Biodegradable composition and biodegradable film

Abstract

The present invention provides: a biodegradable composition comprising a polybutylene adipate terephthalate and a polybutylene adipate terephthalate in which a maleic acid is ester-bonded to a terminal hydroxyl group; and a biodegradable film.

Description

Biodegradable compositions and biodegradable films

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

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0177649, filed December 8, 2023, and Korean Patent Application No. 10-2024-0179459, filed December 5, 2024, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a biodegradable composition and a biodegradable film.

[0004] With the recent surge in interest in environmental protection and eco-friendliness, the need for eco-friendly agricultural production methods is growing. One such eco-friendly farming method is mulching, which involves covering the soil surface with mulching film to prevent weed growth, prevent pests and diseases, maintain soil moisture and temperature, prevent soil erosion during rain, and reduce pesticide use.

[0005] Mulching films used in these mulching methods significantly contribute to agricultural productivity, but their collection and recycling pose challenges. While synthetic resins like polypropylene and polyethylene are typically used and biodegradable ingredients are added as additives to enhance biodegradability, the synthetic resin itself is not biodegradable. Furthermore, any synthetic resin that remains unused can contaminate the soil.

[0006] There have been attempts to manufacture mulching films using the biodegradable plastic polybutylene adipate terephthalate (PBAT). However, while PBAT has high elongation, its mechanical properties, such as Young's modulus, are lower than those of conventional films such as polyethylene. Furthermore, because PBAT is 100% petroleum-based, its bio-based content is low.

[0007] Accordingly, attempts have been made to improve the physical properties and increase the bio-raw material content by compounding various biodegradable materials into polybutylene adipate terephthalate (PBAT), but there is a problem that the tensile properties are low due to low compatibility between polybutylene adipate terephthalate and other biodegradable materials.

[0008] The present invention provides a biodegradable composition having excellent biodegradability, compatibility and thermal diffusivity, and a biodegradable film manufactured from the composition having excellent biodegradability and mechanical properties such as tensile strength and having an increased content of bio-raw materials.

[0009] According to one embodiment of the present invention, a biodegradable composition is provided, which comprises polybutylene adipate terephthalate and polybutylene adipate terephthalate having maleic acid ester-bonded to a terminal hydroxyl group, wherein the polybutylene adipate terephthalate having maleic acid ester-bonded to a terminal hydroxyl group contains maleic acid in an amount of 2.0 wt% or more and 5.0 wt% or less.

[0010] In addition, according to another embodiment of the present invention, a biodegradable film is provided, which comprises polybutylene adipate terephthalate and polybutylene adipate terephthalate having maleic acid ester-bonded to a terminal hydroxyl group, wherein the polybutylene adipate terephthalate having maleic acid ester-bonded to a terminal hydroxyl group contains maleic acid in an amount of 2.0 wt% or more and 5.0 wt% or less.

[0011] Hereinafter, a biodegradable composition and a biodegradable film according to specific embodiments of the invention will be described in more detail.

[0012] Unless otherwise specified throughout this specification, the terms “include” or “comprising” refer to the inclusion of a component (or component) without limitation, and cannot be construed as excluding the addition of other components (or components).

[0013] In addition, unless otherwise stated herein, the weight average molecular weight of polybutylene adipate terephthalate, polybutylene adipate terephthalate in which maleic acid is ester-bonded to the terminal hydroxyl group, etc. can be measured using gel permeation chromatography (GPC). Specifically, the prepolymer or copolymer is dissolved in chloroform to a concentration of 2 mg / ml, 20 μl is injected into GPC, and GPC analysis is performed at 40°C. At this time, chloroform is used as the mobile phase of GPC, and it is introduced at a flow rate of 1.0 mL / min, two Agilent Mixed-B columns are used in series, and an RI Detector is used as the detector. The Mw value is derived using a calibration curve formed using a polystyrene standard sample. Nine weight-average molecular weights of polystyrene standard specimens were used: 2,000 g / mol, 10,000 g / mol, 30,000 g / mol, 70,000 g / mol, 200,000 g / mol, 700,000 g / mol, 2,000,000 g / mol, 4,000,000 g / mol, and 10,000,000 g / mol.

[0014]

[0015] In order to prepare a composition for producing a biodegradable film, another biodegradable material, such as thermoplastic starch, can be compounded into polybutylene adipate terephthalate. However, since polybutylene adipate terephthalate is hydrophobic while thermoplastic starch is hydrophilic, there is a problem that polybutylene adipate terephthalate and thermoplastic starch do not mix well, resulting in poor compatibility.

[0016] Accordingly, the inventors of the present invention have found that when a 'polybutylene adipate terephthalate in which maleic acid is ester-bonded to a terminal hydroxyl group' containing a predetermined amount of maleic acid as a compatibilizer is used in a biodegradable composition containing polybutylene adipate terephthalate, compatibility is improved, and the mechanical properties such as tensile strength of a biodegradable film manufactured from such a composition are improved, thereby completing the present invention.

