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. 10-2024-0191856 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 suffer from poor mechanical properties when manufactured into films, resulting in lower performance compared to conventional PE films in terms of tensile strength, tear strength, and impact resistance. Additionally, there are issues with degraded appearance characteristics during the manufacturing process, such as the formation of uneven patterns like wavy lines on the surface or reduced gloss. These limitations are acting as obstacles to biodegradable resins completely replacing PE.

[0006] Therefore, there is a need for the development of technology that can achieve excellent mechanical properties and outstanding appearance characteristics simultaneously during film manufacturing by improving the biodegradable resin composition.

[0007] One objective of the present invention is to provide a biodegradable resin composition that exhibits excellent biodegradability when manufactured into a film, as well as excellent mechanical properties such as strength and flexibility, and superior appearance characteristics.

[0008] 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 also excellent appearance characteristics.

[0009] 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.

[0010] According to one embodiment of the present invention, a biodegradable resin composition comprising polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA) is provided, wherein the degree of crystallization (X1) of polybutylene adipate terephthalate, measured by differential scanning calorimetry (DSC) on a film prepared from said resin composition, satisfies Formula 1 below, and the degree of crystallization (X2) of polylactic acid satisfies Formula 2 below:

[0011] [Equation 1]

[0012] 5 % ≤ X1 ≤ 9 %

[0013] [Equation 2]

[0014] 7 % ≤ X2 ≤ 20 %

[0015] The above biodegradable resin composition may have a weight ratio of polybutylene adipate terephthalate and polylactic acid of 70:30 to 95:5.

[0016] The density of the above polybutylene adipate terephthalate is 1.1 g / cm³ 3 Up to 1.5 g / cm 3 It could be.

[0017] The density of the above polylactic acid is 1.1 g / cm³ 3 Up to 1.5 g / cm 3 It could be.

[0018] The above polybutylene adipate terephthalate may have a weight-average molecular weight of 50,000 to 200,000 g / mol.

[0019] The above polylactic acid may have a weight-average molecular weight of 100,000 to 300,000 g / mol.

[0020] The melt index (190°C, 2.16 kg) of the above polybutylene adipate terephthalate may be 2.5 g / 10 min to 6.0 g / 10 min.

[0021] The melt index (190°C, 2.16 kg) of the above polylactic acid may be 1.5 g / 10 min to 4.5 g / 10 min.

[0022] The above biodegradable resin composition may further include at least one of an inorganic filler and a compatibilizer.

[0023] The above inorganic filler may be included in an amount of 6 to 35 parts by weight based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

[0024] 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.

[0025] According to another embodiment of the present invention, a biodegradable film comprising polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA) is provided, wherein when the film is measured by differential scanning calorimetry (DSC), the degree of crystallization (X1) of polybutylene adipate terephthalate satisfies Equation 1 and the degree of crystallization (X2) of polylactic acid satisfies Equation 2.

[0026] The weight ratio of the above polybutylene adipate terephthalate and polylactic acid may be 70:30 to 95:5.

[0027] The density of the above polybutylene adipate terephthalate is 1.1 g / cm³ 3 Up to 1.5 g / cm 3 It could be.

[0028] The density of the above polylactic acid is 1.1 g / cm³ 3 Up to 1.5 g / cm 3 It could be.

[0029] The above polybutylene adipate terephthalate may have a weight-average molecular weight of 50,000 to 200,000 g / mol.

[0030] The above polylactic acid may have a weight-average molecular weight of 100,000 to 300,000 g / mol.

[0031] The melt index (190°C, 2.16 kg) of the above polybutylene adipate terephthalate may be 2.5 g / 10 min to 6.0 g / 10 min.

[0032] The melt index (190°C, 2.16 kg) of the above polylactic acid may be 1.5 g / 10 min to 4.5 g / 10 min.

[0033] The above biodegradable film may further include at least one of an inorganic filler and a compatibilizer.

[0034] The above inorganic filler may be included in an amount of 6 to 35 parts by weight based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

[0035] 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.

