Biodegradable molded articles and biodegradable polyester resin compositions

Abstract

The example includes a polyester resin containing a diol, an aromatic dicarboxylic acid, and an aliphatic dicarboxylic acid, and has a biodegradability per degree of hydrolysis of 1.35 or more. The biodegradability per degree of hydrolysis is a value obtained by dividing the biodegradability after 9 weeks by the degree of hydrolysis after 1 week. The biodegradability after 9 weeks and the degree of hydrolysis after 1 week disclose a biodegradable molded article measured by the following measurement method.

Description

[Technical Field]

[0001] The examples relate to biodegradable molded articles, biodegradable polyester resin compositions, and biodegradable polyester films. [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 used product ends, they have the disadvantage of releasing harmful substances when incinerated, and some types take hundreds of years 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 biodegradable molded articles, biodegradable polyester resin compositions, and biodegradable polyester films that have an appropriate degree of hydrolysis resistance and high biodegradability. [Means for solving the problem]

[0006] The biodegradable molded articles according to the examples contain a polyester resin containing a diol, an aromatic dicarboxylic acid, and an aliphatic dicarboxylic acid, and have a biodegradation rate of 1.4 or higher per degree of hydrolysis. The biodegradation rate per degree of hydrolysis is the value obtained by dividing the biodegradation rate after 9 weeks by the biodegradation rate after 1 week, and the biodegradation rate after 9 weeks and the biodegradation rate after 1 week are measured by the following measurement method.

[0007] [Measurement method] The degree of biodegradation after 9 weeks is the rate of decrease in molecular weight of the biodegradable molded product compared to its initial state, when the biodegradable molded product is processed into flakes with a thickness of 300 μm and dimensions of 30 mm × 30 mm, and left for 63 days under composting conditions, at a temperature of 60°C and a humidity of 90%. The degree of hydrolysis after one week is the rate of decrease in molecular weight of the biodegradable molded article compared to its initial state when the flakes are left at a temperature of 80°C and a humidity of 100% for 7 days.

[0008] One example of a biodegradable molded article has an average diameter of 0.5 nm to 10 nm, an average length of 20 nm to 300 nm, and contains nanocellulose containing metal.

[0009] The biodegradable molded article according to one embodiment further contains a metal salt and a silicon element, and the mass ratio of the metal element contained in the metal salt to the silicon element is 0.1 to 0.7.

[0010] The polyester resin composition according to the example comprises a polyester resin containing a diol, an aromatic dicarboxylic acid, and an aliphatic dicarboxylic acid, and has a biodegradability of 1.35 or more per degree of hydrolysis. The biodegradability per degree of hydrolysis is the value obtained by dividing the biodegradability after 9 weeks by the biodegradability after 1 week, and the biodegradability after 9 weeks and the biodegradability after 1 week are measured by the following measurement method.

[0011] [Measurement method] The degree of biodegradation after 9 weeks is the rate of decrease in molecular weight of the polyester resin relative to its initial state when the biodegradable polyester resin composition is processed into flakes with a thickness of 300 μm and dimensions of 30 mm × 30 mm and left to stand for 63 days under composting conditions, a temperature of 60°C, and a humidity of 90%, and the degree of hydrolysis after 1 week is the rate of decrease in molecular weight of the polyester resin relative to its initial state when the flakes are left to stand for 7 days under conditions of a temperature of 80°C and a humidity of 100%.

[0012] In the biodegradable resin composition according to one embodiment, the degree of biodegradation after 9 weeks may be 75% or more, and the degree of hydrolysis after 1 week may be 60%.

[0013] In one embodiment of the biodegradable polyester resin composition, the degree of biodegradation after one week is 45% to 75%, and the degree of biodegradation after one week may be the percentage decrease in molecular weight of the flakes compared to their initial state when the flakes are placed under composting conditions, at a temperature of 60°C and a humidity of 90% for 7 days.

[0014] In one embodiment of the biodegradable polyester resin composition, the degree of hydrolysis after 9 weeks is 80% or more, and the degree of hydrolysis after 9 weeks may be the rate of decrease in molecular weight of the flakes relative to their initial state when the flakes are placed at a temperature of 80°C and a humidity of 100% for 63 days.

[0015] In the biodegradable polyester resin composition according to one example, the acid value may be 2.0 mg KOH / g or less.

[0016] In one embodiment of the biodegradable polyester resin composition, the rate of increase in the degree of biodegradation from week 1 to week 4 may be 3.5% / week to 8% / week.

[0017] In one example of a biodegradable polyester resin composition, the rate of increase in the degree of hydrolysis from week 1 to week 2 is 29% / week to 50% / week, and the rate of increase in the degree of hydrolysis from week 3 to week 6 may be 0.01% / week to 3% / week.

[0018] In the biodegradable polyester resin composition according to one embodiment, the rate of increase in the degree of hydrolysis from 2 weeks to 3 weeks may be 3% / week to 10% / week.

[0019] The biodegradable polyester resin composition according to one embodiment contains a metal salt and a silicon element, and the ratio of the mass of the metal element contained in the metal salt to the silicon element may be 0.1 to 0.7.

[0020] The biodegradable polyester resin composition according to another embodiment contains a polyester resin containing a diol, an aromatic dicarboxylic acid, and an aliphatic dicarboxylic acid, and the degree of biodegradation per aliphatic carboxylic acid is 1.7 or more. The degree of biodegradation per aliphatic carboxylic acid is a value obtained by dividing the degree of biodegradation after 9 weeks by the ratio of the aliphatic dicarboxylic acid in the total dicarboxylic acids. The degree of biodegradation after 9 weeks is 85% or more, and the degree of biodegradation after 9 weeks is measured by the following measurement method.

[0021] [Measurement method] The degree of biodegradation after 9 weeks is the rate of decrease in the molecular weight of the polyester resin composition with respect to the initial value when the biodegradable polyester resin composition is placed under composting conditions, at a temperature of 60°C and a humidity of 90% for 9 weeks.

[0022] In the biodegradable polyester resin composition according to one embodiment, the degree of biodegradation after 9 weeks may be 88% or more.

[0023] In the biodegradable polyester resin composition according to one embodiment, the degree of biodegradation after 1 week is 45% to 65%, and the degree of biodegradation after 1 week may be the rate of decrease in the molecular weight of the biodegradable polyester resin composition with respect to the initial value when the biodegradable polyester resin composition is placed under composting conditions, at a temperature of 60°C and a humidity of 90% for 1 week.

[0024] In a biodegradable polyester resin composition according to an embodiment, the biodegradation degree after 2 weeks is 55% to 70%, and the biodegradation degree after 2 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 2 weeks under composting conditions, a temperature of 60°C, and a humidity of 90%.

[0025] In a biodegradable polyester resin composition according to an embodiment, the increase rate of the biodegradation degree from 1 week to 2 weeks may be about 4% / week to about 15% / week.

[0026] In a biodegradable polyester resin composition according to an embodiment, the biodegradation degree after 4 weeks is 73% to 85%, and the biodegradation degree 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%, and the increase rate of the biodegradation degree from 1 week to 4 weeks may be 3.5% / week to 8% / week.

[0027] In a biodegradable polyester resin composition according to an embodiment, the hydrolysis degree after 1 week is 35% to 60%, and the hydrolysis degree after 1 week 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 film is placed for 1 week under high temperature and high humidity conditions of a temperature of 80°C and a humidity of 100%.

[0028] In a biodegradable polyester resin composition according to an embodiment, it may contain a nitrogen element.

Advantages of the Invention

[0029] The biodegradable molded articles, biodegradable polyester resin compositions, and biodegradable films according to the examples may have a biodegradation rate of 1.35 or higher per degree of hydrolysis. This allows the biodegradable molded articles, biodegradable polyester resin compositions, and biodegradable films according to the examples to have a high degree of biodegradation while having an appropriately low degree of hydrolysis. In particular, the biodegradable molded articles, biodegradable polyester resin compositions, and biodegradable films according to the examples may have a high degree of biodegradation in the later stages while having a low initial degree of hydrolysis.

