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. 10-2024-0191812 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, a biodegradable film, and a biodegradable article comprising the same.

[0004] Polyethylene (PE) film has traditionally established itself as a widely used material for various film products, such as mulching films and food packaging. Based on its excellent mechanical strength, durability, and cost-effectiveness, PE film has been utilized as an essential material across various industries. However, as a fossil fuel-based synthetic plastic, PE poses serious environmental problems due to the difficulty of biodegradation in the natural environment and the limitations of recycling. These issues, coupled with a shift in global awareness regarding plastic waste and stricter environmental regulations, have led to active research and development of biodegradable materials capable of replacing PE film.

[0005] Currently, biodegradable polymer resin compositions such as polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA) are attracting attention as biodegradable film materials. These resins are evaluated as eco-friendly alternatives to PE because they can be naturally decomposed by microorganisms. However, PBAT and PLA-based biodegradable resin compositions have a problem in that, when manufactured into films, the mechanical properties of the film are insufficient, resulting in inferior performance compared to conventional PE films in terms of tensile strength, tear strength, and impact resistance.

[0006] Accordingly, research and development on biodegradable resins are being conducted to increase the strength of the film; however, this results in reduced flexibility, which leads to problems such as poor adhesion to soil topography when the film is used as a mulching film, the formation of unintended patterns like waves on the film surface, and reduced gloss.

[0007] Therefore, there is a need for the development of biodegradable resins that enable the production of films with excellent balanced strength and flexibility, as well as superior appearance characteristics.

[0008] One objective of the present invention is to provide a biodegradable resin composition that has excellent biodegradability, and when manufactured into a film, exhibits excellent balanced strength and flexibility, as well as superior appearance characteristics.

[0009] 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 and superior appearance characteristics and processability.

[0010] 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.

[0011] According to one embodiment of the present invention, a biodegradable resin composition comprising polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA), wherein the T2 relaxation time (T) of the resin composition is 0.4 × 10⁻⁶ as a result of TD-NMR analysis. -3A biodegradable resin composition is provided, wherein the absorption time is less than or equal to seconds (s), and the ratio of the integrated area of ​​the butylene adipate peak to the integrated area of ​​the butylene terephthalate peak in the IR absorption spectrum of the resin composition (BA / BT ratio, R) is 0.75 or more and 0.95 or less.

[0012] The above biodegradable resin composition has a value (A) obtained by multiplying the T2 relaxation time (T) calculated by Formula 1 below and the ratio (R) of 25 × 10 -5 (s) to 33 × 10 -5 (s)can be:

[0013] [Equation 1]

[0014] A = T × R

[0015] As a result of the Thermogravimetric Analysis (TGA) of the above biodegradable resin composition, the temperature of the two-stage peak calculated by Equation 2 below (T P2 ) and the temperature of the first stage peak (T P1 The difference in ) may be 100 ℃ or less.

[0016] [Equation 2]

[0017] T P2 - T P1

[0018] The above biodegradable resin composition may have a weight ratio of polybutylene adipate terephthalate and polylactic acid of 70:30 to 95:5.

[0019] The density of the above polybutylene adipate terephthalate is 1.1 g / cm³ 3 Up to 1.5 g / cm 3 It could be.

[0020] The density of the above polylactic acid is 1.1 g / cm³ 3 Up to 1.5 g / cm 3 It could be.

[0021] The above polybutylene adipate terephthalate may have a weight-average molecular weight of 50,000 to 200,000 g / mol.

[0022] The above polylactic acid may have a weight-average molecular weight of 100,000 to 300,000 g / mol.

[0023] 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.

[0024] 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.

[0025] The above biodegradable resin composition may further include at least one of an inorganic filler and a compatibilizer.

[0026] The above inorganic filler may be included in an amount of 10 parts by weight or more and less than 20 parts by weight based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

[0027] 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.

[0028] According to another embodiment of the present invention, a biodegradable film is provided comprising a biodegradable resin composition according to the present invention and satisfying at least one of 1) to 4) below. Preferably, all of 1) to 4) may be satisfied:

[0029] 1) TD modulus of biodegradable film: 2400 kgf / cm² 2 more;

[0030] 2) The value of [(MD modulus - TD modulus) / MD modulus] × 100% of the biodegradable film is 5% to 25%;

[0031] 3) The sum of the MD tear strength and TD tear strength of the biodegradable film is 2500 N / cm or more;

[0032] 4) The 20° gloss of the biodegradable film is 7 GU to 9.8 GU

[0033] In addition, the thickness of the biodegradable film may be 10 to 200 μm.

[0034] The average value of the surface roughness of the above biodegradable film may be 0.55 μm or less. In addition, the percentage (%) of the standard deviation of the average value of the surface roughness of the above biodegradable film may be 10% or less.

[0035] According to another embodiment of the present invention, a biodegradable article comprising a biodegradable resin composition according to the present invention is provided.

[0036] The resin composition of the present invention exhibits excellent biodegradability. When manufactured into a film, it not only displays excellent balanced strength and flexibility but also possesses various other excellent mechanical properties, such as impact resistance and dimensional stability. Furthermore, the film exhibits superior surface appearance characteristics, such as transparency and gloss.

[0037] Accordingly, the biodegradable resin composition of the present invention can be applied to the manufacture of molded products such as films in various fields such as agriculture, food, and industry, and can be used as a substitute for conventional non-degradable plastics that cause environmental pollution.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] According to one embodiment of the present invention, the invention relates to a biodegradable resin composition comprising polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA).

