Thermoplastic starch composition and biodegradable resin composition comprising same

Abstract

The present invention relates to: a thermoplastic starch composition which has improved melt flow characteristics and processability and comprises a modified starch having a controlled molecular weight due to treatment with an acid; and a biodegradable resin composition and a film which have excellent mechanical properties and comprise the thermoplastic starch composition.

Description

Thermoplastic starch composition and biodegradable resin composition comprising the same

[0001] The present invention relates to a thermoplastic starch composition having improved melt flow characteristics and processability, including a modified starch treated with an acid to control the molecular weight, and a biodegradable resin composition and film having excellent mechanical properties, including the same.

[0002] Biodegradable polymers can be categorized into petroleum-derived and bio-derived biodegradable polymers, with relatively high interest in eco-friendly and renewable bio-derived polymers. Polymers that are fully biodegradable in the global environment contain functional groups in their backbone structure that enable microbial decomposition. Among these, polyester polymers are the most widely studied due to their excellent processability and easy control of biodegradation properties. For example, polylactic acid (PLA) is a bio-derived biodegradable polymer synthesized from lactic acid, obtained by fermenting corn starch. It has a global market size of approximately 100,000 tons and is widely used in general plastic applications such as food packaging and containers, and electronic device cases. However, PLA resins have poor formability, mechanical strength, and heat resistance, making thin-film products susceptible to breakage. Furthermore, their low temperature resistance can cause deformation of the molded product when the external temperature increases.

[0003] In addition, polybutylene adipate-co-terephthalate (PBAT), the most widely used petroleum-derived biodegradable polyester polymer, is a copolymer resin containing aliphatic and aromatic groups. Although it has relatively excellent mechanical properties and various processability, it has the disadvantages of low structural strength and high manufacturing cost. In order to improve the low physical properties of the above-mentioned polyester resin and reduce the high manufacturing cost compared to the manufacturing cost of non-biodegradable polymers, various research methods are being proposed to make composite materials by including biomass, an eco-friendly material.

[0004] Accordingly, research has been conducted to reduce costs and improve biodegradability by incorporating starch, a representative plant-based biomass, into biodegradable resins. However, the application of starch to biodegradable resins has generally been limited by its inherent hydrophilicity and reduced processability, resulting in deteriorated physical properties. This limits the amount of starch added, and can lead to lower product quality.

[0005] To solve these problems, there have been various attempts to make composite materials by reacting starch with plasticizers to impart thermoplasticity and mixing it with biodegradable resins. However, these attempts have not yet met the standards of industrial sites.

[0006] Furthermore, natural starch is commonly used as a raw material for thermoplastic starch. However, its high molecular weight and viscosity negatively impact its ability to react with various additives during reactive extrusion, leading to poor processability. Therefore, the development of a starch processing method that can address these issues is urgently needed.

[0007] The purpose of the present invention is to improve melt flowability and processability when producing a thermoplastic starch composition by controlling the molecular weight by treating natural starch with acid.

[0008] Another object of the present invention is to provide a biodegradable resin composition and film with improved mechanical strength manufactured using a thermoplastic starch composition containing acid-treated modified starch.

[0009] One aspect of the present invention provides a thermoplastic starch composition comprising a modified starch having a controlled molecular weight, a plasticizer, a compatibilizer, and a reaction initiator, wherein the modified starch is a starch produced by a hydrolysis reaction of starch with at least one acid selected from hydrochloric acid, sulfuric acid, and acetic acid.

[0010] According to an embodiment, the hydrolysis reaction of the acid and starch can be performed at a molar ratio of acid:starch in the range of 0.9:1 to 5.4:1.

[0011] According to an embodiment, the hydrolysis reaction may be performed at a temperature range of 40°C to 60°C.

[0012] According to an embodiment, the acid hydrolyzed modified starch can gelatinize a starch solution of 8% concentration so that the final viscosity analyzed through Brabender Visco / Amylogram (Germany) can be in the range of 200 to 800 BU.

[0013] According to an embodiment, the starch usable in the thermoplastic starch composition may be at least one selected from the group consisting of corn starch, waxy corn starch, rice starch, potato starch, tapioca starch, wheat starch, sweet potato starch, or modified starches thereof, but is not limited thereto.

[0014] According to an embodiment, the plasticizer usable in the thermoplastic starch composition may be one or more selected from the group consisting of glycerin, ethylene glycol, sorbitol, or pentaerythritol, but is not limited thereto.