[0036] 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):

[0037] 1) The sum of the MD tensile strength and TD tensile strength of the biodegradable film is 540 kgf / cm² 2 Up to 700 kgf / cm² 2 ;

[0038] 2) The sum of the MD tearing strength and TD tearing strength of the biodegradable film is 2200 N / cm to 2900 N / cm;

[0039] 3) Drop impact of biodegradable film of 350g or more;

[0040] 4) The sum of the MD modulus and TD modulus of the biodegradable film is 5000 kgf / cm² 2 Up to 6500 kgf / cm² 2 ;

[0041] 5) The 20° gloss of the biodegradable film is 7 GU to 9.8 GU

[0042] In addition, the thickness of the biodegradable film may be 10 to 200 μm.

[0043] According to another embodiment of the present invention, a biodegradable article comprising a biodegradable resin composition according to the present invention is provided.

[0044] The resin composition of the present invention, when manufactured into a film, exhibits excellent biodegradability and various mechanical properties such as strength, impact resistance, and dimensional stability, as well as superior appearance characteristics such as transparency and gloss.

[0045] Therefore, the biodegradable resin composition of the present invention can be applied to various fields such as industry, food, and agriculture, and can be used as a substitute for conventional non-biodegradable plastics that cause environmental pollution.

[0046] 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.

[0047] 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 form includes the plural form unless the context clearly indicates otherwise.

[0048] 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.

[0049] Generally, various packaging and mulching materials have been manufactured from synthetic resins, such as polyethylene resin, which can undergo continuous deformation upon 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 that they have not reached satisfactory levels compared to existing films in terms of mechanical properties or surface characteristics.

[0050] As a result of diligent efforts, the inventors of the present invention have discovered that by including polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA), and including polybutylene adipate terephthalate and polylactic acid that satisfy a specific level of crystallinity, when manufacturing a film with such resin, the polymer chains are uniformly aligned and the bonding strength between the polymer chains is increased, so not only are the mechanical strengths such as tensile strength, tear strength, modulus, and drop impact all excellent, but the film can also have excellent appearance characteristics.

[0051] 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), wherein a film prepared from the resin composition is characterized in that the degree of crystallization (X1) of the polybutylene adipate terephthalate is 5% or more and 9% or less as shown in Formula 1 below, and the degree of crystallization (X2) of the polylactic acid (PLA) is 7% or more and 20% or less as shown in Formula 2 below:

[0052] [Equation 1]

[0053] 5 % ≤ X1 ≤ 9 %

[0054] [Equation 2]

[0055] 7 % ≤ X2 ≤ 20 %

[0056] In this specification, "weight fraction crystallinity" refers to the percentage (%) of the measured enthalpy of melt relative to the theoretical enthalpy of melt when the polymer is 100% crystallin (excluding the nucleating agent and only the resin). The said crystallinity is an indicator showing the degree of alignment of the polymer structure and has a significant impact on the performance of polymer resin films. If the crystallinity of the polymer resin is too low, there are many amorphous regions within the polymer, which reduces mechanical strength when manufactured into a film and increases the likelihood of the film easily deforming and tearing. Conversely, if the crystallinity is excessively high, the rigidity of the polymer increases but flexibility decreases, which may result in lower impact strength and tear strength of the film or molded article. Furthermore, high crystallinity can cause crystalline regions to scatter light, increasing the opacity of the film or forming non-uniform patterns such as wavy lines on the film surface. Therefore, the crystallinity of the polymer resin is an important factor that must be considered when optimizing the performance of the film.

[0057] In the biodegradable resin composition of the present invention, the degree of crystallization (X1) of the polybutylene adipate terephthalate is 5% to 9% as indicated by Formula 1 above. The degree of crystallization (X1) of the polybutylene adipate terephthalate may be 5% or more, 5.5% or more, 6% or more, or 7% or more, 9% or less, or 8.5% or less, 5.5% to 9%, or 6% to 9%, or 6.5% to 9%, or 7% to 9%, or 5.5% to 8.5%, or 6% to 8.5%, or 6.5% to 8.5%, or 7% to 8.5%.

[0058] In the biodegradable resin composition of the present invention, the degree of crystallization (X2) of the polylactic acid is 7% to 20% as shown by Formula 2 above. The degree of crystallization (X2) of the polylactic acid may be 7% or more, 7.5% or more, or 8% or more, 20% or less, 19% or less, or 18% or less, or 7.5% to 20%, or 8% to 20%, or 7% to 19%, or 7.5% to 19%, or 8% to 19%, or 7% to 18%, or 7.5% to 18%, or 8% to 18%, or 8% to 18%.