[0017] In addition, the biodegradable composition containing the polybutylene adipate terephthalate has the advantages of being economical because the price is low, biodegradability is improved, and the content of bio-based carbon is increased as the content of thermoplastic starch in the biodegradable composition increases. By using 'polybutylene adipate terephthalate in which maleic acid is ester-bonded to a terminal hydroxyl group' as a compatibilizer in the biodegradable composition, the above-described effects can be exhibited by including a large amount of the thermoplastic starch.

[0018]

[0019] According to one embodiment of the invention, a biodegradable composition is provided, which comprises polybutylene adipate terephthalate and polybutylene adipate terephthalate having maleic acid ester-bonded to a terminal hydroxyl group, wherein the polybutylene adipate terephthalate having maleic acid ester-bonded to a terminal hydroxyl group contains maleic acid in an amount of 2.0 wt% or more and 5.0 wt% or less.

[0020] For example, the polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxy group at the terminal may contain maleic acid in an amount of 2.2 wt% or more, 2.4 wt% or more, 2.5 wt% or more, 2.7 wt% or more, 2.9 wt% or more, 3.0 wt% or more, and 4.8 wt% or less, 4.6 wt% or less, 4.5 wt% or less, 4.3 wt% or less, 4.1 wt% or less, or 4.0 wt% or less, based on 100 wt% of the polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxy group at the terminal.

[0021] If the polybutylene adipate terephthalate having maleic acid ester-bonded to the hydroxyl group at the terminal contains too little maleic acid, the compatibility of the biodegradable composition including the polybutylene adipate terephthalate having maleic acid ester-bonded to the hydroxyl group at the terminal may be reduced. The compatibility of the biodegradable composition can be evaluated by measuring the specific surface area, which is a factor of the extent to which the composition recovers when the strain is increased and then decreased again. The smaller the specific surface area, the better the distribution of the dispersed phase to the continuous phase included in the composition, and thus the better the compatibility. On the other hand, if the polybutylene adipate terephthalate having maleic acid ester-bonded to the hydroxyl group at the terminal contains too little maleic acid, the non-recovery area may be high, which may reduce the compatibility.

[0022] In addition, if the polybutylene adipate terephthalate in which maleic acid is ester-bonded to the terminal hydroxyl group contains too much maleic acid, the thermal diffusivity of the biodegradable composition may decrease, which may result in poor formability and / or processability, and high process operation costs. Specifically, in the process of manufacturing a film by reaction extrusion of a biodegradable composition, the compound discharged from the extruder is cooled by passing through a cooling tank and then cut (pelletized). However, in the case of a biodegradable composition including polybutylene adipate terephthalate in which maleic acid is ester-bonded to the terminal hydroxyl group containing too much maleic acid, the thermal diffusivity is low, which slows down the cooling speed of the compound discharged from the extruder, making cutting difficult. Accordingly, there is a problem that the formability and / or processability may decrease, or the process operation cost may increase as additional cooling equipment is required.

[0023]

[0024] The above-mentioned 'polybutylene adipate terephthalate having maleic acid ester-bonded to the hydroxyl group at the terminal' can be used as a compatibilizer that improves the compatibility of biodegradable compositions. In addition, the 'polybutylene adipate terephthalate having maleic acid ester-bonded to the hydroxyl group at the terminal' can act as a chain extender to increase molecular weight, increase melt viscosity, and improve moldability such as extensibility.

[0025] The above 'polybutylene adipate terephthalate having maleic acid ester-bonded to the terminal hydroxyl group' can be produced by an ester reaction of maleic acid to the terminal hydroxyl group of polybutylene adipate terephthalate. For example, the polybutylene adipate terephthalate having maleic acid ester-bonded to the terminal hydroxyl group can be represented by the following chemical formula 1 or 2.

[0026] [Chemical Formula 1]

[0027]

[0028] [Chemical Formula 2]

[0029]

[0030] In the above chemical formulas 1 and 2,

[0031] a to d can each independently be an integer from 1 to 500, 5 to 450, 10 to 400, or 20 to 300.

[0032] The 'polybutylene adipate terephthalate having maleic acid ester-bonded to a terminal hydroxyl group' represented by the above chemical formula 1 may be an ester-bonded product through an ester reaction between one carboxyl group contained in maleic acid and a terminal hydroxyl group of polybutylene adipate terephthalate. In addition, the 'polybutylene adipate terephthalate having maleic acid ester-bonded to a terminal hydroxyl group' represented by the above chemical formula 2 may be an ester-bonded product through an ester reaction between each of the two carboxyl groups contained in maleic acid and a terminal hydroxyl group of another polybutylene adipate terephthalate.

[0033]

[0034] Polybutylene adipate terephthalate having maleic acid ester-bonded to the hydroxyl group at the terminal can be manufactured by esterifying maleic acid and polybutylene adipate terephthalate as described above. By controlling the content of maleic acid, the content of polybutylene adipate terephthalate, the reaction temperature, the reaction time, the type and content of the additive, etc., polybutylene adipate terephthalate having maleic acid ester-bonded to the hydroxyl group at the terminal can be manufactured, and the weight average molecular weight, structure, viscosity, etc. of polybutylene adipate terephthalate having maleic acid ester-bonded to the hydroxyl group at the terminal can be controlled.

