to about 90,000 g / mol. By having the average water molecular weight of the polymer within the above range, the physical properties, impact resistance, durability, and moldability can be further improved.

[0321] Furthermore, the second recovery unit 520 recovers reaction by-products such as water from the polymerization reaction unit 300. The second recovery unit 520 can also recover by-products generated in the polymerization reaction by applying vacuum pressure to the polymerization reaction unit 300.

[0322] The second recovery unit 520 can apply a vacuum pressure of approximately 0.1 torr to approximately 1 torr inside the polymerization reaction unit 300. The second recovery unit 520 can apply a vacuum pressure of approximately 0.1 torr to approximately 0.9 torr inside the polymerization reaction unit 300.

[0323] Subsequently, the hydrolysis-resistant agent and / or the chain extender are added to the polymer. The polymer, hydrolysis-resistant agent and chain extender are then uniformly mixed and maintained at a temperature of approximately 200°C to 260°C for approximately 1 to 15 minutes. This causes the polymer to react with the hydrolysis-resistant agent and / or the chain extender.

[0324] In contrast, the hydrolysis-resistant agent and / or the chain extender may be added to the polymerization condensation reaction section 300 by a static mixer and reacted with the polymer. The reaction temperature of the hydrolysis-resistant agent and / or the chain extender in the polymerization condensation reaction section 300 may be about 200°C to about 260°C. The reaction time of the hydrolysis-resistant agent and / or the chain extender in the polymerization condensation reaction section 300 may be about 1 minute to about 15 minutes.

[0325] The hydrolysis-resistant agent may have the same characteristics as described above.

[0326] The chain extender may have the same characteristics as described above.

[0327] As a result, the biodegradable polyester resin compositions according to the examples may have an appropriate degree of hydrolysis and a high degree of biodegradation.

[0328] Subsequently, pellets can be produced from the polymer.

[0329] Specifically, the polymer can be cooled to approximately 15°C or below, approximately 10°C or below, or approximately 6°C or below, and then the cooled polymer can be cut to produce pellets. Alternatively, the polymer can be cut at a temperature of approximately 40°C to approximately 60°C.

[0330] The aforementioned cutting step can be performed using any pellet cutting machine used in this industry without limitation, and the pellets may have various shapes. The pellet cutting method may include an underwater cutting method or a strand cutting method.

[0331] The pellets can undergo further post-processing steps. The pellets can be fed into the post-processing unit 400 to perform the post-processing steps.

[0332] The post-processing step can be carried out within the post-processing unit 400. The pellets are fed into the post-processing unit 400. The post-processing unit 400 can then melt the fed pellets by frictional heat and re-extrude them. That is, the post-processing unit 400 may include a press, such as a twin-screw press.

[0333] The post-processing temperature may be approximately 230°C to approximately 270°C. The post-processing temperature may be approximately 230°C to approximately 260°C. The post-processing temperature may be approximately 240°C to approximately 265°C. The post-processing temperature may be approximately 240°C to approximately 260°C.

[0334] The post-processing time may be approximately 30 seconds to approximately 3 minutes. The post-processing time may be approximately 50 seconds to approximately 2 minutes. The post-processing time may be approximately 1 minute to approximately 2 minutes.

[0335] Subsequently, the resin extruded by the press may be cooled, cut, and processed into pellets. In other words, the resin extruded from the press may be reprocessed into pellets by the cutting step described above.

[0336] The degree of crystallinity of the pellets can be improved by the post-treatment step. Furthermore, the content of residual substances in the pellets can be adjusted by the post-treatment step. In particular, the content of oligomers in the pellets can be adjusted by the post-treatment step. The content of residual solvents in the pellets can also be adjusted by the post-treatment step.

[0337] This allows the post-processing step to appropriately adjust the mechanical properties, degree of biodegradation, UV resistance, optical properties, or hydrolysis resistance of the biodegradable polyester resin.

[0338] The characteristics and content of the oligomer may vary depending on the esterification reaction, the chain extension reaction, and the post-treatment steps.

[0339] After the pellets are manufactured, the biodegradable polyester resin can be compounded with the two types of biodegradable resins. In addition, at least one of the inorganic filler, light stabilizer, color corrector, elongation improver, or other additives can be compounded with the biodegradable polyester resin and the two types of biodegradable resins.

[0340] The compounding process is as follows:

[0341] The biodegradable polyester resin and the two types of biodegradable resins are mixed with at least one of the inorganic filler, the heat stabilizer, the color corrector, the metal salt, or the other additives, and then fed into a press. The mixed biodegradable polyester resin composition is melted in the press at a temperature of about 120°C to about 260°C and mixed with each other. The molten and mixed biodegradable polyester resin composition is then extruded, cooled, cut, and re-pelletized. Through this process, the biodegradable polyester resin composition according to the example can be produced by compounding it with the two types of biodegradable resins.