[0059] The resin composition according to the present invention comprises polybutylene adipate terephthalate (PBAT) satisfying the degree of crystallinity described above and polylactic acid (PLA), thereby harmoniously maintaining the bonding strength between polymer chains and the flexibility of the amorphous region when molded into a film, etc., so that both the mechanical strength and flexibility of the film are excellent, and the appearance characteristics are also outstanding.

[0060] The degree of crystallization of polybutylene adipate terephthalate and polylactic acid constituting the above-described biodegradable resin composition is measured for a film made of the above-described biodegradable resin composition. At this time, the manufacturing method or thickness of the film is not particularly limited, and any film having any thickness within the range of about 30 to 70 μm that satisfies the above degree of crystallization is included within the scope of the present invention. In the examples of this specification, only an example of a film with a thickness of about 50 ± 5 μm is shown as a representative example falling within the above thickness range, but the scope of the present invention is not limited thereto.

[0061] The degree of crystallinity of the above polybutylene adipate terephthalate and polylactic acid can be measured by Differential Scanning Calorimeter (DSC) analysis. Specifically, a film prepared from the above biodegradable resin composition is heated from 25°C to 200°C at a rate of 10°C / min, maintained at 200°C for 5 minutes, and then cooled down to -20°C at a rate of 10°C / min, repeating the heating and cooling cycle twice. For the heating curve appearing during the heating process of the second cycle, a new baseline is established so that the curve is smoothly connected at temperatures before and after melting from the start of the endothermic peak to the end of the peak, thereby obtaining the melting peak, which is the highest endothermic peak, and the heat of fusion (△Hf) of polybutylene adipate terephthalate and polylactic acid, respectively, is obtained by integrating the area of ​​the melting peak. Based on the heat of fusion of a resin having 100% crystallinity, the crystallinity of each of polybutylene adipate terephthalate and polylactic acid is calculated according to the following mathematical formula 1.

[0062] [Mathematical Formula 1]

[0063] Degree of Crystallinity (%) = (△Hf / △H0) × 100

[0064] As a specimen for measuring the degree of crystallization, the film may be a blown film. Such a blown film may be manufactured by the following method, but is not limited thereto, and measurements may also be taken on a film manufactured by other methods: A blown film with the thickness range described above may be manufactured by using a single screw extruder (Blown Film M / C) to mold a biodegradable resin composition (e.g., in pellet form) according to the present invention with an expansion ratio of 1.5 to 2.0. At this time, the extruder may have a screw diameter (phi) of 19 mm and a screw length / diameter (L / D) ratio of 25, but is not limited thereto. In addition, during the molding process for manufacturing the blown film, the extrusion temperature may be 140°C to 150°C and the linear speed may be controlled to 5 m / min to 10 m / min.

[0065] In addition, the pellets, which are the raw materials for manufacturing the blown film, may be manufactured by the following method, but are not limited thereto. First, a biodegradable resin composition is fed into a twin-screw extruder and then manufactured by extruding under conditions of a barrel temperature of 200°C, a feed rate of 30 kg / hr, and a compressor rotation speed of 300 rpm. As an example, the twin-screw extruder may have a screw diameter of 32 mm, but is not limited thereto.

[0066] 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.

[0067] The above 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 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, 100,000 to 300,000 g / mol.

[0068] 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).

[0069] 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 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 or equal to 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.

[0070] 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 or equal to 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.

[0071] Density (g / cm³) of the above polybutylene adipate terephthalate and polylactic acid 3 ) may be measured according to ASTM D1505.

[0072] In addition, the melt index (190°C, 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, it may be 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.

[0073] The melt index (190°C, 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, it 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.

[0074] 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.

[0075] In the above biodegradable resin composition, 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 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.

[0076] 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.

[0077] 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.

[0078] The above chain extender may be 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, 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 to 0.8 parts by weight, 0.25 to 0.75 parts by weight, or 0.25 to 0.65 parts by weight, but is not limited thereto.

[0079] 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.