[0015] According to an embodiment, the compatibilizer usable in the thermoplastic starch composition may be, but is not limited to, one or more selected from carboxylic acids or carboxylic anhydrides.

[0016] According to an embodiment, in the thermoplastic starch composition, the content of the modified starch may be 70 to 90 wt%, the content of the plasticizer may be 5 to 30 wt%, the content of the compatibilizer may be 0.1 to 1.0 wt%, and the content of the reaction initiator may be 0.01 to 1.0 wt%.

[0017] Another aspect of the present invention provides a biodegradable resin composition comprising 20 to 40 wt% of thermoplastic starch including modified starch having a controlled molecular weight and 60 to 80 wt% of a biodegradable resin.

[0018] Usable biodegradable resins may be one or more selected from the group consisting of polybutylene adipate terephthalate, polylactic acid, polycaprolactone, polybutylene succinate, polyglycolic acid, polyhydroxyalkanoate, polyhydroxybutyrate, copolymers thereof, and mixtures thereof, but are not limited thereto.

[0019] The acid-treated modified starch according to the present invention can provide a thermoplastic starch composition with improved melt flowability and processability by controlling the molecular weight of the starch.

[0020] The acid-treated modified starch according to the present invention can replace natural starch, which is a raw material in the production of thermoplastic starch, and when mixed with a biodegradable resin to produce a composite material, the mechanical strength and durability are improved compared to a resin composition using existing thermoplastic starch, so that it can be applied to various industrial fields.

[0021] The present invention will be described in more detail below with reference to examples. However, the following examples are provided for illustrative purposes only to aid understanding of the present invention and are not intended to limit its scope. It should be understood that the present invention is susceptible to various modifications and implementations in various different forms, and encompasses all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0022] Additionally, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0023] Natural starch is generally used as a raw material for thermoplastic starch. Natural starch is characterized by high molecular weight and high viscosity, which adversely affect its reaction with various additives in reactive extrusion, and its high viscosity results in poor processability. To address these issues, the molecular weight of starch is controlled through acid treatment, thereby improving the melt flowability and processability of a thermoplastic starch composition, and the mechanical strength of a biodegradable resin composition manufactured by mixing thermoplastic starch and a biodegradable resin is improved. The acid-treated modified starch according to the present invention can replace natural starch as a raw material in the manufacture of thermoplastic starch and provide a biodegradable composite material with higher strength than existing thermoplastic starch.

[0024] A thermoplastic starch composition according to one embodiment of the present invention comprises a modified starch having a controlled molecular weight, a plasticizer, a compatibilizer, and a reaction initiator, wherein the modified starch is prepared by a hydrolysis reaction of the starch with at least one acid selected from hydrochloric acid, sulfuric acid, and acetic acid.

[0025] The hydrolysis reaction of starch mainly utilizes hydrochloric acid or sulfuric acid to randomly break α1-4 or α1-6 glycosidic bonds, thereby inducing a decrease in viscosity or molecular weight, which has the advantage of increasing the flexibility and melt flowability of thermoplastic starch due to the shortened molecular chain structure.

[0026] According to one embodiment of the present invention, in the thermoplastic starch composition, the content of the modified starch may be 70 to 90 wt%, the content of the plasticizer may be 5 to 30 wt%, the content of the compatibilizer may be 0.1 to 1.0 wt%, and the content of the reaction initiator may be 0.01 to 1.0 wt%.

[0027] As a specific example, the hydrolysis reaction of acid and starch can be carried out at a molar ratio of acid:starch in the range of 0.9:1 to 5.4:1.

[0028] When the molar ratio of acid:starch is less than 0.9:1, the viscosity during reaction is similar to that of natural starch, making it difficult to control the molecular weight. When the molar ratio exceeds 5.4:1, excessive hydrolysis occurs during reaction, reducing the elongation when applied to a film, and the more polar chain ends produced cause problems in that they promote the penetration of water molecules to the outer surface of the film.

[0029] In addition, the hydrolysis reaction of acid and starch can be carried out in the temperature range of 40°C to 60°C. When reacting at a temperature below 40°C, the reaction efficiency of hydrochloric acid is very low, and when reacting at a temperature exceeding 60°C, starch is gelatinized, making it difficult to manufacture and obtain modified starch.