[0042] Generally, various packaging materials, such as mulching films, are manufactured from synthetic resins, such as polyethylene resin, which can undergo continuous deformation when heated. However, these polyethylene films do not decompose in the natural environment and have limitations in recycling. Consequently, films made from biodegradable polymer resins are being developed to replace conventional thermoplastics. Nevertheless, biodegradable films developed to date have had limitations in that they have not reached a satisfactory level compared to existing films in terms of mechanical properties or surface characteristics.

[0043] As described above, the resin composition of the present invention includes polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA), which are biodegradable resins, as the main resins; in addition to having excellent biodegradability, when manufactured into a film, it exhibits harmoniously excellent strength and flexibility, as well as excellent appearance characteristics. To analyze these features of the present invention, particularly stiffness, Time-Domain Nuclear Magnetic Resonance (TD-NMR) analysis was performed.

[0044] Through the aforementioned TD-NMR analysis 1 H₂Nuclear Magnetic Resonance (H₃) signals are obtained, and the decrease in magnetization is recorded using the Free Induction Decay (FID) signal generated by the initial pulse (90°). This yields a curve (graph) where the x-axis represents signal acquisition time and the y-axis represents peak intensity. Subsequently, a 180° pulse is applied following the 90° pulse to generate a refocused spin-echo signal. The time interval between the 90° and 180° pulses is designated as the "tau time (τ)," and the echo signal is measured repeatedly while gradually increasing this time. The intensity of the acquired echo signal at each tau time is recorded. As the tau time increases, the dephasing phenomenon of magnetization increases, causing the echo signal intensity to gradually decrease. By plotting the measured echo signal intensity (y-axis) against the tau time (x-axis), a curve representing the exponentially decreasing signal can be drawn. The curve is an exponential function (Here, M(t) is the signal strength at time t, M0 is the initial signal strength, which is the magnetization amount at t=0, T2 is the relaxation time, and t is the tau time) fitting is done to set the time at which the signal decreases to 1 / e as the T2 relaxation time. Here, fitting with the above exponential function can be done by nonlinear regression analysis using, for example, MATLAB, Origin, Python's SciPy, but is not limited thereto.

[0045] The above T2 relaxation time is not affected by the strength of the external magnetic field and represents the intrinsic properties of the material, reflecting the mobility and interactions of molecules as well as the structural density of the molecules. A shorter T2 relaxation time indicates that the molecules are dense and rigid, or that the intermolecular interactions are strong.

[0046] As a result of TD-NMR analysis of the biodegradable resin composition of the present invention, the T2 relaxation time (hereinafter referred to as 'T') is 0.4 × 10 -3 seconds or less, 0.39 × 10⁻⁶ -3 seconds or less, 0.38 × 10⁻⁶ -3 seconds or less, 0.37 × 10⁻⁶ -3 less than a second (s) or 0.36 × 10⁻⁶ -3 less than or equal to seconds, and 0.25 × 10⁻⁶ -3 Seconds or more or 0.3 × 10⁻⁶ -3 It is characterized by being at least seconds (s). Preferably, the T2 relaxation time (T) of the biodegradable resin composition is 0.25 × 10⁻⁶ -3 Seconds or more, 0.4 × 10⁻⁶ -3 It can be less than a second.

[0047] In the present invention, the TD-NMR analysis may be performed on a biodegradable resin composition, particularly a pellet containing the same. If necessary, in order to exclude the influence of moisture or external environmental factors, the sample for the TD-NMR analysis may be dried at about 40 to 50°C for 12 hours or more, for example, 24 to 96 hours.

[0048] In the resin composition according to the present invention through the above TD-NMR analysis 1 The peak intensity resulting from observing free induction decay (FID), which manifests as the decay of the H signal, is obtained, and said intensity is observed sequentially over time. At this time, the time at which the intensity is observed corresponds to the signal acquisition time. Here, as the tau time, which represents the time interval between pulses, is gradually increased, the dephasing phenomenon increases, causing the intensity of the refocused magnetization to decrease, and these values ​​are plotted. Subsequently, the T2 relaxation time is calculated from the plotted graph according to a defined criterion.

[0049] The biodegradable resin composition of the present invention having the above-described features comprises, in the polybutylene adipate terephthalate included therein, butylene adipate (BA) which contributes to the flexibility of the resin and butylene terephthalate (BT) which contributes to the rigidity of the resin in an appropriate ratio. Specifically, in the polybutylene adipate terephthalate, the ratio of the butylene adipate (BA) unit to the butylene terephthalate (BT) unit (BA / BT ratio, hereinafter also referred to as 'R') may be 0.75 or more, 0.76 or more, or 0.77 or more, and may be 0.95 or less, 0.93 or less, 0.91 or less, or 0.90 or less, and preferably may be 0.75 or more and 0.95 or less.

[0050] The above ratio (R) can be calculated through FTIR (Fourier Transform Infrared Spectroscopy) analysis of the resin composition. Specifically, specimens of the resin composition are prepared in the form of pellets with a particle size of approximately 1 cm or larger, and these specimens are analyzed using the ATR crystal of an FTIR instrument to obtain an IR absorption spectrum where the x-axis represents the wavenumber and the y-axis represents absorbance. Absorption peaks associated with the functional groups of the major components within the resin composition appear in the derived IR spectrum. Among the absorption peaks, the 1730 cm⁻¹ peak is -1 The BA peak observed at 1710 cm⁻¹ -1 The area of ​​the region corresponding to the BT peak observed in is calculated, and the ratio of said area is defined herein as the weight ratio (R) of the butylene adipate (BA) unit to the butylene terephthalate (BT) unit. The area of ​​the BA peak is 1900 cm² -1 up to 1600 cm -1 Set the area as the baseline and 1740 cm -1 to 1724 cm -1It is a value obtained by integrating the region, and the area of ​​the BT peak is 1900 cm² -1 up to 1600 cm -1 Set the area as the baseline and 1717 cm -1 to 1704 cm -1 It is a value obtained by integrating the range.