[0080] In addition, the above-mentioned inorganic filler may be included in an amount of 6 parts by weight or more, 10 parts by weight or more, or 15 parts by weight or more based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid, and may be included in an amount of 35 parts by weight or less, 30 parts by weight or less, or 25 parts by weight or less, and may be included in an amount of 6 to 35 parts by weight, 6 to 30 parts by weight, 6 to 25 parts by weight, 10 to 35 parts by weight, 10 to 30 parts by weight, 10 to 25 parts by weight, 15 to 35 parts by weight, 15 to 30 parts by weight, or 15 to 25 parts by weight.

[0081] As an example, the biodegradable resin composition may contain 3 parts by weight or more, or 5 parts by weight or more, and 20 parts by weight or less, or 15 parts by weight or less, based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid, and may contain calcium carbonate in an amount of 3 to 20 parts by weight, 3 to 15 parts by weight, 5 to 20 parts by weight, or 5 to 15 parts by weight.

[0082] As an example, the biodegradable resin composition may contain 3 parts by weight or more, or 5 parts by weight or more, 20 parts by weight or less, or 15 parts by weight or less, based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid, and may contain talc in an amount of 3 to 20 parts by weight or 5 to 15 parts by weight.

[0083] As an example, the biodegradable resin composition may contain 3 to 15 parts by weight of calcium carbonate and 3 to 20 parts by weight of talc, based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

[0084] 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.

[0085] The maleic anhydride copolymer, which is the above compatibilizer, may be included in an amount of 0.3 parts by weight or more, 0.4 parts by weight or more, or 0.5 parts by weight or more based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid, and may be included in an amount of 1.5 parts by weight or less, 1.2 parts by weight or less, 1.1 parts by weight or less, or 1.0 parts by weight or less, or may be included in an amount of 0.3 to 1.5 parts by weight, 0.3 to 1.2 parts by weight, 0.4 to 1.5 parts by weight or 0.4 to 1.2 parts by weight, or 0.5 to 1.5 parts by weight, or 0.5 to 1.2 parts by weight.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] First, in order to manufacture a biodegradable resin composition, a step of preparing polybutylene adipate terephthalate and polylactic acid may be performed.

[0090] The above-mentioned polybutylene adipate terephthalate may be prepared by the following method, but is not limited to this method; any method capable of producing polybutylene adipate terephthalate satisfying the above-mentioned density, melt index, and weight-average molecular weight, etc., may be used without limitation.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] The above second step may include a step of pre-polycondensation of the prepolymer and a step of polycondensation.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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).

[0120] 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.

[0121] 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.

[0122] 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, it may be 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, 0.9 to 1.2, or 0.9 to 1.1, and more preferably, it may be 0.8 to 1.2, 0.8 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.

[0123] 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.

[0124] 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.

[0125] The above polybutylene adipate terephthalate and polylactic acid may be mixed in a weight ratio of 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.

[0126] 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.

[0127] In the present invention, when a biodegradable resin composition is prepared as described above, a step of extrusion molding thereof may be further performed.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] In addition, the barrel temperature inside the extruder may be 190°C or higher, 195°C or higher, or 200°C or higher, and may be 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.

[0134] 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.

[0135] According to another embodiment of the present invention, the invention relates to a biodegradable article comprising the above-degradable composition.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] A biodegradable article of the present invention, in particular a film, may satisfy at least one of 1) to 5) below, and preferably may satisfy all of 1) to 5):

[0141] 1) The sum of the MD tensile strength and TD tensile strength of the biodegradable film is 540 kgf / cm² 2 Up to 700 kgf / cm² 2 ;

[0142] 2) The sum of the MD tearing strength and TD tearing strength of the biodegradable film is 2200 N / cm to 2900 N / cm;

[0143] 3) Drop impact of biodegradable film of 350g or more;

[0144] 4) The sum of the MD modulus and TD modulus of the biodegradable film is 5000 kgf / cm² 2 Up to 6500 kgf / cm² 2 ;

[0145] 5) The 20° gloss of the biodegradable film is 7 GU to 9.8 GU

[0146] Specifically, the sum of the tensile strength in the machine direction (MD) and the tensile strength in the transverse direction (TD) of the above biodegradable article, particularly the film, is 540 kgf / cm² 2 Above, or 545 kgf / cm² 2 That is all, 700 kgf / cm² 2 Below, 690 kgf / cm² 2 Below, 680 kgf / cm² 2 Below, 670 kgf / cm² 2 Below, 660 kgf / cm² 2 Less than or equal to 650 kgf / cm² 2 It may be less than or equal to, preferably 540 kgf / cm² 2 Up to 670 kgf / cm² 2 or 545 kgf / cm² 2 Up to 650 kgf / cm² 2 It could be.