[0035] Meanwhile, in the past, there were cases where a compatibilizer was used in which maleic anhydride was graft-bonded to polybutylene adipate terephthalate, but the grafting reaction efficiency was low due to the difficulty in generating a radical in the middle of the polybutylene adipate terephthalate chain or steric hindrance, whereas the polybutylene adipate terephthalate in which the maleic anhydride was ester-bonded has the advantage of significantly high reaction efficiency.

[0036] In addition, when using a 'compatibility agent in which maleic anhydride is grafted onto polybutylene adipate terephthalate' instead of 'polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal' in the biodegradable composition and biodegradable film, there are problems in that additional process operations and long process operation times are required to manufacture a compatibilizer with low reaction efficiency, resulting in high manufacturing costs, and that work must be done with care for environmental safety as a highly toxic radical initiator must be used.

[0037]

[0038] The polybutylene adipate terephthalate having maleic acid ester-bonded to the hydroxyl group at the terminal may have a weight average molecular weight of 50,000 or more and 200,000 or less, 70,000 or more and 190,000 or less, 90,000 or more and 180,000 or less, 100,000 or more and 170,000 or less, or 120,000 or more and 160,000 or less. If the polybutylene adipate terephthalate having maleic acid ester-bonded to the hydroxyl group at the terminal does not satisfy the above-described range in weight average molecular weight, the effect of improving compatibility may not be exhibited, and thus the mechanical properties such as tensile strength of a film manufactured from the composition may deteriorate.

[0039] In addition, it is preferable that the polybutylene adipate terephthalate having maleic acid ester-bonded to the hydroxyl group at the terminal has a weight average molecular weight smaller than the polybutylene adipate terephthalate included in the biodegradable film according to the above embodiment, and for example, the weight average molecular weight of the polybutylene adipate terephthalate having maleic acid ester-bonded to the hydroxyl group at the terminal may be 0.9 times or less than the weight average molecular weight of the polybutylene adipate terephthalate. For example, the weight average molecular weight of the polybutylene adipate terephthalate having maleic acid ester-bonded to the hydroxyl group at the terminal may be 0.4 times or more and 0.8 times or less, 0.5 times or more and 0.7 times or less, or 0.5 times or more and 0.6 times or less than the weight average molecular weight of the polybutylene adipate terephthalate.

[0040] In addition, when manufacturing a film by reaction extrusion of the biodegradable composition according to the above embodiment, it is preferable that the polybutylene adipate terephthalate in which maleic acid is ester-bonded to the terminal hydroxyl group at the process temperature has a lower viscosity than other components, such as polybutylene adipate terephthalate and thermoplastic starch. When the polybutylene adipate terephthalate in which maleic acid is ester-bonded to the terminal hydroxyl group as a compatibilizer has a lower viscosity than other components, the polybutylene adipate terephthalate can have excellent fluidity during extrusion and be well distributed at the interface between the polybutylene adipate terephthalate and thermoplastic starch, thereby improving compatibility.

[0041] For example, polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal may have a viscosity of 1,000 Pa.s or more and 5,000 Pa.s or less at a temperature of 120°C to 180°C, 130°C to 170°C, 140°C to 160°C, or 150°C. For example, the viscosity may be 1,300 Pa.s or more, 1,600 Pa.s or more, 1,800 Pa.s or more, 2,000 Pa.s or more, 2,100 Pa.s or more, 2,200 Pa.s or more, and 4,800 Pa.s or less, 4,600 Pa.s or less, or 4,400 Pa.s or less.

[0042] If the viscosity of polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal is excessively high, the effect of improving compatibility may not be achieved, and thus the mechanical properties, such as tensile strength, of a film manufactured from the composition may deteriorate. In addition, if the viscosity of polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal is excessively low, the thermal diffusivity of the biodegradable composition may be reduced, resulting in poor formability and / or processability and increased process operation costs.

[0043] In the biodegradable composition according to the above embodiment, the polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxy group at the terminal may be included in an amount of 0.5 wt% or more and 10.0 wt% or less, based on 100 wt% of the total solid content of the biodegradable composition. For example, the polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxy group at the terminal may be included in an amount of 0.7 wt% or more, 0.9 wt% or more, 1.0 wt% or more, 2.0 wt% or more, and may be included in an amount of 9.0 wt% or less, 7.0 wt% or less, 6.0 wt% or less, or 5.0 wt% or less, based on 100 wt% of the total solid content of the biodegradable composition. If the amount of polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal is too small, the compatibility improvement effect may not be achieved, and thus the mechanical properties, such as tensile strength, of the film manufactured from the composition may deteriorate. If the amount of polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal is too large, the melt viscosity may excessively increase, and thus the formability may deteriorate.

