Biodegradable resin composition, biodegradable film, and biodegradable article comprising same

Abstract

The present invention relates to a biodegradable resin composition, a biodegradable film, and a biodegradable article.

Description

Biodegradable resin composition, biodegradable film, and biodegradable article comprising the same

[0001] Cross-citation with related application(s)

[0002] The present application claims the benefit of the filing date of Korean Patent Application No. 10-2024-0191858 filed with the Korean Intellectual Property Office on December 19, 2024, the entire contents of which are incorporated herein as part.

[0003] The present invention relates to a biodegradable resin composition and a biodegradable article comprising the same.

[0004] Thermoplastic polymer resins, such as polyethylene film, possess excellent mechanical properties and are harmless to the human body. Because they can be continuously deformed when heated, they are used in various fields including drinking water containers, medical applications, food packaging, food containers, automotive molded parts, and agricultural vinyl. Based on their superior functionality and low cost, their consumption is increasing every year.

[0005] Polyethylene (PE) films are widely used for various purposes, such as mulching films and food packaging. However, PE films are difficult to recycle and do not decompose in the natural environment, causing serious environmental problems such as the formation of microplastics. In particular, PE used as mulching film in agriculture remains in the soil, negatively impacting crop growth, and due to the difficulties in waste management, the need for sustainable alternative materials is steadily increasing.

[0006] Accordingly, the development and utilization of biodegradable resins capable of replacing PE films are attracting attention, and related research is actively underway. Biodegradable resins are materials that can reduce environmental burden by decomposing through microorganisms in the natural environment after a certain period of time following use; in particular, polybutylene adipate terephthalate (PBAT) is evaluated as a major candidate due to its excellent flexibility and processability. Currently, attempts are being made to improve various mechanical properties by blending PBAT with other polymers, such as polylactic acid (PLA).

[0007] However, conventional biodegradable resins have several limitations. Biodegradable resins generally struggle to achieve the sufficient mechanical strength required by films, a problem particularly evident in physical properties such as tensile strength and impact resistance. Furthermore, while films must maintain stable durability over their service life, there is a concern that physical properties may deteriorate rapidly during use if biodegradation proceeds too quickly. In addition, biodegradable resins may easily deform due to non-uniform crystallization structures or insufficient dimensional stability, which often limits their use in high-temperature environments.

[0008] Therefore, there is a need to develop biodegradable resins that not only possess the characteristic of being able to decompose in the environment, but also maintain excellent mechanical properties stably during the service period while allowing for rapid decomposition after the point of need.

[0009] One objective of the present invention is to provide a biodegradable resin composition that has excellent mechanical properties when manufactured into a film, controls the initial biodegradability so that the properties are maintained stably during product use, and exhibits high biodegradability after the required time.

[0010] Another objective of the present invention is to provide a biodegradable article manufactured using the above-described biodegradable resin composition, which has excellent mechanical properties such as strength, dimensional stability, and durability, as well as excellent appearance characteristics and excellent biodegradability.

[0011] However, the technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below.

[0012] According to one embodiment of the present invention, a biodegradable resin composition comprising polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA) is provided, wherein for a film made of said resin composition, the surface modulus (E1) by nanoindenter at 25±5℃ satisfies the following Equation 1, the modulus (E2) at a depth of 10% thickness from the surface of the film satisfies the following Equation 2, and the ratio of E1 to E2 satisfies the following Equation 3:

[0013] [Equation 1]

[0014] E1 ≥ 0.3

[0015] [Equation 2]

[0016] 0.2 ≤ E2 ≤ 0.5

[0017] [Equation 3]

[0018] E1 / E2 ≥ 1.3

[0019] The surface modulus (E1) may be 0.3 GPa to 0.6 GPa.

[0020] The modulus (E2) at a depth of 10% from the surface of the film may be 0.2 GPa to 0.45 GPa.

[0021] The ratio (E1 / E2) of the surface modulus (E1) to the modulus (E2) at a depth of 10% from the surface of the film may be 1.4 to 2.5.

[0022] The ratio of the dispersion index (PDI1) of the composition measured on Day 1 to the dispersion index (PDI0) of the composition measured on Day 0 while hydrolyzing the above resin composition at 90°C can satisfy the following Equation 4:

[0023] [Equation 4]

[0024] (PDI1 / PDI0) ≥ 0.9

[0025] In the above Equation 4, PDI0 is the dispersion index (PDI) of the resin composition subject to hydrolysis testing, and PDI1 is the dispersion index (PDI) of the composition measured 24 hours after the start of the hydrolysis test at 90°C.

[0026] The ratio of the dispersion index (PDI0) of the composition measured on day 3 to the dispersion index (PDI3) of the composition measured on day 0 while hydrolyzing the above resin composition at 90°C can satisfy the following Equation 5:

[0027] [Equation 5]

[0028] (PDI3 / PDI0) ≤ 0.8

[0029] In the above Equation 5, PDI0 is the dispersion index (PDI) of the resin composition subject to hydrolysis testing, and PDI3 is the dispersion index (PDI) of the composition measured at 72 hours after the start of the hydrolysis test at 90°C.

[0030] While hydrolyzing the resin composition at 90°C, the ratio of the dispersion index (PDI0) of the composition measured on day 1 to the dispersion index (PDI1) of the composition measured on day 0 satisfies the following Equation 4, and the ratio of the dispersion index (PDI0) of the composition measured on day 0 to the dispersion index (PDI3) of the composition measured on day 3 satisfies the following Equation 5:

[0031] [Equation 4]

[0032] (PDI1 / PDI0) ≥ 0.9

[0033] [Equation 5]

[0034] (PDI3 / PDI0) ≤ 0.8

[0035] In the above formulas 4 and 5, PDI0 is the dispersion index (PDI) of the resin composition subject to the hydrolysis test, PDI1 is the dispersion index (PDI) of the composition measured 24 hours after the start of the hydrolysis test at 90°C, and PDI3 is the dispersion index (PDI) of the composition measured 72 hours after the start of the hydrolysis test at 90°C.

[0036] The weight ratio of the above polybutylene adipate terephthalate and polylactic acid may be 70:30 to 95:5.

[0037] The density of the above polybutylene adipate terephthalate is 1.1 g / cm³ 3 Up to 1.5 g / cm 3 It could be.

[0038] The density of the above polylactic acid is 1.1 g / cm³ 3 Up to 1.5 g / cm 3 It could be.

[0039] The above polybutylene adipate terephthalate may have a weight-average molecular weight of 50,000 to 200,000 g / mol.

[0040] The above polylactic acid may have a weight-average molecular weight of 100,000 to 300,000 g / mol.

[0041] The melt index (190 ℃, 2.16 kg) of the above polybutylene adipate terephthalate may be 2.5 g / 10 min to 6.0 g / 10 min.

[0042] The melt index (190 ℃, 2.16 kg) of the above polylactic acid may be 1.5 g / 10 min to 4.5 g / 10 min.

[0043] The above biodegradable resin composition may further include at least one of an inorganic filler and a compatibilizer.

[0044] The above inorganic filler may be included in an amount of 15 to 20 parts by weight based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

[0045] The above compatibilizer may be included in an amount of 0.3 to 1.2 parts by weight based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

[0046] According to another embodiment of the present invention, a biodegradable film comprising polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA) is provided, wherein the surface modulus (E1) by nanoindenter at 25±5℃ for the film satisfies Equation 1, the modulus (E2) at a depth of 10% from the surface of the film satisfies Equation 2, and the ratio of E1 to E2 satisfies Equation 3.

[0047] The surface modulus (E1) may be 0.3 GPa to 0.6 GPa.

[0048] The modulus (E2) at a depth of 10% from the surface of the film may be 0.2 GPa to 0.45 GPa.

[0049] The ratio (E1 / E2) of the surface modulus (E1) to the modulus (E2) at a depth of 10% from the surface of the film may be 1.4 to 2.5.

[0050] The weight ratio of the above polybutylene adipate terephthalate and polylactic acid may be 70:30 to 95:5.

[0051] The density of the above polybutylene adipate terephthalate is 1.1 g / cm³ 3 Up to 1.5 g / cm 3 It could be.

[0052] The density of the above polylactic acid is 1.1 g / cm³ 3 Up to 1.5 g / cm 3 It could be.

[0053] The above polybutylene adipate terephthalate may have a weight-average molecular weight of 50,000 to 200,000 g / mol.

[0054] The above polylactic acid may have a weight-average molecular weight of 100,000 to 300,000 g / mol.

[0055] The melt index (190 ℃, 2.16 kg) of the above polybutylene adipate terephthalate may be 2.5 g / 10 min to 6.0 g / 10 min.

[0056] The melt index (190 ℃, 2.16 kg) of the above polylactic acid may be 1.5 g / 10 min to 4.5 g / 10 min.

[0057] The above biodegradable resin composition may further include at least one of an inorganic filler and a compatibilizer.

[0058] The above inorganic filler may be included in an amount of 15 to 20 parts by weight based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

[0059] The above compatibilizer may be included in an amount of 0.3 to 1.2 parts by weight based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

[0060] In addition, the biodegradable film may satisfy at least one of the following 1) to 5). Preferably, it may satisfy all of 1) to 5):

[0061] 1) The MD modulus of the biodegradable film is 2500 kgf / cm² 2 Up to 4000 kgf / cm² 2 ;

[0062] 2) The TD modulus of the biodegradable film is 2400 kgf / cm² 2 Up to 3300 kgf / cm² 2 ;

[0063] 3) The MD elongation of the biodegradable film is 550% to 700%;

[0064] 4) The TD elongation of the biodegradable film is 580% to 720%;

[0065] 5) The 20° gloss of the biodegradable film is 7 GU to 9.8 GU

[0066] In addition, the thickness of the biodegradable film may be 10 to 200 μm.

[0067] According to another embodiment of the present invention, a biodegradable article comprising a biodegradable resin composition according to the present invention is provided.

[0068] The biodegradable resin composition of the present invention has excellent mechanical properties, particularly strength, dimensional stability, and durability, when processed into a film, and the initial biodegradability is controlled so that the properties do not deteriorate during product use, while exhibiting high biodegradability after a certain period of time has elapsed after use, thereby minimizing the environmental burden.

[0069] The present invention is described in detail below so that those skilled in the art can easily implement it. However, the present invention may be embodied in various different forms and is not limited to the configurations described herein.

[0070] Unless otherwise defined in this specification, all technical and scientific terms are used merely to describe exemplary embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0071] In this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Specifically, in this specification, terms such as "comprising," "having," or "having" are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0072] Generally, various packaging and mulching materials have been manufactured from synthetic resins, such as polyethylene resin, which can undergo continuous deformation upon the application of heat. However, these polyethylene films do not decompose in the natural environment and have limitations in recycling. Consequently, the development of biodegradable polymer films to replace conventional thermoplastics is actively underway. Nevertheless, biodegradable films developed to date have had limitations in providing satisfactory performance in terms of mechanical strength, durability, and dimensional stability, and there has been a problem where physical properties deteriorate during product use due to the high initial biodegradability.

