Biodegradable resin composition containing a high amount of calcium carbonate

Abstract

The examples relate to a biodegradable resin composition, a biodegradable polyester film, a biodegradable polyester sheet, and a manufacturing method thereof that contain a high content of calcium carbonate, and provide a biodegradable resin composition, a biodegradable polyester film, a biodegradable polyester sheet, and a manufacturing method thereof that contain a high content of calcium carbonate while maintaining excellent tensile strength and elongation, and that have excellent biodegradability, are effective in preventing soil acidification, and can reduce production costs.

Description

[Technical Field]

[0001] Examples of realization include biodegradable resin compositions containing a high content of calcium carbonate, biodegradable polyester films, biodegradable polyester sheets, and methods for producing the same. [Background technology]

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

[0003] To overcome the limitations of such polymers, research on biodegradable polymers that decompose relatively quickly is being actively pursued. Examples of biodegradable polymers being introduced include polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), and polybutylene succinate (PBS).

[0004] However, while polylactic acid, an aliphatic polyester, has good mechanical properties, its inherent crystal structure makes it inflexible, and polybutylene adipate terephthalate, an aromatic aliphatic polyester, has poor mechanical properties such as strength, thus limiting its applications.

[0005] To address these issues, Patent Document 1 discloses a biodegradable polyester foil in which tear propagation characteristics are improved by mixing a low amount of calcium carbonate with a composition containing PBAT, PBSet, PBAzt, PBST, etc. However, such biodegradable polyester foils have limitations: increasing the calcium carbonate content weakens their physical properties, and the manufacturing process requires high energy consumption, leading to increased manufacturing costs and reduced manufacturing efficiency. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] U.S. Registered Patent No. 9096758 [Overview of the project] [Problems that the invention aims to solve]

[0007] Therefore, the aim is to provide a biodegradable resin composition, biodegradable polyester film, biodegradable polyester sheet, and a method for producing the same, which contain a high amount of calcium carbonate, maintain excellent tensile strength and elongation, and also exhibit excellent biodegradability, soil acidification prevention effect, and reduction in production costs. [Means for solving the problem]

[0008] One example of a biodegradable resin composition contains a biodegradable polyester resin and calcium carbonate (CaCO3), and exhibits a reduction rate of 50% or more in the crystal peak represented by the following formula 1.

[0009] Another example of a biodegradable polyester film comprises a biodegradable polyester resin and a biodegradable resin composition containing calcium carbonate (CaCO3), wherein the biodegradable resin composition has a reduction rate of 50% or more of the crystal peak represented by the following formula 1.

[0010] Another biodegradable polyester sheet according to another embodiment includes a biodegradable resin composition containing a biodegradable polyester resin and calcium carbonate (CaCO3), and the biodegradable resin composition has a reduction rate of the crystal peak represented by the following formula 1 of 50% or more. [Formula 1] Reduction rate of crystal peak = (R p -C p ) / R p In the above formula 1, R p is the heat of crystal melting (J / g) of the biodegradable polyester resin in the temperature range of 70°C to 90°C measured during the process of heating from 40°C to 180°C at a rate of 10°C / min and then cooling to -50°C at a rate of 10°C / min using a differential scanning calorimeter (DSC), C p is the heat of crystal melting (J / g) of the biodegradable resin composition measured under the same conditions as above.

Advantages of the Invention

[0011] The biodegradable resin composition according to one embodiment can reduce the cost of the product by using calcium carbonate at a low price in a high content by including calcium carbonate in a specific content, and can save production costs. By increasing the biodegradation starting point and promoting the chemical decomposition reaction, the biodegradability can be further improved.

[0012] Also, it is possible to neutralize the acid component generated during the decomposition of the product using the biodegradable resin composition and prevent soil acidification.

[0013] The biodegradable resin composition according to one embodiment includes a high content of calcium carbonate, changes the flow characteristics of the polymer, and can adjust the glass transition temperature (Tg) and crystal peak of the biodegradable resin composition.

[0014] The biodegradable resin composition according to one implementation example can maintain the isothermal weight loss rate at a low level and maintain a high content of calcium carbonate even during high-temperature processing, despite containing a high content of calcium carbonate.

[0015] Molded articles produced from the biodegradable resin composition according to other implementation examples, particularly biodegradable polyester films, can maintain the tensile strength, elongation rate, and tear strength at a certain level or higher despite containing a low content of the biodegradable polyester resin.

Brief Description of the Drawings

[0016] [Figure 1] Figure 1 shows the results of differential scanning calorimetry of the biodegradable resin compositions of the implementation examples and reference examples.

Modes for Carrying Out the Invention

[0017] Hereinafter, the invention will be described in detail with reference to implementation examples. The implementation examples are not limited to the content disclosed below, and can be modified into various forms without changing the gist of the invention.

[0018] In this specification, when a certain part states that a certain component "includes", it means that other components can be further included, rather than excluding other components, unless otherwise stated.

[0019] Also, all numerical ranges representing physical property values, dimensions, etc. of the components described in this specification should be understood to be modified by the term "about" in all cases, unless otherwise specified.

[0020] In this specification, terms such as first, second, primary, secondary, etc. are used to describe various components, and the components are not limited by the terms. The terms are only used to distinguish one component from another.

[0021] [Biodegradable Resin Composition] A biodegradable resin composition according to one implementation example contains a biodegradable polyester resin and calcium carbonate (CaCO3), and the reduction rate of the crystal peak represented by the following formula 1 is 50% or more. [Formula 1] Reduction rate of crystal peak = (R p -C p ) / R p In the above formula 1, R p is the heat of crystal melting (J / g) of the biodegradable polyester resin in the temperature range of 70°C to 90°C measured during the process of cooling from 40°C to 180°C at a rate of 10°C / min and then cooling to -50°C at a rate of 10°C / min using a differential scanning calorimeter (DSC), C p is the heat of crystal melting (J / g) of the biodegradable resin composition measured under the same conditions as above.

[0022] [Biodegradable polyester resin] The biodegradable polyester resin contains a first repeating unit and a second repeating unit. The first repeating unit contains a diol component and an aromatic dicarboxylic acid component, and the second repeating unit contains a diol component and an aliphatic dicarboxylic acid component.

[0023] -Diol component- The diol component contains 1,4-butanediol or its derivative.

[0024] Specifically, the diol component may contain 95 mol% or more, 97 mol% or more, 98 mol% or more, 99 mol% or more, or 100 mol% of 1,4-butanediol or its derivative based on the total molar number of the diol component.

[0025] By including 1,4-butanediol or its derivative in the diol component, biodegradability, flexibility, and strength can be improved. In particular, when the diol component consists only of 1,4-butanediol, the improvement effects of biodegradability and strength can be maximized.

[0026] If necessary, the diol component may further include a secondary diol different from the primary diol, which is 1,4-butanediol or a derivative thereof.

[0027] The second diol may be one or more selected from the group consisting of propanediol, hexanediol, cyclohexanedimethanol, or ethylene glycol. Specifically, the second diol may be one or more selected from the group consisting of 1,3-propanediol, 1,2-propanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,6-hexanediol, 2,3-hexanediol, 2,4-hexanediol, 2,5-hexanediol, 2,6-hexanediol, 3,4-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, or ethylene glycol.

[0028] Furthermore, the diol component may further contain a secondary diol in an amount of 5 mol% or less, 3 mol% or less, 2 mol% or less, or 1 mol% or less, based on the total number of moles of the diol component.

[0029] -Dicarboxylic acid components- The dicarboxylic acid component of the present invention includes an aliphatic dicarboxylic acid component and an aromatic dicarboxylic acid component.

[0030] The aforementioned aromatic dicarboxylic acid component is one or more selected from the group consisting of terephthalic acid, dimethylterephthalic acid, and its derivatives.

[0031] The aliphatic dicarboxylic acid component is one or more selected from the group consisting of adipic acid, succinic acid, and its derivatives.

[0032] Specifically, the aromatic dicarboxylic acid component may be terephthalic acid or dimethylterephthalic acid, and the aliphatic dicarboxylic acid component may be adipic acid or succinic acid.

[0033] The dicarboxylic acid component contains the aromatic dicarboxylic acid component in amounts of 15 mol% or more, 30 mol% or more, 45 mol% or more, 50 mol% or more, or 75 mol% or more, based on the total number of moles of dicarboxylic acid components, and may contain 30 mol% to 90 mol%, 35 mol% to 80 mol%, 40 mol% to 75 mol%, 45 mol% to 65 mol%, or 45 mol% to 55 mol%.

[0034] Furthermore, the dicarboxylic acid component may contain the aliphatic dicarboxylic acid component in amounts of 15 mol% or more, 30 mol% or more, 45 mol% or more, 50 mol% or more, or 75 mol%, based on the total number of moles of the dicarboxylic acid component, and may contain 30 mol% to 90 mol%, 35 mol% to 80 mol%, 40 mol% to 75 mol%, 45 mol% to 65 mol%, or 45 mol% to 55 mol%.