[0030] Furthermore, the biodegradable polyester resin compositions according to the examples can be efficiently applied to packaging films and the like. The biodegradable molded articles and biodegradable films according to the examples can be used for ordinary purposes such as packaging.

[0031] The biodegradable molded articles, biodegradable polyester resin compositions, and biodegradable films according to the examples have a low degree of hydrolysis initially, and therefore can maintain a certain level of mechanical and chemical properties within the user's normal usage period.

[0032] Furthermore, the biodegradable molded articles, biodegradable polyester resin compositions, and biodegradable films according to the examples have a high degree of biodegradation relative to the degree of hydrolysis, and can therefore be easily decomposed when disposed of after use.

[0033] Furthermore, the biodegradable polyester resin compositions according to the examples have a biodegradability of 1.6 or more per aliphatic carboxylic acid. In other words, the biodegradable polyester resin compositions according to the examples have a low aliphatic carboxylic acid content and a high biodegradability.

[0034] As a result, the biodegradable polyester resin composition according to the examples may have a relatively high aromatic carboxylic acid content, and therefore may have a high degree of hydrolysis resistance and a high degree of biodegradation.

[0035] Furthermore, the biodegradable polyester resin composition according to the examples may have a low initial degree of hydrolysis and a high later degree of hydrolysis.

[0036] As a result, the biodegradable polyester resin composition 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 composition according to the examples has a high degree of late-stage hydrolysis, it can be easily decomposed in rivers or the sea. In other words, the biodegradable polyester resin composition according to the examples can solve environmental problems such as marine plastic pollution. [Brief explanation of the drawing]

[0037] [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]

[0038] 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 into various forms as long as the gist of the invention remains unchanged.

[0039] In this specification, when a part is described as "including" a certain component, unless otherwise stated, this does not mean that it excludes other components, but rather that it may further include other components.

[0040] 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.

[0041] The terms first, second, primary, secondary, etc., used herein are used to describe various components, and the components are not limited to those terms. The terms are used solely for the purpose of distinguishing one component from another.

[0042] 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.

[0043] 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.

[0044] 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 may also be represented as the component.

[0045] The diol may be an aliphatic diol. The diol may be a bio-derived 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.

[0046] 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.

[0047] 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.

[0048] The diol may include 1,4-butanediol or a derivative thereof.

[0049] 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.

[0050] 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.

[0051] The aromatic dicarboxylic acid may include terephthalic acid, dimethyl terephthalate, or derivatives thereof.

[0052] 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.

[0053] 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.

[0054] The aliphatic dicarboxylic acid may include adipic acid or a derivative thereof.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] The biodegradable polyester resin may contain aromatic dicarboxylic acid residues derived from terephthalic acid or dimethyl terephthalate in an amount of about 30 mol% to about 70 mol% based on the total dicarboxylic acid. The biodegradable polyester resin may contain aromatic dicarboxylic acid residues derived from terephthalic acid or dimethyl terephthalate in an amount of about 35 mol% to about 65 mol% based on the total dicarboxylic acid. The biodegradable polyester resin may contain dicarboxylic acid residues derived from terephthalic acid or dimethyl terephthalate in an amount of about 40 mol% to about 60 mol% based on the total dicarboxylic acid. The biodegradable polyester resin may contain aromatic dicarboxylic acid residues derived from terephthalic acid or dimethyl terephthalate in an amount of about 43 mol% to about 53 mol% based on the total dicarboxylic acid.

[0059] 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.

[0060] 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.

[0061] 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 they are bonded to the aliphatic dicarboxylic acid.

[0062] 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.

[0063] 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 approximately 0.5 to approximately 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 approximately 0.6 to approximately 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 approximately 0.7 to approximately 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 approximately 0.75 to approximately 1.2. Furthermore, 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. The number of the first blocks may be even smaller than the number of the second blocks.

[0064] 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.

[0065] The number of the first blocks may vary depending on the content of the aromatic dicarboxylic acid and the molecular weight of the biodegradable polyester resin. That is, 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.

[0066] 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.

[0067] 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 degree of alternation described later.

[0068] 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.

[0069] The first block may be represented by the following formula 1.

[0070] [ka]

[0071] 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.

[0072] R1 may be a substituted or unsubstituted phenylene group, and R2 may be a butylene group.

[0073] The second block may be represented by the formula shown in 2 below.

[0074] [ka]

[0075] 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.

[0076] R3 and R4 may be butylene groups.

[0077] 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.

[0078] [ka]

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] The first block may be represented by the following formula 4, and the second block may be represented by the following formula 5.

[0087] [ka]

[0088] Here, m may range from 1 to 20.

[0089] [ka]

[0090] Here, n may range from 1 to 20.

[0091] The biodegradable polyester resin may be represented by the following chemical formula 6.

[0092] [ka]

[0093] Here, m is between 1 and 20, and n may also be between 1 and 20.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] Because 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 and improved UV resistance.

[0101] 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.

[0102] The aforementioned trivalent or higher alcohol may be selected from at least one of the group consisting of glycerol, pentaerythritol, or trimethylolpropane.

[0103] 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 (acids) may be selected.

[0104] 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.

[0105] Since the biodegradable polyester resin contains the branching agent within the above range, the biodegradable polyester resin composition according to the example may have improved UV properties, appropriate mechanical properties, and appropriate biodegradability.

[0106] 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 about 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 about 100 wt% based on the weight of the total composition.

[0107] 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.

[0108] The reinforcing material may be a fiber derived from biomass. The reinforcing material may be a fiber made of an organic substance. The reinforcing material may be nanocellulose.

[0109] 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.

[0110] 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.

[0111] The nanocellulose may be represented by the following chemical formula 7.

[0112] [ka]

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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%.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] The diameter and length of the nanocellulose can be measured by atomic force microscopy while it is dispersed in water.

[0121] The sulfur content of the nanocellulose may be about 0.1 wt% to about 1.2 wt% based on the total nanocrystalline cellulose.

[0122] The pH of the nanocellulose may be 5 to 8. The pH of the nanocellulose may be 6 to 8.

[0123] 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.

[0124] 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.

[0125] Because the nanocellulose has the characteristics described above, it can be uniformly dispersed in the biodegradable polyester resin composition according to the examples.

[0126] Because the nanocellulose has the characteristics described above, it can improve the mechanical properties of the biodegradable polyester resin composition according to the examples.

[0127] Furthermore, the nanocellulose acts 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.

[0128] Since the nanocellulose has the characteristics described above, the biodegradable polyester resin composition according to the examples may have appropriate UV resistance properties.

[0129] Since the nanocellulose has the characteristics described above, the biodegradable polyester resin composition according to the examples may have an appropriate biodegradation rate.

[0130] Since the nanocellulose has the characteristics described above, the biodegradable polyester resin composition according to the examples may have an appropriate hydrolysis rate.

[0131] The biodegradable polyester resin compositions according to the examples may also contain metal salts.

[0132] The metal salt may be included in a content of about 0.1 ppm to about 1000 ppm based on the total weight of the biodegradable polyester resin composition according to the examples. The metal salt may be included in a content of about 1 ppm to about 500 ppm based on the total weight of the biodegradable polyester resin composition according to the examples. The metal salt may be included in a content of about 1 ppm to about 100 ppm based on the total weight of the biodegradable polyester resin composition according to the examples. The metal salt may be included in a content of about 1 ppm to about 50 ppm based on the total weight of the biodegradable polyester resin composition according to the examples.

[0133] 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.

[0134] 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).

[0135] Furthermore, the metal salt may be selected from the group consisting of acetate, nitrate, nitride, sulfide, sulfate, sulfoxide, hydrooxide, hydrate, chloride, chlorinate, and bromide.

[0136] 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.

[0137] The biodegradable polyester resin composition according to the examples may further contain a hydrolysis-resistant agent.