[0073] To overcome these limitations, the present invention provides a biodegradable resin designed to have a high surface modulus when manufactured into a film, and to have a modulus ratio at 10% of the film thickness relative to the surface modulus that is below a certain level. Through this, the film maintains excellent mechanical properties and dimensional stability while controlling the initial biodegradability to maintain durability during use, and rapidly biodegrades after a certain period of time after use, thereby providing the effect of reducing environmental burden.

[0074] According to one embodiment of the present invention, the invention relates to a resin composition comprising polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA), wherein the surface modulus (E1) on the surface of a film prepared from the resin composition is 0.3 GPa or more as shown in Formula 1 below, the surface modulus (E2) at a point 10% of the film thickness from the film surface is 0.2 GPa or more and 0.5 GPa or less as shown in Formula 2 below, and the ratio of E1 to E2 (E1 / E2) is 1.3 or more as shown in Formula 3 below:

[0075] [Equation 1]

[0076] E1 ≥ 0.3

[0077] [Equation 2]

[0078] 0.2 ≤ E2 ≤ 0.5

[0079] [Equation 3]

[0080] E1 / E2 ≥ 1.3

[0081] In this specification, "surface modulus" refers to the stiffness of the surface and its resistance to deformation. The larger the surface modulus, the better the mechanical properties of the biodegradable film. However, if the surface modulus is too large, it may be easily damaged by external impact. Like the general modulus, the surface modulus is an indicator of mechanical stiffness; however, while the general modulus is an indicator of properties for the entire material, the surface modulus differs in that it intensively indicates properties for the surface layer within 10% of the total thickness of the material.

[0082] When the biodegradable resin composition according to the present invention is manufactured into a film, it has a high modulus on the surface while having a limited modulus inside the film. A film according to the present invention having these characteristics can possess excellent mechanical properties, such as tensile strength and dimensional stability. In particular, the high modulus characteristic on the film surface provides resistance to initial biodegradation, thereby preventing degradation of physical properties during use and maintaining stable durability. Furthermore, the difference in modulus between the interior and the surface of the film can contribute to the gradual progression of the biodegradation process over time. The surface modulus below is based on the resin composition being manufactured into a film with a thickness of about 30 to 70 μm, preferably about 50 ± 5 μm.

[0083] Specifically, the surface modulus of the film is 0.3 GPa or higher as shown in Equation 1 above, and the upper limit may be 0.6 GPa or lower or 0.55 GPa or lower, and preferably 0.3 GPa to 0.6 GPa, or 0.3 GPa to 0.55 GPa.

[0084] In addition, the modulus at a point 10% of the thickness from the surface of the film (e.g., a point about 5 µm deep from the surface when the film thickness is about 50 µm) is 0.2 GPa or more, as shown in Equation 2 above, and the upper limit may be 0.5 GPa or less, 0.45 GPa or less, or 0.4 GPa or less, and may be 0.2 GPa to 0.5 GPa, or 0.2 GPa to 0.45 GPa, or 0.2 GPa to 0.4 GPa.

[0085] In addition, the film has a relatively high modulus on the film surface compared to the interior of the film, so it has excellent initial resistance to a decomposition environment, and after a certain period of time has elapsed since the start of decomposition, decomposition can be carried out with high efficiency. In this regard, the ratio of the modulus on the film surface (E1 / E2) to the modulus at a point 10% of the thickness depth from the surface of the present invention is 1.3 or higher, as shown in Equation 3 above, and preferably 1.3 or higher or 1.4 or higher. At this time, the upper limit may be 3 or lower or 2.4 or lower. Preferably, it may be 1.3 to 3 or 1.4 to 2.5.

[0086] The above surface modulus can be measured using the indentation method. Specifically, after preparing a blown film with dimensions of 20 mm × 20 mm and a thickness of approximately 50 ± 5 μm, a nano-indenter (UNHT) 3Using Anton Paar, modulus profile analysis according to film indentation depth is performed in Sinus mode. The film surface is indented at a temperature of 25±5℃ using the Vickers square pyramid tip of the nano-indenter, with a maximum applied load of 5 mN and a maximum film indentation depth of 1 µm. However, in Sinus mode, Oscillation frequency: 10 Hz, Oscillation amplitude: 0.1 mN, Constant strain rate: 0.1 sec -1 It is set to this. Through the above analysis, a modulus profile according to depth from the surface of the film can be obtained. However, during the analysis process, data deviation may occur in the initial thickness range due to the so-called 'particle size effect' that occurs as the indenter begins to contact a local area on the film surface. To correct this, linear extrapolation is performed in the mid-to-late range where the modulus profile stabilizes to calculate the surface modulus from which the particle size effect has been removed. The modulus at the surface of the film and at a point 10% of the film thickness from the surface are each represented as the average value after performing the above analysis at three arbitrary points on the specimen.

[0087] The biodegradable resin composition according to the present invention initially exhibits resistance to biodegradation, maintaining its physical properties during use, and subsequently undergoes gradual biodegradation over a certain period of time, thereby achieving high degradation efficiency. The slow-release biodegradation pattern of the resin composition according to the present invention was evaluated by the change in the Polydispersity Index (PDI) when hydrolyzed for 3 days (72 hours) under a temperature of 90°C.

[0088] The 90°C hydrolysis experiment is an accelerated biodegradability evaluation experiment, and the initial biodegradability resistance can be predicted from the change in PDI after 1 day (24 hours) of the hydrolysis experiment, and the long-term biodegradability can be predicted from the change in PDI after 3 days (72 hours) of the hydrolysis experiment. Specifically, the ratio of the dispersion index (PDI1) of the composition measured on day 1 to the dispersion index (PDI0) of the composition measured on day 0 while hydrolyzing the biodegradable resin composition of the present invention at 90°C for 3 days (72 hours) may be 0.9 or higher, as shown in Formula 4 below. Specifically, (PDI1 / PDI0) may be 0.9 or higher, or 0.92 or higher, and may be 1.3 or lower, 1.25 or lower, or 1.2 or lower, and preferably 0.9 to 1.3, 0.92 to 1.25, or 0.94 to 1.2.

[0089] [Equation 4]

[0090] (PDI1 / PDI0) ≥ 0.9

[0091] In the above Equation 4, PDI0 is the dispersion index of the composition on day 0, and is the dispersion index (PDI) of the resin composition to be subjected to the hydrolysis experiment. Also, PDI1 is the dispersion index (PDI) of the composition measured at 90°C on day 1 (at the point 24 hours after the start of the hydrolysis experiment).

[0092] In addition, the present invention may have a ratio of the dispersion index (PDI0) of the composition measured on day 3 to the dispersion index (PDI3) of the composition measured on day 0 while hydrolyzing the resin composition at 90°C for 3 days (72 hours) that may be 0.8 or less, or 0.76 or less, as shown in Formula 5 below. At this time, the lower limit may be 0.5 or more, or 0.55 or more. Preferably, it may be 0.5 to 0.8 or 0.55 to 0.76.

[0093] [Equation 5]

[0094] (PDI3 / PDI0) ≤ 0.8

[0095] In the above Equation 5, PDI0 is the dispersion index of the composition on day 0, and is the dispersion index (PDI) of the resin composition to be subjected to the hydrolysis experiment. Also, PDI3 is the dispersion index (PDI) of the composition measured at 90°C on day 3 (72 hours after the start of the hydrolysis experiment).

[0096] A hydrolysis experiment on the above resin composition conducted at 90°C for 3 days (72 hours) can be performed by the following method: First, freeze-grind the resin composition to a particle size of approximately 500 μm or less, and then place 1 g of the ground resin composition into each of three vials. Add 20 ml of deionized water to only two of the three vials containing the sample, and proceed with hydrolysis at a temperature of 90°C. At this time, for Vial 1, the experiment is terminated (preparation of the Day 1 sample) after 24 hours have elapsed from the time of adding deionized water, and the sample is taken, dried, and the dispersion index (PDI) is measured. For Vial 2, the experiment is terminated (preparation of the Day 3 sample) after 72 hours have elapsed, and the sample is taken, dried, and the dispersion index (PDI) is measured. In addition, for comparison, a sample without added deionized water is also dried and the dispersion index (PDI) is measured. Drying is carried out at a temperature of 50°C using nitrogen purging.

[0097] At this time, the PDI measured for the dried sample (Day 1 sample) after 24 hours have elapsed since the addition of ultrapure water is set as the dispersion index (PDI1) of the composition on Day 1 of hydrolysis at 90°C. Also, the PDI measured for the dried sample (Day 3 sample) after 72 hours have elapsed since the addition of ultrapure water is set as the dispersion index (PDI3) of the composition on Day 3 of hydrolysis at 90°C. Additionally, the dispersion index (PDI) for the dried sample without the addition of ultrapure water (Day 0 sample) is set as the dispersion index (PDI0) of the composition on Day 0 of hydrolysis.

[0098] The dispersion index (PDI) of the above composition is the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the resin composition, and is also called the polydispersity index. The above dispersion index can be calculated by measuring the weight-average molecular weight (Mw) and the number-average molecular weight (Mn) of the resin composition. At this time, the weight-average molecular weight (Mw) and the number-average molecular weight (Mn) are converted values ​​for standard polystyrene measured using gel permeation chromatography (GPC).

[0099] The dispersion index (PDI) of the above composition can be measured by the following method, but is not limited thereto: the dried sample after the hydrolysis experiment is diluted in chloroform to 10 mg / mL, centrifuged at 2500 rpm for 30 minutes, and filtered through a 0.2 μm filter to prepare a sample solution. 1000 mL of chloroform is filtered to prepare the mobile phase. A molecular weight distribution curve over time is obtained for each sample using a gel permeation chromatography (GPC) / refractive index (RI) detector.

[0100] The measurement conditions shown below are exemplary and are not limited thereto. In this case, the molecular weight of the resin composition can be determined using a calibration curve formed using polystyrene standards. Eight types of polystyrene standards with molecular weights of 1180 / 5610 / 9690 / 17780 / 74650 / 181800 / 474500 / 1014000 were used.

[0101] <GPC 측정 조건>

[0102] - Stationary phase: Agilent PLgel MIXED-B, MIXED-C (7.5 mm × 300 mm, 5 μm)

[0103] - Mobile phase: Chloroform = 100 (v / v, %)

[0104] - Flow rate: 1.0 mL / min

[0105] - Stationary bed temperature: 40 ℃

[0106] - Injection volume: 100 µl (0.2 μm filtered)

[0107] - STD : PSH

[0108] The above polybutylene adipate terephthalate may have a weight-average molecular weight of 50,000 g / mol or more, 80,000 g / mol or more, 90,000 g / mol or more, or 100,000 g / mol or more, and 200,000 g / mol or less, 150,000 g / mol or less, 120,000 g / mol or less, or 115,000 g / mol or less, and for example, may be 50,000 to 200,000 g / mol.

[0109] The above polylactic acid may have a weight-average molecular weight of 50,000 g / mol or more, 100,000 g / mol or more, 150,000 g / mol or more, 200,000 g / mol or more, or 250,000 g / mol or more, and may be 300,000 g / mol or less, 280,000 g / mol or less, 250,000 g / mol or less, or 220,000 g / mol or less, for example, 50,000 g / mol to 300,000 g / mol or 100,000 to 300,000 g / mol.