[0035] The molar ratio of the aromatic dicarboxylic acid component to the aliphatic dicarboxylic acid component may be 0.5 to 1.5:1, 0.7 to 1.3:1, or 0.8 to 1.2:1. By satisfying the above range for the molar ratio of the aromatic dicarboxylic acid component to the aliphatic dicarboxylic acid component, biodegradability and processability can be improved.

[0036] Furthermore, the molar ratio of the diol component to the dicarboxylic acid component may be 0.5 to 2:1. For example, the molar ratio of the diol component to the dicarboxylic acid component may be 0.5 to 1.8:1, 0.7 to 1.5:1, or 0.9 to 1.2:1. By satisfying the above range for the molar ratio of the diol component to the dicarboxylic acid component, biodegradability, strength, and processability can all be improved without discoloration such as yellowing.

[0037] -Nanocellulose- The biodegradable polyester resin of the present invention may further contain nanocellulose.

[0038] The nanocellulose is a natural material nanocellulose in gel or dry powder form, and can improve the dispersion stability, strength, and processability of the biodegradable polyester resin containing the nanocellulose.

[0039] The biodegradable polyester resin may contain nanocellulose in an amount of 0.01% to 3% by weight, based on the total weight of the biodegradable polyester resin. For example, the nanocellulose content may be 0.01% to 2.5% by weight, 0.05% to 2% by weight, 0.07% to 1.8% by weight, 0.1% to 1.2% by weight, 0.1% to 1% by weight, or 0.15% to 0.7% by weight, based on the total weight of the biodegradable polyester resin. By satisfying the above range for nanocellulose content, biodegradability and strength can be further improved.

[0040] The nanocellulose may be in the form of a dry powder or gel having aggregated secondary particles with a particle size of 1 μm to 50 μm. For example, the nanocellulose may be in the form of a dry powder or gel having aggregated secondary particles rather than single particles, and the size of the secondary particles may be 2 μm to 45 μm or 5 μm to 50 μm. Furthermore, the nanocellulose may be in the form of a freeze-dried powder to reduce its volume for easier storage and transport.

[0041] The diameter of the nanocellulose may be between 1 nm and 100 nm. For example, the diameter of the nanocellulose may be between 1 nm and 95 nm, 5 nm and 90 nm, 10 nm and 80 nm, 5 nm and 60 nm, or 15 nm and 60 nm.

[0042] Furthermore, the length of the nanocellulose can range from 5 nm to 10 μm. For example, the length of the nanocellulose can range from 5 nm to 5 μm, 5 nm to 1 μm, 10 nm to 700 nm, 20 nm to 500 nm, 60 nm to 300 nm, 80 nm to 200 nm, and 100 nm to 250 nm.

[0043] By ensuring that the diameter and length of the nanocellulose satisfy the aforementioned range, the strength, particularly the tear strength, can be further improved.

[0044] Furthermore, the nanocellulose can function as a crystal nucleating agent, thereby improving the crystallization rate of the biodegradable resin composition and increasing the crystallization temperature of the biodegradable resin composition.

[0045] The nanocellulose is one or more selected from the group consisting of cellulose nanocrystals, cellulose nanofibers, and microfibrillated cellulose, with cellulose nanocrystals or cellulose nanofibers being preferred from the viewpoint of strength and thermal properties. When the nanocellulose is included in a biodegradable polyester resin, its biodegradability, strength, and thermal properties can be further improved.

[0046] The biodegradable resin composition containing the aforementioned nanocellulose may have appropriate UV resistance, biodegradation rate, and hydrolysis rate.

[0047] More specifically, the nanocellulose may be one or more selected from the group consisting of hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, cellulose acetate, methylcellulose, ethylcellulose, propylcellulose, butylcellulose, pentylcellulose, hexylcellulose, and cyclohexylcellulose.

[0048] In the implemented examples, the average particle size of nanocellulose is 200 nm or less, and the particle size deviation may be 20% or less. Specifically, the average particle size of water-dispersed nanocellulose is 190 nm or less or 185 nm or less, and the particle size deviation may be 18% or less or 16% or less. By satisfying the above ranges for both the average particle size and particle size deviation of the nanocellulose, both the dispersibility and durability of the nanocellulose are excellent.

[0049] In other realizations, the nanocellulose may be pre-treated with a bead mill or ultrasonically. Specifically, the nanocellulose may be water-dispersed nanocellulose that has been pre-treated with a bead mill or ultrasonically.

[0050] For example, the nanocellulose may be obtained by dispersing a dry powder or gel-like cellulose nanocrystal having a particle size of 1 μm to 50 μm in water, and then pre-treating it with a bead mill or ultrasonic pre-treatment.

[0051] When the nanocellulose, specifically water-dispersed nanocellulose, is pre-treated with a bead mill or ultrasonic pre-treatment, the number of nanocellulose particles increases, and its dispersibility can be maximized.

[0052] Furthermore, the nanocellulose may be pretreated with a silane coupling agent in an amount of 0.01% to 10% by weight, based on the total weight of the nanocellulose. For example, the nanocellulose may be pretreated with a silane coupling agent in an amount of 0.05% to 8% by weight, 0.1% to 8% by weight, 0.5% to 6% by weight, or 0.7% to 6% by weight, based on the total weight of the nanocellulose.

[0053] By satisfying the above range for the silane coupling agent content, interfacial adhesion, dispersibility, and compatibility can be maximized, thereby further improving the mechanical properties, durability, and especially hydrolysis resistance of the biodegradable polyester resin containing it.

[0054] -Calcium carbonate (CaCO3)- One example of a biodegradable resin composition contains 30% to 80% by weight of calcium carbonate, based on the total weight of the biodegradable resin composition.

[0055] For example, the biodegradable resin composition contains calcium carbonate (CaCO3) in amounts of 30.5% or more by weight, 35% or more by weight, 45% or more by weight, 50% or more by weight, 55% or more by weight, 60% or more by weight, 65% or more by weight, 70% or more by weight, or 75% or more by weight, based on the total weight of the biodegradable resin composition, and may contain 30% to 70% by weight, 40% to 75% by weight, 45% to 70% by weight, 30% to 45% by weight, 45% to 55% by weight, 45% to 49% by weight, 55% to 65% by weight, 60% to 75% by weight, 65% to 72% by weight, 60% to 70% by weight, or 65% to 70% by weight.

[0056] If the biodegradable resin composition contains calcium carbonate within the specified range, the cost of the product can be reduced by using calcium carbonate, which is readily available and inexpensive as a raw material, in a high content, thereby lowering production costs. Furthermore, the biodegradation initiation point can be raised, further improving biodegradability. Despite containing a high content of calcium carbonate, dispersibility can be improved, preventing a deterioration in the physical properties of the product.

[0057] Furthermore, when molded products made from biodegradable resin compositions decompose, acidic components are generated. Since these acidic components react with calcium carbonate to produce carbon dioxide gas and water, the biodegradation rate at the molecular level is further improved, and as shown in reaction equation 1 below, calcium carbonate neutralizes the acidic components, reducing the environmental burden and preventing soil acidification. [Reaction Equation 1] CaCO3(s) + 2H + (aq) → CO2(g) + H2O(l) + Ca 2+ (aq)

[0058] The calcium carbonate may be natural calcium carbonate obtained by mechanically crushing or classifying natural calcium carbonate mainly composed of CaCO3, such as limestone, chalk, marble, seashells, and coral, or it may be synthetic calcium carbonate prepared by a chemical precipitation reaction or the like. Natural calcium carbonate is preferred because it increases the surface area between the biodegradable particles and the calcium carbonate, thereby improving the efficiency of biodegradation.

[0059] Furthermore, to improve the dispersibility or reactivity of calcium carbonate, the surface of the calcium carbonate can be modified by physical or chemical treatment. For example, physical surface modification methods may include physical methods such as plasma treatment and corona treatment, or chemical treatment of the surface with coupling agents such as silane coupling agents or titanium coupling agents, or surfactants.

[0060] The particle size of the calcium carbonate is calculated from the specific surface area measurement results using an air permeability method with a specific surface area measuring device, and the average particle size is 0.1 μm to 10.0 μm, specifically 0.5 μm to 5.0 μm or 1.0 μm to 3.0 μm.

[0061] When the particle size of calcium carbonate is within the aforementioned range, the viscosity when kneading the biodegradable polyester resin and calcium carbonate can be maintained within a certain range, increasing the uniformity of particle size and potentially facilitating the manufacture of molded products.

[0062] The specific surface area of ​​the calcium carbonate was measured by nitrogen gas adsorption, and the specific surface area was 0.1 m². 2 / g~10.0m 2 / g, specifically 0.2m 2 / g~5.0m 2 / g or 1.0m 2 / g~3.0m 2 It could be / g

[0063] When the specific surface area of ​​calcium carbonate is within the aforementioned range, the biodegradation reaction surface area of ​​the biodegradable polyester resin in molded articles produced from the biodegradable resin composition is increased, which promotes biodegradability in the natural environment, while reducing the decrease in processability of the biodegradable resin composition caused by the addition of calcium carbonate.

[0064] The amorphous nature of the calcium carbonate is expressed based on the sphericity of the calcium carbonate, which may be 0.30-0.95, 0.50-0.93, or 0.60-0.90.