[0342] A biodegradable polyester film can be manufactured using the biodegradable polyester resin described in the examples.

[0343] The thickness of the biodegradable polyester film may be approximately 5 μm to approximately 300 μm. For example, the thickness of the biodegradable polyester film may be approximately 5 μm to approximately 180 μm, approximately 5 μm to approximately 160 μm, approximately 10 μm to approximately 150 μm, approximately 15 μm to approximately 130 μm, approximately 20 μm to approximately 100 μm, approximately 25 μm to approximately 80 μm, or approximately 25 μm to approximately 60 μm.

[0344] The biodegradable polyester film according to the examples may have substantially the same degree of hydrolysis and biodegradation as the biodegradable polyester resin composition described above.

[0345] On the other hand, the biodegradable polyester film can be manufactured using the biodegradable polyester resin or biodegradable polyester resin pellets.

[0346] Specifically, the method for producing the biodegradable polyester film may include the steps of producing a biodegradable resin composition according to the examples, and drying and melt-extruding the biodegradable resin composition.

[0347] In the step of drying and melt-extruding the biodegradable polyester resin composition, the drying can be carried out at a temperature of approximately 60°C to approximately 100°C for approximately 2 to approximately 12 hours. Specifically, the drying can be carried out at a temperature of approximately 65°C to approximately 95°C, approximately 70°C to approximately 90°C, or approximately 75°C to approximately 85°C for approximately 3 to approximately 12 hours, or approximately 4 to approximately 10 hours. By ensuring that the drying process conditions for the pellets meet the above range, the quality of the biodegradable polyester film or molded product produced can be further improved. The moisture content of the biodegradable polyester resin composition after the drying step may be approximately 500 ppm or less, based on the total weight of the biodegradable polyester resin composition.

[0348] In the drying and melt extrusion steps, the melt extrusion can be carried out at a temperature of approximately 250°C or lower. For example, the melt extrusion can be carried out at a temperature of approximately 245°C or lower, approximately 220°C or lower, approximately 215°C or lower, approximately 100°C to approximately 250°C, approximately 120°C to approximately 245°C, or approximately 130°C to approximately 215°C. The melt extrusion can be carried out in the blown film process.

[0349] Biodegradable polyester molded products Biodegradable polyester molded articles can be manufactured using the aforementioned biodegradable polyester resin.

[0350] Specifically, the molded article can be manufactured by molding the biodegradable polyester resin composition using methods known in the industry, such as extrusion or injection molding. The molded article may be, but is not limited to, an injection-molded article, an extruded article, a thin-film molded article, a blow-molded or blow-molded article, a 3D filament, or an interior building material.

[0351] For example, the molded product may be in the form of a film or sheet used in agricultural mulching films, disposable gloves, disposable films, disposable envelopes, food packaging materials, and weight-based garbage bags, or it may be in the form of fibers used in woven fabrics, knitted fabrics, nonwoven fabrics, ropes, etc. Also, as shown in Figure 2, the molded product may be in the form of a disposable container used for food packaging such as bento boxes. Furthermore, the molded product may be in the form of various shapes such as disposable straws, spoons and chopsticks, eating boards, and forks.

[0352] In particular, since the molded product can be formed from the biodegradable polyester resin, which can improve physical properties such as impact absorption energy and hardness, as well as impact resistance and durability, it can exhibit excellent properties when applied to packaging materials for products stored and transported at low temperatures, automotive interior materials requiring durability, garbage bags, mulching films, and disposable products.

[0353] The biodegradability of the biodegradable polyester resin compositions according to the examples can be measured by the following method.

[0354] To measure the degree of biodegradation, the biodegradable resin composition according to the above example was mixed with compost and subjected to an accelerated biodegradation test at a temperature of 60°C and a humidity of 90%. After a certain period of time, the number-average molecular weight of the biodegradable polyester resin composition according to the example was measured using gel permeation chromatography (GPC). The degree of biodegradation was derived by dividing the difference between the initial number-average molecular weight and the number-average molecular weight after a certain period of biodegradation by the initial number-average molecular weight.

[0355] The degree of biodegradation may also be expressed by the following formula 1.

[0356] [Formula 1] JPEG0007897338000019.jpg16158

[0357] In this example, the biodegradable polyester resin composition is mixed with compost and subjected to an accelerated biodegradation test at a temperature of 60°C and a humidity of 90% for a certain period. Before the accelerated biodegradation test, the initial number-average molecular weight of the biodegradable polyester resin composition and the number-average molecular weight of the biodegradable polyester resin composition after biodegradation following the accelerated biodegradation test are measured by gel permeation chromatography (GPC).

[0358] The degree of biodegradation was derived by dividing the difference between the initial number-average molecular weight and the number-average molecular weight after a certain period of biodegradation by the initial number-average molecular weight.