[0110] The weight-average molecular weight of the above polybutylene adipate terephthalate and polylactic acid may be a converted value relative to standard polystyrene measured using gel permeation chromatography (GPC).

[0111] The above polybutylene adipate terephthalate has a density of 1.1 g / cm³ 3 Above, 1.15 g / cm³3 Above or 1.2 g / cm³ 3 It may be more than 1.5 g / cm³ 3 Below, 1.4 g / cm³ 3 Less than or equal to 1.3 g / cm³ 3 It may be less than, for example, 1.1 g / cm³ 3 Up to 1.5 g / cm 3 , 1.15 g / cm 3 Up to 1.4 g / cm³ 3 or 1.2 g / cm³ 3 Up to 1.3 g / cm 3 It could be.

[0112] The above polylactic acid has a density of 1.1 g / cm³ 3 Above, 1.15 g / cm³ 3 Above or 1.2 g / cm³ 3 It may be more than 1.5 g / cm³ 3 Below, 1.4 g / cm³ 3 Less than or equal to 1.3 g / cm³ 3 It may be less than, for example, 1.1 g / cm³ 3 Up to 1.5 g / cm 3 , 1.15 g / cm 3 Up to 1.4 g / cm³ 3 or 1.2 g / cm³ 3 Up to 1.3 g / cm 3 It could be.

[0113] Density (g / cm³) of the above polybutylene adipate terephthalate and polylactic acid 3 ) may be measured according to ASTM D1505.

[0114] In addition, the melt index (190 ℃, 2.16 kg) of the polybutylene adipate terephthalate may be 2.5 g / 10 min or higher, 6.0 g / 10 min or lower, 5.5 g / 10 min or lower, or 5.0 g / 10 min or lower, for example, 2.5 g / 10 min to 6.0 g / 10 min, 2.5 g / 10 min to 5.5 g / 10 min, or 2.5 g / 10 min to 5.0 g / 10 min.

[0115] The melt index (190 ℃, 2.16 kg) of the above polylactic acid may be 1.5 g / 10 min or more, 2.0 g / 10 min or more, or 2.5 g / 10 min or more, for example, 4.5 g / 10 min or less, 4.0 g / 10 min or less, or 3.5 g / 10 min or less, and may be 1.5 g / 10 min to 4.5 g / 10 min, 2.0 g / 10 min to 4.0 g / 10 min, or 2.5 g / 10 min to 3.5 g / 10 min.

[0116] The above melt index can be expressed as the weight (g) of the resin melted for 10 minutes at 190°C with a load of 2.16 kg according to ASTM D1238.

[0117] The weight ratio of the polybutylene adipate terephthalate and polylactic acid in the above biodegradable resin composition may be 70:30 to 95:5 or 80:20 to 90:10. If the mixing ratio of the polybutylene adipate terephthalate and polylactic acid falls outside the above-mentioned content range, it may be difficult to secure the desired level of mechanical strength when manufacturing it into a film.

[0118] Additionally, the polybutylene adipate terephthalate may include an extender group connected by a chain extender within its main chain. The chain extender may include a diisocyanate compound, and two isocyanate groups present at both ends of the diisocyanate compound may react with the -OH groups at the ends of the other polybutylene adipate terephthalate to form a urethane bond. Through this reaction, two polybutylene adipate terephthalate chains are connected, thereby extending the polybutylene adipate terephthalate chain and increasing the molecular weight.

[0119] Examples of the above diisocyanate compounds include, specifically, ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 1,2-dodecane diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 2,4-hexahydrotoluene diisocyanate, 2,6-hexahydrotoluene diisocyanate, hexahydro-1,3-phenylene diisocyanate, hexahydro-1,4-phenylene diisocyanate, perhydro-2,4-diphenylmethane diisocyanate, perhydro-4,4'-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate. Examples include 1,4-stilbene diisocyanate, 3,3'-dimethyl-4,4'-diphenylene diisocyanate, toluene 2,4-diisocyanate (TDI), toluene 2,6-diisocyanate, diphenylmethane-2,4'-diisocyanate (MDI), diphenylmethane-2,2'-diisocyanate, diphenylmethane-4,4'-diisocyanate, or naphthylene-1,5-diisocyanate, and examples of polyvalent isocyanate compounds having an equivalent weight of 3 or more of the isocyanate groups include oligomers of the diisocyanate compounds, polymers of the diisocyanate compounds, cyclic polymers of the diisocyanate compounds, hexamethylene diisocyanate isocyanurate, triisocyanate compounds, and their equivalents. Examples include compounds selected from the group consisting of isomers, but preferably, it may be hexamethylene diisocyanate.

[0120] The content of the chain extender is 0.2 parts by weight or more or 0.25 parts by weight or more based on 100 parts by weight of the polybutylene adipate terephthalate, and may be 0.8 parts by weight or less, 0.75 parts by weight or less, or 0.65 parts by weight or less, and may be 0.2 parts by weight to 0.8 parts by weight, 0.25 parts by weight to 0.75 parts by weight, or 0.25 parts by weight to 0.65 parts by weight, but is not limited thereto.

[0121] The above biodegradable resin composition comprises an inorganic filler together with the above-mentioned polybutylene adipate terephthalate and polylactic acid. Examples of the inorganic filler may be one or more selected from the group consisting of calcium carbonate, talc, kaolin clay, silica, alumina, barium carbonate, sodium carbonate, titanium dioxide, zeolite, magnesium carbonate, calcium oxide, magnesium oxide, and aluminum hydroxide, but preferably may include calcium carbonate and talc.

[0122] In addition, the above-mentioned inorganic filler may be included in an amount of 15 to 20 parts by weight based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

[0123] As an example, the biodegradable resin composition may contain calcium carbonate in an amount of 5 to 15 parts by weight, or 10 to 15 parts by weight, based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

[0124] As an example, the biodegradable resin composition may contain talc in an amount of 3 to 5 parts by weight based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

[0125] As an example, the biodegradable resin composition may contain 5 to 15 parts by weight of calcium carbonate and 3 to 5 parts by weight of talc, based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

[0126] If the content of the above-mentioned inorganic filler, particularly the calcium carbonate and talc, falls outside the above range, it is difficult to achieve a desired level of surface and internal modulus gradient in the film subsequently produced from the composition, and biodegradation may be excessively delayed.

[0127] In addition, the biodegradable resin composition further includes a compatibilizer to enhance the miscibility of the polybutylene adipate terephthalate and polylactic acid. In this case, a maleic anhydride copolymer may be used as the compatibilizer.

[0128] The maleic anhydride copolymer, which is the above compatibilizer, may be included in an amount of 0.3 parts by weight or more or 0.4 parts by weight based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid, may be included in an amount of 1.2 parts by weight or less or 1.1 parts by weight or less, and may be included in an amount of 0.3 parts by weight to 1.2 parts by weight or 0.4 parts by weight to 1.1 parts by weight.

[0129] The biodegradable resin composition of the present invention can secure the desired mechanical properties and appearance characteristics when manufactured into a film by including polybutylene adipate terephthalate and polylactic acid having the above-described characteristics, along with the above-described type of inorganic filler and compatibilizer in the above-described content range.

[0130] In addition, the above-described biodegradable resin composition may further include additives such as melt stabilizers, processing stabilizers, heat stabilizers, light stabilizers, antioxidants, heat aging stabilizers, whitening agents, antiblocking agents, binders, or mixtures thereof, as needed.

[0131] The biodegradable resin composition of the present invention may be prepared by the steps of: preparing polybutylene adipate terephthalate and polylactic acid; and mixing the polybutylene adipate terephthalate and polylactic acid to produce a biodegradable resin composition, but is not limited thereto. Each step will be described in more detail below.

[0132] First, in order to manufacture a biodegradable resin composition, a step of preparing polybutylene adipate terephthalate and polylactic acid may be performed.

[0133] The polybutylene adipate terephthalate described above may be prepared by the following method, but is not limited to this method; any method capable of producing polybutylene adipate terephthalate satisfying the density, melt index, and weight-average molecular weight, etc. described above may be used without limitation.

[0134] The method for manufacturing the above-described polybutylene adipate terephthalate may include the step of manufacturing a polybutylene adipate terephthalate prepolymer by polymerizing 1,4-butanediol, terephthalic acid, and adipic acid as monomers; and the step of manufacturing a polybutylene adipate terephthalate resin by condensation polymerizing the prepolymer.

[0135] The above prepolymer preparation step may first involve mixing 1,4-butanediol, terephthalic acid, and adipic acid. The order of mixing is not particularly limited and may be administered sequentially in any order, and two or more components may be administered simultaneously.

[0136] In the above prepolymer manufacturing step, terephthalic acid and adipic acid may be mixed in a molar ratio of 30:70 to 70:30, or 40:60 to 60:40. If the molar ratio of terephthalic acid and adipic acid falls outside the above range, the biodegradability may be reduced or the desired level of strength may not be obtained.

[0137] In the above prepolymer manufacturing step, 1,4-butanediol may be added in an amount of 100 to 250 parts by weight per 100 parts by weight of adipic acid. The 1,4-butanediol not only contributes to molecular chain formation and esterification reactions, but may also serve as a medium and a dispersant.

[0138] In the above prepolymer manufacturing step, a prepolymer can be prepared by polymerizing 1,4-butanediol, terephthalic acid, and adipic acid in the presence of a titanium (Ti)-based catalyst. The above prepolymer refers to a polymer with a relatively low degree of polymerization obtained by stopping the polymerization reaction midway.

[0139] The above titanium (Ti)-based polymerization catalyst may be one or more selected from the group consisting of titanium methoxide, titanium ethoxide, titanium propoxide, titanium isopropoxide, titanium butoxide, titanium isobutoxide, and titanium citrate, but is not limited thereto.

[0140] In addition, the titanium (Ti)-based polymerization catalyst may be included in an amount of about 0.001 to about 10 parts by weight per 100 parts by weight of the adipic acid. Within this range, the esterification reaction of the monomer mixture can be appropriately mediated. If the amount of catalyst added is too small, the polymerization time may be prolonged, which may reduce productivity. If the amount of catalyst added is too large, the polymerization time may be shortened, but the possibility of discoloration of the final resin produced increases; therefore, the amount of heat stabilizer added must be increased in proportion to the amount of catalyst added, and the manufacturing cost increases.

[0141] A crosslinking agent (or branching agent) may be additionally added during the polymerization reaction of the above-mentioned prepolymer manufacturing step. When an esterification reaction is carried out by adding a crosslinking agent, an internally crosslinked prepolymer may be produced. Accordingly, the mechanical properties of the final polybutylene adipate terephthalate resin may be improved. The crosslinking agent is a low-molecular-weight compound containing three or more hydroxyl groups or three or more carboxyl groups within the molecule, and may, for example, use erythritol-based compounds, glycerol-based compounds, or citric acid, but is not limited thereto.

[0142] In the above prepolymer manufacturing step, the polymerization reaction for manufacturing the prepolymer can be carried out at a temperature of 150 ℃ or higher, 170 ℃ or higher, 190 ℃ or higher, or 210 ℃ or higher, and 350 ℃ or lower, 320 ℃ or lower, or 290 ℃ or lower.