[0044]

[0045] The biodegradable composition according to the above embodiment may include polybutylene adipate terephthalate (PBAT) as a biodegradable resin. The polybutylene adipate terephthalate may be included in an amount of 30 to 80 wt% based on 100 wt% of the total biodegradable solid content, and more specifically, may be included in an amount of 30 wt% or more, 35 wt% or more, 40 wt% or more, 80 wt% or less, 75 wt% or less, or 70 wt% or less. If the polybutylene adipate terephthalate (PBAT) is included in the biodegradable composition in an excessively small amount, the elongation of a film manufactured therefrom may be lowered, and if the polybutylene adipate terephthalate is included in an excessively large amount, the tensile properties such as Young's modulus and yield tensile strength of a film manufactured therefrom may be lowered.

[0046]

[0047] In addition, the biodegradable composition may include thermoplastic starch to improve the processability of polybutylene adipate terephthalate and to accelerate the biodegradation rate. The thermoplastic starch may be a starch that is a natural polymer and to which a plasticizer is added so that it can be thermoplastic and can freely change shape even at a certain temperature or higher without being carbonized, unlike conventional general-purpose resins such as polyethylene, polystyrene, and polypropylene.

[0048] The thermoplastic starch may include at least one selected from the group consisting of rice starch, wheat starch, corn starch, sweet potato starch, potato starch, tapioca starch, cassava starch, and modified starches thereof.

[0049] In addition, the plasticizer contained in the natural polymer starch may be at least one selected from the group consisting of isosorbide, glycerol, sorbitol, fructose, formamide, xylitol, corn oil, and edible oil. The plasticizer may be contained in an amount of 5 wt% to 50 wt%, 10 wt% to 45 wt%, or 15 wt% to 35 wt%, based on 100 wt% of the total thermoplastic starch.

[0050] The biodegradable composition according to the above embodiment may contain the thermoplastic starch in an amount of 10 wt% or more and 50 wt% or less, based on 100 wt% of the total solid content of the biodegradable composition. For example, the thermoplastic starch may be contained in an amount of 10 wt% or more, 15 wt% or more, 20 wt% or more, or 25 wt% or more, and may be contained in an amount of 45 wt% or less, 40 wt% or less, or 35 wt% or less, based on 100 wt% of the total solid content of the biodegradable composition. As the content of thermoplastic starch in the biodegradable composition increases, the price becomes cheaper and more economical, biodegradability improves, and the content of bio-based carbon can increase. However, if the thermoplastic starch is included in an excessive amount in the biodegradable composition, the elongation of the film manufactured from it may decrease, and if the thermoplastic starch is included in an excessive amount in the biodegradable composition, the biodegradation rate may be slowed and the tensile properties such as Young's modulus and yield tensile strength of the film manufactured from it may decrease.

[0051]

[0052] The biodegradable composition according to the above embodiment may include hydrophobic polybutylene adipate terephthalate and hydrophilic thermoplastic starch, and the compatibility thereof is improved when the dispersed phase of thermoplastic starch is dispersed on the polybutylene adipate terephthalate matrix, and the more densely and uniformly the dispersed phase of thermoplastic starch is distributed, the better the compatibility is. In addition, the compatibility is improved when the adhesive force at the interface between the polybutylene adipate terephthalate and the thermoplastic starch is stronger. That is, the compatibility is improved when the dispersed phase of thermoplastic starch is densely and uniformly distributed on the polybutylene adipate terephthalate matrix, and the compatibility is improved when the adhesive force at the interface between the polybutylene adipate terephthalate and the thermoplastic starch is stronger.

[0053] In addition, whether compatibility is improved can be numerically confirmed through analysis using a dynamic mechanical analyzer (DMA) device. For example, whether compatibility is improved can be confirmed by measuring the glass transition temperature (Tg) of thermoplastic starch and polybutylene adipate terephthalate using a dynamic mechanical analyzer (DMA) device.

[0054] Specifically, the more densely and uniformly the thermoplastic starch dispersion is distributed on the polybutylene adipate terephthalate matrix, the lower the glass transition temperature (Tg) of the thermoplastic starch. By analyzing the glass transition temperature of this thermoplastic starch using a polymer viscoelasticity analyzer, it is possible to determine whether compatibility is improved. In addition, the stronger the adhesive force at the interface between polybutylene adipate terephthalate and thermoplastic starch, the more effectively the thermoplastic starch dispersion transfers stress to polybutylene adipate terephthalate, thereby increasing the glass transition temperature (Tg) of polybutylene adipate terephthalate, especially the glass transition temperature (Tg) of the butylene-adipate repeating unit, which is the soft segment. By analyzing the glass transition temperature of this polybutylene adipate terephthalate using a polymer viscoelasticity analyzer, it is possible to determine whether compatibility is improved.