[0359] Furthermore, the compost may contain approximately 40 wt% pig manure, approximately 15 wt% chicken manure, approximately 37 wt% sawdust, approximately 5 wt% zeolite, and approximately 3 wt% microbial preparations.

[0360] Furthermore, the manufacturer of the compost may be Taeheung F&G, and the product name of the compost may be Chisei-do (by-product fertilizer, Grade 1 compost).

[0361] Furthermore, when the degree of biodegradation is measured, the biodegradable polyester resin composition according to the example is manufactured into a sheet having a thickness of approximately 300 μm. Subsequently, the manufactured sheet is cut into pieces approximately 30 mm x 30 mm in size to produce flakes. The flakes can then be mixed with the compost to perform the accelerated biodegradation test.

[0362] In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after one week may be about 40% to about 70%. In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after one week may be about 45% to about 65%. In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after one week may be about 47% to about 63%. In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after one week may be about 49% to about 62%.

[0363] In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after two weeks may be about 50% to about 70%. In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after two weeks may be about 55% to about 68%.

[0364] In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after 3 weeks may be about 63% to about 75%.

[0365] In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after 4 weeks may be about 73% to about 85%. In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after 4 weeks may be 75% to 82%.

[0366] In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after 6 weeks may be about 80% to about 90%. In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after 6 weeks may be about 82% to about 88%.

[0367] In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after 9 weeks may be about 85% or more. In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after 9 weeks may be about 87% or more. In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after 9 weeks may be about 88% or more. In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after 9 weeks may be about 89% or more. In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after 9 weeks may be about 90% or more.

[0368] In the biodegradable polyester resin composition according to the examples, the rate of increase in the degree of biodegradation from one week to two weeks may be about 4% / week to about 15% / week. In the biodegradable polyester resin composition according to the examples, the rate of increase in the degree of biodegradation from one week to two weeks may be about 5% / week to about 13% / week.

[0369] The degree of hydrolysis of the biodegradable polyester resin composition according to the examples can be measured by the following method.

[0370] To measure the degree of hydrolysis, the biodegradable resin composition according to the example was immersed in water (100% RH) at 80°C, and then an accelerated hydrolysis test was performed. After a certain period of time, the number-average molecular weight of the biodegradable polyester resin composition according to the example was measured using gel permeation chromatography (GPC). The degree of hydrolysis was derived by dividing the difference between the initial number-average molecular weight and the number-average molecular weight after hydrolysis for a certain period by the initial number-average molecular weight.

[0371] The degree of hydrolysis may be expressed by the following formula 2.

[0372] [Formula 2] JPEG0007897338000020.jpg15153

[0373] In this example, the biodegradable polyester resin composition is immersed in water at 80°C and then subjected to an accelerated hydrolysis test for a certain period. Before the accelerated hydrolysis test, the initial number-average molecular weight of the biodegradable polyester resin composition and the number-average molecular weight of the biodegradable polyester resin composition after hydrolysis following the accelerated hydrolysis test for a certain period are measured by gel permeation chromatography (GPC).

[0374] The degree of hydrolysis was derived by dividing the difference between the initial number-average molecular weight and the number-average molecular weight after hydrolysis for a certain period by the initial number-average molecular weight.

[0375] Furthermore, when the degree of hydrolysis is measured, the biodegradable polyester resin composition according to the example is manufactured into a sheet having a thickness of approximately 300 μm. Subsequently, the manufactured sheet is cut into pieces approximately 30 mm x 30 mm in size to produce flakes. The flakes can then be immersed in the hot water to perform the hydrolysis acceleration test.

[0376] In the biodegradable polyester resin composition according to the examples, the degree of hydrolysis after one week may be about 40% to about 65%. In the biodegradable polyester resin composition according to the examples, the degree of hydrolysis after one week may be about 45% to about 63%.

[0377] In the biodegradable polyester resin composition according to the examples, the degree of hydrolysis after 2 weeks may be about 80% to about 93%. In the biodegradable polyester resin composition according to the examples, the degree of hydrolysis after 2 weeks may be about 85% to about 92%.

[0378] In the biodegradable polyester resin composition according to the examples, the degree of hydrolysis after 3 weeks may be about 90% to about 97%. In the biodegradable polyester resin composition according to the examples, the degree of hydrolysis after 3 weeks may be about 91% to about 96%.

[0379] In the biodegradable polyester resin composition according to the examples, the degree of hydrolysis after 4 weeks may be about 92% to about 99%. In the biodegradable polyester resin composition according to the examples, the degree of hydrolysis after 4 weeks may be about 93% to about 97%.

[0380] In the biodegradable polyester resin composition according to the examples, the degree of hydrolysis after 6 weeks may be approximately 94% or higher. In the biodegradable polyester resin composition according to the examples, the degree of hydrolysis after 6 weeks may be approximately 95% or higher.

[0381] In the biodegradable polyester resin composition according to the examples, the degree of hydrolysis after 9 weeks may be about 95% or more. In the biodegradable polyester resin composition according to the examples, the degree of hydrolysis after 9 weeks may be about 96% or more.