[0138] The hydrolysis-resistant agent may be selected from at least one silicon-based compound such as silane, silazane, or siloxane.

[0139] 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 3-glycidyloxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyl methyldimethoxysilane, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl methyldiethoxysilane, or 3-glycidoxypropyl triethoxysilane.

[0140] The hydrolysis-resistant agent may be included in the biodegradable polyester resin composition according to the examples at a content of about 1 ppm to about 30,000 ppm based on the weight of the total composition. The hydrolysis-resistant agent may be included in the biodegradable polyester resin composition according to the examples at 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 at a content of about 5 ppm to 5,000 ppm. The hydrolysis-resistant agent may be included in the biodegradable polyester resin composition according to the examples at a content of about 10 ppm to 3,000 ppm.

[0141] 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.

[0142] 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.

[0143] 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 1000 ppm. The biodegradable polyester resin composition according to the examples may contain silicon in a content of about 0.1 ppm to about 500 ppm. The biodegradable polyester resin composition according to the examples may contain silicon in a content of about 0.1 ppm to about 100 ppm.

[0144] 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.

[0145] 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.

[0146] The biodegradable polyester resin composition according to the examples may further contain a chain extender.

[0147] The chain extender may contain an isocyanate.

[0148] The chain extender may be selected from the group consisting of monofunctional isocyanates or polyfunctional isocyanates, with at least one selected from this group.

[0149] 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-isocyanatocyclohexane).

[0150] The chain extender may contain triisocyanate. The chain extender may also contain tri(4-isocyanatophenyl)methane.

[0151] 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.

[0152] The chain extender may include a styrene copolymer. The chain extender may also include a styrene glycidyl acrylate.

[0153] 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.

[0154] 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%.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] The biodegradable polyester resin composition according to the examples may contain a heat stabilizer. The heat stabilizer may be a phosphorus-based heat stabilizer.

[0159] The heat stabilizer may be at least one selected from the group consisting of amine-based high-temperature heat stabilizers such as tetraethylenepentamine, triethylphosphonoacetate, phosphoric acid, phosphorous acid, polyphosphoric acid, trimethyl phosphate (TMP), triethyl phosphate, trimethyl phosphine, or triphenyl phosphine.

[0160] Furthermore, the heat stabilizer may be an antioxidant having an antioxidant function.

[0161] 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 1,000 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.

[0162] 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.

[0163] The elongation improver may be included in the biodegradable polyester resin composition according to the examples at a content 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 at a content of about 0.01 parts by weight to about 1 part by weight based on 100 parts by weight of the biodegradable polyester resin.

[0164] The biodegradable polyester resin composition according to the examples 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.

[0165] Regarding the inorganic filler, the particle size (D 50 ) at which the cumulative volume is 50% based on the volume in the particle size distribution obtained by the laser diffraction method 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.

[0166] 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.

[0167] The inorganic filler may be included in the biodegradable polyester resin composition according to the examples in an amount of about 3 to about 50 parts by weight based on 100 parts by weight of the biodegradable polyester resin. The inorganic filler may be included in the biodegradable polyester resin composition according to the examples in an amount of about 5 to about 30 parts by weight based on 100 parts by weight of the biodegradable polyester resin.

[0168] The inorganic filler may be included in a content of about 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 about 3,000 ppm or less, about 1,500 ppm or less, about 1,200 ppm or less, about 800 ppm or less, or about 600 ppm or less based on the total weight of the biodegradable polyester resin composition according to the examples, and may be about 50 ppm or more, about 100 ppm or more, about 130 ppm or more, about 150 ppm or more, or about 180 ppm or more.

[0169] 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.

[0170] 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.

[0171] 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).

[0172] 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.

[0173] 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.

[0174] The process by which the biodegradable polyester resin composition according to the examples is produced is as follows:

[0175] 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.

[0176] The method for producing the biodegradable polyester resin includes the step of producing a slurry containing the diol and the aromatic dicarboxylic acid.

[0177] 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. In this case, the diol may include a biomass-based diol component.

[0178] 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.

[0179] The diol and the aromatic dicarboxylic acid can be added to the slurry stirrer 100 and stirred to produce the slurry.

[0180] 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.

[0181] 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 plays 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.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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 180 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.

[0186] In the aforementioned pretreatment step, the diol and the aromatic dicarboxylic acid can be mixed and then introduced into the slurry agitator 100 (tank).

[0187] The slurry agitator 100 may be even more advantageous in achieving an efficient stirring effect 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 three or more rotating blades.

[0188] For example, the slurry stirrer 100 may have a height of 20 mm or more from the stirrer, meaning that there is almost no contact between the reactor and the bottom of the stirrer, in which case a slurry can be obtained without sedimentation. If the pattern, shape, and blades of the stirrer 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, in which case phase separation may occur.

[0189] 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.

[0190] The aforementioned diol may have the characteristics described above.

[0191] The diol can be added all at once or in portions. For example, the diol can be added separately when mixed with an aromatic dicarboxylic acid and when mixed with an aliphatic dicarboxylic acid.

[0192] The aforementioned aromatic dicarboxylic acid may have the same characteristics as described above.

[0193] 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.

[0194] If the diol is added in an even larger amount than the aromatic dicarboxylic acid, the aromatic dicarboxylic acid can be easily dispersed.

[0195] 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.

[0196] 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, and then using that slurry to carry out an esterification reaction to obtain a prepolymer. By carrying out a condensation polymerization reaction on the prepolymer, the desired structure and physical properties of the biodegradable polyester resin can be efficiently achieved through the embodiment of the present invention.

[0197] The method for producing the biodegradable polyester resin includes a step of producing a prepolymer by esterifying the slurry and the aliphatic dicarboxylic acid. The slurry and the aliphatic dicarboxylic acid can be reacted in the esterification reaction section.

[0198] In the esterification reaction, the reaction time can be shortened by using the slurry. For example, the slurry obtained in the pretreatment step can shorten the reaction time of the esterification reaction by 1.5 times or more.

[0199] The esterification reaction can be carried out at least twice. The esterification reaction can form a prepolymer that will be introduced into the condensation polymerization step.

[0200] In one embodiment, the esterification reaction can be carried out in one step after adding an aliphatic dicarboxylic acid, or a diol and an aliphatic dicarboxylic acid, to the slurry. That is, the slurry can be introduced into the esterification reactor, and the esterification reaction can be carried out by introducing either the aliphatic dicarboxylic acid alone, or the aliphatic dicarboxylic acid and the diol, into the esterification reactor.

[0201] The diol and the aliphatic dicarboxylic acid may be added in slurry form to a slurry containing the aromatic dicarboxylic acid.

[0202] The average particle size (D50) of the aliphatic dicarboxylic acid in the slurry of the diol and the aliphatic dicarboxylic acid may be about 50 μm to about 150 μm. The average particle size (D50) of the aliphatic dicarboxylic acid in the slurry of the diol and the aliphatic dicarboxylic acid may be about 60 μm to about 120 μm.

[0203] In the esterification reaction, the total number of moles of diol added 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 added 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.

[0204] Furthermore, the temperature of the slurry of the diol and the aliphatic dicarboxylic acid may be about 5°C to 15°C higher than the melting point of the diol.

[0205] Furthermore, the various additives, such as the nanocellulose, may also be added to the slurry of the diol and the aliphatic dicarboxylic acid.

[0206] The esterification reaction can be carried out at a temperature of approximately 250°C or lower for approximately 0.5 to 5 hours. Specifically, the esterification reaction can be carried out at a temperature of approximately 180°C to 250°C, approximately 185°C to 240°C, or approximately 200°C to 240°C, under atmospheric or reduced pressure until the by-product water theoretically accounts for 95%. For example, the esterification reaction can be carried out for 0.5 to 5.5 hours, 0.5 to 4.5 hours, or 1 to 4 hours, but is not limited to these.