[0143] In the above prepolymer manufacturing step, the polymerization reaction for manufacturing the prepolymer may be carried out for 10 minutes or more, 15 minutes or more, 20 minutes or more, 25 minutes or more, or 30 minutes or more, and, 240 minutes or less, 120 minutes or less, 90 minutes or less, 60 minutes or less, or 40 minutes or less, but is not limited thereto.

[0144] The polymerization reaction in the above prepolymer manufacturing step can be performed with stirring. At this time, the stirring speed is not specifically limited, but for example, it may be 10 rpm or more, 30 rpm or more, or 50 rpm or more, 100 rpm or less, or 80 rpm or less, or 10 to 100 rpm, 30 to 100 rpm, or 50 to 80 rpm.

[0145] In addition, the polymerization reaction during the prepolymer manufacturing step may be performed by introducing nitrogen gas into the reactor. By performing the polymerization reaction under a nitrogen gas atmosphere, the generation of by-products can be suppressed and the conversion rate of the monomer can be increased. The nitrogen gas may be supplied at a flow rate of 0.01 ml / min or more, 0.02 ml / min or more, 0.05 ml / min or more, 100 ml / min or less, 50 ml / min or less, or 10 ml / min or less, but is not limited thereto.

[0146] When a polybutylene adipate terephthalate prepolymer is prepared by the above prepolymer preparation step, a second step of preparing a polybutylene adipate terephthalate resin by condensation polymerizing the prepolymer can be performed.

[0147] The above second step may include a step of pre-polycondensation of the prepolymer and a step of polycondensation.

[0148] The above pre-condensation reaction can be carried out in the presence of a titanium (Ti)-based polymerization catalyst. During the above pre-condensation reaction, polymer chains can be linked by the esterification reaction between the hydroxyl groups and carboxyl groups at the ends of the polybutylene adipate terephthalate prepolymer. Therefore, the titanium (Ti)-based polymerization catalyst used in the condensation polymerization reaction of the second step may be of the same or different type as that used in the first step.

[0149] In the resin manufacturing step above, a titanium (Ti)-based polymerization catalyst may be added in an amount of about 0.001 to about 0.5 parts by weight per 100 parts by weight of polybutylene adipate terephthalate prepolymer.

[0150] In addition, by adding a heat stabilizer during the pre-condensation reaction of the resin manufacturing step, discoloration of the finally manufactured polybutylene adipate terephthalate resin can be suppressed.

[0151] The above heat stabilizer may include one or more selected from the group consisting of phosphoric acid, phosphoric acid, trialkyl phosphate, and trialkyl phosphonoacetate, but is not limited thereto.

[0152] The above heat stabilizer may be added in an amount of about 0.001 to about 0.1 parts by weight per 100 parts by weight of the polybutylene adipate terephthalate prepolymer, but is not limited thereto.

[0153] During the pre-condensation reaction in the resin manufacturing step above, the temperature inside the reactor can first be raised to a temperature of 150 ℃ or higher, 170 ℃ or higher, 190 ℃ or higher, or 210 ℃ or higher, and then to a temperature of 350 ℃ or lower, 320 ℃ or lower, or 290 ℃ or lower.

[0154] In addition, when the temperature of the reactor reaches the above temperature range, the pressure inside the reactor may be 10 mbar or more, 10 mbar or less, 50 mbar or less, or 30 mbar or less, and may be reduced until it reaches 10 to 100 mbar, 10 to 50 mbar, or 10 to 30 mbar. The reduction time may be performed for 10 minutes or more, 15 minutes or more, 20 minutes or more, 25 minutes or more, or 30 minutes or more, and 240 minutes or less, 120 minutes or less, 90 minutes or less, 60 minutes or less, or 40 minutes or less, but is not limited thereto.

[0155] The above total condensation reaction may be carried out with stirring. At this time, the stirring speed is not specifically limited, but, for example, it may be 10 rpm or more, 30 rpm or more, or 50 rpm or more, 100 rpm or less, or 80 rpm or less, or 10 to 100 rpm, 30 to 100 rpm, or 50 to 80 rpm.

[0156] In the present invention, by controlling the temperature, reduced pressure, and stirring speed of the above-mentioned pre-condensation reaction, the thermal properties of the finally produced polybutylene adipate terephthalate resin can be controlled within a desired range.

[0157] After the above pre-condensation reaction, a condensation polymerization reaction may be performed. The above condensation polymerization reaction may be performed under conditions of 3 mbar or less, 2 mbar or less, 1.5 mbar or less, or 1.1 mbar or less, while maintaining the temperature inside the reactor at the temperature of the above pre-condensation reaction.

[0158] In the present invention, by controlling the pressure conditions, stirring speed, and stirrer torque of the condensation polymerization reaction, the thermal properties of the finally manufactured polybutylene adipate terephthalate resin can be controlled within a desired range.

[0159] The present invention may further include the step of adding a chain extender to the polybutylene adipate terephthalate polymer prepared as described above. The characteristics of the chain extender overlap with those previously described, so a detailed description thereof is omitted below.

[0160] When mixing the above-mentioned chain extender, general methods used for manufacturing blended resins may be used, and in particular, general methods used for feeding the polymer obtained from polymerization into an extrusion molding machine may be used. As a non-limiting example, the chain extender may be mixed in the above-mentioned amount after grinding the polymer obtained above.

[0161] In addition, the above polybutylene adipate terephthalate has zero shear viscosity (η PBAT ) may be 3000 Pa·s or less, 2900 Pa·s or less, or 2800 Pa·s or less, and may be 1600 Pa·s or more, 1800 Pa·s or more, or 2000 Pa·s or more, specifically, 1600 Pa·s to 3000 Pa·s, 1600 Pa·s to 2900 Pa·s, 1600 Pa·s to 2800 Pa·s, 1800 Pa·s to 3000 Pa·s, 1800 Pa·s to 2900 Pa·s, 1800 Pa·s to 2800 Pa·s, 2000 Pa·s to 3000 Pa·s, 2000 Pa·s to 2900 Pa·s, or 1600 Pa·s to 2800 Pa·s.

[0162] In this specification, the "zero-shear viscosity" is an indicator of the fluidity of the resin. The zero-shear viscosity may be measured at 190°C according to the ASTM 2857-87 standard using the Oscillation Test of a Rotational Rheometer (Ex.ARES).

[0163] Next, the polylactic acid may be produced by a chemical synthesis method, such as converting lactic acid into lactide and synthesizing polylactic acid through ring-opening polymerization (ROP) of the lactide ring in the presence of a tin-based catalyst, but the production method is not limited thereto. Here, examples of the tin-based catalyst may include Sn(Oct)2, but are not limited thereto.

[0164] The zero shear viscosity (η) of the above polylactic acid PLA) may be 3000 Pa·s or less, 2900 Pa·s or less, or 2800 Pa·s or less, and may be 1600 Pa·s or more, 1800 Pa·s or more, or 2000 Pa·s or more, and specifically may be 1600 Pa·s to 3000 Pa·s, 1600 Pa·s to 2900 Pa·s, 1600 Pa·s to 2800 Pa·s, 1800 Pa·s to 3000 Pa·s, 1800 Pa·s to 2900 Pa·s, 1800 Pa·s to 2800 Pa·s, 2000 Pa·s to 3000 Pa·s, 2000 Pa·s to 2900 Pa·s, or 1600 Pa·s to 2800 Pa·s.

[0165] In the present invention, the ratio of the zero-shear viscosity of the polybutylene adipate terephthalate and the polylactic acid for preparing the biodegradable resin composition, i.e. (η PBAT / η PLA It is desirable that ) be a value close to 1, as this allows for excellent appearance characteristics when the resin composition is subsequently manufactured into a film. More specifically, the ratio of polybutylene adipate terephthalate (η) to the zero shear viscosity of the polylactic acid. PBAT / η PLA) is 0.65 or higher, 0.7 or higher, 0.75 or higher, 0.8 or higher, 0.85 or higher, or 0.90 or higher, and may be 1.2 or lower, or 1.1 or lower, preferably 0.65 to 1.2 or lower, 0.65 to 1.1, 0.7 to 1.2, 0.7 to 1.1, 0.75 to 1.2, 0.75 to 1.1, 0.8 to 1.2, 0.8 to 1.1, 0.85 to 1.2, 0.85 to 1.1, 0.9 to 1.2, or 0.9 to 1.1. If the zero shear viscosity ratio deviates from the above-mentioned range, phase separation occurs between polybutylene adipate terephthalate and polylactic acid, resulting in the formation of a non-uniform polymer chain structure during film manufacturing, which may cause unintended patterns to form on the film surface or excessive reduction in gloss, or the mechanical properties of the film to deteriorate.

[0166] The zero shear viscosity ratio of the above-mentioned polybutylene adipate terephthalate and the above-mentioned polylactic acid can be controlled by adjusting the content of the chain extender during the manufacture of polybutylene adipate terephthalate.

[0167] In the present invention, once the polybutylene adipate terephthalate and polylactic acid described above are prepared, the step of preparing a biodegradable resin composition by mixing the polybutylene adipate terephthalate and polylactic acid can be performed.

[0168] When mixing the above polybutylene adipate terephthalate and polylactic acid, based on 100 parts by weight of polybutylene adipate terephthalate, the polylactic acid may be mixed in an amount of 1 part by weight or more, 5 parts by weight or more, or 10 parts by weight or more, and 35 parts by weight or less, or 30 parts by weight or less, and preferably, in an amount of 1 to 35 parts by weight, 1 to 30 parts by weight, 5 to 35 parts by weight, 5 to 30 parts by weight, 10 to 35 parts by weight, or 10 to 30 parts by weight. If the mixing ratio of the above polybutylene adipate terephthalate and polylactic acid deviates from the above-mentioned content range, it may be difficult to secure the desired level of mechanical strength when manufacturing it into a film.

[0169] When manufacturing the above-degradable resin composition, a film having excellent mechanical properties and appearance characteristics can be produced by additionally mixing the above-described inorganic filler and compatibilizer together with the above-described polybutylene adipate terephthalate and polylactic acid.

[0170] In the present invention, when a biodegradable resin composition is prepared as described above, a step of extrusion molding thereof may be further performed.

[0171] The extruder used at this time can be of a different type depending on the conditions, but a twin-screw extruder type that is advantageous for mixed molding is generally preferred.

[0172] The diameter and size of the extruder above can be determined according to extrusion conditions such as discharge volume, and the ratio of screw length to outer diameter (L / D) may be about 40 or more, or about 40 to about 60, most preferably about 40 to about 50.

[0173] If the amount of resin composition fed into the extruder is too large or the molecular weight of the resin is too high, the extrusion pressure increases, causing an overload, which not only affects the physical properties of the extruded resin molded product but also may cause mechanical problems.

[0174] The feeding speed of the resin composition into the feed of the extruder may be 20 kg / hr or more or 25 kg / hr or more, 50 kg / hr or less or 40 kg / hr or less, 20 kg / hr to 50 kg / hr, 20 kg / hr to 40 kg / hr, 25 kg / hr to 50 kg / hr, or 25 kg / hr to 40 kg / hr, but is not limited thereto.