[0382] In the biodegradable polyester resin composition according to the examples, the rate of increase in the degree of hydrolysis from week 1 to week 2 may be about 25% / week to about 50% / week. In the biodegradable polyester resin composition according to the examples, the rate of increase in the degree of hydrolysis from week 1 to week 2 may be about 29% / week to about 50% / week. In the biodegradable polyester resin composition according to the examples, the rate of increase in the degree of hydrolysis from week 1 to week 2 may be about 30% / week to about 45% / week.

[0383] Since the biodegradable polyester resin compositions according to the examples have a degree of hydrolysis and a rate of increase in the degree of hydrolysis within the range described above, the biodegradable polyester resin compositions according to the examples may have appropriate durability in the realm of daily life and may be easily hydrolyzed upon disposal. In other words, since the biodegradable polyester resin compositions according to the examples have a degree of hydrolysis and a rate of increase in the degree of hydrolysis within an appropriate range, they may have sufficient hydrolysis resistance when used for a suitable period of time in disposable packaging, etc. Furthermore, the biodegradable polyester resin compositions according to the examples may be easily decomposed by hydrolysis and biodegradation after a sufficient amount of time has passed, not only in soil but also when disposed of in rivers or the sea, etc.

[0384] In the biodegradable polyester resin composition according to the examples, the degree of biodegradation per aliphatic carboxylic acid may be about 1.5 or higher. Alternatively, the degree of biodegradation per aliphatic carboxylic acid may be about 1.65 or higher. The degree of biodegradation per aliphatic carboxylic acid may be about 1.75 or higher. The degree of biodegradation per aliphatic carboxylic acid may be about 1.8 or higher. The degree of biodegradation per aliphatic carboxylic acid may be about 1.85 or higher. The degree of biodegradation per aliphatic carboxylic acid may be about 1.90 or higher. The maximum value of the degree of biodegradation per aliphatic carboxylic acid may be about 4.

[0385] The biodegradation rate per unit of aliphatic carboxylic acid is the value obtained by dividing the biodegradation rate after 9 weeks by the proportion of the aliphatic carboxylic acid, based on the total dicarboxylic acid.

[0386] The degree of biodegradation per unit of aliphatic carboxylic acid may be expressed by the following formula 3.

[0387] [Formula 3] JPEG0007897338000021.jpg13157

[0388] The composition of the biodegradable polyester resin, such as the number of the first block, the number of the second block, the content of the aliphatic dicarboxylic acid or the content of the aromatic dicarboxylic acid, the process conditions for manufacturing the biodegradable polyester resin, the reinforcing material, the metal salt, the hydrolysis-resistant agent, the chain extender, the oligomer, or the heat stabilizer may be adjusted as appropriate so that the degree of biodegradation per unit of aliphatic carboxylic acid is within the above range.

[0389] Furthermore, the acid value of the biodegradable polyester resin composition according to the examples may be approximately 0.01 mg KOH / g to approximately 3 mg KOH / g. The acid value of the biodegradable polyester resin composition according to the examples may be approximately 0.1 mg KOH / g to approximately 2.5 mg KOH / g. The acid value of the biodegradable polyester resin composition according to the examples may be approximately 0.1 mg KOH / g to approximately 2.3 mg KOH / g.

[0390] The biodegradable polyester resin compositions according to the examples have an acid value within the above range, and therefore may have the above-mentioned degree of hydrolysis and biodegradation characteristics.

[0391] Furthermore, the biodegradable polyester resin composition according to the examples may contain nitrogen elements. The nitrogen elements may be derived from the metal salt and / or the chain extender, etc. The nitrogen element content may be about 0.1 ppm to about 500 ppm based on the biodegradable polyester resin composition according to the examples. The nitrogen element content may be about 1 ppm to about 400 ppm based on the biodegradable polyester resin composition according to the examples. The nitrogen element content may be about 1 ppm to about 300 ppm based on the biodegradable polyester resin composition according to the examples. The nitrogen element content may be about 1 ppm to about 100 ppm based on the biodegradable polyester resin composition according to the examples.

[0392] Furthermore, the biodegradable polyester resin composition according to the examples may contain silicon elements. The silicon elements may be derived from the hydrolysis-resistant agent or the like. The content of the silicon elements may be about 0.1 ppm to about 100 ppm based on the biodegradable polyester resin composition according to the examples. The content of the silicon elements may be about 0.5 ppm to about 90 ppm based on the biodegradable polyester resin composition according to the examples. The content of the silicon elements may be about 1 ppm to about 80 ppm based on the biodegradable polyester resin composition according to the examples. The content of the silicon elements may be about 1 ppm to about 50 ppm based on the biodegradable polyester resin composition according to the examples.