[0065] When the sphericity of the calcium carbonate is within the aforementioned range, it contains numerous fine voids at the interface between the biodegradable polyester resin and the calcium carbonate due to very weak adhesion or lack of adhesion, thereby enhancing biodegradability in the natural environment without reducing the strength or moldability of the product.

[0066] - Additives - If necessary, additives may be incorporated into the biodegradable resin composition of the present invention as auxiliary agents.

[0067] As additives, in addition to calcium carbonate, fillers, lubricants, plasticizers, colorants, antioxidants, flame retardants or foaming agents, chain extenders, etc. may be included, for example, any additive that can be commonly added to polyester biodegradable resin compositions, such as coupling agents, flow improvers, dispersants, UV absorbers, stabilizers, and antistatic agents. These additives may be used alone or in combination of two or more. Preferably, the biodegradable resin composition may further contain one or more selected from the group consisting of lubricants, plasticizers, antioxidants, chain extenders, and dispersants.

[0068] For example, the biodegradable resin composition includes a plasticizer and an antioxidant. The additive may be incorporated during the mixing process, or it may be incorporated into the biodegradable resin composition before the mixing process.

[0069] In the biodegradable resin composition of the present invention, the amount of these other additives added is not particularly limited as long as it is within a range that can achieve the effects of the present invention. However, it is preferable that each of the other additives is in an amount of 0.01% to 5% by weight based on the total weight of the biodegradable resin composition, and that the total weight of the other additives is 10% by weight or less based on the total weight of the biodegradable resin composition.

[0070] Other fillers besides calcium carbonate include magnesium carbonate, zinc oxide, titanium dioxide, silica, alumina, clay, talc, kaolin, aluminum hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, calcium silicate, aluminum sulfate, magnesium sulfate, calcium sulfate, magnesium phosphate, barium sulfate, silica sand, carbon black, zeolite, molybdenum, diatomaceous earth, sericite, white sand, calcium sulfite, sodium sulfate, potassium titanate, bentonite, or graphite.

[0071] Examples of the lubricants include fatty acid-based lubricants containing stearic acid, aliphatic alcohol-based lubricants, aliphatic amide-based lubricants containing stearamide, aliphatic ester-based lubricants such as n-butyl stearate, methyl hydroxystearate, polyhydric alcohol fatty acid esters, saturated fatty acid esters, and ester waxes, as well as fatty acid metal soap-based lubricants.

[0072] The lubricant may be a stearic acid-based lubricant and may include one or more selected from the group consisting of calcium stearate, zinc stearate, barium stearate, magnesium stearate, glyceryl stearate, and butyl stearate.

[0073] The aforementioned stearic acid-based lubricant reduces heat generation due to friction during raw material mixing, melting, and processing, and offers excellent dispersion and lubrication effects for biodegradable polyester resins relative to its cost, thus potentially improving manufacturing efficiency.

[0074] The lubricant content may be 5% by weight or less, 1% by weight or less, less than 1% by weight, 0.9% by weight or less, 0.8% by weight or less, 0.7% by weight or less, 0.5% by weight or less, 0.3% by weight or less, or 0.1% by weight or less, based on the total weight of the biodegradable resin composition.

[0075] The lubricant may be included in an amount of 0.1% to 1% by weight based on the total weight of the biodegradable resin composition, and more specifically, in an amount of 0.1% to 0.5% by weight or 0.2% to 0.3% by weight.

[0076] When the content of the lubricant is within the above range, the physical properties of the biodegradable resin composition are not reduced, and the manufacturing efficiency of the biodegradable resin composition can be improved.

[0077] Plasticizers are added to impart processability and flexibility to the resulting molded articles, and may include glycerol, acrylate, glycerin, glycerol monostearate (GMS), sorbitol, or mixtures thereof.

[0078] In the biodegradable resin composition of the present invention, the content of these plasticizers is not particularly limited as long as it is within a range that can achieve the effects of the present invention. The plasticizer is 0 to 15% by weight based on the total weight of the biodegradable resin composition, and specifically, it may be 0 to 13% by weight, 0.1% to 3% by weight, 4% to 11% by weight, 8% to 11% by weight, 4% to 8% by weight, 2% to 4% by weight, 1% to 3% by weight, or 1% to 2% by weight.

[0079] When the content of the plasticizer is within the aforementioned range, the elongation of the molded article formed from the biodegradable resin composition can be improved, and the tear resistance can be improved.

[0080] The colorants may be organic pigments, inorganic pigments, or dyes. Specifically, examples include organic pigments such as azo, anthraquinone, phthalocyanine, quinacridone, isoindolinone, deoxazine, perinone, quinophthalone, and perylene pigments, and inorganic pigments such as ultramarine, titanium dioxide, titanium yellow, iron oxide, chromium oxide, zinc oxide, or carbon black.

[0081] The antioxidant is selected from the group consisting of phosphorus-based antioxidants, phenol-based antioxidants, or pentaerythritol-based antioxidants, and each antioxidant can be used alone or in combination of two or more. When two or more antioxidants are included, it is preferable to use a mixture of phosphorus-based antioxidants and phenol-based antioxidants to obtain effects across a wide temperature range.

[0082] The phosphorus-based antioxidants include triesters, diesters, monoesters, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, tris(nonylphenyl) phosphate, or 2-ethylphenyldiphenyl phosphate.

[0083] The aforementioned phenolic antioxidants, α-tocopherol, butylhydroxytoluene, synaphyll alcohol, vitamin E, n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2-t-butyl-6-(3'-t-butyl-5'-methyl-2'-hydroxybenzyl)-4-methylphenyl acrylate, 2,6-di-t-butyl-4-(N,N-dimethylaminomethyl)phenol, 3,5-di-t-butyl-4-hydroxybenzylphosphonate diethyl ester, 2,2-bis({[3-(3,5-di-t Examples include ert-butyl-4-hydroxyphenyl)propanoyl]oxymethyl)propane-1,3-diylbis[3-(3,5-di-tert)-butyl-4-hydroxyphenyl]propanoate, pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], or tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl]methane.

[0084] Furthermore, one or more antioxidants selected from the group consisting of BHT, ascorbic acid, catechin, quercetin, dodecyl gallate, TBHQ, Ralox (registered trademark), Irganox (registered trademark) 1135, Irganox 1076, nordihydroguaiaretic acid, epicatechin gallate, epigallocatechin gallate, epigallocatein, propyl gallate, 2,3,5-trihydroxybutyrophenone, butylated hydroxyanisole, 4-hydroxymethyl-2,6-di-tert-butylphenol, α-tocopherol, resveratrol, rutin, astaxanthin, lycopene, beta-carotene, or melatonin may be used as the antioxidant.

[0085] The antioxidant is 5% by weight or less, 3% by weight or less, 2% by weight or less, 1.5% by weight or less, 1% by weight or less, 0.5% by weight or less, or 0.3% by weight or less, based on the total weight of the biodegradable resin composition, and may be 0-5% by weight, 0.01%-4% by weight, 0.1%-3% by weight, 1%-3% by weight, 1%-2% by weight, 0.01%-0.3% by weight, or 0.05%-0.3% by weight.

[0086] If the antioxidant includes both a phosphorus-based antioxidant and a phenol-based antioxidant, the weight ratio of the phosphorus-based antioxidant to the phenol-based antioxidant may be 1:10-10:1, 1:5-5:1, 1:1-5:1, 2:1-4:1, 2.5:1-3.5:1, 1:5-1:1, 1:2-1:4, or 1:2.5-1:3.5.

[0087] By mixing phosphorus-based antioxidants and phenol-based antioxidants within the aforementioned range, desired effects can be obtained over a wide range of temperatures.

[0088] Flame retardants can include halogenated flame retardants, phosphorus-based flame retardants, or non-phosphorus halogenated flame retardants such as metal hydrates.

[0089] Examples of halogenated flame retardants include halogenated bisphenol compounds such as halogenated bisphenylalkanes, halogenated bisphenyl ethers, halogenated bisphenyl thioethers, and halogenated bisphenyl sulfones, as well as bisphenol-bis(alkyl ether) compounds such as brominated bisphenol A, brominated bisphenol S, chlorinated bisphenol A, or chlorinated bisphenol S.

[0090] Phosphorus-based flame retardants include aluminum tris(diethylphosphinate), bisphenol A bis(diphenyl phosphate), triarylisopropyl phosphate, cresyl di2,6-xylenyl phosphate, or aromatic condensed phosphate esters.

[0091] Examples of metal hydrates include aluminum trihydrate, magnesium dihydrate, or combinations thereof.

[0092] To improve the flame-retardant effect, antimony oxides such as antimony trioxide and antimony pentoxide, zinc oxide, iron oxide, aluminum oxide, molybdenum oxide, titanium oxide, calcium oxide, and magnesium oxide can also be used in combination as flame-retardant additives.

[0093] The foaming agent is a substance that undergoes a phase change from solid to gas, liquid to gas, or is a gas itself, when mixed with or injected under pressure into a molten biodegradable resin composition, and is used to control the foaming ratio (foaming density) of the foamed sheet.