[0051] As described above, the resin composition of the present invention exhibits excellent, balanced strength and flexibility, wherein A, a value calculated as the product of the T2 relaxation time (T) and the BA / BT ratio (R) as shown in Equation 1 below, is 25 × 10 -5 (s) to 33 × 10 -5 Characterized by being (s):

[0052] [Equation 1]

[0053] A = T × R

[0054] A, expressed as the product of the above T2 relaxation time (T) and the BA / BT ratio (R), may be an indicator comprehensively representing molecular motional and structural characteristics, and its value is 25 × 10 -5 (s) or more or 26 × 10 -5 (s) may be more than, and 33 × 10 -5 (s) or less, 32 × 10 -5 (s) or less or 31 × 10 -5 It may be less than or equal to (s), for example, 25 × 10⁻⁶ -5 Up to 32 × 10 -5 , 25 × 10 -5 Up to 31 × 10 -5 , 26 × 10 -5 Up to 31 × 10 -5 It can be. In this case, the unit of A is seconds (s).

[0055] In addition, there is a high interaction between polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA) in the resin composition according to the present invention having the above-described characteristics. In this regard, the temperature (T) of the two-step peak calculated by Equation 2 below in the Thermogravimetric Analysis (TGA) graph P2 ) and the temperature of the first stage peak (T P1 The difference in ) may be 100 ℃ or less.

[0056] [Equation 2]

[0057] T P2 - T P1

[0058] A curve of the rate of change in mass per unit temperature change (d(weight) / dT(% / ℃)) according to temperature can be obtained through the above thermogravimetric analysis (TGA). In the curve obtained in the present invention, two or more multiple peaks originating from the components included in the resin composition are observed. Since the y-axis of the curve represents the change in mass (d(weight)) per unit temperature change (dT), the value of d(weight) becomes negative when the mass of the sample decreases. Therefore, the maximum value of the y-axis is 0, and the peak appears in the negative direction. In the curve of the present invention, a first-stage peak originating from polylactic acid (PLA) is observed in the temperature range of 250 to 350 ℃, and a second-stage peak originating from polybutylene adipate terephthalate (PBAT) is observed in the temperature range of 350 to 450 ℃. The first-step peak temperature (T) for evaluating the interaction between the above polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA) P1 ) refers to the x-axis temperature at the point where the absolute value of the y-axis is highest at the above-mentioned 1st stage peak, and the above-mentioned 2nd stage peak temperature (T P2 ) refers to the x-axis temperature at the point where the absolute value of the y-axis is highest in the above 2-stage peak.

[0059] Preferably, the temperature (T of the second-stage peak in the above TGA curve) P2 ) and the temperature of the first stage peak (T P1 The difference of ) may be 90 ℃ or less, 80 ℃ or less, or 70 ℃ or less, and the lower limit may be 50 ℃ or more or 60 ℃ or more, although not specifically limited.

[0060] In addition, the biodegradable resin composition of the present invention has a uniform internal polymer arrangement, so when manufactured into a film, it has an overall uniform surface roughness.

[0061] The average value of the surface roughness of a film made of the biodegradable resin composition of the present invention may be 0.55 μm or less, 0.54 μm or less, 0.53 μm or less, 0.52 μm or less, 0.51 μm or less, or 0.50 μm or less. In this case, the lower limit is not specifically restricted, but may be 0.30 μm or more.

[0062] In addition, the standard deviation of the surface roughness of the film may be 0.05 μm or less, 0.04 μm or less, 0.03 μm or less, 0.02 μm or less, or 0.01 μm or less.

[0063] In addition, the percentage (%) of the standard deviation of the average value of the surface roughness of the film may be 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, or 3% or less, and preferably 5% or less. The lower limit is not specifically restricted, but considering actual process limitations, it may be 0.001% or more.

[0064] The above surface roughness is the average value and standard deviation value of surface roughness measured at 9 or more non-overlapping points on a film cut to a width × height of 10 mm × 10 mm.

[0065] The surface roughness of the above film can be measured through optical profiler (OP) analysis. More specifically, 2D and 3D images of the film surface shape are obtained using an optical profiler. At this time, in order to measure surface roughness while minimizing surface waviness, the lens is adjusted so that the field of view (FoV) is 434 μm × 434 μm. From the images obtained in this way, the surface roughness (Ra) can be obtained through the following Equation 1.

[0066] [Mathematical Formula 1]

[0067]

[0068] In the above mathematical formula 1, ℓ represents the length of the measurement section, x represents the measurement position, and Z(x) represents the surface height at the measurement position.

[0069] In the biodegradable resin composition of the present invention, the weight ratio of polybutylene adipate terephthalate and polylactic acid may be 70:30 to 95:5 or 80:20 to 90:10. If the mixing ratio of 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.

[0070] 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.

[0071] In addition, the polylactic acid may have a weight-average molecular weight of 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 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, and for example, 100,000 to 300,000 g / mol.

[0072] 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).

[0073] The above polybutylene adipate terephthalate has a density of 1.1 g / cm³ 3 Above, 1.15 g / cm³ 3 Above or 1.2 g / cm³ 3 Isanggogo, 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.