[0207] In one embodiment, the slurry, the aliphatic dicarboxylic acid, and the diol can be mixed to carry out the first esterification reaction. In this case, the molar ratio of the aromatic dicarboxylic acid to the aliphatic dicarboxylic acid in the reaction mixture for the first esterification reaction may be 1:0.05 to 1:0.5.

[0208] Furthermore, after the first esterification reaction, the slurry, the aliphatic dicarboxylic acid, and the diol mixture can be added to the esterification reaction chamber to carry out a second esterification reaction together with the first esterification reaction product. In this case, the molar ratio of the aromatic dicarboxylic acid to the aliphatic dicarboxylic acid in the mixture added in the second esterification reaction may be 0.05:1 to 0.5:1.

[0209] The first esterification reaction can be carried out at a temperature of 250°C or lower for 1.25 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 atmospheric or reduced pressure until the by-product water theoretically accounts for 95%. For example, the first esterification reaction can be carried out for 1.25 to 4 hours, 1.25 to 3.5 hours, or 2.5 to 3 hours, but is not limited to these.

[0210] 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 2.5 hours, but is not limited to these.

[0211] In the first and second esterification reactions, the reaction temperature, reaction time, and the content of the diol, aromatic dicarboxylic acid, and aliphatic dicarboxylic acid added can be adjusted to control the ratio of the first and second blocks. Furthermore, when the esterification reaction is carried out separately as a first and second esterification reaction, the overall esterification reaction can be precisely controlled. This can improve the reaction stability and reaction uniformity of the esterification reaction when it is carried out separately.

[0212] Furthermore, the branching agent can be added to the second ester reaction. That is, the slurry, the aliphatic dicarboxylic acid, the mixture of the diol, the branching agent, and the first ester reaction product can react to form the prepolymer. The characteristics and content of the branching agent may be the same as those described above.

[0213] The second esterification reaction described above can form a prepolymer.

[0214] The number-average molecular weight of the prepolymer may be approximately 500 to approximately 10,000 g / mol. For example, the number-average 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 800 g / mol to approximately 4,000 g / mol. By satisfying the above range for the number-average molecular weight of the prepolymer, the molecular weight of the polymer in the condensation polymerization reaction can be efficiently increased.

[0215] The aforementioned number-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 number-average molecular weight (Mn) as the reference.

[0216] The reinforcing material and / or the metal salt may be added together with the slurry before the esterification reaction. The reinforcing material and / or the metal salt may be added to the esterification reaction section 200 during the esterification reaction. The reinforcing material and / or the metal salt may be added to the esterification reaction product after the esterification reaction. The reinforcing material and / or the metal salt may also be added together with the aliphatic dicarboxylic acid. The reinforcing material and / or the metal salt may also be added to the esterification reaction section 200 after the first esterification reaction and before the second esterification reaction.

[0217] 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.

[0218] The reinforcing material may have the characteristics described above. In particular, nanocellulose can be used as the reinforcing material.

[0219] The nanocellulose may be pretreated by a bead mill, by ultrasound, or by high-speed dispersion at approximately 1000 rpm to 1500 rpm before being introduced. Specifically, the nanocellulose may be water-dispersed nanocellulose that has been pretreated by a bead mill or by ultrasound.

[0220] For the time being, the bead mill pretreatment can be carried out using a wet milling apparatus, either a vertical mill or a horizontal mill. A horizontal mill is preferable because it can fill the chamber with a larger quantity of beads, reduces uneven wear on the machine, reduces bead wear, and facilitates maintenance, but it is not limited to this.

[0221] The bead mill pretreatment described above can be carried out using one or more beads selected from the group consisting of zirconium, zircon, zirconia, quartz, and aluminum oxide.

[0222] Specifically, the bead mill pretreatment can be carried out using beads having a diameter of approximately 0.3 mm to approximately 1 mm. For example, the diameter of the beads may be approximately 0.3 mm to approximately 0.9 mm, approximately 0.4 mm to approximately 0.8 mm, approximately 0.45 mm to approximately 0.7 mm, or approximately 0.45 mm to approximately 0.6 mm.

[0223] By keeping the bead diameter within the above range, the dispersibility of nanocellulose can be further improved. If the bead diameter exceeds this range, the average particle size and particle size deviation of the nanocellulose may increase, potentially leading to decreased dispersibility.

[0224] 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 the method is not limited thereto.

[0225] 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.

[0226] 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 output exceeds the above range, the nanoparticles may re-aggregate, resulting in lower dispersibility.

[0227] The nanocellulose in the embodiment may be pre-treated with a bead mill or ultrasonically. Alternatively, the nanocellulose in the embodiment may be pre-treated with both a bead mill and ultrasonically. In this case, performing ultrasonic pre-treatment after bead mill pre-treatment is preferable in that it prevents re-aggregation and improves dispersibility.

[0228] The nanocellulose in the embodiment may be pre-treated with a bead mill or ultrasonically. Alternatively, the nanocellulose in the embodiment may be pre-treated with both a bead mill and ultrasonically. In this case, performing ultrasonic pre-treatment after bead mill pre-treatment is preferable in that it prevents re-aggregation and improves dispersibility.

[0229] 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. The content of the nanocellulose in the aqueous dispersion of the nanocellulose may be about 1 wt% to about 50 wt%.

[0230] 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.

[0231] 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.

[0232] The biodegradable polyester resin may contain one or more titanium-based catalysts selected from the group consisting of titanium isopropoxide, antimony trioxide, dibutyltine oxide, 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.

[0233] Furthermore, the content of the catalyst may be approximately 50 ppm to 2000 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 60 ppm to 1600 ppm, approximately 70 ppm to 1400 ppm, approximately 80 ppm to 1200 ppm, or approximately 100 ppm to 1100 ppm. By satisfying the above range for the catalyst content, the physical properties can be further improved.

[0234] 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.

[0235] The characteristics of the heat stabilizer may be the same as those described above.

[0236] 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 1,000 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.

[0237] 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.

[0238] 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 can be added and stabilized, and then the polymerization condensation reaction can be carried out. The characteristics of the inorganic filler are as described above. The inorganic filler can 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 can be uniformly dispersed in the biodegradable polyester resin.

[0239] 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 to the esterification reaction unit 200 or by refluxing.

[0240] 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.

[0241] 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.

[0242] 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 4.5 hours, or approximately 2 hours to approximately 4 hours.

[0243] Furthermore, the condensation polymerization reaction may include primary and secondary condensation polymerization.

[0244] 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.

[0245] 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.

[0246] 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 tetraethylenepentamine; and polymerization catalysts such as antimontrioxide, antimony trioxide, or tetrabutyl titanate may be added to the prepolymer.

[0247] The number-average molecular weight of the polymer may be approximately 30,000 g / mol or more. For example, the number-average molecular weight of the polymer may be approximately 33,000 g / mol or more, approximately 35,000 g / mol or more, or approximately 40,000 g / mol to approximately 90,000 g / mol. By satisfying the above range for the number-average molecular weight of the polymer, the physical properties, impact resistance, durability, and moldability can be further improved.

[0248] 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.

[0249] 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.

[0250] 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.

[0251] 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 react 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.

[0252] The hydrolysis-resistant agent may have the same characteristics as described above.

[0253] The chain extender may have the same characteristics as described above.

[0254] 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.

[0255] Subsequently, pellets can be produced from the polymer.

[0256] 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.

[0257] The aforementioned cutting stage can be carried out 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.

[0258] 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.

[0259] 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 extrude them again. In other words, the post-processing unit 400 may include an extruder such as a twin-screw extruder.

[0260] 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.

[0261] 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.

[0262] Subsequently, the resin extruded by the extruder may be cooled, cut, and processed into post-treated pellets. In other words, the resin extruded from the extruder may be reprocessed into pellets by the cutting step described above.

[0263] The degree of crystallinity of the pellets can be improved by the post-processing step. Furthermore, the content of residues contained in the pellets can be adjusted by the post-processing step. In particular, the content of oligomers contained in the pellets can be adjusted by the post-processing step. The content of residual solvents contained in the pellets can also be adjusted by the post-processing step.