[0393] Furthermore, the biodegradable polyester resin composition according to the examples may contain a metal element. The metal element may be derived from the metal salt. The content of the metal element may be about 0.1 ppm to about 100 ppm based on the biodegradable polyester resin composition according to the examples. The content of the metal element may be about 0.5 ppm to about 90 ppm based on the biodegradable polyester resin composition according to the examples. The content of the metal element may be about 1 ppm to about 80 ppm based on the biodegradable polyester resin composition according to the examples. The content of the metal element may be about 1 ppm to about 50 ppm based on the biodegradable polyester resin composition according to the examples.

[0394] Furthermore, the biodegradable polyester resin compositions according to the examples may have surface tension, water contact angle, diode methane contact angle, surface free energy, dispersion, and polarity.

[0395] The surface tension, water contact angle, diode methane contact angle, surface free energy, dispersion, and polarity can be measured on the surface of the polyester sheet.

[0396] In the biodegradable polyester resin composition according to the examples, the surface tension may be about 30 dyne to about 55 dyne.

[0397] In the biodegradable polyester resin composition according to the examples, the water contact angle may be about 60° to about 90°. In the biodegradable polyester resin composition according to the examples, the water contact angle may be about 65° to about 85°. In the biodegradable polyester resin composition according to the examples, the water contact angle may be about 67° to about 80°.

[0398] In the biodegradable polyester resin composition according to the examples, the diode-methane contact angle may be about 20° to about 40°. In the biodegradable polyester resin composition according to the examples, the diode-methane contact angle may be about 20° to about 35°.

[0399] In the biodegradable polyester resin composition according to the examples, the surface free energy may be about 40 mN / m to about 60 mN / m. In the biodegradable polyester resin composition according to the examples, the surface free energy may be about 42 mN / m to about 55 mN / m.

[0400] In the biodegradable polyester resin composition according to the examples, the degree of dispersion may be about 35 mN / m to about 55 mN / m. In the biodegradable polyester resin composition according to the examples, the degree of dispersion may be about 40 mN / m to about 50 mN / m.

[0401] In the biodegradable polyester resin composition according to the examples, the degree of polarity may be about 2 mN / m to about 8 mN / m. In the biodegradable polyester resin composition according to the examples, the degree of polarity may be about 3 mN / m to about 7 mN / m.

[0402] The biodegradable polyester resin composition according to the examples may have the following characteristics: the composition of the biodegradable polyester resin, the oligomer, the reinforcing material, the chain extender, the metal salt, the hydrolysis-resistant agent, and the heat stabilizer, and the surface tension, water contact angle, diode methane contact angle, surface free energy, dispersion, and polarity may be within the above ranges due to the processes of the esterification reaction, the condensation polymerization reaction, the chain extension reaction, and the heat treatment reaction. Thus, the biodegradable polyester resin composition according to the examples may have an appropriate degree of hydrolysis and an appropriate degree of biodegradation.

[0403] The above will be explained in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and the scope of the present invention is not limited to these examples.

[0404] <Manufacturing example> Production of pre-treated cellulose nanocrystals Dry powder cellulose nanocrystals (NVC-100, manufactured by Celluforce) with particle sizes ranging from approximately 1 μm to 50 μm were dispersed in water at a concentration of 1% by weight. The mixture was then ultrasonically treated for 1 minute at an output of 20,000 J / s using a tip-type ultrasonic disperser to produce pre-treated nanocellulose.

[0405] Monomer composition for oligomer production 1,4-butanediol (1,4-BDO), terephthalic acid (TPA), and adipic acid (AA) were uniformly mixed in a molar ratio of approximately 3:1:2. At this time, the average particle size of terephthalic acid (TPA) was approximately 150 μm.

[0406] Oligomer manufacturing 1,4-butanediol (1,4-BDO), terephthalic acid (TPA), and adipic acid (AA) were uniformly mixed in a molar ratio of approximately 3:1:2. At this time, the average particle size of the terephthalic acid (TPA) was approximately 130 μm. Subsequently, the mixture was subjected to an esterification reaction at a temperature of approximately 220°C and atmospheric pressure for approximately 10 minutes to produce the hydrolysis regulator.

[0407] Chain extender: Tri(4-isocyanatophenyl)methane

[0408] <Examples> Example 1 Manufacturing of biodegradable polyester resins Stage 1: Pre-treatment to obtain slurry As shown in Table 1, pre-treated nanocellulose, 1,4-butanediol (1,4-BDO), and terephthalic acid (TPA) were mixed in a molar ratio (1,4-BDO:TPA) of 1.2:1 and introduced into a slurry tank (the bottom of the slurry tank was anchor-type, with a height of 40 mm to the agitator, and equipped with three rotating blades) without a catalyst. At this time, the D50 of terephthalic acid (TPA) was 130 μm, and the standard deviation (SD) of terephthalic acid (TPA) to D50 was 30.