[0030] The above acid hydrolyzed modified starch gelatinizes starch solution at a concentration of 8% and has a final viscosity of 400 to 800 BU as analyzed by Brabender Visco / Amylogram (Germany), which is reduced in viscosity compared to natural starch, thereby improving melt flowability and processability.

[0031] The starch usable for acid treatment may be, for example, one or more selected from the group consisting of corn starch, waxy corn starch, rice starch, potato starch, tapioca starch, wheat starch, and sweet potato starch, but is not limited thereto.

[0032] Among thermoplastic starch compositions, when modified starch is used in an amount of less than 70 wt%, raw materials other than starch may be used in excess, which increases the cost and makes it uneconomical. When modified starch is used in an amount of more than 90 wt%, some unplasticized starch may remain, which may cause a deterioration in the physical properties when manufacturing thermoplastic starch and biodegradable composite resin.

[0033] The plasticizer usable in the thermoplastic starch composition may be one or more selected from the group consisting of glycerin, ethylene glycol, sorbitol, and pentaerythritol, but is not limited thereto. It is preferable to use the plasticizer in an amount of 1 to 30 wt% based on the total weight of the thermoplastic starch composition. If the content of the plasticizer is less than the above range, a plasticization reaction does not occur, and if it exceeds the content, excessive plasticization occurs, resulting in a problem of a paste-like state.

[0034] The compatibilizer usable in the thermoplastic starch composition may be at least one selected from carboxylic acids or carboxylic anhydrides, for example, maleic anhydride and tartaric acid may be used. It is preferable to use the compatibilizer in an amount of 0.1 to 1.0 wt% based on the total weight of the thermoplastic starch composition.

[0035] Reaction initiators usable in the thermoplastic starch composition include, for example, benzoyl peroxide, acetyl peroxide, dilauryl peroxide, di-t-butyl peroxide, cumyl peroxide, di-t-butyl hydroperoxide, dibenzoyl peroxide, succinic peroxide, dilaurylyl peroxide, didecanoyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, α-cumyl peroxyneodecarbonate, 1,1-dimethyl-3-hydroxybutylperoxy-2-ethylhexanoate, t-amyl peroxybenzoate, t-butyl peroxypivalate, 2,5-dihydroxyperoxy-2,5-dimethylhexane, cumene hydroperoxide or 1,3-bis(t-butylperoxy)hexane. One or more peroxide-based reaction initiators selected from the group consisting of isopropyl)benzene may be used, but is not limited thereto. It is preferable to use the reaction initiator in an amount of 0.01 to 1.0 wt% based on the total weight of the thermoplastic starch composition.

[0036] In the present invention, the thermoplastic starch composition can be manufactured into pellets by extruding using a twin-screw extruder or the like, which is preferable because it provides convenience in processing or manufacturing a product by mixing with a biodegradable resin.

[0037] According to one embodiment of the present invention, a biodegradable resin composition may be prepared by mixing a biodegradable resin after preparing a thermoplastic starch composition including an acid-treated modified starch. The biodegradable resin composition may be prepared by mixing 20 to 40 wt% of the thermoplastic starch composition and 60 to 80 wt% of the biodegradable resin in a mixing ratio.

[0038] The biodegradable resin usable in the biodegradable resin composition may be, for example, one or more selected from the group consisting of polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), polycaprolactone (PCL), polyglycolic acid (PGA), polyhydroxy alkanoate (PHA), polyhydroxybutyrate (PHB), copolymers thereof, and mixtures thereof, but is not limited thereto.

[0039] The biodegradable resin composition may further include a process of mixing a thermoplastic starch composition and a biodegradable resin, extruding the mixture to form pellets, and then feeding the mixture into a film forming machine to form a biodegradable film.

[0040] In the present invention, the molecular weight of starch is reduced through acid treatment, thereby enhancing the reactivity of the thermoplastic starch itself, thereby improving the mechanical strength of a resin composition produced by mixing it with a biodegradable resin. The acid-treated modified starch according to the present invention can replace native starch, a raw material used in the production of thermoplastic starch, and can provide a biodegradable composite material with higher strength than existing thermoplastic starches.

[0041] According to an embodiment, the tensile strength of a compound manufactured using a biodegradable resin composition containing modified starch with controlled molecular weight is 17 to 30 N / mm. 2 The range is , and the elongation can be in the range of 350 to 600 %.

[0042] Another aspect of the present invention provides a biodegradable film manufactured using a biodegradable resin composition comprising modified starch having a controlled molecular weight.