[0094] Examples of foaming agents include aliphatic hydrocarbons such as propane, butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclobutane, cyclopentane, and cyclohexane; halogenated hydrocarbons such as chlorodifluoromethane, difluoromethane, trifluoromethane, trichlorofluoromethane, dichloromethane, dichlorodifluoromethane, chloromethane, chloroethane, dichlorotrifluoroethane, dichloropentafluoroethane, tetrafluoroethane, difluoroethane, pentafluoroethane, trifluoroethane, dichlorotetrafluoroethane, trichlorotrifluoroethane, tetrachlorodifluoroethane, and perfluorocyclobutane; inorganic gases such as carbon dioxide, nitrogen, and air; and water.

[0095] The dispersant is used to enhance the dispersibility of the solvent and solute, and the dispersant may be one or more selected from the group consisting of aliphatic polyester, poly(lactic acid) (hereinafter PLA), poly(glycolic acid) (hereinafter PGA), polycaprolactone (hereinafter PCL), and polyhydroxyalkanoate (hereinafter PHA), but is not limited to these.

[0096] The biodegradable resin composition of the present invention further comprises one or more dispersants selected from the group consisting of polylactic acid, polyglycolic acid, polycaprolactone, and polyhydroxyalkanoate.

[0097] The content of the dispersant is not particularly limited as long as it is within a range that can achieve the effects of the present invention, but the dispersant may be included in an amount of 1% to 20% by weight based on the total weight of the biodegradable resin composition, and specifically, the dispersant may be included in amounts of 1% to 15% by weight, 1% to 13% by weight, 1% to 11% by weight, 2% to 10% by weight, 5% to 15% by weight, 7% to 12% by weight, 2% to 8% by weight, 5% to 8% by weight, or 2% to 5% by weight.

[0098] The chain extenders are aromatic diisocyanates, aliphatic diisocyanates, isocyanurates, bisoxazolines, carboxylic acid anhydrides, or epoxides.

[0099] The aromatic diisocyanate includes torylene 2,4-diisocyanate, torylene 2,6-diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthylene 1,5-diisocyanate, or xylylene diisocyanate. Of these, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 4,4'-diphenylmethane diisocyanate are particularly preferred.

[0100] The aliphatic diisocyanate refers to 1,6-hexamethylene diisocyanate, isophorone diisocyanate, or methylenebis(4-isocyanatocyclohexane). Particularly preferred aliphatic diisocyanates are isophorone diisocyanate, and 1,6-hexamethylene diisocyanate is particularly preferred.

[0101] The isocyanurate includes isophorone diisocyanate or methylenebis(4-isocyanatocyclohexane).

[0102] The bisoxazoline mentioned above is 2,2'-bis(2-oxazoline), bis(2-oxazolinyl)methane, 1,2-bis(2-oxazolinyl)ethane, 1,3-bis(2-oxazolinyl)propane, or 1,4-bis(2-oxazolinyl)butane, particularly 1,4-bis(2-oxazolinyl)benzene, 1,2-bis(2-oxazolinyl)benzene, or 1,3-bis(2-oxazolinyl)benzene.

[0103] The epoxide refers to an epoxy-containing copolymer based on styrene, acrylic acid ester, and / or methacrylic acid ester, preferably a copolymer having a copolymer content of more than 20% by weight, more than 30% by weight, or more than 50% by weight containing glycidyl (meth)acrylate, with an epoxy equivalent weight (EEW) of 150 g / Eq to 3000 g / Eq or 200 g / Eq to 500 g / Eq. The weight-average molecular weight (Mw) is in the range of 2000 to 25000 or 3000 to 8000, the number-average molecular weight (Mn) is 400 to 6000 or 1000 to 4000, and the polydispersity (Q) is generally 1.5 to 5. The epoxide is available from BASF Resins BV's Joncryl® ADR.

[0104] The chain extender is 1.5% by weight or less, 1% by weight or less, 0.5% by weight or less, or 0.3% by weight or less, based on the total weight of the biodegradable resin composition, and may be 0 to 1.5% by weight, 0.01% to 1% by weight, 0.1% to 1% by weight, 0.01% to 0.5% by weight, 0.01% to 0.3% by weight, or 0.1% to 0.5% by weight.

[0105] The COOH terminal groups of the biodegradable polyester resin are 10-50 eq / 10 6 gr, 15-40 eq / 10 6 gr, or 20-30 eq / 10 6 It could be gr

[0106] Differential scanning calorimeter (DSC) uses a differential scanning calorimeter to measure the heat flow related to the thermal transitions of a sample. This allows for the acquisition of qualitative information from the position, shape, and number of peaks, and quantitative information on the change in heat quantity (such as glass transition temperature (Tg), cold crystallization temperature (Tcc), crystallization temperature (Tmc), and melting temperature (Tm)) from the area of ​​the peaks.

[0107] When the biodegradable polyester resin is subjected to DSC temperature rise measurement by differential scanning heat capacity analysis, the glass transition temperature is measured at approximately -20°C, and a crystal peak due to butanediol (heat of fusion of crystals of 1-5 J / g or 1-3 J / g) appears in the temperature range of 70°C to 90°C, while a crystal peak due to the biodegradable polyester resin (PBAT) itself (heat of fusion of crystals of 5-20 J / g or 13-17 J / g) is detected in the temperature range of 100°C to 150°C, resulting in a crystal melting temperature curve.

[0108] In the case of the biodegradable resin composition of the present invention, when measured by differential scanning heat capacity analysis (DSC) during temperature rise, the reduction rate of the crystal peak according to Equation 1 is 50% or more, 70% or more, 80% or more, 85% or more, 90% or more, 95% or more, 97% or more, 99% or more, or 100% in the temperature range of 70°C to 90°C. This means that the crystal peak due to butanediol decreases significantly during DSC temperature rise measurement of the biodegradable resin composition. This indicates that in the case of a biodegradable resin composition containing an excess amount of calcium carbonate, the inorganic substance calcium carbonate prevents the formation of self-crystals by butanediol, resulting in a change in crystal behavior.

[0109] In DSC temperature measurement of the biodegradable resin composition of the present invention, the rate of decrease of the crystal peak according to formula 1A in the temperature range of 100°C to 150°C is 15% or more, 24% or more, 30% or more, 45% or more, 50% or more, 60% or more, 70% or more, 75% or more, 80% or more, 85% or more, or 90% or more, and may be, for example, 45% to 98%, 45% to 96%, or 50% to 90%.

[0110] [Equation 1A] Decrease rate of crystal peaks = (R p1 -C p1 ) / R p1 In the above formula 1A, R p1 This is the heat of fusion (J / g) of the biodegradable polyester resin in the temperature range of 100°C to 150°C, measured using a differential scanning calorimeter (DSC) during the process of heating from 40°C to 180°C at a rate of 10°C / min, followed by cooling to -50°C at a rate of 10°C / min. Cp1 This is the heat of fusion (J / g) of the biodegradable resin composition measured under the same conditions as described above.

[0111] This means that in DSC temperature-controlled measurements of biodegradable resin compositions, the crystal peaks caused by the biodegradable polyester resin (PBAT) itself are significantly reduced. This indicates that in biodegradable resin compositions containing an excess amount of calcium carbonate, the inorganic calcium carbonate suppresses the flow of polymers within a certain unit volume, hindering the formation of self-crystals by the biodegradable polyester resin and potentially altering its crystal behavior.

[0112] When the biodegradable resin composition is analyzed by differential scanning heat capacity analysis, the glass transition temperature (Tg) is -50°C or higher, -40°C or higher, -30°C or higher, -20°C or higher, -10°C or higher, and may be 30°C or lower, 20°C or lower, or 10°C or lower. This is because, in the case of a biodegradable resin composition containing an excess amount of calcium carbonate, steric hindrance occurs between polymer chains due to the inorganic substance calcium carbonate, suppressing the fluidity of the polymer chains and tending to increase the glass transition temperature (Tg).

[0113] The melting temperature (Tm) of the biodegradable resin composition may be 60°C or higher, 80°C or higher, 90°C or higher, 100°C or higher, 110°C or higher, and possibly 150°C or lower, 140°C or lower, 130°C or lower, or 120°C or lower.

[0114] The crystallization temperature (Tmc) of the biodegradable resin composition is -10°C or higher, -5°C or higher, 0°C or higher, and may be 80°C or lower, 60°C or lower, 50°C or lower, or 40°C or lower.

[0115] Figure 1 shows the differential scanning calorimetry results when heating measurements were performed twice at a rate of 20°C per minute. For 100% biodegradable polyester resin (PBAT resin) in Reference Example A1, the glass transition temperature (Tg) was measured at -24.2°C, the melting temperature (Tm) at 113.9°C, and the crystallization temperature (Tmc) at 33°C. The cold crystallization temperature (Tcc) was not measured separately. In addition, the heat of fusion due to the butanediol peak was 1 J / g, and the heat of fusion due to the biodegradable polyester resin (PBAT) itself was 15 J / g.