[0147] The sum of the MD tearing strength and the TD tearing strength of the above biodegradable article, particularly the film, is 2200 N / cm or more, 2230 N / cm or more, or 2250 N / cm or more, and 2900 N / cm or less, or 2850 N / cm or less, and preferably 2200 N / cm to 2900 N / cm, 2230 N / cm to 2900 N / cm, or 2250 N / cm to 2850 N / cm.

[0148] The above biodegradable article, in particular the film, may have a drop impact of 350g or more or 360g or more, 550g or less or 500g or less, and preferably 350g to 550g or 360g to 550g.

[0149] The above drop impact may be measured using a drop impactor in accordance with ASTM D 17409-040 standards.

[0150] The sum of the MD modulus and TD modulus of the above biodegradable article, particularly the film, is 5000 kgf / cm² 2 Above, 5050 kgf / cm² 2 Above, or 5100 kgf / cm² 2 That is all, 6500 kgf / cm² 2 Below, 6400 kgf / cm² 2 Below, 6300 kgf / cm² 2 Less than, or 6200 kgf / cm² 2 It is less than or equal to, preferably 5000 kgf / cm² 2 Up to 6500 kgf / cm² 2 or 5100 kgf / cm² 2 Up to 6200 kgf / cm² 2 It could be.

[0151] The above tensile strength and modulus may be measured according to ISO 527. Also, the above tear strength may be measured according to ISO 6383-2.

[0152] However, the tensile strength, tear strength, drop impact, and modulus for 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.

[0153] The above biodegradable article, particularly the film, may have a 20° gloss of 7 GU or more or 7.5 GU or more, 10 GU or less, or 9.8 GU or less, and preferably 7 to 9.8 GU. 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 a large amount of light and have less glare. In addition, it is advantageous to print specific content on the surface of the film. However, if the 20° gloss is too low, such as 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 10 GU, there may be a problem of increased light reflection and scattering. 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 (°).

[0154] 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.

[0155] Examples

[0156] [Example 1] Preparation of a biodegradable resin composition

[0157] 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.

[0158] 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 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.

[0159] 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).

[0160] 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°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.

[0161] [Example 2] Preparation of a biodegradable resin composition

[0162] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190℃, 2.16kg) was prepared.

[0163] 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 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.

[0164] 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.

[0165] 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°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.

[0166] [Example 3] Preparation of a biodegradable resin composition

[0167] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190℃, 2.16kg) was prepared.

[0168] 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 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.

[0169] 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.

[0170] 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 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.

[0171] [Example 4] Preparation of a biodegradable resin composition

[0172] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190℃, 2.16kg) was prepared.

[0173] 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 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.

[0174] 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.

[0175] Polybutylene adipate terephthalate resin with such controlled viscosity and polylactic acid resin were mixed in a weight ratio of 80:20. 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 for every 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°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.

[0176] [Example 5] Preparation of a biodegradable resin composition

[0177] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190℃, 2.16kg) was prepared.

[0178] 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 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.

[0179] 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 1.01. At this time, the zero shear viscosity was measured in the same way as in Example 1.

[0180] 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 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°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.

[0181] [Comparative Example 1] Preparation of a biodegradable resin composition

[0182] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190℃, 2.16kg) was prepared.

[0183] 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 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.

[0184] 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.

[0185] 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°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.

[0186] [Comparative Example 2] Preparation of a biodegradable resin composition

[0187] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190℃, 2.16kg) was prepared.

[0188] 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 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.

[0189] 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.

[0190] 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 with 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.

[0191] [Comparative Example 3] Preparation of a biodegradable resin composition

[0192] As for polylactic acid resin, Total Corbion product (density 1.24 g / cm³) 3 , melt index (3g / 10min at 190℃, 2.16kg) was prepared.

[0193] 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 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.