[0074] 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 That is all, 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 / cm3 , 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.

[0075] Density (g / cm³) of the above polybutylene adipate terephthalate and polylactic acid 3 ) may be measured according to ASTM D1505.

[0076] 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.

[0077] 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, and may be 4.5 g / 10 min or less, 4.0 g / 10 min or less, or 3.5 g / 10 min or less, for example, 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] The above 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.

[0082] The above biodegradable resin composition further comprises an inorganic filler along 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.

[0083] In addition, the above-mentioned inorganic filler may be included in an amount of 10 parts by weight or more and less than 20 parts by weight, or 10 parts by weight or more and 15 parts by weight or less, based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid. If the content of the above-mentioned inorganic filler falls outside the above-mentioned range, the continuity of the resin may be reduced when manufacturing a film, etc. using the resin composition, making it difficult to achieve the desired mechanical properties or appearance characteristics.

[0084] As an example, the biodegradable resin composition may contain calcium carbonate in an amount of 5 parts by weight or more and 15 parts by weight or 5 parts by weight or more and 10 parts by weight or less, based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

[0085] As an example, the biodegradable resin composition may contain talc in an amount of 1 part by weight or more and less than 10 parts by weight, or 3 parts by weight or more and 8 parts by weight or less, or 4 parts by weight or more and 6 parts by weight or less, based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

[0086] As an example, the biodegradable resin composition may contain calcium carbonate in an amount of 5 parts by weight or more and 15 parts by weight or 5 parts by weight or more and 10 parts by weight or less, based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid, and talc in an amount of 1 part by weight or more and less than 10 parts by weight or 3 parts by weight or more and 8 parts by weight or less, or 4 parts by weight or more and 6 parts by weight or less, based on 100 parts by weight of the mixed resin.

[0087] If the content of the above-mentioned inorganic filler, particularly the calcium carbonate and talc, falls outside the above range, the continuity of the resin is reduced, making it difficult to achieve the desired mechanical properties or appearance characteristics.

[0088] 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.

[0089] The maleic anhydride copolymer, which is the compatibilizer mentioned above, 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, or in an amount of 1.2 parts by weight or less or 1.1 parts by weight or less, for example, in an amount of 0.3 to 1.2 parts by weight, or 0.4 to 1.1 parts by weight, or 0.5 to 1.0 parts by weight. If the content of the maleic anhydride copolymer falls outside the above range, the interaction between polybutylene adipate terephthalate and polylactic acid is reduced, making it difficult to achieve the desired mechanical properties or appearance characteristics.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] First, in order to manufacture a biodegradable resin composition, a step of preparing polybutylene adipate terephthalate and polylactic acid may be performed.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] The above second step may include a step of pre-polycondensation of the prepolymer and a step of polycondensation.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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).

[0124] 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.

[0125] The zero shear viscosity (η) of the above polylactic acid PLA) may be 3000 Pas or less, 2900 Pas 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.

[0126] 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 more, 0.7 or more, 0.75 or more, 0.8 or more, 0.85 or more, or 0.9 or more, and may be 1.2 or less, or 1.1 or less. Preferably, it may be 0.65 to 1.2 or less, 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, the interaction between polybutylene adipate terephthalate and polylactic acid deteriorates, such as through phase separation, which results in the formation of a non-uniform polymer chain structure during film manufacturing. This can lead to the formation of unintended patterns on the film surface, excessive reduction in gloss, or a deterioration in the mechanical properties of the film.

[0127] 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 production of polybutylene adipate terephthalate.

[0128] 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.

[0129] The above polybutylene adipate terephthalate and polylactic acid may be mixed in a weight ratio of 70:30 to 95:5, and preferably in a weight ratio of 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.

[0130] 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.

[0131] In the present invention, when a biodegradable resin composition is prepared as described above, a step of extrusion molding thereof may be further performed.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] According to another embodiment of the present invention, the invention relates to a biodegradable article comprising the above-degradable composition.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] The above film may satisfy at least one of the following 1) to 4). Preferably, it may satisfy all of 1) to 4).

[0145] 1) TD modulus of biodegradable film: 2400 kgf / cm² 2 more;

[0146] 2) The percentage of deviation between the MD modulus and the TD modulus relative to the MD modulus of Formula 3 below for the biodegradable film is 5% to 25%;

[0147] 3) The sum of the MD tear strength and TD tear strength of the biodegradable film is 2500 N / cm or more;

[0148] 4) The 20° gloss of the biodegradable film is 7 GU to 9.8 GU

[0149] [Equation 3]

[0150] [(MD Modulus - TD Modulus) / MD Modulus] × 100 %

[0151] Specifically, the sum of the MD (Machine Direction) tearing strength and the TD (Transverse Direction) tearing strength of the film is 2500 N / cm or more, 2550 N / cm or more, or 2600 N / cm or more, and 2900 N / cm or less, or 2850 N / cm or less, and preferably 2500 N / cm to 2900 N / cm, 2550 N / cm to 2900 N / cm, or 2600 N / cm to 2850 N / cm. MD refers to the mechanical direction of movement of the film in the production process, and TD refers to the direction perpendicular to the machine direction (MD).

[0152] The above tear strength may be measured according to ISO 6383-2 standards.

[0153] The MD modulus of the above film is 2500 kgf / cm² 2 Above, or 2600 kgf / cm² 2 That is all, 3200 kgf / cm² 2 3100 kgf / cm² or less 2 It is less than or equal to, preferably 2500 kgf / cm² 2 Up to 3200 kgf / cm² 2 or 2600 kgf / cm²2 Up to 3100 kgf / cm² 2 It could be.