[0264] 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.

[0265] 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, the light stabilizer, the color corrector, or the other additives can be compounded with the biodegradable polyester resin and the two types of biodegradable resins.

[0266] The compounding process is as follows:

[0267] 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 fed into an extruder. The mixed biodegradable polyester resin composition is melted in the extruder 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.

[0268] In contrast, the inorganic filler, the heat stabilizer, the color corrector, the metal salt, and the other additives may be introduced during the polymerization process of the biodegradable polyester resin.

[0269] A biodegradable polyester film can be produced using the biodegradable polyester resin composition according to the examples.

[0270] 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.

[0271] 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.

[0272] On the other hand, the biodegradable polyester film can be manufactured using the biodegradable polyester resin or biodegradable polyester resin pellets.

[0273] Specifically, the method for producing the biodegradable polyester film may include the steps of producing a biodegradable polyester resin composition according to the examples, and drying and melt-extruding the biodegradable polyester resin composition.

[0274] In the step of drying and melt-extruding the biodegradable polyester resin composition, the drying can be carried out at approximately 60°C to approximately 100°C for approximately 2 to approximately 12 hours. Specifically, the drying can be carried out at 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.

[0275] 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 a blown film process. The melt extrusion can be carried out using a T-die.

[0276] Furthermore, the film manufacturing process may also be a calendering process.

[0277] Biodegradable polyester molded articles can be manufactured using the aforementioned biodegradable polyester resin.

[0278] 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.

[0279] For example, the molded product may be in the form of a film or sheet used for agricultural mulching films, disposable gloves, disposable films, disposable envelopes, food packaging materials, weight-based garbage bags, etc., or may be in the form of fibers used for textiles, knitted fabrics, non-woven fabrics, ropes, etc. Further, as shown in FIG. 2, the molded product may be in the form of a disposable container used for food packaging containers such as lunch boxes. Also, the molded product may be molded products in various forms such as disposable straws, spoons, food plates, forks, etc.

[0280] In particular, since the molded product can be formed from the biodegradable polyester resin which can improve not only physical properties such as impact absorption energy and hardness, but particularly impact resistance and durability, it can exhibit excellent characteristics 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.

[0281] The physical properties of the biodegradable film and the biodegradable molded product can be measured in a manner similar to the biodegradable polyester resin composition according to the examples.

[0282] The biodegradable polyester resin composition according to the examples can measure the degree of biodegradation by the following method.

[0283] In order to measure the degree of biodegradation, the biodegradable polyester resin composition according to the above examples was mixed with compost, and a biodegradation acceleration test was carried out 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 examples was measured using gel permeation chromatography (GPC). The degree of biodegradation was derived from the value obtained by dividing the difference between the initial number average molecular weight and the number average molecular weight after biodegradation for a certain period by the initial number average molecular weight.

[0284] The degree of biodegradation may be represented by the following formula 10.

[0285] [Formula 1] JPEG0007879276000008.jpg13158

[0286] 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 for a certain period are measured by gel permeation chromatography (GPC).

[0287] 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.

[0288] 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.

[0289] 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).

[0290] 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.

[0291] 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%.

[0292] 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%.

[0293] In the biodegradable polyester resin composition according to the examples, the degree of biodegradation after 3 weeks may be about 63% to about 75%.

[0294] 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%.

[0295] 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%.

[0296] 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.

[0297] In the biodegradable polyester resin composition according to the examples, the rate of increase in biodegradation from week 1 to week 2 may be about 4% / week to about 15% / week. In the biodegradable polyester resin composition according to the examples, the rate of increase in biodegradation from week 1 to week 2 may be about 5% / week to about 13% / week.

[0298] The rate of increase in the biodegradability may be expressed by the following formula 2.

[0299] [Formula 2] JPEG0007879276000009.jpg12132

[0300] In other words, the rate of increase in biodegradation in formula 2 above refers to the rate of increase in biodegradation from week X to week Y.

[0301] In the biodegradable polyester resin composition according to the examples, the rate of increase in the degree of biodegradation from 2 to 3 weeks may be about 3% / week to about 10% / week. In the biodegradable polyester resin composition according to the examples, the rate of increase in the degree of biodegradation from 2 to 3 weeks may be about 4% / week to about 9% / week.

[0302] In the biodegradable polyester resin composition according to the embodiment, the rate of increase in biodegradability from 3 weeks to 4 weeks may be about 4% / week to about 10% / week. In the biodegradable polyester resin composition according to the embodiment, the rate of increase in biodegradability from 3 weeks to 4 weeks may be about 5% to about 9%.

[0303] In the biodegradable polyester resin composition according to the embodiment, the rate of increase in biodegradability from 4 weeks to 6 weeks may be about 3% / week to about 7% / week. In the biodegradable polyester resin composition according to the embodiment, the rate of increase in biodegradability from 4 weeks to 6 weeks may be about 4% / week to about 6% / week.

[0304] In the biodegradable polyester resin composition according to the embodiment, the rate of increase in biodegradability from 6 weeks to 9 weeks may be about 3% / week or less. In the biodegradable polyester resin composition according to the embodiment, the rate of increase in biodegradability from 6 weeks to 9 weeks may be about 2% / week or less.

[0305] Also, in the biodegradable polyester resin composition according to the embodiment, the rate of increase in biodegradability from 1 week to 4 weeks may be about 3% / week to about 10% / week. In the biodegradable polyester resin composition according to the embodiment, the rate of increase in biodegradability from 1 week to 4 weeks may be about 3.5% / week to about 8% / week.

[0306] The biodegradable polyester resin composition according to the embodiment has the biodegradability and the rate of increase in biodegradability as described above, so it may have appropriate durability in the actual living area and have a high biodegradability when discarded after use.

[0307] The degree of hydrolysis of the biodegradable polyester resin composition according to the embodiment can be measured by the following method.

[0308] To measure the degree of hydrolysis, the biodegradable polyester resin composition according to the above example was immersed in water at 80°C (100% RH), 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.

[0309] The degree of hydrolysis may be expressed by the following formula 3.

[0310] [Formula 3] JPEG0007879276000010.jpg13155

[0311] 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).

[0312] 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.

[0313] 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.

[0314] 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%.

[0315] 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%.

[0316] 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%.

[0317] 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%.

[0318] 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.

[0319] 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.

[0320] 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.

[0321] The rate of increase in the degree of hydrolysis may be expressed by the following formula 4.

[0322] [Equation 4] JPEG0007879276000011.jpg13151

[0323] In other words, the rate of increase in the degree of hydrolysis in the above formula 4 represents the rate of increase in the degree of hydrolysis from week X to week Y.

[0324] In the biodegradable resin composition according to the examples, the rate of increase in the degree of hydrolysis from 2 to 3 weeks may be about 3% / week to about 10% / week. In the biodegradable resin composition according to the examples, the rate of increase in the degree of hydrolysis from 2 to 3 weeks may be about 4% to about 8%.

[0325] Furthermore, in the biodegradable resin composition according to the examples, the rate of increase in the degree of hydrolysis from 3 to 6 weeks may be approximately 0.01% / week to approximately 3% / week. In the biodegradable resin composition according to the examples, the rate of increase in the degree of hydrolysis from 3 to 6 weeks may be approximately 0.01% / week to approximately 2% / week.

[0326] Furthermore, in the biodegradable resin composition according to the examples, the degree of biodegradation per degree of hydrolysis may be 1.35 or higher. The degree of biodegradation per degree of hydrolysis is the value obtained by dividing the degree of biodegradation after 9 weeks by the degree of hydrolysis after 1 week. The degree of biodegradation per degree of hydrolysis may also be represented by the following formula 5.

[0327] Because the biodegradable 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 resin compositions according to the examples have appropriate durability in everyday life, while being easily hydrolyzed upon disposal. In other words, because the biodegradable 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, even when the biodegradable resin compositions according to the examples are disposed of in rivers or the sea, they can be easily decomposed by hydrolysis and biodegradation after a sufficient amount of time has passed.