[0043] According to an embodiment, the tensile strength of the biodegradable film is 20 to 30 N / mm. 2 The range is , and the elongation can be in the range of 700 to 900 %.

[0044] In this way, a biodegradable resin composition containing modified starch with controlled molecular weight through acid treatment has improved mechanical strength and excellent durability, and thus can be used in various products such as disposable bags, disposable packaging materials, tablecloths, and mulching films.

[0045] The present invention is described in more detail below through examples and comparative examples, but these are illustrative and should not be construed as limiting the scope of the present invention.

[0046] <Example 1>

[0047] A) Manufacturing of acid-thinning modified starch

[0048] A corn starch suspension (Daesang Corporation) having a starch concentration of 38 wt% was heated to 50°C, hydrochloric acid was added so that the molar ratio of hydrochloric acid:starch was 0.9:1 to 5.4:1, and an acid hydrolysis reaction was induced for 1 to 3 hours. Afterwards, a sodium hydroxide aqueous solution diluted to a concentration of 4 wt% was added, and the pH of the starch suspension was adjusted to 5.0, thereby terminating the hydrolysis reaction by acid treatment. The reaction suspension was filtered, dehydrated, and dried to obtain acid-thinning modified starch.

[0049] B) Preparation of thermoplastic starch composition

[0050] 85 parts by weight of acid-treated modified starch and 15 parts by weight of glycerin were mixed and placed in a mixing mixer. 0.5 phr of maleic anhydride and 0.1 phr of peroxide initiator were added based on the weight of the mixture, and the mixture was stirred in the mixing mixer for 10 minutes.

[0051] The uniformly mixed composition was fed into a twin-screw extruder. The extruder barrel temperature was 135 to 160°C, the main screw speed was 150 rpm, and the raw material feeding speed was 3 rpm. The extrudate was pelletized to produce thermoplastic starch.

[0052] C) Preparation of biodegradable resin composition

[0053] 30 parts by weight of the above thermoplastic starch composition and 70 parts by weight of PBAT were mixed. The uniformly mixed composition was fed into a twin-screw extruder. The extruder barrel temperature was 160°C, the main screw speed was 290 rpm, and the raw material feeding speed was 160°C. The extrudate discharged through the extruder die was water-cooled and pelletized through a water channel. The pellets were dried at 60°C for more than 24 hours to prepare compound specimens.

[0054] In addition, a biodegradable resin composition was introduced into a physical specimen making machine to produce a biodegradable injection molded specimen. The temperature of the physical specimen making machine was 210 to 220°C.

[0055] D) Manufacturing of biodegradable films

[0056] The above biodegradable composition was fed into a film forming machine to produce a biodegradable film with an average thickness of 25-35㎛. The film forming machine temperature was 150 to 170℃, and the raw material feeding speed was 700 to 800 rpm.

[0057] <Example 2>

[0058] A) Manufacturing of acid-thinning modified starch

[0059] A corn starch suspension (Daesang Corporation) having a starch concentration of 38 wt% was heated to 50°C, hydrochloric acid was added so that the molar ratio of hydrochloric acid:starch was 0.9:1 to 5.4:1, and an acid hydrolysis reaction was induced for 1 to 3 hours. Afterwards, a sodium hydroxide aqueous solution diluted to a concentration of 4 wt% was added, and the pH of the starch suspension was adjusted to 5.0, thereby terminating the hydrolysis reaction by acid treatment. The reaction suspension was filtered, dehydrated, and dried to obtain acid-thinning modified starch.

[0060] B) Preparation of thermoplastic starch composition

[0061] 85 parts by weight of acid-treated modified starch and 15 parts by weight of glycerin were mixed and placed in a mixing mixer. 0.3 phr of maleic anhydride, 0.1 phr of peroxide initiator, and 0.2 phr of tartaric acid were added based on the weight of the mixture, and the mixture was stirred in the mixing mixer for 10 minutes.

[0062] The uniformly mixed composition was fed into a twin-screw extruder. The extruder barrel temperature was 135 to 160°C, the main screw speed was 150 rpm, and the raw material input was 40 g / min. The extrudate was pelletized to produce thermoplastic starch.