[0154] The TD modulus of the above film is 2400 kgf / cm² 2 Above, or 2450 kgf / cm² 2 That is all, 3000 kgf / cm² 2 2800 kgf / cm² or less 2 It is less than or equal to, preferably 2400 kgf / cm² 2 Up to 3000 kgf / cm² 2 or 2450 kgf / cm² 2 Up to 2800 kgf / cm² 2 It could be.

[0155] The above film has a small deviation between the modulus in the MD direction and the modulus in the TD direction. Specifically, the value of Equation 3 of the above film may be 5% or more or 7% or more, and may be 25% or less, 23% or less, or 20% or less, for example, 5% to 25%, 5% to 23%, or 7% to 20%.

[0156] The above modulus may be measured according to ISO 527 standards.

[0157] The above film may have a surface gloss of 7 GU or more or 7.5 GU or more, and may have a high surface gloss of 9.8 GU or less, or 9.5 GU or less, for example, 7 to 9.8 GU.

[0158] The above surface gloss may be measured according to ASTM D523 based on a light reception angle of 20 degrees (°).

[0159] The average value of the surface roughness of a film made of the biodegradable resin composition of the present invention may be 0.55 μm or less, 0.54 μm or less, 0.53 μm or less, 0.52 μm or less, 0.51 μm or less, or 0.50 μm or less. In this case, the lower limit is not specifically restricted, but may be 0.30 μm or more.

[0160] In addition, the standard deviation of the surface roughness of the film may be 0.05 μm or less, 0.04 μm or less, 0.03 μm or less, 0.02 μm or less, or 0.01 μm or less.

[0161] In addition, the percentage (%) of the standard deviation of the average value of the surface roughness of the film may be 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, or 3% or less, and preferably 5% or less. The lower limit is not specifically restricted, but considering actual process limitations, it may be 0.001% or more.

[0162] As mentioned above, the film produced from the biodegradable resin composition of the present invention has excellent mechanical strength and appearance characteristics, making it suitable for use as a mulching film or various packaging material in various fields such as agriculture, food, and industry.

[0163] 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.

[0164] Examples

[0165] [Example 1] Preparation of a biodegradable resin composition

[0166] 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.

[0167] Next, to prepare a polybutylene adipate terephthalate polymer, 1,180 g of 1,4-butanediol, 610 g of adipic acid, 640 g of terephthalic acid, 0.5 g of pentaerythritol, and 0.7 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 60 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.

[0168] 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).

[0169] 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.

[0170] [Example 2] Preparation of a biodegradable resin composition

[0171] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190 ℃, 2.16kg) was prepared.

[0172] Next, to prepare a polybutylene adipate terephthalate polymer, 1,180 g of 1,4-butanediol, 610 g of adipic acid, 640 g of terephthalic acid, 0.5 g of pentaerythritol, and 0.7 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 60 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.

[0173] 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.

[0174] 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.

[0175] [Comparative Example 1] Preparation of a biodegradable resin composition

[0176] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190 ℃, 2.16kg) was prepared.

[0177] Next, to prepare a polybutylene adipate terephthalate polymer, 1,180 g of 1,4-butanediol, 610 g of adipic acid, 640 g of terephthalic acid, 0.5 g of pentaerythritol, and 0.7 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 60 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.

[0178] 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.

[0179] 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.

[0180] [Comparative Example 2] Preparation of a biodegradable resin composition

[0181] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190 ℃, 2.16kg) was prepared.

[0182] Next, to prepare a polybutylene adipate terephthalate polymer, 1,180 g of 1,4-butanediol, 610 g of adipic acid, 640 g of terephthalic acid, 0.5 g of pentaerythritol, and 0.7 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 60 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.

[0183] 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.

[0184] 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 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.

[0185] [Comparative Example 3] Preparation of a biodegradable resin composition

[0186] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190 ℃, 2.16kg) was prepared.

[0187] Next, to prepare a polybutylene adipate terephthalate polymer, 1,180 g of 1,4-butanediol, 610 g of adipic acid, 640 g of terephthalic acid, 0.5 g of pentaerythritol, and 0.7 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 60 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.

[0188] 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.

[0189] A viscosity-controlled polybutylene adipate terephthalate resin and a polylactic acid resin were mixed in a weight ratio of 90:10. Subsequently, a mixture was obtained by mixing 10 phr of calcium carbonate as an inorganic filler with 100 parts by weight of the mixed resin. The obtained mixture was fed into a twin-screw extruder (32 mm), and then 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.

[0190] [Experimental Example 1] Measurement of T2 Relaxation Time (T) and BA / BT Ratio of Resin Composition

[0191] 1. TD-NMR Analysis

[0192] The T2 relaxation time of the biodegradable resin compositions prepared in the above examples and comparative examples was measured via TD-NMR analysis. The specific measurement method is as follows: First, the resin compositions of the examples and comparative examples, prepared in pellet form, were subjected to pretreatment by drying at approximately 40°C for about 48 hours. The dried pellets were filled into a 10 mm NMR tube to a sample height of approximately 5 cm. Subsequently, the tube was sealed with Parafilm to prepare a sample for TD-NMR analysis. The prepared sample was stabilized at approximately 40°C for about 1 hour.