[0328] [Formula 5] JPEG0007879276000012.jpg17139

[0329] In the biodegradable resin composition according to the examples, the degree of biodegradation per degree of hydrolysis may be about 1.4 or more. In the biodegradable resin composition according to the examples, the degree of biodegradation per degree of hydrolysis may be about 1.45 or more. In the biodegradable resin composition according to the examples, the degree of biodegradation per degree of hydrolysis may be about 1.47 or more. In the biodegradable resin composition according to the examples, the degree of biodegradation per degree of hydrolysis may be about 1.50 or more. In the biodegradable resin composition according to the examples, the upper limit of the degree of biodegradation per degree of hydrolysis may be about 5.

[0330] As a result, the biodegradable polyester resin composition according to the examples may have a high degree of biodegradation while having a suitably low degree of hydrolysis. In particular, the biodegradable polyester resin composition according to the examples may have a high degree of biodegradation in the later stages while having a low initial degree of hydrolysis.

[0331] 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.

[0332] Furthermore, since the biodegradable polyester resin compositions according to the examples have a high degree of biodegradation relative to the degree of hydrolysis, films produced using the biodegradable polyester resin compositions according to the examples can be easily decomposed when disposed of after use.

[0333] Furthermore, the biodegradable polyester resin compositions according to the examples have a biodegradability of 1.6 or more per aliphatic carboxylic acid. In other words, the biodegradable polyester resin compositions according to the examples have a low aliphatic carboxylic acid content and a high biodegradability.

[0334] As a result, the biodegradable polyester resin composition according to the examples may have a relatively high aromatic carboxylic acid content, and therefore may have high hydrolysis resistance and a high degree of biodegradation.

[0335] Furthermore, the biodegradable polyester resin composition according to the examples may have a low initial degree of hydrolysis and a high later degree of hydrolysis.

[0336] As a result, the biodegradable polyester resin composition according to the examples can maintain a certain level of mechanical and chemical properties within the user's service life. In addition, because the biodegradable polyester resin composition according to the examples has a high degree of late-stage hydrolysis, it may decompose easily in rivers or the sea. In other words, the biodegradable polyester resin composition according to the examples can solve environmental problems such as marine plastic pollution.

[0337] In the biodegradable polyester resin composition according to the examples, the biodegradation rate per aliphatic carboxylic acid may be about 1.7 or higher. Alternatively, the biodegradation rate per aliphatic carboxylic acid may be about 1.75 or higher. Alternatively, the biodegradation rate per aliphatic carboxylic acid may be about 1.79 or higher. Alternatively, the biodegradation rate per aliphatic carboxylic acid may be about 1.8 or higher. Alternatively, the biodegradation rate per aliphatic carboxylic acid may be about 1.85 or higher. Alternatively, the biodegradation rate per aliphatic carboxylic acid may be about 1.90 or higher. The maximum value of the biodegradation rate per aliphatic carboxylic acid may be about 4.

[0338] 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. The biodegradation rate per unit of aliphatic carboxylic acid is the value obtained by dividing the biodegradation rate after 9 weeks by the mole percentage of the aliphatic carboxylic acid, based on the total dicarboxylic acid.

[0339] The degree of biodegradation per unit of aliphatic carboxylic acid may be expressed by the following formula 6.

[0340] [Formula 6] JPEG0007879276000013.jpg11160

[0341] The composition of the biodegradable polyester resin, such as the number of the first blocks, the number of the second blocks, 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.

[0342] For example, the hydrolysis-resistant agent and / or the chain extender can couple the polymer contained in the biodegradable polyester resin, thereby imparting hydrophobicity to the biodegradable polyester resin composition according to the example and reducing the initial hydrolysis rate. The strengthening agent, the oligomer, and / or the metal salt can accelerate the biodegradation rate of the biodegradable polyester resin composition after a sufficient period of time has elapsed. That is, the strengthening agent, the oligomer, and / or the metal salt can improve the degree of biodegradation after 9 weeks. Furthermore, the strengthening agent, the oligomer, and / or the metal salt can improve the degree of biodegradation after 9 weeks even if the molar ratio of aliphatic dicarboxylic acid is low. In other words, the hydrolysis-resistant agent, the chain extender, the strengthening agent, the oligomer, and / or the metal salt can be appropriately combined to achieve an appropriate degree of hydrolysis and an appropriate degree of biodegradation.

[0343] As mentioned above, the biodegradable polyester resin compositions according to the examples have a high degree of biodegradation per unit of aliphatic dicarboxylic acid content. Therefore, the biodegradable polyester resin compositions according to the examples have a high degree of biodegradation even if they contain aliphatic dicarboxylic acids at a low level. Consequently, the biodegradable polyester resin compositions according to the examples may have a high content of aromatic dicarboxylic acids and also have a high degree of biodegradation.

[0344] Therefore, the biodegradable polyester resin compositions according to the examples exhibit improved physical properties during actual use and can be easily biodegraded after use.

[0345] The biodegradable polyester resin compositions according to the examples can be efficiently applied to packaging films and the like. That is, films made from the biodegradable polyester resin compositions according to the examples can be used for ordinary purposes such as packaging. In this case, the biodegradable polyester resin compositions according to the examples have a low degree of hydrolysis initially, and the biodegradable polyester film can maintain a certain level of mechanical and chemical properties within the user's normal usage period.

[0346] In addition, since the biodegradable polyester resin composition according to the examples has a high degree of biodegradability, the film produced using the biodegradable polyester resin composition according to the examples can be easily decomposed when disposed of after use.

[0347] Furthermore, the biodegradable polyester resin compositions according to the examples have a high degree of late-stage hydrolysis, and can therefore be easily decomposed not only in soil but also 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.

[0348] 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.

[0349] The biodegradable polyester resin compositions according to the examples have an acid value within the range described above, and therefore may have the hydrolysis and biodegradation characteristics described above.

[0350] 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.

[0351] 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 1000 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 500 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 250 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 100 ppm based on the biodegradable polyester resin composition according to the examples.

[0352] 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 500 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 150 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 100 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.

[0353] Furthermore, the ratio of the mass of the metal element contained in the metal salt to the silicon element may be about 0.1 to about 0.7. Also, the ratio of the mass of the metal element contained in the metal salt to the silicon element may be about 0.2 to about 0.7. Furthermore, the ratio of the mass of the metal element contained in the metal salt to the silicon element may be about 0.3 to about 0.6.

[0354] Since the content of the nitrogen element, the silicon element, or the metal element is the same as in the above range, the biodegradable resin composition according to the examples may have an appropriate degree of hydrolysis and an appropriate degree of biodegradation.

[0355] Furthermore, the proportions of carbon, hydrogen, and oxygen elements in the biodegradable polyester resin compositions according to the examples may vary depending on the diol, aromatic dicarboxylic acid, aliphatic dicarboxylic acid, metal salt, hydrolysis-resistant agent, and chain extender. In the biodegradable polyester resin compositions according to the examples, the number of hydrogen elements relative to one carbon atom may be 1.27 to 1.36. In the biodegradable polyester resin compositions according to the examples, the number of oxygen elements relative to one carbon atom may be 0.34 to 0.38.

[0356] The nitrogen content may be measured by elemental analysis.

[0357] The content of the silicon element and the metal can be measured by inductively coupled plasma optical emission spectroscopy.

[0358] The proportions of carbon, hydrogen, and oxygen can be measured by elemental analysis.

[0359] The biodegradable polyester resin compositions according to the examples contain nitrogen, silicon, metals, carbon, hydrogen, and oxygen within the ranges described above, and may therefore have appropriate hydrolysis resistance and improved biodegradability. Thus, the biodegradable polyester resin compositions according to the examples, as described above, have a high degree of biodegradability per degree of hydrolysis, appropriate durability, and can be used as environmentally friendly plastic compositions.