[0116] In Figure 1, the biodegradable resin composition of Example A2, which contains 65% calcium carbonate and 35% PBAT resin, was measured to have a glass transition temperature (Tg) of -23.1°C, a heat of fusion due to the butanediol peak of 0.02 J / g, and a heat of fusion due to the biodegradable polyester resin (PBAT) itself of 2.5 J / g.

[0117] Thermogravimetric analysis (TGA) is an analytical method that continuously measures the weight of a sample as a function of time or temperature while increasing the temperature under constant conditions.

[0118] TGA analysis indicates that when the biodegradable resin composition is maintained at an isothermal temperature of 210°C for 1 hour, the isothermal weight loss of the biodegradable resin composition may be 5% or less.

[0119] Specifically, the isothermal weight loss may be 4% or less, 3% or less, 2.5% or less, 2% or less, 1.5% or less, 1% or less, or 0.5% or less, and may be 0% or more or 0.1% or more.

[0120] The isothermal weight loss is calculated as (W0-W1) / W0×100, where W0 is the initial weight of the pellet and W1 is the change in weight of the pellet after it has been left at 210°C under isothermal conditions for 1 hour.

[0121] When the isothermal weight loss is within the aforementioned range, the heat resistance of the biodegradable resin composition is ensured, preventing vapor generation and molecular weight reduction due to heat during extrusion, and maintaining mechanical properties at or above a certain level.

[0122] TGA analysis indicates that when the biodegradable resin composition is heated at a rate of 20°C / min, the variation in the calcium carbonate content of the biodegradable resin composition at 600°C may be 5% or less.

[0123] Specifically, the variation in the calcium carbonate content is 4% or less, 3% or less, 2.5% or less, 2% or less, 1.5% or less, 1% or less, or 0.8% or less, and may be 0% or more or 0.1% or more.

[0124] The variability of calcium carbonate content is (W c0 -W c1 ) / W c0 Calculate by multiplying by 100 to obtain the initial weight of calcium carbonate (W) of the pellets of the biodegradable resin composition. c0 ) and when heating the pellets of the biodegradable resin composition at a rate of 20°C / min, the weight of the calcium carbonate of the biodegradable resin composition (W) at 600°C. c1 )

[0125] When the variability of the calcium carbonate content in the TGA analysis is within the aforementioned range, the biodegradable resin composition can maintain a high calcium carbonate (CaCO3) content even after high-temperature processing.

[0126] [Molded products] The implementation example makes it possible to provide molded articles manufactured from the biodegradable resin composition.

[0127] Specifically, the molded article is manufactured by molding the biodegradable resin composition by methods known in the industry, such as extrusion or injection molding, and the molded article may, but is not limited to, an injection-molded article, an extruded article, a thin-film molded article, or a blow-molded article.

[0128] For example, the molded product may be in the form of a film or sheet that can be used as an agricultural mulching film, disposable gloves, food packaging material, garbage bag, etc., or it may be in the form of a fiber that can be used as a woven fabric, knitted fabric, nonwoven fabric, rope, etc., or it may be in the form of a container that can be used as a food packaging container such as a bento box.

[0129] In particular, since the molded articles can be formed from the biodegradable resin composition which can improve not only strength and processability but also durability, they can exhibit excellent properties when applied to packaging materials for products stored and transported at low temperatures, or to garbage bags, mulching films, or disposable products that require excellent durability and elongation.

[0130] The biodegradable resin composition or molded articles produced therefrom will be 60% to 100% biodegraded within 45 to 180 days under natural conditions and can be composted under constant temperature conditions of 20°C to 60°C and constant humidity conditions of 30% to 90%.

[0131] -Biodegradable polyester film- One example of the molded product described above is a biodegradable polyester film, which includes the biodegradable resin composition.

[0132] The biodegradable polyester film comprises a biodegradable polyester resin and a biodegradable resin composition containing calcium carbonate (CaCO3), wherein the biodegradable resin composition has a reduction rate of 50% or more of the crystal peak represented by Formula 1.

[0133] The thickness of the biodegradable polyester film may be between 5 μm and 200 μm. For example, the thickness of the biodegradable polyester film may be between 5 μm and 180 μm, 5 μm and 160 μm, 10 μm and 150 μm, 15 μm and 130 μm, 20 μm and 100 μm, 25 μm and 80 μm, 10 μm and 50 μm, 10 μm and 30 μm, or 25 μm and 60 μm.

[0134] Furthermore, the tensile strength of the biodegradable polyester film may be 5 MPa or higher. For example, the tensile strength of the biodegradable polyester film may be 7 MPa or higher, 9 MPa or higher, 10 MPa or higher, 11 MPa or higher, and may be 30 MPa or lower, 27 MPa or lower, 25 MPa or lower, 23 MPa or lower, or 21 MPa or lower.

[0135] When the tensile strength of a biodegradable polyester film is within the aforementioned range, it can be stretched within a certain range while containing a high amount of calcium carbonate, and its excellent mechanical properties allow for diverse applications. Furthermore, once biodegradation begins, the rate of biodegradation can be further improved.

[0136] Furthermore, the tear strength of the biodegradable polyester film may be 75 N / mm or higher. For example, the tear strength of the biodegradable polyester film may be 75 N / mm or higher, 80 N / mm or higher, 85 N / mm or higher, or 90 N / mm or higher, and may be 200 N / mm or lower, 180 N / mm or lower, 150 N / mm or lower, or 135 N / mm or lower.

[0137] When the tear strength of a biodegradable polyester film is within the aforementioned range, it has excellent mechanical properties that make it difficult to tear in a certain direction, even though it contains a high amount of calcium carbonate, allowing for diverse applications, and the biodegradation rate can be further improved after biodegradation has begun.

[0138] The elongation rate of the biodegradable polyester film may be 85% or more. For example, the elongation rate of the biodegradable polyester film may be 90% or more, 95% or more, 700% or less, 650% or less, 600% or less, or 550% or less.

[0139] If the elongation rate of the biodegradable polyester film is within the aforementioned range, it will stretch well in certain areas, ensuring elasticity during product packaging, and thus it can withstand a certain load.

[0140] Furthermore, the seal strength of the biodegradable polyester film may be 500 gf or more. For example, the seal strength of the biodegradable polyester film may be 600 gf or more, 700 gf or more, or 800 gf or more.

[0141] -Biodegradable polyester sheet- A biodegradable polyester sheet, which is one example of the molded product, contains the biodegradable resin composition.

[0142] The biodegradable polyester sheet comprises a biodegradable polyester resin and a biodegradable resin composition containing calcium carbonate (CaCO3), wherein the biodegradable resin composition has a reduction rate of 50% or more of the crystal peak represented by Formula 1.

[0143] The thickness of the biodegradable polyester sheet can be 5 μm to 180 μm, 5 μm to 160 μm, 10 μm to 150 μm, 15 μm to 130 μm, 20 μm to 100 μm, 25 μm to 80 μm, 10 μm to 50 μm, or 10 μm to 30 μm.

[0144] Furthermore, the tensile strength of the biodegradable polyester sheet may be 5 MPa or higher. For example, the tensile strength of the biodegradable polyester sheet may be 6 MPa or higher, 9 MPa or higher, 10 MPa or higher, 11 MPa or higher, 12 MPa or higher, and may be 40 MPa or lower, 35 MPa or lower, 30 MPa or lower, 27 MPa or lower, 25 MPa or lower, 23 MPa or lower, or 21 MPa or lower.

[0145] If the tensile strength of the biodegradable polyester sheet is within the aforementioned range, it can be tensile within a certain range while containing a high amount of calcium carbonate, and its excellent mechanical properties allow for diverse applications. Furthermore, once biodegradation begins, the rate of biodegradation can be further improved.

[0146] Furthermore, the modulus of the biodegradable polyester sheet may be between 110 MPa and 350 MPa. For example, the modulus of the biodegradable polyester sheet may be between 120 MPa and 340 MPa, between 150 MPa and 330 MPa, or between 200 MPa and 330 MPa.

[0147] The elongation rate of the biodegradable polyester sheet may be 10% or more. For example, the elongation rate of the biodegradable polyester sheet may be 15% or more, 20% or more, 50% or more, or 70% or more, and may be 700% or less, 650% or less, 550% or less, 500% or less, or 450% or less.

[0148] If the elongation rate of the biodegradable polyester sheet is within the aforementioned range, it will stretch well in certain areas, ensuring elasticity during product packaging, and thus capable of withstanding a certain load.

[0149] [Method for manufacturing biodegradable polyester film or biodegradable polyester sheet] A method for producing a biodegradable polyester film or biodegradable polyester sheet according to an example of implementation includes the steps of: preparing a prepolymer by esterifying a diol component and a dicarboxylic acid component; preparing a biodegradable polyester resin (polymer) by polycondensing the prepolymer; preparing a biodegradable resin composition by mixing the biodegradable polyester resin and calcium carbonate; producing pellets from the biodegradable resin composition; and drying and melt-extruding the pellets.

[0150] First, a prepolymer is prepared by esterifying the diol component and the dicarboxylic acid component.