[0193] After stabilization, TD-NMR analysis was performed using the Bruker TD-NMR the minispec mq20 TD-NMR analyzer under the measurement conditions shown below. However, other TD-NMR analyzers commonly used in the field may be used in addition to the above equipment. As a result of this analysis, a curve (graph) was obtained with the x-axis representing signal acquisition time and the y-axis representing peak intensity. The values ​​of the intensity of the refocused magnetization observed as the tau time was gradually increased were plotted. Subsequently, the T2 relaxation time was calculated based on the defined criteria derived from the plotted graph.

[0194] <Measurement Conditions>

[0195] 1) Temperature: 40℃

[0196] 2) Nuclide: 1 H

[0197] 3) Method: Hahn spin-Echo

[0198] 4) Delay time: 30 sec

[0199] 5) Number of scans: 4

[0200] 6) Receiver gain: Use the automatic value measured by the instrument for each sample.

[0201] 7) first pulse separation 0.080 ms

[0202] 8) final pulse separation 0.800 ms

[0203] 9) Number of data points for fitting: 50

[0204] 10) Time for decay curve display: 3 sec

[0205] 2. BA / BT Ratio (BA / BT ratio, R) - FTIR Analysis

[0206] Specimens were prepared by forming the biodegradable resin compositions prepared in the above examples and comparative examples into pellets with a particle size of approximately 1 cm or larger. Subsequently, the resin compositions were analyzed using an ATR crystal of an FTIR (Fourier Transform Infrared Spectroscopy) instrument (equipment name: Agilent Cary620), thereby obtaining IR absorption spectra where the x-axis represents the wavenumber and the y-axis represents the absorbance. The analysis conditions were a wavelength range of 600 to 4000 cm⁻¹. -1 , resolution 4 or 8 cm -1 , the number of scans was set to 16 or more. Among the absorption peaks of the derived IR spectrum, 1730 cm⁻¹ -1 The BA peak observed at 1710 cm⁻¹ -1 The area of ​​the region corresponding to the BT peak observed in was calculated. At this time, the area of ​​the BA peak region (S1) is 1900 cm⁻¹ -1 up to 1600 cm -1Set the area as the baseline, 1740 cm -1 to 1724 cm -1 It is a value obtained by integrating the region, and the area of ​​the BT peak (S2) is 1900 cm⁻¹ to 1600 cm⁻¹ -1 Set the area as the baseline and 1717 cm -1 to 1704 cm -1 This is a value obtained by integrating the region. The ratio of the areas obtained at this time is considered to correspond to the weight ratio. The ratio of the integrated area of ​​the BA peak region to the integrated area of ​​the BT peak region (S1 / S2) is defined as the BA / BT ratio (R). However, in addition to the above equipment, equipment commonly used in the field may be used for FTIR (Fourier Transform Infrared Spectroscopy).

[0207] 3. Derivation of A, the product of T and R

[0208] For each example and comparative example, the T2 relaxation time (T) obtained in 1. above, the BA / BT Ratio (R) obtained in 2. above, and the value A obtained by multiplying them are shown in Table 1 below.

[0209] T2 relaxation time (T, 10 -3 s)BA / BT Ratio (R)R × T (A, 10 -5 s) Example 10.33 0.9 29.7 Example 20.34 50.7 726.6 Comparative Example 10.37 90.9 636.4 Comparative Example 20.36 10.9 735.0 Comparative Example 30.33 90.7 224.4

[0210] From the results in Table 1 above, the resin compositions of Examples 1 and 2 each have a T2 relaxation time (T) of 0.33 × 10 of the present invention. -3 s and 0.345 × 10⁻⁶ -3 It was s, and the BA / BT ratio (R) was 0.9 and 0.77, respectively. In addition, the resin compositions of Examples 1 and 2 were A (= R × T, unit: 10 -5 It was confirmed that s) were 29.7 and 26.6, respectively.

[0211] On the other hand, the resin compositions of Comparative Examples 1 to 3 each had a T2 relaxation time (T) of 0.379 × 10 -3 s, 0.361 × 10 -3 s and 0.339 × 10⁻⁶ -3 It was confirmed that s, and the BA / BT ratio (R) was 0.96, 0.97, and 0.72, respectively. In addition, the resin compositions of Comparative Examples 1 to 3 were A (= R × T, unit: 10 -5 It was confirmed that s) were 36.4, 35.0, and 24.4, respectively.

[0212] [Experimental Example 2] Thermogravimetric Analysis (TGA) of Resin Composition

[0213] For the biodegradable resin compositions of Examples 1 and 2 and Comparative Examples 1 to 3, the temperature of the first peak (T1) and the temperature of the second peak (T2) were determined through thermogravimetric analysis. The specific measurement method is as follows: First, about 3 mg of the resin compositions of the Examples and Comparative Examples, prepared in pellet form, were weighed and prepared as samples. The prepared samples were analyzed using a Thermogravimetric Analyzer (TGA) (Equipment name: METTLER TOLEDO TGA 2), and the weight change was observed in each section while increasing the temperature at a rate of 10 ℃ / min in a N2 atmosphere with a flow rate of 50 ml / min, and in a temperature range of 50 to 800 ℃.

[0214] From the analysis results, a curve of the mass change rate per unit temperature change (d(weight) / dT(% / ℃)) according to temperature was obtained. From the above curve, the first stage peak temperature (T1), which is the temperature at the point where the absolute value of the y-axis of the first peak is highest, and the second stage peak temperature (T2), which is the temperature at the point where the absolute value of the y-axis of the second peak is highest, were determined. At this time, the first stage peak is attributed to polylactic acid (PLA), and the second stage peak is attributed to polybutylene adipate terephthalate (PBAT).