[0409] Next, the mixture was pretreated by stirring at 60°C at 100 rpm for 1 hour to obtain a slurry without phase separation.

[0410] Stage 2: Stage for obtaining the preliminary polymer The slurry obtained in the first step was introduced into the reactor via a supply line, and 250 ppm of tetrabutyl titanate (manufactured by Dupont, Tyzor TnBT), a titanium-based catalyst, was added. The primary esterification reaction was then carried out at 220°C and atmospheric pressure for approximately 1 hour and 30 minutes until 95% of the by-product water was discharged.

[0411] To the aforementioned reaction product, 53 mol% of 1,4-butanediol (1,4-BDO) based on the total moles of the diol component, 53 mol% of adipic acid (AA) based on the total moles of the dicarboxylic acid component, and 200 ppm of tetrabutyl titanate (Dupont, Tyzor TnBT), a titanium-based catalyst, based on the total weight of the diol, aromatic dicarboxylic acid, and aliphatic dicarboxylic acid were added. Then, a secondary esterification reaction was carried out at 210°C and atmospheric pressure for approximately 2 hours and 30 minutes until 95% of the by-product water was discharged, thereby generating a secondary esterification reaction product.

[0412] Subsequently, the monomer composition was added to the secondary esterification reaction product at a content of approximately 1 part by weight, based on 100 parts by weight of the esterification reaction product. The mixture of the monomer composition and the secondary esterification reaction product underwent a tertiary esterification reaction for approximately 20 minutes at a temperature of approximately 220°C. Subsequently, the tertiary esterification reaction produced a prepolymer having a number-average molecular weight of approximately 1200 g / mol.

[0413] Stage 3: Stage in which a polymerization reaction is carried out. The aforementioned prepolymer was mixed with 400 ppm of a titanium-based catalyst, tetrabutyl titanate (manufactured by Dupont, Tyzor TnBT), and 200 ppm of a triethylene phosphate stabilizer, and stabilized for approximately 10 minutes. Subsequently, the reaction mixture was heated to 250°C and subjected to a condensation polymerization reaction at 0.5 torr for 4 hours to produce a polymer having a water-average molecular weight of 55,000 g / mol.

[0414] Subsequently, approximately 0.5 wt% of tri(4-isocyanatophenyl)methane was added to the polymer based on the polymer itself. The polymer was then subjected to a chain extension reaction at a temperature of approximately 240°C for approximately 10 minutes. After cooling to 5°C, it was cut using a pellet cutter to obtain biodegradable polyester resin pellets.

[0415] Example 2 As shown in Tables 1 and 2 below, the contents of adipic acid, terephthalic acid, cellulose nanocrystals, monomer composition, and chain extender may vary. Without the chain extension reaction, the polymer was cooled to obtain biodegradable polyester resin pellets. The biodegradable polyester resin pellets were then fed into a twin-screw press and melt-extruded at a temperature of approximately 250°C for approximately 2 minutes, cooled to approximately 5°C, cut, and produced again as pellets. Except for the contents and the steps described above, the other steps were carried out substantially with reference to Example 1.

[0416] Examples 3-6 and Comparative Examples 1-2 As shown in Tables 1 and 2 below, the contents of adipic acid, terephthalic acid, cellulose nanocrystals, monomer composition, and chain extender differ. Except for the contents and the steps described above, the other steps were carried out with substantially reference to Example 1 or Example 2.

[0417] Examples 7-13 and Comparative Example 3 Primary and secondary esterification reactions were carried out, but a tertiary esterification reaction was not performed. Furthermore, the condensation polymerization step was carried out by adding the oligomer to the prepolymer to produce the polymer. As shown in Tables 3 and 4 below, the contents of adipic acid, terephthalic acid, cellulose nanocrystals, oligomer, and chain extender differed, resulting in different process conditions. Other steps were carried out substantially by reference to Example 1 or Example 2.

[0418] Manufacturing of biodegradable polyester sheets After preparing two Teflon® sheets, a stainless steel (SUS) frame (area 12cm x 12cm) was placed on one of the Teflon® sheets. Approximately 7g of the manufactured polyester resin pellets were placed in the stainless steel (SUS) frame (area 12cm x 12cm), then covered with the other Teflon® sheet and placed in the center of a hot press (manufacturer: Wizwrap, model: WL1600SA) with a surface area of ​​approximately 25cm x 25cm. This was maintained at approximately 210°C under a pressure of approximately 10 MPa for approximately 3 minutes, then removed, and immediately cooled in water at approximately 20°C for approximately 30 seconds to produce a biodegradable polyester sheet with an area of ​​approximately 10cm x 10cm and a thickness of approximately 300 μm.

[0419] Manufacturing of biodegradable polyester film The biodegradable polyester resin pellets were dried at 80°C for 5 hours, and then melt-extruded at 160°C using a Blown Film Extrusion Line (manufactured by Yujin Engineering) to produce a biodegradable polyester film with a thickness of 50 μm.