[0194] 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 0.48. At this time, the zero shear viscosity was measured in the same way as in Example 1.

[0195] 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 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.

[0196] [Experimental Example 1] Measurement of Crystallinity of PBAT and PLA

[0197] In order to measure the degree of crystallization of the polybutylene adipate terephthalate resin and polylactic acid resin included in the biodegradable resin compositions of Examples 1 to 5 and Comparative Examples 1 to 3 prepared above, a blown film with a thickness of about 50±5 μm was first prepared using the resin composition. Specifically, the pellets obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were extruded using a single screw extruder (Blown Film M / C, 19 pi, L / D=25) to produce a blown film with a thickness of about 50±5 μm under conditions of extrusion temperature: about 145℃, expansion ratio (Blown-Up Ratio): about 1.5, and linear speed: 5 m / min to 10 m / min.

[0198] The degree of crystallinity of polybutylene adipate terephthalate and polylactic acid contained in the films prepared in each example and comparative example was measured using a Differential Scanning Calorimeter (DSC, device name: DSC 2500, manufacturer: TA instrument). Specifically, the blown films prepared above were cut to a size of 3 mm × 3 mm in width × length. A cycle was performed in which the film specimens of each example or comparative example were heated from 20°C to 220°C at a rate of 10°C / min, maintained at 220°C for 1 minute, cooled to -20°C at a rate of 10°C / min, and then heated again from -20°C to 220°C at a rate of 10°C / min. For the heating curve appearing during the second heating process, a new baseline was established to ensure that the curve is smoothly connected at temperatures before and after melting, from the onset of the endothermic peak to the end of the peak, and the melting peak, which is the highest endothermic peak, was obtained. The heat of fusion (△Hf) of polybutylene adipate terephthalate and polylactic acid, respectively, was calculated by integrating the area of ​​the melting peak. Based on the heat of fusion of a resin having 100% crystallinity, the crystallinity (X1) of polybutylene adipate terephthalate and the crystallinity (X2) of polylactic acid contained in the film were calculated according to the following mathematical formula 1.

[0199] [Mathematical Formula 1]

[0200] Degree of Crystallinity (%) = (△Hf / △H0) × 100

[0201] The results were as shown in Table 1 below.

[0202] X1 (%) X2 (%) Example 17.5 11 Example 27 8 Example 38 12 Example 47.5 18 Example 58.5 15 Comparative Example 110 7.5 Comparative Example 210 11 Comparative Example 35.5 23

[0203] In Table 1 above, it was confirmed that the degree of crystallization (X1) of polybutylene adipate terephthalate included in the biodegradable resin compositions of Examples 1 to 5 according to the present invention is 5% or more and 9% or less, and the degree of crystallization (X2) of polylactic acid (PLA) is 7% or more and 20% or less.

[0204] On the other hand, it was confirmed that the degree of crystallization (X1) of polybutylene adipate terephthalate included in the biodegradable resin composition of Comparative Examples 1 to 3 was greater than 9%, or the degree of crystallization (X2) of polylactic acid (PLA) was greater than 20%.

[0205] [Experimental Example 2] Evaluation of Mechanical Properties

[0206] In order to evaluate the mechanical properties 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 1, and the following properties were evaluated.

[0207] 1) Drop impact according to ASTM D 17409-040,

[0208] 2) The sum of the tensile strength in the MD direction and the tensile strength in the TD direction according to ISO 527 standards,

[0209] 3) The sum of the tear strength in the MD direction and the tear strength in the TD direction according to ISO 6383-2 standards,

[0210] 4) Sum of the MD direction modulus and the TD direction modulus according to ISO 527 standards

[0211] The results were as shown in Table 2 below.

[0212] Sum of drop impact (g / 0.05mm film) and tensile strength (kgf / cm²) 2 Sum of tear strengths (N / cm) Sum of moduli (kgf / cm) 2Example 1 47854926835149 Example 2 45460526535617 Example 3 42055028296184 Example 4 38061424725944 Example 5 40261922555905 Comparative Example 1 27952024455272 Comparative Example 2 37953525585835 Comparative Example 3 26750323086305

[0213] As shown in Table 2 above, the films prepared from the resin compositions of Examples 1 to 5 according to the present invention have a drop impact strength of 380 g / 0.05 mm or higher and a total tensile strength of 549 kgf / cm² 2 The above is true, the total tear strength is 2255 N / cm or greater, and the total modulus is 5149 kgf / cm 2 In summary, it demonstrated excellent results in impact strength, tensile strength, tear strength, and modulus, exhibiting outstanding strength and flexibility.