[0063] c) Preparation of biodegradable resin composition

[0064] 40 parts by weight of the above thermoplastic starch composition and 60 parts by weight of PBAT were mixed. The uniformly mixed composition was fed into a twin-screw extruder. The extruder barrel temperature was 160°C, the main screw speed was 290 rpm, and the raw material feeding speed was 40 g / min. The extrudate discharged through the extruder die was water-cooled and pelletized through a water channel. The pellets were dried at 60°C for more than 24 hours to prepare a compound specimen.

[0065] In addition, a biodegradable resin composition was introduced into a physical specimen making machine to produce a biodegradable injection molded specimen. The temperature of the physical specimen making machine was 210 to 220°C.

[0066] D) Manufacturing of biodegradable films

[0067] The above biodegradable composition was fed into a film forming machine to produce a biodegradable film with an average thickness of 27 μm. The film forming machine temperature was 150 to 170°C, and the raw material feeding speed was 700 to 800 rpm.

[0068] <Comparative Example 1>

[0069] B) Preparation of thermoplastic starch composition

[0070] 85 parts by weight of general corn starch and 15 parts by weight of glycerin were mixed and placed in a mixing mixer, and 0.3 phr of maleic anhydride, 0.1 phr of peroxide initiator, and 0.2 phr of tartaric acid were added based on the weight of the mixture, and then stirred in the mixing mixer for 10 minutes.

[0071] The uniformly mixed composition was fed into a twin-screw extruder. The extruder barrel temperature was 135 to 160°C, the main screw speed was 150 rpm, and the raw material input was 40 g / min. The extrudate was pelletized to produce thermoplastic starch.

[0072] C) Preparation of biodegradable resin composition

[0073] 30 parts by weight of the above thermoplastic starch composition and 70 parts by weight of PBAT were mixed. The uniformly mixed composition was fed into a twin-screw extruder. The extruder barrel temperature was 160°C, the main screw speed was 290 rpm, and the raw material feeding speed was 40 g / min. The extrudate discharged through the extruder die was water-cooled and pelletized through a water channel. The pellets were dried at 60°C for more than 24 hours to prepare compound specimens.

[0074] In addition, a biodegradable resin composition was introduced into a physical specimen making machine to produce a biodegradable injection molded specimen. The temperature of the physical specimen making machine was 210 to 220°C.

[0075] D) Manufacturing of biodegradable films

[0076] The above biodegradable composition was fed into a film forming machine to produce a biodegradable film with an average thickness of 27 μm. The film forming machine temperature was 150 to 170°C, and the raw material feeding speed was 700 to 800 rpm.

[0077] Comparative Example 2

[0078] B) Preparation of thermoplastic starch composition

[0079] 85 parts by weight of general corn starch and 15 parts by weight of glycerin were mixed and placed in a mixing mixer, and 0.5 phr of maleic anhydride and 0.1 phr of a peroxide initiator were added based on the weight of the mixture, and then stirred in the mixing mixer for 10 minutes.

[0080] The uniformly mixed composition was fed into a twin-screw extruder. The extruder barrel temperature was 135 to 160°C, the main screw speed was 150 rpm, and the raw material input was 40 g / min. The extrudate was pelletized to produce thermoplastic starch.

[0081] C) Preparation of biodegradable resin composition

[0082] 40 parts by weight of the above thermoplastic starch composition and 60 parts by weight of PBAT were mixed. The uniformly mixed composition was fed into a twin-screw extruder. The extruder barrel temperature was 160°C, the main screw speed was 290 rpm, and the raw material feeding speed was 40 g / min. The extrudate discharged through the extruder die was water-cooled and pelletized through a water channel. The pellets were dried at 60°C for more than 24 hours to prepare a compound specimen.

[0083] In addition, a biodegradable resin composition was introduced into a physical specimen making machine to produce a biodegradable injection molded specimen. The temperature of the physical specimen making machine was 210 to 220°C.

[0084] D) Manufacturing of biodegradable films

[0085] The above biodegradable composition was fed into a film forming machine to produce a biodegradable film with an average thickness of 27 μm. The film forming machine temperature was 150 to 170°C, and the raw material feeding speed was 700 to 800 rpm.

[0086] < Evaluation example >

[0087] The results of measuring the physical properties of the thermoplastic starch composition and biodegradable resin composition according to the above examples and comparative examples are shown in Tables 1 and 2 below.