[0175] In addition, the rotational speed of the extruder may be 200 rpm or more or 250 rpm or more, 500 rpm or less, 400 rpm or less or 350 rpm or less, and may be 200 rpm to 500 rpm, 200 rpm to 400 rpm, 200 rpm to 350 rpm, 250 rpm to 500 rpm, 250 rpm to 400 rpm, or 250 rpm to 350 rpm, but is not limited thereto.

[0176] In addition, the barrel temperature inside the extruder may be 190°C or higher, 195°C or higher, or 200°C or higher, and 220°C or lower or 210°C or lower, and preferably 190°C to 210°C. If the barrel temperature is too high, a decrease in molecular weight due to thermal decomposition of the polymer may occur, and if the barrel temperature is too low, the melting efficiency of the polymer may decrease.

[0177] The biodegradable resin composition according to the present invention can be manufactured into a molded article having a predetermined shape or a film, etc., by molding such as injection molding, blow molding, extrusion molding, or thermoforming using an extruder. Alternatively, the resin may be dissolved in a suitable solvent (e.g., chloroform, THF, toluene, dichloromethane, etc.) and used as a coating material. More specifically, it may be manufactured into eco-friendly consumer goods such as biodegradable plastic bags, agricultural mulching films, packaging materials (e.g., food packaging materials, bubble wrap, plastic containers, etc.), envelope materials, disposable tableware, straws, cups, disposable gloves, and masks. Alternatively, for the purpose of enhancing biodegradability, it may be used as a coating material on the surface of various materials such as paper, fibers, fabrics, plastic films, plastic bags, containers, aluminum foil, non-woven fabrics, or fertilizers.

[0178] According to another embodiment of the present invention, the invention relates to a biodegradable article comprising the above-degradable composition.

[0179] The biodegradable article according to the present invention comprises a resin composition according to the present invention and not only has excellent biodegradability, but also has high mechanical strength and excellent appearance characteristics.

[0180] The above article may be a molded article manufactured using the above resin, and may be, for example, a film. In addition, since the above film has excellent biodegradability, it may also be referred to as a biodegradable film.

[0181] The above-mentioned molded article may be manufactured by molding the above-mentioned resin by methods known in the art, such as extrusion or injection, and the above-mentioned molded article may be an injection molded article, an extrusion molded article, a thin film molded article, a blow molding or blow molded article, a 3D filament, an interior building material, etc., but is not limited thereto.

[0182] The thickness of the above film is not specifically limited, but, for example, it may be 1 to 500 μm, specifically 10 to 200 μm, but is not limited thereto, and the thickness can be adjusted according to the intended use. The above film may be in the form of a film or sheet that can be used as an agricultural mulching film, packaging material (e.g., food packaging material, bubble wrap, pharmaceutical packaging material, product protection packaging film, plastic container, etc.), shrink film, envelope material, or other disposable tableware, straws, cups, disposable gloves, masks, etc., and may be in the form of a fiber that can be used as a fabric, knitted fabric, non-woven fabric, rope, etc.

[0183] The above biodegradable article, in particular a film, may satisfy at least one of 1) to 5) below, and preferably may satisfy all of 1) to 5) below.

[0184] 1) The MD modulus of the biodegradable film is 2500 kgf / cm² 2 Up to 4000 kgf / cm² 2 ;

[0185] 2) The TD modulus of the biodegradable film is 2400 kgf / cm² 2 Up to 3300 kgf / cm² 2 ;

[0186] 3) The MD elongation of the biodegradable film is 550% to 700%;

[0187] 4) The TD elongation of the biodegradable film is 580% to 720%;

[0188] 5) The 20° gloss of the biodegradable film is 7 GU to 9.8 GU

[0189] The MD modulus of the above biodegradable film is 2500 kgf / cm² 2 or higher or 2600 kgf / cm² 2 It may be more than 4000 kgf / cm² 2 3900 kgf / cm² or less 2It may be less than or equal to 2500 kgf / cm² 2 Up to 4000 kgf / cm² 2 or 2600 kgf / cm² 2 Up to 3900 kgf / cm² 2 It could be.

[0190] The TD modulus of the above biodegradable film is 2400 kgf / cm² 2 It may be above 3300 kgf / cm² 2 3200 kgf / cm² or less 2 It may be less than or equal to 2400 kgf / cm² 2 Up to 3300 kgf / cm² 2 or 2400 kgf / cm² 2 Up to 3200 kgf / cm² 2 It could be.

[0191] The MD elongation of the above biodegradable film is 550% It may be greater than or equal to 560%, or less than or equal to 700%, or 650% It may be less than or equal to 550% to 700% or 560% to 650%.

[0192] The TD elongation of the above biodegradable film is 580% It may be greater than or equal to 600% or greater, and less than or equal to 720% or 700% It may be less than or equal to 580% to 720% or 600% to 700%.

[0193] The above modulus and elongation may be measured according to ISO 527 standards.

[0194] However, the modulus and elongation of the above film may be based on a film with a thickness of about 20 to 100 μm, and as an example, may be based on a film with a thickness of about 50 ± 5 μm.

[0195] The above biodegradable film may have a 20° gloss of 7 GU or higher or 7.5 or higher, 10 GU or lower, or 9.8 GU or lower. The fact that the 20° gloss satisfies the above range means that the biodegradable article or film is an ultra-low gloss article or film. Ultra-low gloss articles, particularly ultra-low gloss films, absorb relatively more light and have less glare. In addition, they are advantageous for printing specific content on the surface of the film. However, if the 20° gloss is too low (less than 7 GU), there is a high possibility of contamination on the surface due to fingerprints, dust, etc., and if the 20° gloss exceeds 9.8 GU, there may be problems with increased light reflection and scattering.

[0196] Since hot sealing bags or mulching materials for food packaging are likely to be used under lighting or sunlight, articles satisfying the above-mentioned gloss range, particularly biodegradable films, are suitable for use as hot sealing bags or mulching materials for food packaging. Here, the gloss is measured according to ASTM D523 based on a light reception angle of 20 degrees (°).

[0197] The present invention will be explained in detail below through the following examples. However, the following examples are merely illustrative of the present invention, and the scope of the present invention is not limited by the following examples.

[0198] [Example 1] Preparation of a biodegradable resin composition

[0199] First, regarding polylactic acid resin, Total Corbion's product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190 ℃, 2.16kg) was prepared.

[0200] Next, to prepare a polybutylene adipate terephthalate polymer, 1210 g of 1,4-butanediol, 603 g of adipic acid, 634 g of terephthalic acid, 0.8 g of pentaerythritol, and 1.0 mmol of titanium butoxide were placed in a polymerization reactor and maintained at approximately 230 °C. The reaction was carried out for approximately 4 hours under a nitrogen atmosphere to prepare a prepolymer. Once the prepolymer was prepared, triethylphosphonoacetate, a heat stabilizer, was added so that the phosphorus (P) atom content in the polymer to be obtained was approximately 70 ppm. The mixture was then stirred for approximately 5 minutes to ensure that the heat stabilizer was uniformly dispersed in the polymer. Subsequently, approximately 0.5 mmol of titanium butoxide was additionally added to the reactor and the temperature was raised to approximately 245 °C. Once the temperature of the reactor reached approximately 245 °C, the expansion condensation was carried out under reduced pressure. The reaction was stopped when the torque value of the reactor reached approximately 100 Ncm, and polybutylene adipate terephthalate polymer was obtained.

[0201] The obtained polybutylene adipate terephthalate polymer is freeze-dried and ground, and hexamethylene diisocyanate (HDI) is added as a chain extender, wherein the ratio of the zero shear viscosity of polybutylene adipate terephthalate to the zero shear viscosity of polylactic acid (η) PBAT / η PLA The amount added was adjusted so that ) became 0.95. At this time, the zero shear viscosity was measured at 190 ℃ according to the ASTM 2857-87 standard using the Oscillation Test of a Rotational Rheometer (Ex.ARES).

[0202] Polybutylene adipate terephthalate resin with such controlled viscosity and polylactic acid resin were mixed in a weight ratio of 90:10. Subsequently, a mixture was obtained by mixing 10 phr of calcium carbonate and 5 phr of talc as inorganic fillers and 1 phr of maleic anhydride copolymer as a compatibilizer with respect to 100 parts by weight of the mixed resin. The obtained mixture was fed into a twin-screw extruder (32 mm), and extrusion was carried out under conditions of a barrel temperature of 200 ℃, a feed rate of 30 kg / hr, and a compressor rotation speed of 300 rpm to produce a resin composition in the form of pellets.

[0203] [Example 2] Preparation of a biodegradable resin composition

[0204] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190 ℃, 2.16kg) was prepared.

[0205] To prepare a polybutylene adipate terephthalate polymer, 1210 g of 1,4-butanediol, 603 g of adipic acid, 634 g of terephthalic acid, 0.8 g of pentaerythritol, and 1.0 mmol of titanium butoxide were placed in a polymerization reactor and maintained at approximately 230 °C. The reaction was carried out for approximately 4 hours under a nitrogen atmosphere to prepare a prepolymer. Once the prepolymer was prepared, triethylphosphonoacetate, a heat stabilizer, was added so that the phosphorus (P) atom content in the polymer to be obtained was approximately 70 ppm. The mixture was then stirred for approximately 5 minutes to ensure that the heat stabilizer was uniformly dispersed in the polymer. Subsequently, approximately 0.5 mmol of titanium butoxide was additionally added to the reactor and the temperature was raised to approximately 245 °C. Once the temperature of the reactor reached approximately 245 °C, the expansion condensation was carried out under reduced pressure. The reaction was stopped when the torque value of the reactor reached approximately 100 Ncm, and polybutylene adipate terephthalate polymer was obtained.

[0206] The obtained polybutylene adipate terephthalate polymer is freeze-dried and ground, and hexamethylene diisocyanate (HDI) is added as a chain extender, wherein the ratio of the zero shear viscosity of polybutylene adipate terephthalate to the zero shear viscosity of polylactic acid (η) PBAT / η PLA The amount was adjusted and added so that ) became 0.93. At this time, the zero shear viscosity was measured in the same way as in Example 1.

[0207] Polybutylene adipate terephthalate resin with such controlled viscosity and polylactic acid resin were mixed in a weight ratio of 90:10, and a mixture was obtained by mixing 10 phr of calcium carbonate and 5 phr of talc as inorganic fillers and 0.5 phr of maleic anhydride copolymer as a compatibilizer with respect to 100 parts by weight of the mixed resin. The obtained mixture was fed into a twin-screw extruder (32 mm), and extrusion was carried out under conditions of a barrel temperature of 200 ℃, a feed rate of 30 kg / hr, and a compressor rotation speed of 300 rpm to produce a resin composition in the form of pellets.

[0208] [Example 3] Preparation of a biodegradable resin composition

[0209] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190 ℃, 2.16kg) was prepared.