[0055] Accordingly, the better the compatibility between polybutylene adipate terephthalate and thermoplastic starch, the lower the glass transition temperature (Tg) of the thermoplastic starch. For example, the thermoplastic starch may have a glass transition temperature (Tg) of 10°C to 140°C, 15°C to 120°C, 20°C to 100°C, 25°C to 80°C, 25°C to 50°C, or 25°C to 40°C.

[0056] In addition, as the compatibility between polybutylene adipate terephthalate and thermoplastic starch is better, the glass transition temperature (Tg) of polybutylene adipate terephthalate increases. For example, the glass transition temperature (Tg) of polybutylene adipate terephthalate may be -23.0°C or more and -10.0°C or less, or -22.5°C or more and -15.0°C or less.

[0057] In addition, the absolute value of the difference in glass transition temperature (Tg) of the thermoplastic starch and polybutylene adipate terephthalate may be 20°C or more and 70°C or less, 25°C or more and 65°C or less, 30°C or more and 60°C or less, or 35°C or more and 59°C or less.

[0058] In addition, the biodegradable composition has a thermal diffusivity of 0.2700 mm as measured by ISO Standard 22007-2. 2 / s or more 10.000 mm 2 / s may be less than 0.2750 mm 2 / s or more, 0.2800 mm 2 / s or more, 0.2850 mm 2 / s or more, 0.2900 mm 2 / s or more, 0.2950 mm 2 / s or more, or 8.000 mm 2 / s or less, 6.000 mm 2 / s or less, 4.000 mm 2 / s or less, 3.000 mm 2 / s or less, 1.000 mm 2 / s or less. If the thermal diffusivity is excessively low, the cooling rate of the compound discharged from the extruder may be slow, making cutting difficult, which may compromise formability and / or processability, or the process operation cost may increase due to the need for additional cooling equipment, and if the thermal diffusivity is excessively high, compatibility may be reduced.

[0059]

[0060] According to another embodiment of the present invention, a biodegradable film is provided, comprising polybutylene adipate terephthalate; and polybutylene adipate terephthalate having maleic acid ester-bonded to a terminal hydroxyl group, wherein the polybutylene adipate terephthalate having maleic acid ester-bonded to a terminal hydroxyl group contains maleic acid in an amount of 2.0 wt% or more and 5.0 wt% or less.

[0061] The method for manufacturing the above biodegradable film is not particularly limited, but can be obtained by a conventional film manufacturing method such as an inflation method, a tubular method, or a T-die casting method, using the biodegradable composition according to the above embodiment. For example, the composition can be pelletized, and the pellets can be dried at 60 to 100°C for 6 hours or more to control the moisture content to 1,200 ppm or less, 500 ppm or less, or 200 ppm or less. Thereafter, the pelletized composite can be applied to a release film, and then placed in a thermocompression machine and pressure can be applied to manufacture a film. At this time, the temperature can be 130 to 250°C, 150 to 220°C, or 160 to 200°C, and the pressure can be 5 MPa to 20 MPa, 8 MPa to 17 MPa, or 10 MPa to 15 MPa.

[0062] Accordingly, the biodegradable film may contain the same composition as described above in the biodegradable composition. For example, the biodegradable film may contain the polybutylene adipate terephthalate, the thermoplastic starch, and the polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal. In addition, the maleic acid content, molecular weight, structure, etc. of the polybutylene adipate terephthalate, the thermoplastic starch, and the polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal are as described above. For example, the weight average molecular weight of the polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal may be 0.01 to 0.30 times the weight average molecular weight of the polybutylene adipate terephthalate. In addition, the biodegradable film may contain 0.5 wt% or more and 10.0 wt% or less of polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal, based on 100 wt% of the total biodegradable film. For example, the biodegradable film may contain 0.7 wt% or more, 0.9 wt% or more, 1.0 wt% or more, 2.0 wt% or more of polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal, based on 100 wt% of the total biodegradable film, and may contain 9.0 wt% or less, 7.0 wt% or less, 6.0 wt% or less, 5.0 wt% or less.

[0063] The thermoplastic starch may be included in an amount of 10 wt% or more and 50 wt% or less based on 100 wt% of the biodegradable film. For example, the thermoplastic starch may be included in an amount of 10 wt% or more, 15 wt% or more, 20 wt% or more, or 25 wt% or more based on 100 wt% of the total biodegradable film, and may be included in an amount of 45 wt% or less, 40 wt% or less, or 35 wt% or less.

[0064] The thickness of the biodegradable film may be 10 to 300 μm, and more specifically, may be 10 μm or more, 13 μm or more, 15 μm or more, 20 μm or more, 20 μm or more, 25 μm or more, or 300 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 80 μm or less, or 50 μm or less. Since the thickness of the film is within the above-described range, the film has strong elasticity, excellent handling properties, and can have good roll winding and unwinding properties.

[0065] If the film thickness is too thin, the tensile strength, tear strength, and elongation may deteriorate, causing holes or tears to form in the film during use. If the film thickness is too thick, the unit price competitiveness may decrease. In addition, the biodegradable film can be used as an agricultural mulching film, disposable gloves, medical individual packaging, food packaging, garbage bags, or various industrial product sacks.