[0151] The biodegradable resin composition is a composition comprising a diol component including 1,4-butanediol or a derivative thereof, and one or more dicarboxylic acid components selected from the group consisting of terephthalic acid, dimethylterephthalic acid, adipic acid, succinic acid, and derivatives thereof, and a prepolymer is prepared by esterification reaction of this composition.

[0152] The descriptions of the diol component, the aromatic dicarboxylic acid component, and the aliphatic dicarboxylic acid component are as described above.

[0153] The step of preparing the prepolymer can be carried out by a one-step esterification reaction in which a composition comprising the diol component, the aromatic dicarboxylic acid component, the aliphatic dicarboxylic acid component, and selectively the nanocellulose is prepared, or by a two-step esterification reaction consisting of a primary esterification reaction and a secondary esterification reaction.

[0154] The two-step esterification reaction may include (1) a step of carrying out a primary esterification reaction between the diol component and the aromatic dicarboxylic acid component, and (2) a step of adding the diol component and the aliphatic dicarboxylic acid component to the reaction product of step (1) to carry out a secondary esterification reaction.

[0155] When the biodegradable polyester resin of the present invention contains nanocellulose, the bonding strength of the nanocellulose can be improved by adding the nanocellulose at the secondary esterification reaction stage when preparing the prepolymer by the two-step esterification reaction. Specifically, adding the nanocellulose, i.e., water-dispersed nanocellulose, at the secondary esterification reaction stage can further improve durability.

[0156] Furthermore, it is preferable to add the nanocellulose at a temperature of 100°C to 160°C, preferably 110°C to 140°C, as this can improve hydrolysis resistance.

[0157] Furthermore, adding the nanocellulose at a rate of 2 kg / min to 10 kg / min, 2.5 kg / min to 9.5 kg / min, or 3 kg / min to 8 kg / min can further improve hydrolysis resistance while preventing aggregation, and maintain an appropriate process speed. When the addition speed is within the above range, additional steps are unnecessary, process efficiency can be improved, and re-aggregation of the nanocellulose can be prevented.

[0158] More specifically, the two-step esterification reaction may include (1) a step of primary esterification of the diol component and the first dicarboxylic acid component, and (2) a step of secondary esterification of the reaction product from step (1) by adding the diol component, the second dicarboxylic acid component, and the nanocellulose.

[0159] Prior to the esterification reaction, the titanium-based catalyst, germanium-based catalyst, antimony-based catalyst, additives, and stabilizers may be added to the composition. The catalysts, additives, and stabilizers are described above.

[0160] The esterification reactions may be carried out at temperatures below 250°C for 0.5 to 5 hours. Specifically, the esterification reactions may be carried out at atmospheric pressure at temperatures below 240°C, below 235°C, between 180°C and 250°C, between 185°C and 240°C, or between 200°C and 240°C, until the by-products of water and methanol theoretically reach 90%. For example, the esterification reactions may be carried out for 0.5 to 4.5 hours, 0.5 to 3.5 hours, or 1 to 3 hours, but are not limited to these.

[0161] The number-average molecular weight of the prepolymer may be between 500 and 10000. For example, the number-average molecular weight of the prepolymer may be between 500 and 8500, 500 and 7000, 1000 and 6000, or 2500 and 5500. By satisfying the above range for the number-average molecular weight of the prepolymer, the molecular weight of the polymer can be efficiently increased in the polycondensation reaction, thereby further improving the strength properties.

[0162] The aforementioned number-average molecular weight can be measured using gel permeation chromatography (GPC). Specifically, the data obtained by gel permeation chromatography includes various parameters such as Mn, Mw, and Mp, and the molecular weight can be measured using the number-average molecular weight (Mn) as the reference.

[0163] Subsequently, the prepolymer is subjected to a polycondensation reaction to prepare a biodegradable polyester resin (polymer).

[0164] The polycondensation reaction may be carried out at 180°C to 280°C and at a temperature of 1.0 Torr or less for 1 to 6 hours. For example, the polycondensation reaction may be carried out at 190°C to 270°C, 210°C to 260°C, or 230°C to 255°C, at a temperature of 0.9 Torr or less, 0.7 Torr or less, 0.2 Torr to 1.0 Torr, 0.3 Torr to 0.9 Torr, or 0.5 Torr to 0.9 Torr, for 1.5 to 5.5 hours, 2 to 5 hours, or 3.5 to 4.5 hours.

[0165] The intrinsic viscosity of the biodegradable polyester resin may range from 0.05 dL / gr to 10 dL / gr.

[0166] The melt viscosity of the biodegradable polyester resin is set to 100s. -1 Under these conditions, when measured by RDS (rheometrics dynamic spectrometer), the poise can range from 1,000 to 30,000.

[0167] The number-average molecular weight (Mn) of the biodegradable polyester resin may be 40,000 or more. For example, the number-average molecular weight of the biodegradable polyester resin may be 43,000 or more, 45,000 or more, or 40,000 to 70,000.

[0168] The weight-average molecular weight (Mw) of the biodegradable polyester resin may be 60,000 or more. For example, the weight-average molecular weight of the biodegradable polyester resin may be 65,000 or more, 75,000 or more, 80,000 or more, or 85,000 to 100,000.

[0169] The polydispersity index (PDI) of the biodegradable polyester resin may be 1.2 to 2.0. For example, the polydispersity index of the biodegradable polyester resin may be 1.5 to 1.9 or 1.6 to 1.8.

[0170] The strength and processability of the biodegradable polyester resin can be further improved by ensuring that the number-average molecular weight, weight-average molecular weight, or polydispersity index of the biodegradable polyester resin satisfies the aforementioned range.

[0171] Furthermore, the acid value of the biodegradable polyester resin may be 1.8 mg KOH / g or less. For example, the acid value of the biodegradable polyester resin may be 1.5 mg KOH / g or less, 1.3 mg KOH / g or less, or 1.25 mg KOH / g or less. By satisfying the above range for the acid value of the biodegradable polyester resin, the improvement in hydrolysis resistance can be maximized.

[0172] Subsequently, the biodegradable polyester resin and calcium carbonate are mixed to prepare a biodegradable resin composition.

[0173] The mixing of the biodegradable polyester resin and calcium carbonate can be appropriately set according to the molding method (extrusion molding, injection molding, vacuum molding, etc.). For example, the biodegradable polyester resin and calcium carbonate can be kneaded and melted before being fed from the hopper into the molding machine, or they can be kneaded and melted simultaneously with molding in the molding machine. For melt kneading, it is preferable to uniformly disperse the calcium carbonate in the biodegradable polyester resin and knead it while applying high shear stress. For example, it is preferable to knead it in a kneader reactor, an extrusion molding machine equipped with a single screw, or a twin-screw kneader.

[0174] Furthermore, one or more of the plasticizers or additives may be added during the mixing stage. The aforementioned mixing stage consists of one or more mixing stages.

[0175] As an example, in the case of a single mixing step, it may consist of a single mixing step in which a biodegradable resin composition is prepared containing 61% to 80% or 65% to 72% by weight of calcium carbonate, based on the total weight of the biodegradable resin composition.

[0176] Another implementation example is a two-stage mixing process, which may consist of a preliminary mixing step to prepare a biodegradable resin composition containing 61% to 80% or 65% to 72% by weight of calcium carbonate based on the total weight of the biodegradable resin composition, and a secondary mixing step to prepare a biodegradable resin composition containing 30% to 60% by weight, 40% to 60% by weight, or 45% to 55% by weight of calcium carbonate based on the total weight of the biodegradable resin composition.

[0177] The aforementioned one or more mixing stages may be tandem continuous processes.

[0178] The temperature during the mixing stage may be 150°C to 190°C, 150°C to 180°C, or 160°C to 180°C. When the temperature during the mixing stage is within this range, the required torque during mixing can be reduced, and thermal decomposition of the mixed biodegradable resin composition can be prevented.

[0179] Subsequently, pellets are produced from the biodegradable resin composition. The biodegradable resin composition can be fed into an extruder equipped with a single screw or a twin-screw extruder and extruded at a temperature of 150°C to 180°C, cut with a hot-cut pellet cutter, and cooled to 50°C or below, 40°C or below, 30°C or below, 25°C or below, 5°C to 50°C, 10°C to 30°C, 15°C to 25°C, or 20°C to 25°C to produce pellets.

[0180] The aforementioned cutting step can be performed using any pellet cutter used in this industry, and the pellets may have various shapes.

[0181] Finally, the pellets are dried and melted and extruded. The pellets are dried and melt-extruded to produce a biodegradable polyester film or a biodegradable polyester sheet.

[0182] The drying process may be carried out at 60°C to 100°C for 2 to 12 hours. Specifically, the drying may be carried out at 65°C to 95°C, 70°C to 90°C, or 75°C to 85°C for 3 to 12 hours or 4 to 10 hours. By satisfying the above range of conditions for the pellet drying process, the quality of the biodegradable polyester film produced can be further improved.

[0183] The melt extrusion may be carried out at a temperature of 270°C or lower. For example, the melt extrusion may be carried out at a temperature of 265°C or lower, 260°C or lower, 255°C or lower, 130°C to 270°C, 130°C to 250°C, 140°C to 230°C, 150°C to 200°C, or 150°C to 180°C. The melt extrusion may be carried out by a blown film process or a press process, but is not limited to these.