[0210] To prepare a polybutylene adipate terephthalate polymer, 1210 g of 1,4-butanediol, 603 g of adipic acid, 634 g of terephthalic acid, 0.8 g of pentaerythritol, and 1.0 mmol of titanium butoxide were placed in a polymerization reactor and maintained at approximately 230 °C. The reaction was carried out for approximately 4 hours under a nitrogen atmosphere to prepare a prepolymer. Once the prepolymer was prepared, triethylphosphonoacetate, a heat stabilizer, was added so that the phosphorus (P) atom content in the polymer to be obtained was approximately 70 ppm. The mixture was then stirred for approximately 5 minutes to ensure that the heat stabilizer was uniformly dispersed in the polymer. Subsequently, approximately 0.5 mmol of titanium butoxide was additionally added to the reactor and the temperature was raised to approximately 245 °C. Once the temperature of the reactor reached approximately 245 °C, the expansion condensation was carried out under reduced pressure. The reaction was stopped when the torque value of the reactor reached approximately 100 Ncm, and polybutylene adipate terephthalate polymer was obtained.

[0211] The obtained polybutylene adipate terephthalate polymer is freeze-dried and ground, and hexamethylene diisocyanate (HDI) is added as a chain extender, wherein the ratio of the zero shear viscosity of polybutylene adipate terephthalate to the zero shear viscosity of polylactic acid (η) PBAT / η PLA The amount was adjusted and added so that ) became 1.1. At this time, the zero shear viscosity was measured in the same way as in Example 1.

[0212] Polybutylene adipate terephthalate resin with such controlled viscosity and polylactic acid resin were mixed in a weight ratio of 80:20, and a mixture was obtained by mixing 15 phr of calcium carbonate and 5 phr of talc as inorganic fillers and 0.5 phr of maleic anhydride copolymer as a compatibilizer with respect to 100 parts by weight of the mixed resin. The obtained mixture was fed into a twin-screw extruder (32 mm), and extrusion was carried out under conditions of a barrel temperature of 200 ℃, a feed rate of 30 kg / hr, and a compressor rotation speed of 300 rpm to produce a resin composition in the form of pellets.

[0213] [Example 4] Preparation of a biodegradable resin composition

[0214] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190 ℃, 2.16kg) was prepared.

[0215] To prepare a polybutylene adipate terephthalate polymer, 1210 g of 1,4-butanediol, 603 g of adipic acid, 634 g of terephthalic acid, 0.8 g of pentaerythritol, and 1.0 mmol of titanium butoxide were placed in a polymerization reactor and maintained at approximately 230 °C. The reaction was carried out for approximately 4 hours under a nitrogen atmosphere to prepare a prepolymer. Once the prepolymer was prepared, triethylphosphonoacetate, a heat stabilizer, was added so that the phosphorus (P) atom content in the polymer to be obtained was approximately 70 ppm. The mixture was then stirred for approximately 5 minutes to ensure that the heat stabilizer was uniformly dispersed in the polymer. Subsequently, approximately 0.5 mmol of titanium butoxide was additionally added to the reactor and the temperature was raised to approximately 245 °C. Once the temperature of the reactor reached approximately 245 °C, the expansion condensation was carried out under reduced pressure. The reaction was stopped when the torque value of the reactor reached approximately 100 Ncm, and polybutylene adipate terephthalate polymer was obtained.

[0216] The obtained polybutylene adipate terephthalate polymer is freeze-dried and ground, and hexamethylene diisocyanate (HDI) is added as a chain extender, wherein the ratio of the zero shear viscosity of polybutylene adipate terephthalate to the zero shear viscosity of polylactic acid (η) PBAT / η PLA The amount added was adjusted so that ) became 0.89. At this time, the zero shear viscosity was measured in the same way as in Example 1.

[0217] Polybutylene adipate terephthalate resin with such controlled viscosity and polylactic acid resin were mixed in a weight ratio of 90:10. A mixture was obtained by mixing 15 phr of calcium carbonate and 5 phr of talc as inorganic fillers and 0.5 phr of maleic anhydride copolymer as a compatibilizer for every 100 parts by weight of the mixed resin. The obtained mixture was fed into a twin-screw extruder (32 mm), and extrusion was carried out under conditions of a barrel temperature of 200 °C, a feed rate of 30 kg / hr, and a compressor rotation speed of 300 rpm to produce a resin composition in the form of pellets.

[0218] [Example 5] Preparation of a biodegradable resin composition

[0219] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190 ℃, 2.16kg) was prepared.

[0220] To prepare a polybutylene adipate terephthalate polymer, 1210 g of 1,4-butanediol, 603 g of adipic acid, 634 g of terephthalic acid, 0.8 g of pentaerythritol, and 1.0 mmol of titanium butoxide were placed in a polymerization reactor and maintained at approximately 230 °C. The reaction was carried out for approximately 4 hours under a nitrogen atmosphere to prepare a prepolymer. Once the prepolymer was prepared, triethylphosphonoacetate, a heat stabilizer, was added so that the phosphorus (P) atom content in the polymer to be obtained was approximately 70 ppm. The mixture was then stirred for approximately 5 minutes to ensure that the heat stabilizer was uniformly dispersed in the polymer. Subsequently, approximately 0.5 mmol of titanium butoxide was additionally added to the reactor and the temperature was raised to approximately 245 °C. Once the temperature of the reactor reached approximately 245 °C, the expansion condensation was carried out under reduced pressure. The reaction was stopped when the torque value of the reactor reached approximately 100 Ncm, and polybutylene adipate terephthalate polymer was obtained.

[0221] The obtained polybutylene adipate terephthalate polymer is freeze-dried and ground, and hexamethylene diisocyanate (HDI) is added as a chain extender, wherein the ratio of the zero shear viscosity of polybutylene adipate terephthalate to the zero shear viscosity of polylactic acid (η) PBAT / η PLA The amount was adjusted and added so that ) became 0.92. At this time, the zero shear viscosity was measured in the same way as in Example 1.

[0222] Polybutylene adipate terephthalate resin with such controlled viscosity and polylactic acid resin were mixed in a weight ratio of 80:20. Subsequently, a mixture was obtained by mixing 15 phr of calcium carbonate and 5 phr of talc as inorganic fillers and 0.5 phr of maleic anhydride copolymer as a compatibilizer with respect to 100 parts by weight of the mixed resin. The obtained mixture was fed into a twin-screw extruder (32 mm), and extrusion was carried out under conditions of a barrel temperature of 200 °C, a feed rate of 30 kg / hr, and a compressor rotation speed of 300 rpm to produce a resin composition in the form of pellets.

[0223] [Comparative Example 1] Preparation of a biodegradable resin composition

[0224] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190 ℃, 2.16kg) was prepared.

[0225] To prepare a polybutylene adipate terephthalate polymer, 1210 g of 1,4-butanediol, 603 g of adipic acid, 634 g of terephthalic acid, 0.8 g of pentaerythritol, and 1.0 mmol of titanium butoxide were placed in a polymerization reactor and maintained at approximately 230 °C. The reaction was carried out for approximately 4 hours under a nitrogen atmosphere to prepare a prepolymer. Once the prepolymer was prepared, triethylphosphonoacetate, a heat stabilizer, was added so that the phosphorus (P) atom content in the polymer to be obtained was approximately 70 ppm. The mixture was then stirred for approximately 5 minutes to ensure that the heat stabilizer was uniformly dispersed in the polymer. Subsequently, approximately 0.5 mmol of titanium butoxide was additionally added to the reactor and the temperature was raised to approximately 245 °C. Once the temperature of the reactor reached approximately 245 °C, the expansion condensation was carried out under reduced pressure. The reaction was stopped when the torque value of the reactor reached approximately 100 Ncm, and polybutylene adipate terephthalate polymer was obtained.

[0226] The obtained polybutylene adipate terephthalate polymer is freeze-dried and ground, and hexamethylene diisocyanate (HDI) is added as a chain extender, wherein the ratio of the zero shear viscosity of polybutylene adipate terephthalate to the zero shear viscosity of polylactic acid (η) PBAT / η PLA The amount was adjusted and added so that ) became 0.96. At this time, the zero shear viscosity was measured in the same way as in Example 1.

[0227] A viscosity-controlled polybutylene adipate terephthalate resin and a polylactic acid resin were mixed in a weight ratio of 90:10, and a mixture was obtained by mixing 10 phr of calcium carbonate and 10 phr of talc as inorganic fillers and 0.5 phr of maleic anhydride copolymer as a compatibilizer with respect to 100 parts by weight of the mixed resin. The obtained mixture was fed into a twin-screw extruder (32 mm), and extrusion was carried out under conditions of a barrel temperature of 200 ℃, a feed rate of 30 kg / hr, and a compressor rotation speed of 300 rpm to produce a resin composition in the form of pellets.

[0228] [Comparative Example 2] Preparation of a biodegradable resin composition

[0229] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190 ℃, 2.16kg) was prepared.

[0230] To prepare a polybutylene adipate terephthalate polymer, 1210 g of 1,4-butanediol, 603 g of adipic acid, 634 g of terephthalic acid, 0.8 g of pentaerythritol, and 1.0 mmol of titanium butoxide were placed in a polymerization reactor and maintained at approximately 230 °C. The reaction was carried out for approximately 4 hours under a nitrogen atmosphere to prepare a prepolymer. Once the prepolymer was prepared, triethylphosphonoacetate, a heat stabilizer, was added so that the phosphorus (P) atom content in the polymer to be obtained was approximately 70 ppm. The mixture was then stirred for approximately 5 minutes to ensure that the heat stabilizer was uniformly dispersed in the polymer. Subsequently, approximately 0.5 mmol of titanium butoxide was additionally added to the reactor and the temperature was raised to approximately 245 °C. Once the temperature of the reactor reached approximately 245 °C, the expansion condensation was carried out under reduced pressure. The reaction was stopped when the torque value of the reactor reached approximately 100 Ncm, and polybutylene adipate terephthalate polymer was obtained.

[0231] The obtained polybutylene adipate terephthalate polymer is freeze-dried and ground, and hexamethylene diisocyanate (HDI) is added as a chain extender, wherein the ratio of the zero shear viscosity of polybutylene adipate terephthalate to the zero shear viscosity of polylactic acid (η) PBAT / η PLA The amount was adjusted and added so that ) became 0.8. At this time, the zero shear viscosity was measured in the same way as in Example 1.

[0232] A viscosity-controlled polybutylene adipate terephthalate resin and a polylactic acid resin were mixed in a weight ratio of 80:20. Subsequently, a mixture was obtained by mixing 10 phr of calcium carbonate and 15 phr of talc as inorganic fillers and 0.5 phr of maleic anhydride copolymer as a compatibilizer with respect to 100 parts by weight of the mixed resin. The obtained mixture was fed into a twin-screw extruder (32 mm), and extrusion was carried out under conditions of a barrel temperature of 200 °C, a feed rate of 30 kg / hr, and a compressor rotation speed of 300 rpm to produce a resin composition in the form of pellets.

[0233] [Comparative Example 3] Preparation of a biodegradable resin composition

[0234] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190 ℃, 2.16kg) was prepared.