[0360] Furthermore, molded articles produced using the biodegradable polyester resin compositions according to the examples can maintain adequate mechanical strength within their normal service life.

[0361] Molded articles produced using the biodegradable polyester resin compositions according to the examples can be efficiently decomposed upon disposal while maintaining the required mechanical properties during their actual service life.

[0362] 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.

[0363] <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.

[0364] Hydrolysis-resistant agent #1: 3-Glycidoxypropylmethyldimethoxysilane Hydrolysis-resistant agent #2: 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane Metal salts: Iron nitrate Chain extender: Tri(4-isocyanatophenyl)methane

[0365] <Examples> Example 1 Manufacturing of biodegradable polyester resins Stage 1: Pre-treatment to obtain slurry As shown in Table 1, pre-treated nanocellulose, metal salt, 1,4-butanediol (1,4-BDO), and terephthalic acid (TPA) were mixed in a molar ratio (1,4-BDO:TPA) of 1.4:1 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 the terephthalic acid (TPA) was 130 μm. The content of the pre-treated nanocellulose and the silver nitrate was based on the total weight of the input raw materials.

[0366] Next, the mixture was pretreated by stirring at 40°C at 100 rpm for 1 hour to obtain a slurry without phase separation.

[0367] 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.

[0368] To the reaction product, 1,4-butanediol (1,4-BDO) was added based on the total moles of the diol component, adipic acid (AA) based on the total moles of the dicarboxylic acid component, and tetrabutyl titanate (Dupont, Tyzor TnBT), a titanium-based catalyst, were added at a concentration of 200 ppm based on the total weight of the diol, aromatic dicarboxylic acid, and aliphatic dicarboxylic acid. A secondary esterification reaction was then 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 producing a prepolymer with a number-average molecular weight of 1200 g / mol.

[0369] Stage 3: Stage in which a polymerization reaction is carried out. To the prepolymer obtained in the second step, 150 ppm of tetrabutyl titanate (Dupont, manufactured by Tyzor TnBT), a titanium-based catalyst, and 500 ppm of triethylene phosphate stabilizer were added based on the total weight of the prepolymer, and the mixture was stabilized for approximately 10 minutes. Subsequently, the reaction mixture was heated to 250°C, and a condensation polymerization reaction was carried out at 0.5 torr for 4 hours to produce a polymer having a number-average molecular weight of 55,000 g / mol.

[0370] Subsequently, approximately 1000 ppm of 3-glycidoxypropylmethyldimethoxysilane and approximately 0.5 wt% of tri(4-isocyanatophenyl)methane were added to the polymer based on the polymer. The polymer was then subjected to a terminal group extension reaction at a temperature of approximately 240°C for approximately 10 minutes. After cooling to 5°C, it was cut with a pellet cutter to obtain biodegradable polyester resin pellets.

[0371] Examples 2-6 and Comparative Examples 1-3 As shown in Table 1 below, the contents of adipic acid, terephthalic acid, cellulose nanocrystals, metal salts, hydrolysis resistant agents, and chain extenders differ. Except for the contents and the steps described above, the other steps were carried out with substantially reference to Example 1.

[0372] Examples 7-13 and Comparative Example 4 As shown in Tables 2 and 3 below, the contents of adipic acid, terephthalic acid, cellulose nanocrystals, metal salts, hydrolysis resistant agents, and chain extenders differ. Except for the contents and the steps described above, the other steps were carried out with substantially reference to Example 1.

[0373] 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 name: WL1600SA) with a surface size 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. A biodegradable polyester sheet with an area of ​​approximately 10cm x 10cm and a thickness of approximately 300 μm was then manufactured.

[0374] 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.

[0375] [Table 1]

[0376] [Table 2]

[0377] [Table 3]

[0378] <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: 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.

[0379] The aforementioned standard deviation represents the square root of the variance and can be calculated using software.

[0380] <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.

[0381] 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 accelerated water decomposition tests.

[0382] Specifically, 5g of the polyester resin from the examples and comparative examples was added to 500mL of deionized water (DI Water), then the container was sealed to prevent evaporation, and a water decomposition acceleration test was performed in a convection oven at 80°C. The humidity environment for the biodegradable polyester sheet was the same as that of 100% RH, as it was immersed in water.

[0383] 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.

[0384] The GPC equipment and measurement conditions are as follows: Sample preparation: Dissolve 0.035 mg of PBAT chip in 1.5 ml of THF. Measuring device: Waters E2695 Flow rate: 1ml / min in THF Injection volume: 50μl Column temperature: 40℃ Detector:ELSD Column: Styragel Column HR 5E, HR4, HR2

[0385] Evaluation Example 3: Biodegradability The biodegradable polyester resins produced in the examples and comparative examples were mixed with the following compost and subjected to accelerated biodegradation tests at a temperature of 60°C and a humidity of 90%.

[0386] Using the aforementioned gel permeation chromatography (GPC), the number-average molecular weight of the polyester resins in the examples and comparative examples was measured after a certain period of time. The difference between the initial number-average molecular weight and the number-average molecular weight after the period of time, divided by the initial number-average molecular weight, was used to derive the biodegradability.

[0387] 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%

[0388] Evaluation Example 4: Elemental Analysis The biodegradable resin compositions in the examples and comparative examples were analyzed using an elemental analyzer (Flash Smart Elemental Analyzer, ThermoFisher).

[0389] The biodegradable resin compositions in the examples and comparative examples were oxidized to CO2, H2O, NO2, and SO2, respectively, at a temperature of approximately 1000°C using a catalyst. The resulting gases were separated by a GC column. Subsequently, they were detected by a TCD (Thermal Conductivity Detector), and calibration curves for each C, H, N, and S were derived using standard substances (CAS no. 7128-64-5, 63-74-1, 56-89-3, 86-73-7). The content of each element could then be quantified in atomic percent or weight percent from the GC chromatogram.

[0390] Evaluation Example 5: Acid Value KOH and ethanol were mixed to prepare a 0.02N KOH solution. Then, approximately 1 g of the biodegradable resin composition according to the examples and comparative examples was dissolved in chloroform. Subsequently, the acid value of the biodegradable resin composition solution was measured by titrating it with the KOH solution using phenolphthalein reagent as a reference. Acid value measurement equipment: Mettler Toledo Titrator Excellence T5

[0391] As shown in Tables 4 and 5 below, the degree of biodegradation has been measured.

[0392] [Table 4]

[0393] [Table 5]

[0394] As shown in Tables 6 and 7 below, the degree of water decomposition was measured.

[0395] [Table 6]

[0396] [Table 7]

[0397] As shown in Table 8 below, the degree of biodegradation per degree of hydrolysis is derived.

[0398] [Table 8]

[0399] As shown in Table 9 below, the degree of biodegradation per aliphatic dicarboxylic acid is derived.

[0400] [Table 9]

[0401] As shown in Tables 10 and 11 below, the carbon, hydrogen, nitrogen, sulfur, and oxygen content were measured.

[0402] [Table 10]

[0403] [Table 11]

[0404] As shown in Table 12 below, the iron and silicon content has been measured.

[0405] [Table 12]

[0406] As described in Tables 4 to 12 above, the biodegradable resin compositions according to the examples may have a high degree of biodegradation relative to a high degree of hydrolysis. That is, the biodegradable resin compositions according to the examples may have a low initial degree of hydrolysis while having a high final degree of biodegradation. [Industrial applicability]

[0407] The examples can be used in biodegradable resin compositions, films, and molded articles.

Claims

1. A polyester resin containing diol residues, aromatic dicarboxylic acid residues, and aliphatic dicarboxylic acid residues, an iron salt, and a silicon element, The aforementioned diol residue is derived from 1,4-butanediol and is present in a content of 95 mol% or more relative to the total diol. The aforementioned aromatic dicarboxylic acid residues are derived from terephthalic acid or dimethyl terephthalate, in a content of 40 mol% to 60 mol% based on the total dicarboxylic acid. The aliphatic dicarboxylic acid residues are derived from adipic acid and are present in a content of 40 mol% to 60 mol% based on the total dicarboxylic acid. The ratio of the mass of iron elements contained in the iron salt to the silicon elements is 0.1 to 0.