[0214] On the other hand, films produced from resin compositions (Comparative Examples 1 to 3) in which the degree of crystallization of polybutylene adipate terephthalate or polylactic acid falls outside the scope of the present invention showed performance similar to the examples in terms of tear strength and modulus, but were found to be inferior compared to the examples in terms of impact strength and tensile strength. In particular, in the case of Comparative Examples 1 and 3, it was found that they were very weak against impact because the drop impact values ​​were small.

[0215] [Experimental Example 3] Evaluation of Appearance Characteristics

[0216] 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.

[0217] The results were as shown in Table 3 below.

[0218] Appearance Wave Gloss (GU) Example 1 OK 9.38 Example 2 OK 8.9 Example 3 OK 7.78 Example 4 OK 8.67 Example 5 OK 9.54 Comparative Example 1 NG 6.79 Comparative Example 2 OK 10.99 Comparative Example 3 NG 5.99

[0219] As shown in Table 3 above, it was confirmed that the film produced from the resin compositions of Examples 1 to 5 according to the present invention satisfies a 20° gloss (Gloss) of 7 to 9.8 GU, and corresponds to an ultra-low gloss product that can prevent problems such as increased light reflection and scattering, and has a low likelihood of contamination caused by fingerprints, dust, etc. on the surface.

[0220] On the other hand, on the surface of the film prepared from the resin composition (Comparative Examples 1 to 4) in which the degree of crystallization 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.

[0221] As can be confirmed from the above experiments, the resin composition according to the present invention, which includes polybutylene adipate terephthalate and polylactic acid as the main resin, not only exhibits excellent biodegradability but also possesses various mechanical properties such as impact resistance, mechanical strength, and dimensional stability, and in terms of appearance, it was found to exhibit excellent gloss without surface defects.

Claims

1. A biodegradable resin composition comprising polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA), wherein A biodegradable resin composition in which the degree of crystallization (X1) of polybutylene adipate terephthalate, measured by differential scanning calorimetry (DSC) for a film prepared from the above resin composition, satisfies the following Equation 1, and the degree of crystallization (X2) of polylactic acid satisfies the following Equation 2: [Equation 1] 5 % ≤ X1 ≤ 9 % [Equation 2] 7 % ≤ X2 ≤ 20 % 2. In Paragraph 1, The above 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.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

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

10. In Paragraph 9, The above biodegradable resin composition comprises 6 to 35 parts by weight of an inorganic filler based on 100 parts by weight of the mixed resin of polybutylene adipate terephthalate and polylactic acid.

11. In Paragraph 9, 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.

12. A biodegradable film comprising polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA), A biodegradable film in which, when measured by differential scanning calorimetry (DSC) with respect to the film, the degree of crystallization (X1) of polybutylene adipate terephthalate satisfies Equation 1 below and the degree of crystallization (X2) of polylactic acid satisfies Equation 2 below: [Equation 1] 5 % ≤ X1 ≤ 9 % [Equation 2] 7 % ≤ X2 ≤ 20 % 13. In Paragraph 12, The above biodegradable film is a biodegradable film satisfying at least one of 1) to 5) below: 1) The sum of the MD tensile strength and TD tensile strength of the biodegradable film is 540 kgf / cm² 2 Up to 700 kgf / cm² 2 ; 2) The sum of the MD tearing strength and TD tearing strength of the biodegradable film is 2200 N / cm to 2900 N / cm; 3) Drop impact of biodegradable film of 350g or more; 4) The sum of the MD modulus and TD modulus of the biodegradable film is 5000 kgf / cm² 2 Up to 6500 kgf / cm² 2 ; 5) The 20° gloss of the biodegradable film is 7 GU to 9.8 GU 14. In Paragraph 12, A biodegradable film having a thickness of 10 to 200 μm.

15. A biodegradable article comprising a biodegradable resin composition according to any one of claims 1 to 11.