[0184] The torque during melt extrusion may be 100 Nm to 300 Nm or 150 Nm to 250 Nm.

[0185] The above content will be further explained in detail by the following examples. However, the following examples are for illustrative purposes only, and the scope of the examples is not limited to these.

[0186] (Example of experiment) (Experimental Example 1: Isothermal Weight Loss) For pellets produced using the biodegradable resin compositions of the examples and reference examples, the initial weight of the pellets (W0) and the weight change of the pellets (W1) after leaving the film at an isothermal temperature of 210°C for 1 hour were measured, and the isothermal weight loss was calculated using the formula (W0-W1) / W0×100%.

[0187] (Experimental Example 2: Variability of Calcium Carbonate Content) For the biodegradable resin composition samples of the examples and reference examples, the temperature was raised to 600°C at a heating rate of 20°C per minute using the Q500 model of TA Instruments' TGA apparatus (Dynamic mode). After that, the remaining amount of Ca was checked, and the calcium carbonate content in the pellet was calculated by converting the remaining amount of Ca to calcium carbonate (CaCO3).

[0188] (Experimental Example 3: Glass transition temperature (Tg)) When the biodegradable resin composition samples of the examples and reference examples were subjected to two heating measurements at a rate of 20°C per minute using a DSC instrument, the Tg was calculated from the differential scanning calorimetry results of the samples.

[0189] (Experimental Example 4: Crystallization temperature (Tc) and heat of fusion (ΔHmc)) The biodegradable resin composition samples of the examples and reference examples were heated from 40°C to 180°C at a rate of 10°C / min using a differential scanning calorimeter (DSC), followed by isothermal cooling for 5 minutes to remove the primary thermal history. Then, they were cooled from 180°C to -50°C at a rate of 10°C / min, followed by isothermal cooling for 5 minutes to perform a secondary cooling process.

[0190] During the secondary cooling process, a heat flow graph was created with respect to temperature to confirm the crystallization temperature (°C), crystal peak, and heat of fusion (J / g).

[0191] (Experimental Example 5: Tensile Strength) The biodegradable polyester films or sheets of the examples, comparative examples, and reference examples were cut to a length of 100 mm and a width of 15 mm. Then, in accordance with ASTM D 882, they were mounted on an INSTRON universal testing machine (4206-001, UTM) with a chuck spacing of 50 mm, and tested at a tensile speed of 500 mm / min. The tensile strength was then measured using the program built into the device.

[0192] (Experimental Example 6: Elongation Rate) The biodegradable polyester films or sheets of the examples, comparative examples, and reference examples were cut to a length of 100 mm and a width of 15 mm. The maximum deformation just before fracture was measured at a speed of 500 mm / min using an INSTRON universal testing machine (4206-001, UTM), and the ratio of the maximum deformation to the original length was calculated.

[0193] (Experimental Example 7: Tear Strength) The biodegradable polyester films of the examples and reference examples were cut according to KPS M 1001-0806, and the maximum load applied until the film was cut was measured by applying a constant speed of 500 mm / min. The tear strength was then calculated using the following formula 2. [Formula 2] Tear strength (N / cm) = Maximum load before breakage (N) / Thickness of the specimen (cm)

[0194] (Experimental Example 8: Modulus) The biodegradable polyester sheets of the examples and comparative examples were cut to a length of 100 mm and a width of 15 mm, and their modulus was measured using an Instron universal tester (4206-001, UTM) according to ASTM D 882.

[0195] (Examples) [Manufacturing of biodegradable polyester resin] (Manufacturing Example 1) A mixture of 50 mol% 1,4-butanediol and 50 mol% dimethyl terephthalic acid was prepared, and 200 ppm of the titanium-based catalyst tetrabutyl titanate (manufactured by Aldrich) was added to the mixture. A primary esterification reaction was then carried out at 210°C and atmospheric pressure for 2 hours.

[0196] To the reaction product, 50 mol% of 1,4-butanediol, 50 mol% of adipic acid, 0.1 wt% of pre-treated nanocellulose, and 150 ppm of the titanium-based catalyst tetrabutyl titanate (manufactured by Aldrich) were added, and a secondary esterification reaction was carried out at 210°C and atmospheric pressure for 2 hours to prepare a prepolymer having a number-average molecular weight of 5000.

[0197] 200 ppm of tetrabutyl titanate (manufactured by Aldrich), a polycondensation catalyst, was added to the aforementioned prepolymer, and after raising the temperature to 240°C, a polycondensation reaction was carried out at 0.5 torr for 4 hours to prepare a biodegradable polyester resin having a number average molecular weight of 50,000.

[0198] (Manufacturing example 2) The biodegradable polyester resin for Production Example 2 was prepared in the same manner as in Production Example 1, except that pre-treated nanocellulose was not added.

[0199] Alternatively, instead of using manufacturing example 2, Kingfa's A400 can be used as a PBAT resin with the same composition but without nanocellulose.

[0200] The mechanical and thermal properties of the biodegradable polyester resins of Production Examples 1 and 2 of the present invention are shown in Table 1.

[0201] [Table 1]

[0202] [Manufacturing of biodegradable resin compositions] (Examples A1-A8) Based on Tables 2 and 3 below, the polymers of Production Example 1 or Production Example 2, with the constituent components of the composition differed, were mixed with calcium carbonate (WS-2200), a plasticizer (acetylated monoglyceride, Biocizer®), additive 1 (polycaprolactone; PCL), additive 2 (polylactic acid; PLA), antioxidant 1 (phenolic antioxidant, AO-60), or antioxidant 2 (phosphorus-based antioxidant, 2112(AO)). The mixture was then placed in a kneader reactor and kneaded at a temperature of 175°C. This mixture was then extruded using an extruder equipped with a single screw, cut with a hot-cut pellet cutter, and cooled to produce pelletized biodegradable resin compositions.

[0203] (Examples A9 and A10) The composition of Example A7 or Example A8, kneaded in a kneader reactor, was fed into an extruder equipped with twin screws. The polymer of Production Example 1 or Production Example 2 was then added to adjust the content of the composition components shown in Table 3 below. This was then extruded in an extruder equipped with a single screw, cut with a hot-cut pellet cutter, and cooled to produce pelletized biodegradable resin compositions.

[0204] (Examples A11-A13) Based on Table 4 below, the polymers of Production Example 1 or Production Example 2, with the compositional components differed, were mixed with additives including PLA, calcium carbonate (WS-2200), plasticizer (acetylated monoglyceride), stabilizer (tris-2,4-teiary buthyl phenyl phosphate, 2112 RG grade), and chain extender (Joncryl). These mixtures were then placed in a kneader reactor and kneaded at a temperature of 175°C. The mixture was then extruded using an extruder equipped with a single screw, cut with a hot-cut pellet cutter, and cooled to produce pelletized biodegradable resin compositions.

[0205] (Reference examples A1 and A2) 100% by weight of the polymer from Production Example 1 (Reference Example A1) or Production Example 2 (Reference Example A2) was placed in a kneader reactor and kneaded at a temperature of 175°C. This mixture was then extruded using an extruder equipped with a single screw, cut with a hot-cut pellet cutter, and cooled to produce a pelletized biodegradable resin composition.

[0206] [Table 2]

[0207] [Table 3]

[0208] [Table 4]

[0209] The measurement results for the thermal properties of the biodegradable resin composition of the present invention are shown in Table 5.

[0210] [Table 5]

[0211] The biodegradable resin compositions of Examples A1 to A10, despite containing a high content of calcium carbonate, exhibited a lower weight loss rate at high temperatures (210°C) compared to the biodegradable resin compositions of Reference Examples A1 and A2, which contained 100% by weight of the resin of Production Example 1 or 2. In particular, Examples A1, A2, A4, and A9 showed a weight loss rate of 1% or less. In experiments on the variability of calcium carbonate content, the change in calcium carbonate content of the biodegradable resin compositions of Examples A1 to A10 was 2.5% or less in all cases, indicating that a high content of CaCO3 can be maintained even after high-temperature processing.

[0212] Furthermore, the biodegradable resin compositions of Examples A1 to A10 exhibit a reduced glass transition temperature (Tg) compared to the biodegradable resin compositions of Reference Examples A1 and A2, which contain 100% by weight of the resin of Production Example 1 or 2.

[0213] Based on Reference Example A1, the biodegradable resin compositions of Examples A1, A3, A4, A7, and A9 showed a 70% to 100% reduction in heat of fusion at 70°C to 90°C, and a 32% to 90% reduction at 100°C to 150°C.

[0214] Based on Reference Example A2, the biodegradable resin compositions of Examples A2, A5, A6, A8, and A10 showed a 50% to 100% reduction in heat of fusion at 70°C to 90°C, and a 24.7% to 96% reduction at 100°C to 150°C.

[0215] [Manufacturing of biodegradable polyester film] (Examples B1-B4 and Reference Example B1) Pellets produced from the biodegradable resin compositions of Examples A9 to A13 in Tables 3 and 4 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 Co., Ltd.) to produce a 15 μm thick biodegradable polyester film.