7. The content of the aforementioned silicon element is 0.1 ppm to 1000 ppm. The iron content is between 0.1 ppm and 500 ppm. The degree of biodegradation per degree of hydrolysis is 1.4 or higher. The biodegradation rate per degree of hydrolysis is the value obtained by dividing the biodegradation rate after 9 weeks by the degree of hydrolysis after 1 week. The degree of biodegradation after 9 weeks and the degree of hydrolysis after 1 week are measured by the following measurement method for biodegradable molded articles. [Measurement method] The degree of biodegradation after 9 weeks is the percentage decrease in molecular weight of the biodegradable molded product compared to its initial state, when the biodegradable molded product is processed into flakes with a thickness of 300 μm and dimensions of 30 mm x 30 mm, and placed for 63 days under composting conditions containing 40 wt% pig manure, 15 wt% chicken manure, 37 wt% sawdust, 5 wt% zeolite, and 3 wt% microbial preparation at a temperature of 60°C and 90% humidity. The degree of hydrolysis after one week is the rate of decrease in molecular weight of the biodegradable molded article compared to its initial state when the flakes are left at a temperature of 80°C and a humidity of 100% for 7 days.

2. The average diameter is 0.5 nm to 10 nm, the average length is 20 nm to 300 nm, and it contains metal-containing nanocellulose. The biodegradable molded article according to claim 1.

3. A polyester resin containing diol residues, aromatic dicarboxylic acid residues, and aliphatic dicarboxylic acid residues, an iron salt, and a silicon element, The aforementioned diol residue is derived from 1,4-butanediol and is present in a content of 95 mol% or more relative to the total diol. The aforementioned aromatic dicarboxylic acid residues are derived from terephthalic acid or dimethyl terephthalate, in a content of 40 mol% to 60 mol% based on the total dicarboxylic acid. The aliphatic dicarboxylic acid residues are derived from adipic acid and are present in a content of 40 mol% to 60 mol% based on the total dicarboxylic acid. The ratio of the mass of iron elements contained in the iron salt to the silicon elements is 0.1 to 0.

7. The content of the aforementioned silicon element is 0.1 ppm to 1000 ppm. The iron content is between 0.1 ppm and 500 ppm. The degree of biodegradation per degree of hydrolysis is 1.35 or higher. The biodegradation rate per degree of hydrolysis is the value obtained by dividing the biodegradation rate after 9 weeks by the degree of hydrolysis after 1 week. The biodegradability of the polyester resin composition after 9 weeks and the degree of hydrolysis after 1 week are measured by the following measurement methods. [Measurement method] The degree of biodegradation after 9 weeks is the rate of decrease in molecular weight of the biodegradable polyester resin composition compared to its initial state, when the biodegradable polyester resin composition is processed into flakes with a thickness of 300 μm and dimensions of 30 mm x 30 mm, and placed for 63 days under composting conditions containing 40 wt% pig manure, 15 wt% chicken manure, 37 wt% sawdust, 5 wt% zeolite, and 3 wt% microbial preparation at a temperature of 60°C and 90% humidity. The degree of hydrolysis after one week is the rate of decrease in molecular weight of the biodegradable polyester resin composition compared to its initial state, when the flakes are left at a temperature of 80°C and a humidity of 100% for 7 days.

4. The degree of biodegradation after 9 weeks is 75% or more, and the degree of hydrolysis after 1 week is 60% or less. The biodegradable polyester resin composition according to claim 3.

5. The degree of biodegradation after one week is 45% to 75%. The degree of biodegradation after one week is the rate of decrease in molecular weight of the flakes compared to their initial state, when the flakes are left for 7 days under composting conditions, at a temperature of 60°C and a humidity of 90%. The biodegradable polyester resin composition according to claim 3.

6. The degree of hydrolysis after 9 weeks is 80% or more. The degree of hydrolysis after 9 weeks is the percentage decrease in molecular weight of the flakes compared to their initial state, when the flakes are left at a temperature of 80°C and a humidity of 100% for 63 days. The biodegradable polyester resin composition according to claim 3.

7. The acid value is 2.0 mg KOH / g or less. The biodegradable polyester resin composition according to claim 3.

8. The rate of increase in biodegradation over 1 to 4 weeks is 3.5% / week to 8% / week. The biodegradable polyester resin composition according to claim 3.

9. The rate of increase in the degree of hydrolysis from week 1 to week 2 was 29% / week to 50% / week. The rate of increase in the degree of hydrolysis from week 3 to week 6 is 0.01% / week to 3% / week. The biodegradable polyester resin composition according to claim 8.

10. The rate of increase in the degree of hydrolysis from week 2 to week 3 is 3% / week to 10% / week. The biodegradable polyester resin composition according to claim 8.

11. A polyester resin containing diol residues, aromatic dicarboxylic acid residues, and aliphatic dicarboxylic acid residues, an iron salt, and a silicon element, The aforementioned diol residue is derived from 1,4-butanediol and is present in a content of 95 mol% or more relative to the total diol. The aforementioned aromatic dicarboxylic acid residues are derived from terephthalic acid or dimethyl terephthalate, in a content of 40 mol% to 60 mol% based on the total dicarboxylic acid. The aliphatic dicarboxylic acid residues are derived from adipic acid and are present in a content of 40 mol% to 60 mol% based on the total dicarboxylic acid. The ratio of the mass of iron elements contained in the iron salt to the silicon elements is 0.1 to 0.

7. The content of the aforementioned silicon element is 0.1 ppm to 1000 ppm. The iron content is between 0.1 ppm and 500 ppm. The biodegradability per aliphatic carboxylic acid is 1.7 or higher. The biodegradation rate per aliphatic carboxylic acid is the value obtained by dividing the biodegradation rate after 9 weeks by the proportion of the aliphatic dicarboxylic acid to the total dicarboxylic acid. The degree of biodegradation after 9 weeks was 85% or more. The degree of biodegradation after 9 weeks is measured by the following method: Biodegradable polyester resin composition. [Measurement method] 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 processed into flakes with a thickness of 300 μm and dimensions of 30 mm × 30 mm, and placed for nine weeks under composting conditions containing 40 wt% pig manure, 15 wt% chicken manure, 37 wt% sawdust, 5 wt% zeolite, and 3 wt% microbial preparation at a temperature of 60°C and a humidity of 90%.

12. The degree of biodegradation after 9 weeks is 88% or higher. The biodegradable polyester resin composition according to claim 11.

13. The degree of biodegradation after one week is 45% to 65%. The degree of biodegradation after one week is the rate of decrease in molecular weight of the biodegradable polyester resin composition compared to its initial state, when the flakes are left for one week under composting conditions, at a temperature of 60°C and a humidity of 90%. The biodegradable polyester resin composition according to claim 11.

14. The degree of biodegradation after two weeks is 55% to 70%. The degree of biodegradation after two weeks is the rate of decrease in molecular weight of the biodegradable polyester resin composition compared to its initial state, when the flakes are left for two weeks under composting conditions, at a temperature of 60°C and a humidity of 90%. The biodegradable polyester resin composition according to claim 12.

15. The rate of increase in biodegradation from week 1 to week 2 is approximately 4% / week to approximately 15% / week. The biodegradable polyester resin composition according to claim 14.

16. The degree of biodegradation after 4 weeks was 73% to 85%. The degree of biodegradation after four 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 flakes are left for four weeks under high temperature and high humidity conditions of 80°C and 100% humidity. The rate of increase in biodegradation over 1 to 4 weeks is 3.5% / week to 8% / week. The biodegradable polyester resin composition according to claim 11.

17. The degree of hydrolysis after one week was 35% to 60%. 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 flakes are left for one week under high-temperature and high-humidity conditions of 80°C and 100% humidity. The biodegradable polyester resin composition according to claim 11.

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