[0215] And, the temperature of the second-stage peak (T P2 ) and the temperature of the first stage peak (T P1 The difference (T) P2 - T P1 ) was obtained.

[0216] The results are listed in Table 2 below.

[0217] T P1 (℃)T P2 (℃)T P2 - T P1 (°C) Example 1 32939768 Example 2 33039666 Comparative Example 1 278398120 Comparative Example 2 292402110 Comparative Example 3 292396104

[0218] In the results of Table 2 above, the difference (T) between the temperature of the step peak (T1) and the temperature of the second step peak (T2) of Examples 1 and 2 P2 - T P1 It was confirmed that the degree of interaction between PBAT and PLA in the resin composition was large, with the temperature being 100°C or lower.

[0219] [Experimental Example 3] Evaluation of Mechanical Properties

[0220] In order to evaluate the mechanical properties of the biodegradable resin compositions prepared in the above examples and comparative examples, blown films with a thickness of approximately 50±5 μm were prepared using the biodegradable resin compositions of the examples and comparative examples. Specifically, the pellets obtained in Examples 1 and 2 and Comparative Examples 1 to 3 were extruded 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 extrusion temperature: approximately 145 ℃, expansion ratio (Blown-Up Ratio): approximately 1.5, and linear speed: 5 m / min to 10 m / min. Subsequently, the following properties were evaluated.

[0221] 1. Tear strength

[0222] The sum of the tearing strength in the MD direction and the tearing strength in the TD direction according to ISO 6383-2 standards,

[0223] 2. Modulus

[0224] The MD direction modulus (MD modulus) and TD direction modulus (TD modulus) were measured according to the ISO 527 standard, and the percentage of deviation of the MD direction modulus and TD direction modulus with respect to the MD direction modulus was calculated as shown in Equation 3 below.

[0225] [Equation 3]

[0226] [(MD Modulus - TD Modulus) / MD Modulus] × 100% value

[0227] The results are shown in Table 3 below.

[0228] Sum of tear strengths (N / cm) MD Modulus (kgf / cm²) 2 )TD Modulus (kgf / cm²) 2 Modulus deviation (%) of Equation 3 Example 1 268 32688 24618 Example 2 265 3309 325 2418 Comparative Example 1 2445 3422 185046 Comparative Example 2 247 236 152 32936 Comparative Example 3 2437 31 102 28427

[0229] As shown in Table 3 above, the films prepared from the resin compositions of Examples 1 and 2 according to the present invention have a total tear strength of 2653 N / cm or more and a TD modulus of 2461 kgf / cm 2 Above, the MD modulus is 2688 kgf / cm² 2 The above is the result, and the percentage deviations of the MD modulus and TD modulus relative to the TD modulus were 8% and 18%, respectively, confirming that the modulus was uniform in the MD and TD directions.

[0230] On the other hand, films prepared from resin compositions (Comparative Examples 1 to 3) in which the T2 relaxation time and BA / BT ratio fall outside the scope of the present invention have a total tear strength of 2400 kgf / cm² 2 It was at a large level, and it was confirmed that the modulus deviation in the MD and TD directions was very large and non-uniform.

[0231] [Experimental Example 4] Evaluation of Appearance Characteristics

[0232] To evaluate the appearance characteristics of the biodegradable resin compositions prepared in the above examples and comparative examples, blown films were prepared in the same manner as in Experimental Example 3, and then visually inspected to check whether ripples were formed on the film surface. If ripples were present, it was recorded as NG, and if no ripples were present, it was evaluated as OK. In addition, the glossiness of each film was measured at a light reception angle of 20° according to ASTM D523.

[0233] The results are shown in Table 4 below.

[0234] Appearance Gloss (GU) Example 1 OK 9.38 Example 2 OK 8.9 Comparative Example 1 NG 6.79 Comparative Example 2 OK 8.67 Comparative Example 3 OK 10.71

[0235] As shown in Table 4 above, the films produced from the resin compositions of Examples 1 and 2 according to the present invention did not have any unwanted patterns on the surface and showed a high level of gloss (Gloss) of 7 to 9.8 GU.

[0236] On the other hand, the surface of the film produced from a resin composition outside the scope of the present invention (Comparative Example 1) showed wavy patterns and very low gloss.

[0237] [Experimental Example 5] Evaluation of Surface Roughness

[0238] To evaluate the surface uniformity of films prepared from the biodegradable resin compositions of Examples 1 and 2 and Comparative Example 3, which exhibited no external wavy appearance and relatively excellent gloss among the films of Experimental Example 4, the average value and standard deviation of surface roughness were measured using an Optical Profiler (OP). First, the films prepared in Experimental Example 3 for each example and comparative example were cut to a size of 10 mm × 10 mm (width × height). After selecting an arbitrary area on the film, two areas were selected by spacing them 1,000 μm away from the selected area in the MD direction. For each of these three selected areas, two additional areas were selected by spacing them 1,000 μm away in the TD direction, resulting in a total of nine selected areas. For each area, 2D and 3D images of the film surface shape were obtained using an Optical Profiler (OP). At this time, to measure surface roughness while minimizing surface waviness, the lens was adjusted so that the field of view (FoV) was 434 μm × 434 μm. From the image obtained in this way, the surface roughness (Ra) was obtained using the following Equation 1. The average value was calculated from the surface roughness in nine regions, and the standard deviation was determined. In addition, the percentage (%) of the standard deviation relative to the average surface roughness value was calculated. The values ​​are shown in Table 5 below, rounded to the third decimal place.