[0216] The measurement results for the mechanical properties of the biodegradable polyester film of the present invention are shown in Table 6.

[0217] [Table 6]

[0218] In the case of the biodegradable polyester films containing high levels of calcium carbonate in Examples B1 and B2, it was confirmed that they exhibited excellent tensile strength and elongation, and maintained excellent tear strength. In the case of the biodegradable polyester films containing high levels of calcium carbonate in Examples B3 and B4, the addition of PLA reduced tensile strength, elongation, and tear strength compared to Examples B1 and B2, but it was confirmed that they were maintained at levels above those required for commercialization.

[0219] [Manufacturing of biodegradable polyester sheets] (Sheets 1-4) Pellets produced from Production Example 1, Production Example 2 (Kingfa, A400), resin A (JINHUI, Ecoworld), resin B (TUNHE, TH80IT), or resin C (BASF, Ecoflex® C1200) were dried at 80°C for 5 hours, and then melt-extruded under the mold conditions shown in Tables 7 and 8 to produce biodegradable polyester sheets with a thickness of 20 μm.

[0220] (Examples C1, Comparative Examples C1 and C2) Except for varying the constituent components of the compositions based on Table 7 below, biodegradable resin compositions were produced by adding calcium carbonate to Production Example 1 or resin A (JINHUI Co., Ltd., Ecoworld) or resin B (TUNHE Co., Ltd., TH80IT) using the same manufacturing method as in Example A1. Then, biodegradable polyester sheets were produced using the same manufacturing method as in Sheet 1.

[0221] (Examples C2-C13) Except for varying the constituent components of the compositions based on Table 8 below, a biodegradable resin composition was prepared by adding one or more substances selected from the group consisting of calcium carbonate (WS-2200), plasticizer (acetylated monoglyceride, Biocizer), polycaprolactone (PCL), or polylactic acid (PLA) to the biodegradable polyester resin of Production Example 1 or Production Example 2. After preparing the biodegradable resin composition using the same manufacturing method as in Example A1, a biodegradable polyester sheet was prepared using the same manufacturing method as in Sheet 1.

[0222] [Table 7]

[0223] Conventional biodegradable polyester sheets containing high levels of calcium carbonate (Comparative Examples C1 and C2) require high torque in the molding conditions for manufacturing, resulting in disadvantages in terms of energy and cost. Furthermore, the reduction in tensile strength or elongation is significantly greater compared to sheets 3 and 4, making them unsuitable for the manufacture of molded products. On the other hand, the biodegradable polyester sheet of the present invention (Example C1) was able to reduce the energy and cost required for molding. In addition, the biodegradable polyester film of the present invention contains a high level of calcium carbonate, reducing raw material costs, while also enhancing the biodegradability of the polyester film and adjusting the acidity of the decomposition products.

[0224] [Table 8]

[0225] Conventional biodegradable polyester sheets containing high levels of calcium carbonate show a significant decrease in tensile strength or elongation (Comparative Examples C1 and C2 in Table 7), making them unsuitable for molded product manufacturing. However, the biodegradable polyester sheets of the present invention (Examples C2 to C13 in Table 8) were able to maintain tensile strength and elongation at a certain level or higher compared to Sheet 1 or Sheet 2.

Claims

1. Biodegradable polyester resin, calcium carbonate (CaCO3) ３ A biodegradable resin composition comprising ) and a chain extender, The biodegradable polyester resin comprises a first repeating unit and a second repeating unit, The first repeating unit comprises a diol component and an aromatic dicarboxylic acid component. The second repeating unit comprises a diol component and an aliphatic dicarboxylic acid component. The molar ratio of the aromatic dicarboxylic acid component to the aliphatic dicarboxylic acid component is 0.5 to 1.

5. The biodegradable polyester resin contains 0.01% to 2.5% by weight of nanocellulose based on the total weight of the biodegradable polyester resin. The biodegradable resin composition contains the chain extender in an amount of 0.01% to 1% by weight, based on the total weight of the biodegradable resin composition. A biodegradable resin composition having a reduction rate of 50% or more of the crystal peak represented by the following formula 1: [Equation 1] Decrease rate of crystal peaks = (R ｐ -C ｐ ) / R ｐ In the above formula 1, R ｐ This is the heat of fusion (J / g) of the biodegradable polyester resin in the 70°C to 90°C temperature range, measured using a differential scanning calorimeter (DSC) during the process of heating from 40°C to 180°C at a rate of 10°C / min, followed by cooling to -50°C at a rate of 10°C / min. C ｐ This is the heat of fusion (J / g) of the biodegradable resin composition measured under the same conditions as described above.

2. The calcium carbonate (CaCO) ３ The biodegradable resin composition according to claim 1, comprising 30% to 80% by weight of the biodegradable resin composition based on the total weight of the biodegradable resin composition.

3. The biodegradable resin composition comprises a plasticizer and an antioxidant. The plasticizer comprises one or more selected from the group consisting of glycerol, acrylate, glycerin, glycerol monostearate, and sorbitol. The aforementioned antioxidant comprises two or more selected from the group consisting of phosphorus-based antioxidants, phenol-based antioxidants, and pentaerythritol-based antioxidants. The biodegradable resin composition according to claim 1, comprising 1% to 3% by weight of the plasticizer and 0.01% to 4% by weight of the antioxidant, based on the total weight of the biodegradable resin composition.

4. The antioxidant comprises the phosphorus-based antioxidant and the phenol-based antioxidant. The biodegradable resin composition according to claim 3, wherein the weight ratio of the phosphorus-based antioxidant to the phenol-based antioxidant is 1:10 to 10:

1.

5. The biodegradable resin composition further comprises one or more dispersants selected from the group consisting of polylactic acid, polyglycolic acid, polycaprolactone, and polyhydroxyalkanoate. The biodegradable resin composition according to claim 1, comprising the dispersant in an amount of 1% to 20% by weight based on the total weight of the biodegradable resin composition.

6. When the biodegradable resin composition is maintained at an isothermal temperature of 210°C for 1 hour, the isothermal weight loss is 5% or less. The biodegradable resin composition according to claim 1, wherein when the biodegradable resin composition is heated at a rate of 20°C / min, the variation in the calcium carbonate content at 600°C is 5% or less.

7. Biodegradable polyester resin, calcium carbonate (CaCO3) ３ ) and a biodegradable resin composition containing a chain extender, The biodegradable polyester resin comprises a first repeating unit and a second repeating unit, The first repeating unit comprises a diol component and an aromatic dicarboxylic acid component. The second repeating unit comprises a diol component and an aliphatic dicarboxylic acid component. The molar ratio of the aromatic dicarboxylic acid component to the aliphatic dicarboxylic acid component is 0.5 to 1.

5. The biodegradable polyester resin contains 0.01% to 2.5% by weight of nanocellulose based on the total weight of the biodegradable polyester resin. The biodegradable resin composition contains the chain extender in an amount of 0.01% to 1% by weight, based on the total weight of the biodegradable resin composition. The biodegradable resin composition is a biodegradable polyester film having a reduction rate of 50% or more of the crystal peak represented by the following formula 1: [Formula 1] Reduction rate of crystal peak = (R ｐ - C ｐ ) / R ｐ In the above formula 1, R ｐ This is the heat of fusion (J / g) of the biodegradable polyester resin in the 70°C to 90°C temperature range, measured using a differential scanning calorimeter (DSC) during the process of heating from 40°C to 180°C at a rate of 10°C / min, followed by cooling to -50°C at a rate of 10°C / min. C ｐ This is the heat of fusion (J / g) of the biodegradable resin composition measured under the same conditions as described above.

8. Biodegradable polyester resin, calcium carbonate (CaCO3) ３ ) and a biodegradable resin composition containing a chain extender, The biodegradable polyester resin comprises a first repeating unit and a second repeating unit, The first repeating unit comprises a diol component and an aromatic dicarboxylic acid component. The second repeating unit comprises a diol component and an aliphatic dicarboxylic acid component. The molar ratio of the aromatic dicarboxylic acid component to the aliphatic dicarboxylic acid component is 0.5 to 1.

5. The biodegradable polyester resin contains 0.01% to 2.5% by weight of nanocellulose based on the total weight of the biodegradable polyester resin. The biodegradable resin composition contains the chain extender in an amount of 0.01% to 1% by weight, based on the total weight of the biodegradable resin composition. The biodegradable resin composition is a biodegradable polyester sheet having a reduction rate of 50% or more of the crystal peak represented by the following formula 1: [Equation 1] Decrease rate of crystal peaks = (R ｐ -C ｐ ) / R ｐ In the above formula 1, R ｐ This is the heat of fusion (J / g) of the biodegradable polyester resin in the 70°C to 90°C temperature range, measured using a differential scanning calorimeter (DSC) during the process of heating from 40°C to 180°C at a rate of 10°C / min, followed by cooling to -50°C at a rate of 10°C / min. C ｐ This is the heat of fusion (J / g) of the biodegradable resin composition measured under the same conditions as described above.

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