[0066] The biodegradable film according to the above embodiment may have a tensile strength of 5 MPa or more, 7 MPa or more, 8 MPa or more, or 5 MPa to 30 MPa as measured according to ASTM D882-07.

[0067] Additionally, the biodegradable film may have an elongation at break of 300% or greater, 350% or greater, 400% or greater, 420% or greater, 430% or greater, or 300% to 700% as measured according to ASTM D882-07.

[0068] Additionally, the biodegradable film may have a Young's Modulus measured according to ASTM D882-07 of 30 MPa or more, 40 MPa or more, 50 MPa or more, 60 MPa or more, or 30 MPa to 800 MPa.

[0069] The maximum tensile strength, elongation at break, and Young's modulus of the biodegradable film measured in the MD (Machine Direction) and TD (Transverse Direction) directions can satisfy the numerical ranges described above, respectively.

[0070] According to the present invention, a biodegradable composition having excellent biodegradability, compatibility and thermal diffusivity, and a biodegradable film manufactured using the composition having excellent biodegradability and mechanical properties such as tensile strength and having an increased content of bio-raw materials can be provided.

[0071] The invention is described in more detail in 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.

[0072]

[0073] Manufacturing Example 1: Manufacturing of thermoplastic starch

[0074] 700 g of corn starch and 300 g of glycerol, based on dry weight, were mixed in a mixer and then placed in an extruder for compounding. The temperature of the extruder was set to 120°C, the screw speed was set to 150 rpm, and the extruded strands were cut with a pelletizer to produce thermoplastic starch pellets.

[0075]

[0076] <Examples and Comparative Examples>

[0077] Example 1

[0078] (1) Manufacturing of polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal.

[0079] 100 g of polybutylene adipate terephthalate (PBAT, Solpol 1000N, SOLTECH) and 2 g of maleic anhydride were placed in an internal mixer and reacted while mixing for 10 minutes at 160°C and 50 rpm to produce polybutylene adipate terephthalate (weight average molecular weight; 140,000, viscosity measured at 150°C and 0.1 rad / s of 4339.54 Pa.s) in which maleic acid is ester-bonded to the hydroxyl group at the terminal.

[0080] (2) Manufacturing of biodegradable compositions and films

[0081] A composition was prepared by hand mixing 750 g of polybutylene adipate terephthalate (PBAT, Solpol 1000N, SOLTECH Co.) based on dry weight, 250 g of the thermoplastic starch prepared in Manufacturing Example 1, and 50 g of the 'polybutylene adipate terephthalate in which maleic acid is ester-bonded to a terminal hydroxyl group'.

[0082] Afterwards, it was put into an extruder and compounded. The temperature range of the extruder was set to 150 ℃, the screw speed was set to 200 rpm, and the extruded strand was cut with a pelletizer to manufacture composite pellets.

[0083]

[0084] Example 2

[0085] (1) Manufacturing of polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal.

[0086] 100 g of polybutylene adipate terephthalate (PBAT, Solpol 1000N, SOLTECH) and 2.5 g of maleic anhydride were added to an internal mixer and reacted while mixing for 10 minutes at 160°C and 50 rpm to produce polybutylene adipate terephthalate (weight average molecular weight; 136,000, viscosity measured at 150°C and 0.1 rad / s of 3966.75 Pa.s) in which maleic acid is ester-bonded to the hydroxyl group at the terminal.

[0087] (2) Manufacturing of biodegradable compositions and films

[0088] A composition was prepared by hand mixing 750 g of polybutylene adipate terephthalate (PBAT, Solpol 1000N, SOLTECH Co.) based on dry weight, 250 g of the thermoplastic starch prepared in Manufacturing Example 1, and 50 g of the 'polybutylene adipate terephthalate in which maleic acid is ester-bonded to a terminal hydroxyl group'.

[0089] Afterwards, it was put into an extruder and compounded. The temperature range of the extruder was set to 150 ℃, the screw speed was set to 200 rpm, and the extruded strand was cut with a pelletizer to manufacture composite pellets.

[0090]

[0091] Example 3

[0092] (1) Manufacturing of polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal.

[0093] 100 g of polybutylene adipate terephthalate (PBAT, Solpol 1000N, SOLTECH) and 3 g of maleic anhydride were placed in an internal mixer and reacted while mixing for 10 minutes at 160°C and 50 rpm to produce polybutylene adipate terephthalate (weight average molecular weight; 133,000, viscosity measured at 150°C and 0.1 rad / s of 3594.68 Pa.s) in which maleic acid is ester-bonded to the hydroxyl group at the terminal.

[0094] (2) Manufacturing of biodegradable compositions and films

[0095] A composition was prepared by hand mixing 750 g of polybutylene adipate terephthalate (PBAT, Solpol 1000N, SOLTECH Co.) based on dry weight, 250 g of the thermoplastic starch prepared in Manufacturing Example 1, and 50 g of the 'polybutylene adipate terephthalate in which maleic acid is ester-bonded to a terminal hydroxyl group'.