[0235] To prepare a polybutylene adipate terephthalate polymer, 1210 g of 1,4-butanediol, 603 g of adipic acid, 634 g of terephthalic acid, 0.8 g of pentaerythritol, and 1.0 mmol of titanium butoxide were placed in a polymerization reactor and maintained at approximately 230 °C. The reaction was carried out for approximately 4 hours under a nitrogen atmosphere to prepare a prepolymer. Once the prepolymer was prepared, triethylphosphonoacetate, a heat stabilizer, was added so that the phosphorus (P) atom content in the polymer to be obtained was approximately 70 ppm. The mixture was then stirred for approximately 5 minutes to ensure that the heat stabilizer was uniformly dispersed in the polymer. Subsequently, approximately 0.5 mmol of titanium butoxide was additionally added to the reactor and the temperature was raised to approximately 245 °C. Once the temperature of the reactor reached approximately 245 °C, the expansion condensation was carried out under reduced pressure. The reaction was stopped when the torque value of the reactor reached approximately 100 Ncm, and polybutylene adipate terephthalate polymer was obtained.

[0236] The obtained polybutylene adipate terephthalate polymer is freeze-dried and ground, and hexamethylene diisocyanate (HDI) is added as a chain extender, wherein the ratio of the zero shear viscosity of polybutylene adipate terephthalate to the zero shear viscosity of polylactic acid (η) PBAT / η PLA The amount was adjusted and added so that ) became 0.58. At this time, the zero shear viscosity was measured in the same way as in Example 1.

[0237] Polybutylene adipate terephthalate resin with such controlled viscosity and polylactic acid resin were mixed in a weight ratio of 90:10. Subsequently, a mixture was obtained by mixing 10 phr of calcium carbonate and 10 phr of talc as inorganic fillers and 0.5 phr of maleic anhydride copolymer as a compatibilizer with respect to 100 parts by weight of the mixed resin. The obtained mixture was fed into a twin-screw extruder (32 mm), and extrusion was carried out under conditions of a barrel temperature of 200 °C, a feed rate of 30 kg / hr, and a compressor rotation speed of 300 rpm to produce a resin composition in the form of pellets.

[0238] [Comparative Example 4] Preparation of a biodegradable resin composition

[0239] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190 ℃, 2.16kg) was prepared.

[0240] To prepare a polybutylene adipate terephthalate polymer, 1210 g of 1,4-butanediol, 603 g of adipic acid, 634 g of terephthalic acid, 0.8 g of pentaerythritol, and 1.0 mmol of titanium butoxide were placed in a polymerization reactor and maintained at approximately 230 °C. The reaction was carried out for approximately 4 hours under a nitrogen atmosphere to prepare a prepolymer. Once the prepolymer was prepared, triethylphosphonoacetate, a heat stabilizer, was added so that the phosphorus (P) atom content in the polymer to be obtained was approximately 70 ppm. The mixture was then stirred for approximately 5 minutes to ensure that the heat stabilizer was uniformly dispersed in the polymer. Subsequently, approximately 0.5 mmol of titanium butoxide was additionally added to the reactor and the temperature was raised to approximately 245 °C. Once the temperature of the reactor reached approximately 245 °C, the expansion condensation was carried out under reduced pressure. The reaction was stopped when the torque value of the reactor reached approximately 100 Ncm, and polybutylene adipate terephthalate polymer was obtained.

[0241] The obtained polybutylene adipate terephthalate polymer is freeze-dried and ground, and hexamethylene diisocyanate (HDI) is added as a chain extender, wherein the ratio of the zero shear viscosity of polybutylene adipate terephthalate to the zero shear viscosity of polylactic acid (η) PBAT / η PLA The amount added was adjusted so that ) became 0.89. At this time, the zero shear viscosity was measured in the same way as in Example 1.

[0242] Polybutylene adipate terephthalate resin with such controlled viscosity and polylactic acid resin were mixed in a weight ratio of 90:10, and a mixture was obtained by mixing 10 phr of calcium carbonate as an inorganic filler with respect to 100 parts by weight of the mixed resin. The obtained mixture was fed into a twin-screw extruder (32 mm), and extrusion was carried out under conditions of a barrel temperature of 200 ℃, a feed rate of 30 kg / hr, and a compressor rotation speed of 300 rpm to produce a resin composition in the form of pellets.

[0243] [Comparative Example 5] Preparation of a biodegradable resin composition

[0244] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190 ℃, 2.16kg) was prepared.

[0245] To prepare a polybutylene adipate terephthalate polymer, 1210 g of 1,4-butanediol, 603 g of adipic acid, 634 g of terephthalic acid, 0.8 g of pentaerythritol, and 1.0 mmol of titanium butoxide were placed in a polymerization reactor and maintained at approximately 230 °C. The reaction was carried out for approximately 4 hours under a nitrogen atmosphere to prepare a prepolymer. Once the prepolymer was prepared, triethylphosphonoacetate, a heat stabilizer, was added so that the phosphorus (P) atom content in the polymer to be obtained was approximately 70 ppm. The mixture was then stirred for approximately 5 minutes to ensure that the heat stabilizer was uniformly dispersed in the polymer. Subsequently, approximately 0.5 mmol of titanium butoxide was additionally added to the reactor and the temperature was raised to approximately 245 °C. Once the temperature of the reactor reached approximately 245 °C, the expansion condensation was carried out under reduced pressure. The reaction was stopped when the torque value of the reactor reached approximately 100 Ncm, and polybutylene adipate terephthalate polymer was obtained.

[0246] The obtained polybutylene adipate terephthalate polymer is freeze-dried and ground, and hexamethylene diisocyanate (HDI) is added as a chain extender, wherein the ratio of the zero shear viscosity of polybutylene adipate terephthalate to the zero shear viscosity of polylactic acid (η) PBAT / η PLA The amount was adjusted and added so that ) became 0.85. At this time, the zero shear viscosity was measured in the same way as in Example 1.

[0247] Polybutylene adipate terephthalate resin with such controlled viscosity and polylactic acid resin were mixed in a weight ratio of 90:10, and a mixture was obtained by mixing 10 phr of calcium carbonate and 5 phr of talc as inorganic fillers with respect to 100 parts by weight of the mixed resin. The obtained mixture was fed into a twin-screw extruder (32 mm), and extrusion was carried out under conditions of a barrel temperature of 200 ℃, a feed rate of 30 kg / hr, and a compressor rotation speed of 300 rpm to produce a resin composition in the form of pellets.

[0248] [Experimental Example 1] Surface Modulus Measurement

[0249] To measure the surface modulus of films prepared with the biodegradable resin compositions of the above Examples and Comparative Examples, blown films with a thickness of approximately 50 ± 5 μm were first prepared using the resin compositions. Specifically, the pellets obtained from Examples 1 to 5 and Comparative Examples 1 to 4 were processed using a single-screw extruder (Blown Film M / C, 19 pi, L / D=25) to produce blown films with a thickness of approximately 50 ± 5 μm under conditions of an extrusion temperature of approximately 145 °C, a blown-up ratio of approximately 1.5, and a linear velocity of 5 m / min to 10 m / min. After cutting the blown films to dimensions of 20 mm × 20 mm, a nano-indenter (UNHT) was applied. 3 Modulus profile analysis according to film indentation depth was performed in Sinus mode using Anton Paar. The film surface was indented at a temperature of 25±5℃ using a Vickers square pyramid tip of a nano-indenter, with a maximum applied load of 5 mN and a maximum film indentation depth of 1 μm. Note that in Sinus mode, the oscillation frequency was 10 Hz, oscillation amplitude was 0.1 mN, and constant strain rate was 0.1 sec. -1It was set as follows. Through the above analysis, a modulus profile according to depth from the surface of the film was obtained. Subsequently, to correct for data deviations in the initial thickness range caused by the so-called 'particle size effect' that occurs as the indenter begins to contact a local area on the film surface, linear extrapolation was performed in the mid-to-late range where the modulus profile stabilizes. Through this, the surface modulus with the particle size effect removed was calculated. The modulus at the surface of the film and at a point 10% of the film thickness from the surface, respectively, were presented as the average value after performing the above analysis at three arbitrary points on the specimen.

[0250] The results were as shown in Table 1 below.

[0251] E1 (GPa)E2 (GPa)E1 / E2 Example 10.47 0.212.22 Example 20.32 0.211.49 Example 30.38 0.251.52 Example 40.55 0.351.51 Example 50.49 0.31.6 Comparative Example 10.58 0.51.16 Comparative Example 20.51 0.451.14 Comparative Example 30.24 0.191.26 Comparative Example 40.24 0.181.35 Comparative Example 50.25 0.191.33

[0252] In Table 1 above, E1 is the surface modulus (GPa) of the surface of the film made of the resin composition, and E2 is the surface modulus (GPa) at a point 10% thick from the surface of the film made of the resin composition.

[0253] In Table 1 above, it was confirmed that the film prepared with the biodegradable resin composition of Examples 1 to 5 according to the present invention has a film surface modulus (E1) of 0.3 GPa or more, a modulus (E2) at a point 10% of the film thickness from the film surface is 0.2 GPa or more and 0.5 GPa or less, and a ratio of E1 to E2 (E1 / E2) is 1.3 or more.

[0254] On the other hand, it was confirmed that the films prepared with the biodegradable resin compositions of Comparative Examples 1 to 5 had at least one value among E1, E2, and the ratio of E1 / E2 outside the above range.

[0255] [Experimental Example 2] Evaluation of Mechanical Properties

[0256] To evaluate the mechanical properties of the biodegradable resin compositions prepared in the above examples and comparative examples, a blown film with a thickness of approximately 50 ± 5 μm was prepared using the same method as in Experimental Example 1. Subsequently, the following properties were evaluated.

[0257] 1) MD Modulus according to ISO 527 standard

[0258] 2) TD Modulus according to ISO 527 standards

[0259] 3) MD elongation according to ISO 527 standards

[0260] 4) TD elongation according to ISO 527 standards

[0261] The results were as shown in Table 2 below.

[0262] MD Modulus (kgf / cm²) 2 )TD Modulus (kgf / cm²) 2)MD Elongation (%) TD Elongation (%) Example 1 26882461642695 Example 2 30932524593696 Example 3 38002840576620 Example 4 31522495597692 Example 5 37502941560605 Comparative Example 1 37472437632639 Comparative Example 2 36152329595648 Comparative Example 3 34221850639701 Comparative Example 4 31102284619723 Comparative Example 5 30492786601675

[0263] As shown in Table 2 above, the film prepared from the resin composition according to the present invention has an MD modulus of 2500 kgf / cm² 2 Up to 4000 kgf / cm² 2 And, the TD modulus is 2400 kgf / cm² 2 Up to 3300 kgf / cm² 2 It was confirmed that the mechanical properties were excellent, with MD elongation of 550% to 700% and TD elongation of 580% to 720%.

[0264] [Experimental Example 3] Evaluation of Appearance Characteristics

[0265] To evaluate the appearance characteristics of the biodegradable resin compositions prepared in the above examples and comparative examples, blown films were prepared using the same method as in Experimental Example 1, and then visually inspected to check whether ripples were formed on the film surface. The presence of ripples was recorded as NG, and the absence of ripples was evaluated as OK. In addition, the glossiness of each film was measured at a light reception angle of 20° according to ASTM D523.