[0420] [Table 1]

[0421] As shown in Table 2 below, the molar ratio of the monomer composition and the conditions for the tertiary esterification reaction differ.

[0422] [Table 2]

[0423] [Table 3]

[0424] [Table 4]

[0425] <Example of evaluation> Evaluation Example 1: Average particle size (D50) and standard deviation <Average particle size (D50) and standard deviation of aromatic dicarboxylic acids> The average particle size (D50) and standard deviation (SD) of aromatic dicarboxylic acids (TPA or DMT) were determined using a Microtrac S3500 particle size analyzer (Microtrac Inc.) under the following conditions:

[0426] Usage environment -Temperature: 10~35℃, Humidity: 90%RH, non-condensing maximum - The average particle size distribution (D50) and standard deviation (SD) for each section were measured.

[0427] The aforementioned standard deviation represents the square root of the variance and can be calculated using software.

[0428] <Particle size of nanocellulose> For nanocellulose, particle size and particle size deviation were measured using the principle of dynamic light scattering (DLS) at a temperature of 25°C and a measurement angle of 175°C, using a Zetasizer Nano ZS (manufacturer: Marven). At this time, the peak value derived from the polydispersity index (PdI) with a confidence interval of 0.5 was measured as the particle size.

[0429] Evaluation Example 2: Degree of Hydrolysis The biodegradable polyester resins produced in the examples and comparative examples were immersed in water at 80°C (100% RH), and then subjected to an accelerated water decomposition test.

[0430] Specifically, 5g each of the polyester resins used in the examples and comparative examples were added to 500mL of deionized water (DI Water). The container was then sealed to prevent evaporation, and a water decomposition acceleration test was conducted in a convection oven at 80°C. The humidity environment for the biodegradable polyester sheets was the same as that used for 100% RH testing, as they were immersed in water.

[0431] The number-average molecular weight of the polyester resins in the examples and comparative examples was measured after a certain period of time using gel permeation chromatography (GPC). The degree of hydrolysis was derived by dividing the difference between the initial number-average molecular weight and the number-average molecular weight after the period of time by the initial number-average molecular weight.

[0432] Evaluation Example 3: Biodegradability The biodegradable polyester resins produced in the examples and comparative examples were mixed with the following compost, and a biodegradation acceleration test was conducted at a temperature of 60°C and a humidity of 90%.

[0433] The number-average molecular weight of the polyester resins in the examples and comparative examples was measured after a certain period of time using gel permeation chromatography (GPC). The biodegradability was derived by dividing the difference between the initial number-average molecular weight and the number-average molecular weight after the period of time by the initial number-average molecular weight.

[0434] compost Manufacturer: TaeheungF&G Product Name: Chisei-do (by-product fertilizer, Grade 1 compost) Compost composition: Pig manure 40 wt%, chicken manure 15 wt%, sawdust 37 wt%, zeolite 5 wt%, microbial preparation 3 wt%

[0435] Evaluation Example 4: Oligomer Content The biodegradable polyester pellets produced in the examples and comparative examples were crushed to obtain biodegradable polyester powder having an average particle size (D50) of approximately 50 μm. The biodegradable polyester powder was immersed in acetonitrile for approximately 24 hours. Subsequently, the upper solution was sampled, and the molecular weight and content of the components extracted by LC mass were measured using dibutyl phthalate as a standard.

[0436] HR-LC-MS equipped: Model (Orbitrap HR LC-MS, Q-Exactive, Thermo Fisher) Column:C18 LC detector: 254nm Eluent:5%ACN(with0.1%Formic acid) / 95%H2O-->100%ACN(with0.1%Formic acid) Ionization mode: ESI mode Mass:Positive50-750, 500-3000

[0437] Evaluation Example 5: Water Contact Angle and Polarity The water contact angle and polarity were measured on the surface of the biodegradable polyester sheets produced in the examples and comparative examples under the following conditions.

[0438] Surface tension: Wet tensile test mixture No. 40-64 Manufacturer: Wako Ingredients: Ethylene glycol, monoethyl ether Surface energy measuring instrument: MSA One-Click SFE (product name) / KRUSS (manufacturer)

[0439] The degree of biodegradation has been measured, as shown in Tables 5 and 6 below.

[0440] [Table 5]

[0441] [Table 6]

[0442] The degree of hydrolysis was measured as shown in Tables 7 and 8 below.

[0443] [Table 7]

[0444] [Table 8]

[0445] As shown in Tables 9 and 10 below, the contents of the first, second, third, and fourth oligomers were measured.

[0446] [Table 9]

[0447] [Table 10]

[0448] Molecular weight of the first oligomer: 421.18 Molecular weight of the second oligomer: 623.3 Molecular weight of the third oligomer: 643.3 Molecular weight of the fourth oligomer: 843.4

[0449] As shown in Tables 11 and 12 below, the surface properties of biodegradable polyester sheets in the examples and comparative examples have been measured.