[0239] [Mathematical Formula 1]

[0240]

[0241] In the above mathematical formula 1, ℓ represents the length of the measurement section, x represents the measurement position, and Z(x) represents the surface height at the measurement position.

[0242] Average Value (㎛) Standard Deviation (㎛) (Deviation / Average) × 100 (%) Example 10.4 90.0 12.04 Example 20.5 10.0 23.92 Comparative Example 30.5 70.0 712.28

[0243] As shown in Table 5 above, the films produced from the resin compositions of Examples 1 and 2 according to the present invention, which have excellent appearance characteristics, had average surface roughness values ​​of 0.49 μm and 0.51 μm, respectively, and standard deviations of 0.01 μm and 0.02 μm, respectively, and the percentage of standard deviation relative to the average value was also very low at 5% or less.

[0244] On the other hand, in the case of a film produced from a resin composition outside the scope of the present invention (Comparative Example 3), the surface roughness was relatively high at 0.57 μm, the standard deviation was 0.07 μm, and the percentage of the standard deviation relative to the mean was 12.28%, indicating that the uniformity of the film surface roughness was poor.

[0245] As such, while the film of the comparative example showed similar results to the film of the example in the evaluation of appearance characteristics, it was confirmed that the surface was not uniform in the evaluation of surface roughness.

[0246] As can be confirmed from the experiments above, the resin composition according to the present invention, comprising polybutylene adipate terephthalate and polylactic acid, not only exhibits excellent biodegradability but also harmoniously excellent rigidity and flexibility. Consequently, the film produced from the above composition showed excellent results in various mechanical property evaluations, and the appearance evaluation also demonstrated excellent gloss without surface defects. Furthermore, it was found that the film exhibited uniform roughness across its entire surface.

Claims

1. A biodegradable resin composition comprising polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA), wherein As a result of TD-NMR analysis of the above resin composition, the T2 relaxation time (T) is 0.4 × 10⁻⁶ -3 It is less than or equal to seconds, and The ratio of the integrated area of ​​the butylene adipate peak to the integrated area of ​​the butylene terephthalate peak in the IR absorption spectrum of the resin composition (BA / BT ratio, R) is 0.75 or higher and 0.95 or lower, Biodegradable resin composition.

2. In Paragraph 1, The above biodegradable resin composition has a value (A) obtained by multiplying the T2 relaxation time (T) calculated by Formula 1 below and the ratio (R) of 25 × 10 -5 (s) to 33 × 10 -5 (s) Biodegradable resin composition: [Equation 1] A = T × R 3. In Paragraph 1, As a result of the Thermogravimetric Analysis (TGA) of the above biodegradable resin composition, the temperature of the two-stage peak calculated by Equation 2 below (T P2 ) and the temperature of the first stage peak (T P1 Biodegradable resin composition having a difference of ) of 100 ℃ or less: [Equation 2] T P2 - T P1 4. In Paragraph 1, The biodegradable resin composition is a biodegradable resin composition in which the weight ratio of the polybutylene adipate terephthalate and polylactic acid is 70:30 to 95:

5.

5. In Paragraph 1, The density of the above polybutylene adipate terephthalate is 1.1 g / cm³ 3 Up to 1.5 g / cm² 3 Phosphorus, biodegradable resin composition.

6. In Paragraph 1, The density of the above polylactic acid is 1.1 g / cm³ 3 Up to 1.5 g / cm² 3 Phosphorus, biodegradable resin composition.

7. In Paragraph 1, The above polybutylene adipate terephthalate is a biodegradable resin composition having a weight-average molecular weight of 50,000 to 200,000 g / mol.

8. In Paragraph 1, The above polylactic acid is a biodegradable resin composition having a weight-average molecular weight of 100,000 to 300,000 g / mol.

9. In Paragraph 1, A biodegradable resin composition having a melt index (190 ℃, 2.16 kg) of the above polybutylene adipate terephthalate of 2.5 g / 10 min to 6.0 g / 10 min.

10. In Paragraph 1, A biodegradable resin composition having a melt index (190 ℃, 2.16 kg) of the above polylactic acid of 1.5 g / 10 min to 4.5 g / 10 min.

11. In Paragraph 1, The above biodegradable resin composition further comprises at least one of an inorganic filler and a compatibilizer.

12. In Paragraph 11, The above biodegradable resin composition comprises 10 parts by weight or more and less than 20 parts by weight of an inorganic filler based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

13. In Paragraph 11, The above biodegradable resin composition comprises 0.3 to 1.2 parts by weight of a compatibilizer based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

14. A biodegradable film comprising a biodegradable resin composition according to any one of claims 1 to 13, satisfying at least one of the following 1) to 4): 1) TD modulus of biodegradable film: 2400 kgf / cm² 2 more; 2) The value of [(MD modulus - TD modulus) / MD modulus] × 100% of the biodegradable film is 5% to 25%; 3) The sum of the MD tear strength and TD tear strength of the biodegradable film is 2500 N / cm or more; 4) The 20° gloss of the biodegradable film is 7 GU to 9.8 GU 15. In Paragraph 14, A biodegradable film having a thickness of 10 to 200 μm.

16. In Paragraph 14, A biodegradable film having an average surface roughness value of 0.55 μm or less.

17. In Paragraph 16, A biodegradable film having a percentage (%) of the standard deviation of the average value of the surface roughness of the above biodegradable film of 10% or less.

18. A biodegradable article comprising a biodegradable resin composition according to any one of claims 1 to 13.

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