[0266] The results were as shown in Table 3 below.

[0267] Appearance Gloss (GU) Example 1 OK 9.38 Example 2 OK 8.9 Example 3 OK 7.98 Example 4 OK 8.54 Example 5 OK 9.61 Comparative Example 1 OK 7.78 Comparative Example 2 OK 8.67 Comparative Example 3 OK 6.79 Comparative Example 4 OK 10.71 Comparative Example 5 OK 10.99

[0268] As shown in Table 3 above, the films produced from the resin compositions of Examples 1 to 5 according to the present invention did not show any unintended wavy patterns and satisfied a 20° gloss (Gloss) of 7 to 9.8 GU, confirming that they correspond to ultra-low gloss products that can prevent problems such as increased light reflection and scattering, and have a low likelihood of contamination caused by fingerprints, dust, etc. on the surface.

[0269] On the other hand, on the surface of the film prepared from the resin composition (Comparative Examples 3 to 5) in which the surface modulus of polybutylene adipate terephthalate or polylactic acid falls outside the scope of the present invention, wavy patterns were observed, and it was confirmed that the glossiness also fell outside the above range.

[0270] [Experimental Example 4] Measurement of hydrolysis

[0271] Hydrolysis was carried out on the biodegradable resin composition of Example 1 at 90°C for 3 days in the following manner.

[0272] 1) After freeze-grinding the resin composition of Example 1 to a particle size of 500 μm or less, 1 g of the sample and 20 ml of deionized water were placed in a vial, and hydrolysis was carried out at 90°C for 3 days (72 hours) to prepare a sample on day 1 (24 hours after the addition of deionized water), a sample on day 3 (72 hours after the addition of deionized water), and a sample on day 0 that was not hydrolyzed.

[0273] Specifically, the Day 1 sample was prepared by drying the vial containing the resin composition of Example 1 24 hours after adding 20 ml of deionized water, and the Day 3 sample was prepared by drying the vial containing the resin composition of Example 1 72 hours after adding 20 ml of deionized water. Drying was performed at a temperature of 50°C using nitrogen purging.

[0274] 2) Each dried sample was diluted with 10 mg / mL of chloroform, centrifuged at 2500 rpm for 30 minutes, and filtered through a 0.2 μm filter to prepare a sample solution.

[0275] 3) 1000 mL of chloroform was filtered to prepare the mobile phase.

[0276] 4) Molecular weight distribution curves over time were obtained for each sample using Gel Permeation Chromatography (GPC) and a Refractive Index (RI) detector. The measurement conditions were as follows.

[0277] <Measurement Conditions>

[0278] - Stationary phase: Agilent PLgel MIXED-B, MIXED-C (7.5 mm × 300 mm, 5 μm)

[0279] - Mobile phase: Chloroform = 100 (v / v, %)

[0280] - Flow rate: 1.0 mL / min

[0281] - Stationary bed temperature: 40 ℃

[0282] - Injection volume: 100 µl (0.2 μm filtered)

[0283] - STD : PSH

[0284] 5) The dispersion index (PDI) was determined from the molecular weight distribution curve of each sample. Specifically, PDI0, PDI1, and PDI3 of the resin composition of Example 1 were determined.

[0285] For the resin compositions of other examples and comparative examples, PDI0, PDI1, and PDI3 of the resin composition were obtained by hydrolyzing at 90°C for 3 days (72 hours) in the same way.

[0286] Next, (PDI1 / PDI0) and (PDI3 / PDI0) were calculated, and the results are listed in Table 4 below.

[0287] PDI1 / PDI0 PDI3 / PDI0 Example 11.1 20.76 Example 20.9 80.68 Example 31.0 50.7 Example 40.9 50.56 Example 51.1 50.73 Comparative Example 11.3 0.84 Comparative Example 21.1 90.9 Comparative Example 30.8 30.71 Comparative Example 40.8 20.7 Comparative Example 50.8 60.55

[0288] The 90°C hydrolysis experiment is an accelerated biodegradability evaluation experiment, and the initial biodegradability can be predicted from the change in PDI after 1 day (24 hours) of the hydrolysis experiment, and the long-term biodegradability can be predicted from the change in PDI after 3 days (72 hours) of the hydrolysis experiment.

[0289] Looking at the results of Table 4 above, it was predicted that the resin compositions of Examples 1 to 5 according to the present invention would have a PDI1 / PDI0 of 0.9 or higher and a PDI3 / PDI0 of 0.8 or lower, so that the initial biodegradability is controlled, the physical properties are maintained at a level higher than the intended level during product use, and then biodegradation proceeds gradually after a certain period of time, resulting in high degradation efficiency.

[0290] However, it was observed that the resin compositions of Comparative Examples 1 and 2 had a PDI1 / PDI0 of 1.19 or higher and a PDI3 / PDI0 of 0.84 or higher, indicating that the biodegradability was too slow. The resin compositions of Comparative Examples 3 to 5 had a PDI1 / PDI0 of 0.82 to 0.86 and a PDI3 / PDI0 of approximately 0.7 or lower, indicating that the initial biodegradability was excessively fast, and a change in quality during product use was expected.

[0291] As can be confirmed from the above experiments, it was found that the film prepared with the resin composition of Examples 1 to 5 according to the present invention maintains excellent mechanical properties and does not deteriorate during product use due to controlled initial biodegradability.

Claims

A biodegradable resin composition comprising polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA), A biodegradable resin composition wherein, for a film prepared from the above resin composition, the surface modulus (E1) by nanoindenter at 25±5℃ satisfies the following Equation 1, the modulus (E2) at a depth of 10% thickness from the surface of the film satisfies the following Equation 2, and the ratio of E1 to E2 satisfies the following Equation 3: [Equation 1] E1 ≥ 0.3 [Equation 2] 0.2 ≤ E2 ≤ 0.5 [Equation 3] E1 / E2 ≥ 1.3 In paragraph 1, A biodegradable resin composition having a surface modulus (E1) of 0.3 GPa to 0.6 GPa. In paragraph 1, A biodegradable resin composition having a modulus (E2) at a depth of 10% from the surface of the film of the above film of 0.2 GPa to 0.45 GPa. In paragraph 1, A biodegradable resin composition in which the ratio (E1 / E2) of the surface modulus (E1) to the modulus (E2) at a depth of 10% from the surface of the film is 1.4 to 2.

5. In paragraph 1, A biodegradable resin composition, wherein the ratio of the dispersion index (PDI0) of the composition measured on day 1 to the dispersion index (PDI1) of the composition measured on day 0 while hydrolyzing the above resin composition at 90°C satisfies the following Equation 4: [Equation 4] (PDI1 / PDI0) ≥ 0.9 In the above Equation 4, PDI0 is the dispersion index (PDI) of the resin composition subject to hydrolysis testing, and PDI1 is the dispersion index (PDI) of the composition measured 24 hours after the start of the hydrolysis test at 90°C. In paragraph 1, A biodegradable resin composition, wherein the ratio of the dispersion index (PDI0) of the composition measured on day 3 to the dispersion index (PDI3) of the composition measured on day 0 while hydrolyzing the resin composition at 90°C satisfies the following Equation 5: [Equation 5] (PDI3 / PDI0) ≤ 0.8 In the above Equation 5, PDI0 is the dispersion index (PDI) of the resin composition subject to hydrolysis testing, and PDI3 is the dispersion index (PDI) of the composition measured at 72 hours after the start of the hydrolysis test at 90°C. In paragraph 1, The ratio of the dispersion index (PDI1) of the composition measured on day 1 to the dispersion index (PDI0) of the composition measured on day 0 while hydrolyzing the above resin composition at 90°C satisfies the following Equation 4, and A biodegradable resin composition in which the ratio of the dispersion index (PDI3) of the composition measured on day 3 to the dispersion index (PDI0) of the composition measured on day 0 satisfies the following Equation 5: [Equation 4] (PDI1 / PDI0) ≥ 0.9 [Equation 5] (PDI3 / PDI0) ≤ 0.8 In the above Equations 4 and 5, PDI0 is the dispersion index (PDI) of the resin composition subject to the hydrolysis experiment, PDI1 is the dispersion index (PDI) of the composition measured 24 hours after the start of the 90°C hydrolysis experiment, and PDI3 is the dispersion index (PDI) of the composition measured 72 hours after the start of the 90°C hydrolysis experiment. am. In paragraph 1, A biodegradable resin composition in which the weight ratio of the polybutylene adipate terephthalate and polylactic acid is 70:30 to 95:

5. In paragraph 1, The density of the above polybutylene adipate terephthalate is 1.1 g / cm³ 3 Up to 1.5 g / cm 3 and the density of the above polylactic acid is 1.1 g / cm³ 3 Up to 1.5 g / cm 3 Phosphorus, biodegradable resin composition. In paragraph 1, A biodegradable resin composition in which the polybutylene adipate terephthalate has a weight-average molecular weight of 50,000 to 200,000 g / mol and the polylactic acid has a weight-average molecular weight of 100,000 to 300,000 g / mol. In paragraph 1, A biodegradable resin composition in which the melt index (190 ℃, 2.16 kg) of the polybutylene adipate terephthalate is 2.5 g / 10 min to 6.0 g / 10 min, and the melt index (190 ℃, 2.16 kg) of the polylactic acid is 1.5 g / 10 min to 4.5 g / 10 min. In paragraph 1, The above biodegradable resin composition further comprises at least one of an inorganic filler and a compatibilizer. A biodegradable film comprising polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA), A biodegradable film wherein, for the above film, the surface modulus (E1) by nanoindenter at 25±5℃ satisfies the following Equation 1, the modulus (E2) at a depth of 10% thickness from the surface of the film satisfies the following Equation 2, and the ratio of E1 to E2 satisfies the following Equation 3: [Equation 1] E1 ≥ 0.3 [Equation 2] 0.2 ≤ E2 ≤ 0.5 [Equation 3] E1 / E2 ≥ 1.3 In Paragraph 13, A biodegradable film having a surface modulus (E1) of 0.3 GPa to 0.6 GPa. In Paragraph 13, A biodegradable film having a modulus (E2) at a depth of 10% from the surface of the film, ranging from 0.2 GPa to 0.45 GPa. In Paragraph 13, A biodegradable film in which the ratio (E1 / E2) of the surface modulus (E1) to the modulus (E2) at a depth of 10% from the surface of the film is 1.4 to 2.

5. In Paragraph 13, The above biodegradable film is a biodegradable film satisfying at least one of 1) to 5) below: 1) The MD modulus of the biodegradable film is 2500 kgf / cm² 2 Up to 4000 kgf / cm² 2 ; 2) The TD modulus of the biodegradable film is 2400 kgf / cm² 2 Up to 3300 kgf / cm² 2 ; 3) The MD elongation of the biodegradable film is 550% to 700%; 4) The TD elongation of the biodegradable film is 580% to 720%; 5) The 20° gloss of the biodegradable film is 7 GU to 9.8 GU In Paragraph 13, A biodegradable film having a thickness of 10 to 200 μm. A biodegradable article comprising a biodegradable resin composition according to any one of claims 1 to 12.