[0096] Afterwards, it was put into an extruder and compounded. The temperature range of the extruder was set to 150 ℃, the screw speed was set to 50 rpm, and the extruded strand was cut with a pelletizer to manufacture composite pellets.

[0097]

[0098] Example 4

[0099] (1) Manufacturing of polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal.

[0100] 100 g of polybutylene adipate terephthalate (PBAT, Solpol 1000N, SOLTECH) and 4 g of maleic anhydride were added to an internal mixer and reacted while mixing for 10 minutes at 160°C and 50 rpm to produce polybutylene adipate terephthalate (weight average molecular weight; 133,000, viscosity measured at 150°C and 0.1 rad / s of 2738.74 Pa.s) in which maleic acid is ester-bonded to the hydroxyl group at the terminal.

[0101] (2) Manufacturing of biodegradable compositions and films

[0102] A composition was prepared by hand mixing 750 g of polybutylene adipate terephthalate (PBAT, Solpol 1000N, SOLTECH Co.) based on dry weight, 250 g of the thermoplastic starch prepared in Manufacturing Example 1, and 50 g of the 'polybutylene adipate terephthalate in which maleic acid is ester-bonded to a terminal hydroxyl group'.

[0103] Afterwards, it was put into an extruder and compounded. The temperature range of the extruder was set to 150 ℃, the screw speed was set to 200 rpm, and the extruded strand was cut with a pelletizer to manufacture composite pellets.

[0104]

[0105] Example 5

[0106] (1) Manufacturing of polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal.

[0107] 100 g of polybutylene adipate terephthalate (PBAT, Solpol 1000N, SOLTECH) and 5 g of maleic anhydride were placed in an internal mixer and reacted while mixing for 10 minutes at 160°C and 50 rpm to produce polybutylene adipate terephthalate (weight average molecular weight; 135,000, viscosity measured at 150°C and 0.1 rad / s of 2269.52 Pa.s) in which maleic acid is ester-bonded to the hydroxyl group at the terminal.

[0108] (2) Manufacturing of biodegradable compositions and films

[0109] A composition was prepared by hand mixing 750 g of polybutylene adipate terephthalate (PBAT, Solpol 1000N, SOLTECH Co.) based on dry weight, 250 g of the thermoplastic starch prepared in Manufacturing Example 1, and 50 g of the 'polybutylene adipate terephthalate in which maleic acid is ester-bonded to a terminal hydroxyl group'.

[0110] Afterwards, it was put into an extruder and compounded. The temperature range of the extruder was set to 150 ℃, the screw speed was set to 200 rpm, and the extruded strand was cut with a pelletizer to manufacture composite pellets.

[0111]

[0112] Comparative Example 1

[0113] (1) Manufacturing of polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal.

[0114] 100 g of polybutylene adipate terephthalate (PBAT, Solpol 1000N, SOLTECH) and 1 g of maleic anhydride were placed in an internal mixer and reacted while mixing for 10 minutes at 160°C and 50 rpm to produce polybutylene adipate terephthalate (weight average molecular weight; 137,000, viscosity measured at 150°C and 0.1 rad / s of 5589.34 Pa.s) in which maleic acid is ester-bonded to the hydroxyl group at the terminal.

[0115] (2) Manufacturing of biodegradable compositions and films

[0116] A composition was prepared by hand mixing 750 g of polybutylene adipate terephthalate (PBAT, Solpol 1000N, SOLTECH Co.) based on dry weight, 250 g of the thermoplastic starch prepared in Manufacturing Example 1, and 50 g of the 'polybutylene adipate terephthalate in which maleic acid is ester-bonded to a terminal hydroxyl group'.

[0117] Afterwards, it was put into an extruder and compounded. The temperature range of the extruder was set to 150 ℃, the screw speed was set to 200 rpm, and the extruded strand was cut with a pelletizer to manufacture composite pellets.

[0118]

[0119] Comparative Example 2

[0120] A composition was prepared in the same manner as in Comparative Example 1, except that 6 g of maleic anhydride was used instead of 1 g of maleic anhydride.

[0121]

[0122] evaluation

[0123] 1. Evaluation of commerciality (non-recoverable area)

[0124] The compatibility of the compositions of the examples and comparative examples was evaluated, and the compatibility was evaluated by measuring the specific surface area of ​​the compositions. Specifically, the compositions were placed on a parallel plate geometry of a 25 mm diameter DHR (Discovery hybrid rheometer) device of TA Instruments, melted, and loaded by pressing so that the gap became 1 mm. The storage modulus was measured while increasing the strain from 0.01% to 75% and then decreasing it to 0.01% at 150°C and a frequency of 1 Hz. The difference between the area of ​​the storage modulus from strain 0.01% to 75% and the area of ​​the storage modulus from strain 75% to 0.01% is the non-recoverable area.