[0450] [Table 11]

[0451] [Table 12]

[0452] As described in Tables 5 to 12 above, the biodegradable resin compositions according to the examples may have an appropriate degree of hydrolysis, an appropriate degree of biodegradation, and appropriate surface properties. [Industrial applicability]

[0453] The examples can be applied to biodegradable resin compositions, films, and molded articles.

Claims

1. Polyester resins containing diols, aromatic dicarboxylic acids and aliphatic dicarboxylic acids; and, It contains a hydrophilicity regulator with a molecular weight of 400 to 1300 in an amount of 5000 ppm to 20000 ppm. The hydrophilic modifier includes an oligomer formed by the reaction of at least two of the diol, the aromatic dicarboxylic acid, and the aliphatic dicarboxylic acid. Biodegradable polyester resin composition.

2. The degree of hydrolysis after one week was 35% to 60%. The degree of hydrolysis after 3 weeks is 85% or higher. The degree of hydrolysis after one week and the degree of hydrolysis after three weeks are measured by the following measurement method. The biodegradable polyester resin composition according to claim 1. [Measurement method] The degree of hydrolysis after one week is the rate of decrease in the number-average molecular weight of the biodegradable polyester resin composition compared to its initial state, when the biodegradable polyester resin composition is left for one week under high temperature and high humidity conditions of 80°C and 100% humidity. The degree of hydrolysis after three weeks is the rate of decrease in the number-average molecular weight of the biodegradable polyester resin composition compared to its initial state, when the biodegradable polyester resin composition is left for three weeks under high temperature and high humidity conditions of 80°C and 100% humidity.

3. The aforementioned hydrophilicity modifier is A first oligomer having a molecular weight between 415 and 425, A second oligomer having a molecular weight between 620 and 630, A third oligomer having a molecular weight between 640 and 650, A fourth oligomer having a molecular weight between 840 and 850, including, The biodegradable polyester resin composition according to claim 1.

4. The content of the first oligomer is 3000 to 5000 ppm based on the polyester resin. The content of the second oligomer is 2000 ppm to 4000 ppm based on the polyester resin. The content of the third oligomer is 500 ppm to 2000 ppm based on the polyester resin. The content of the fourth oligomer is 700 ppm to 2500 ppm based on the polyester resin. The biodegradable polyester resin composition according to claim 3.

5. The hydrophilicity regulator comprises a first oligomer, The first oligomer contains one first unit represented by the following chemical formula 8 and one second unit represented by the following chemical formula 9. The biodegradable polyester resin composition according to claim 1. 【Transformation 8】 【Chemistry 9】

6. The hydrophilicity regulator comprises a second oligomer and a third oligomer. The second oligomer contains one of the first units and two of the second units. The third oligomer contains two of the first unit and one of the second unit. The second oligomer is included in the hydrophilicity regulator in an even higher content than the third oligomer. The biodegradable polyester resin composition according to claim 5.

7. The hydrophilicity regulator further comprises a fourth oligomer, The fourth oligomer contains two of the first unit and two of the second unit. The biodegradable polyester resin composition according to claim 6.

8. The water contact angle measured by the following method is 65° to 90°, and the polarity measured by the following method is 4 mN / m to 7 mN / m. The biodegradable polyester resin composition according to claim 1. [Measurement method] The biodegradable polyester resin composition is dried at a temperature of 80°C, placed in a stainless steel frame, and compressed at a temperature of 210°C and a pressure of 10 MPa for 3 minutes to produce a polyester sheet having a thickness of 300 μm. The water contact angle and polarity are measured on the surface of the polyester sheet.

9. The degree of biodegradation after one week is 45% to 65%. The degree of biodegradation after 9 weeks is 85% or more. The degree of biodegradation after one week and the degree of biodegradation after nine weeks are measured by the following measurement method. The biodegradable polyester resin composition according to claim 1. [Measurement method] The degree of biodegradation after one week is the rate of decrease in molecular weight of the polyester resin composition compared to its initial state when the biodegradable polyester resin composition is left for one week under composting conditions, at a temperature of 60°C and a humidity of 90%. The degree of biodegradation after nine weeks is the rate of decrease in molecular weight of the polyester resin composition compared to its initial state, when the biodegradable polyester resin composition is left under composting conditions, at a temperature of 60°C and a humidity of 90% for nine weeks.

10. A polyester resin containing diols, aromatic dicarboxylic acids and aliphatic dicarboxylic acids; and a hydrophilicity regulator having a molecular weight of 400 to 1300, in an amount of 5000 ppm to 20000 ppm. The hydrophilic modifier includes an oligomer formed by the reaction of at least two of the diol, the aromatic dicarboxylic acid, and the aliphatic dicarboxylic acid. Biodegradable molded articles containing a biodegradable resin composition.

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