[0088] [Starch property evaluation]

[0089] 1) Luxurious viscosity (amylograph)

[0090] Examples and Comparative Examples Starch was suspended in water to prepare a starch slurry having a dry weight concentration of 8 wt%. Brabender amylograph conditions were as follows: heating from 50°C to 95°C at a rate of 3°C per minute, then maintaining the slurry at 95°C for 20 minutes. Then, cooling from 95°C to 50°C at a rate of 3°C per minute, and maintaining the slurry at 50°C for 10 minutes to determine the final viscosity.

[0091] [Evaluation of the properties of injection-molded biodegradable composites]

[0092] 1) Tensile strength property evaluation

[0093] A biodegradable injection molded specimen was manufactured using the manufacturing method of the example, and the tensile strength and elongation were measured using the UTM tensile test method.

[0094] 2) Impact strength property evaluation

[0095] Biodegradable composite specimens were manufactured using the manufacturing method of the example, and the impact strength of each specimen was measured using the Notched IZOD impact test method.

[0096] [Film property evaluation]

[0097] After cutting the biodegradable film manufactured through the manufacturing method of the example to manufacture a specimen according to the standard, the tensile strength and elongation were measured using an Instron tensile tester.

[0098] Comparison Example 1 Example 1 Modification Conditions Acid Treatment Molar Ratio (Acid:Starch) 01.18:1 Reaction Time (h) 038% Final Viscosity (BU, 50℃) 1,156697 MFI (g / 10min, 200℃) 0.01.5 COMPOUND Mixing Ratio TPS3030 PBAT7070 Tensile Strength (MPa) 21.62 4.5 Elongation (%) 399.95 19.2 Film Tensile Strength (MPa) 28.73 4.0 Elongation (%) 875.08 11.5

[0099] Comparison Example 2 Example 2 Modification Conditions Acid Treatment Molar Ratio (Acid:Starch) 01.18:1 Reaction Time (h) 038% Final Viscosity (BU, 50℃) 1,156697 MFI (g / 10min, 200℃) 0.01.5 COMPOUND Mixing Ratio TPS4040 PBAT6060 Tensile Strength (MPa) 13.6 17.3 Elongation (%) 306.0 353.4 Film Tensile Strength (MPa) 19.7 23.2 Elongation (%) 441.5 830.7

[0100] As shown in the above table, it can be confirmed that the processability of the thermoplastic starch composition including the starch having a controlled molecular weight by acid treatment according to Examples 1 and 2 is excellent, and the mechanical properties of the biodegradable resin composition (compound) and biodegradable film manufactured using the same are improved.

Claims

1. A thermoplastic starch composition comprising a modified starch having a controlled molecular weight, a plasticizer, a compatibilizer, and a reaction initiator, wherein the modified starch is a starch produced by a hydrolysis reaction of starch with at least one acid selected from hydrochloric acid, sulfuric acid, and acetic acid.

2. In paragraph 1, A thermoplastic starch composition wherein the hydrolysis reaction of the acid and starch is performed at a molar ratio of acid:starch in the range of 0.9:1 to 5.4:

1.

3. In paragraph 1, A thermoplastic starch composition wherein the above hydrolysis reaction is performed at a temperature range of 40°C to 60°C.

4. In paragraph 1, A thermoplastic starch composition having a viscosity of the modified starch in the range of 200 to 800 BU.

5. In paragraph 1, A thermoplastic starch composition, wherein the plasticizer is at least one selected from the group consisting of glycerin, ethylene glycol, sorbitol, and pentaerythritol.

6. In paragraph 1, A thermoplastic starch composition, wherein the compatibilizer is at least one selected from carboxylic acid or carboxylic anhydride.

7. In paragraph 1, A thermoplastic starch composition wherein the content of the modified starch is 70 to 90 wt%, the content of the plasticizer is 5 to 30 wt%, the content of the compatibilizer is 0.1 to 1.0 wt%, and the content of the reaction initiator is 0.01 to 1.

0.

8. A biodegradable resin composition comprising 20 to 40 wt% of the thermoplastic starch composition according to paragraph 1 and 60 to 80 wt% of a biodegradable resin.

9. In paragraph 8, A biodegradable resin composition, wherein the biodegradable resin is at least one selected from the group consisting of polybutylene adipate terephthalate, polylactic acid, polycaprolactone, polybutylene succinate, polyglycolic acid, polyhydroxyalkanoate, polyhydroxybutyrate, copolymers thereof, and mixtures thereof.

10. A biodegradable film manufactured using the biodegradable resin composition according to Article 8.