[0125] Here, the area of ​​the storage modulus refers to the area under the line graph with strain as the x-axis and the storage modulus as the y-axis. In addition, the non-recoverable area is a factor that determines the extent to which the composition recovers when the strain is increased and then decreased again. The smaller the non-recoverable area, the better the distribution of the dispersed phase to the continuous phase included in the composition, and thus the better the compatibility.

[0126]

[0127] 2. Thermal diffusivity measurement

[0128] The thermal conductivity of the compositions of the examples and comparative examples was measured using a TPS 2200 thermal diffusivity meter from Hot Disk Instrument according to ISO Standard 22007-2.

[0129]

[0130] 3. Tensile properties evaluation

[0131] The pellets of the examples and comparative examples were blown into films having a thickness of 15 μm at 150°C using a film blown unit (BL50T) from Collin, and the tensile properties of the films were evaluated according to ASTM D882-07. The tensile properties include tensile strength, elongation at break, and Young's modulus in the machine direction (MD), and the results are shown in Table 1 below.

[0132]

[0133] Thermal diffusivity (non-recoverable area) (mm) 2 / s)Tensile strength (MPa)Elongation at break (%)Young's modulus (MPa)Example 145680.860619.0332.457.7Example 246710.612219.1339.558.0Example 343270.462721.3363.359.1Example 441880.338422.8386.459.9Example 537190.295224.0415.561.6Comparative example 150591.125617.2317.656.4Comparative example 234150.263324.5467.362.1

[0134] According to Table 1 above, Examples 1 to 4 including polybutylene adipate terephthalate in which maleic acid is ester-bonded to a terminal hydroxyl group and which contains 2.0 wt% or more and 5.0 wt% or less of maleic acid have excellent compatibility compared to Comparative Example 1 using 1.0 wt% of maleic acid. On the other hand, Comparative Example 2 using 6.0 wt% of maleic acid has a significantly low thermal diffusivity, which slows down the cooling rate of the compound discharged from the extruder, making it difficult to cut into pellets.

Claims

1. Polybutylene adipate terephthalate; and Contains polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal; A biodegradable composition comprising polybutylene adipate terephthalate having maleic acid ester-bonded to a hydroxyl group at the terminal, wherein the polybutylene adipate terephthalate contains 2.0 wt% or more and 5.0 wt% or less of maleic acid.

2. In paragraph 1, A biodegradable composition comprising polybutylene adipate terephthalate having a maleic acid ester bonded to a hydroxyl group at the terminal, and having a viscosity of 1,000 Pa.s or more and 5,000 Pa.s or less.

3. In paragraph 1, A biodegradable composition comprising 0.5 wt% or more and 10.0 wt% or less of polybutylene adipate terephthalate in which maleic acid is ester-bonded to a hydroxyl group at the terminal, based on 100 wt% of the total solid content of the biodegradable composition.

4. In paragraph 1, A biodegradable composition, wherein polybutylene adipate terephthalate having maleic acid ester-bonded to the hydroxyl group at the terminal is represented by the following chemical formula 1 or 2: [Chemical Formula 1] [Chemical formula 2] In the above chemical formulas 1 and 2, a to d are each independently integers from 1 to 500.

5. In paragraph 1, A biodegradable composition further comprising thermoplastic starch.

6. In paragraph 5, A biodegradable composition, wherein the thermoplastic starch comprises at least one selected from the group consisting of rice starch, wheat starch, corn starch, sweet potato starch, potato starch, tapioca starch, cassava starch, and modified starches thereof.

7. In paragraph 5, A biodegradable composition comprising 10 wt% or more and 50 wt% or less of the thermoplastic starch relative to 100 wt% of the total solid content of the biodegradable composition.

8. In paragraph 5, The above thermoplastic starch is a biodegradable composition having a glass transition temperature (Tg) of 10°C or more and 140°C or less.

9. In paragraph 5, A biodegradable composition, wherein the absolute value of the difference between the glass transition temperatures (Tg) of the thermoplastic starch and polybutylene adipate terephthalate is 20°C or more and 70°C or less.

10. In paragraph 1, The above biodegradable composition has a thermal diffusivity of 0.2700 mm as measured by ISO Standard 22007-2. 2 / s more than 10,000 mm 2 / s or less, biodegradable composition.

11. Polybutylene adipate terephthalate; and Contains polybutylene adipate terephthalate in which maleic acid is ester-bonded to the hydroxyl group at the terminal; A biodegradable film, wherein polybutylene adipate terephthalate, in which maleic acid is ester-bonded to a hydroxyl group at the terminal, contains 2.0 wt% or more and 5.0 wt% or less of maleic acid.

12. In paragraph 11, A biodegradable film comprising 0.5 wt% or more and 10.0 wt% or less of polybutylene adipate terephthalate in which maleic acid is ester-bonded to a hydroxyl group at the terminal, based on 100 wt% of the total biodegradable film.

13. In paragraph 11, A biodegradable film further comprising thermoplastic starch.

14. In paragraph 11, The above biodegradable film is a biodegradable film having a tensile strength of 5 MPa or more as measured according to ASTM D882-07.

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