WO2007073109A1

WO2007073109A1 - Biodegradable resin composition and plastic product made thereof

Info

Publication number: WO2007073109A1
Application number: PCT/KR2006/005642
Authority: WO
Inventors: Wan Pyo Hong
Original assignee: Wan Pyo Hong
Priority date: 2005-12-23
Filing date: 2006-12-22
Publication date: 2007-06-28
Also published as: KR100739369B1; KR20070066992A

Abstract

Disclosed is a biodegradable resin composition, which is biodegraded by microorganisms and naturally degraded by oxidation. Specifically, the biodegradable resin composition contains chitosan waste powder processed from industrial waste remaining after extracting chitosan, instead of containing chitosan extract. Also, because the composition contains recycled industrial waste, it can provide a reduction of at least 30% in production cost, and thus it is possible to construct a mass production system for biodegradable plastic products and films, which are prepared using the composition.

Description

BIODEGRADABLE RESIN COMPOSITION AND PLASTIC

PRODUCT MADE THEREOF

Technical Field

[1] The present invention relates to a biodegradable resin, and more particularly to a biodegradable resin composition, which contains, as a natural polymer substance, chitosan waste powder processed from industrial waste remaining after extracting chitosan, instead of containing chitosan extract, and thus has excellent biodegradability, low cost, and excellent mechanical and thermal properties and is biodegraded in nature without causing hazardous substances. Background Art

[2] Recently, from the viewpoint of prevention of environmental pollution caused by plastic wastes, many kinds of biodegradable plastics or films have been studied in main research institutes or enterprises in all countries of the world, and some thereof have entered a practical use stage.

[3] Generally, commercial biodegradable polymer resins broadly include chemically synthesized biodegradable resins and naturally occurring polymer substances, which are expensive.

[4] The chemically synthesized biodegradable resins most typically include aliphatic polyester biodegradable resins. Although the chemically synthesized biodegradable resins have biodegradability, the price thereof is about 6-7 times as high as that of general use plastics such as polyethylene. Thus, in view of not only environment friendliness, but also business, the price of the biodegradable polymers should be reduced to the price of the existing plastics.

[5] However, the chemically synthesized biodegradable resins have problems to be overcome in practical use, despite many efforts which have been made. Specifically, these biodegradable resins are not promising due to various problems, including low mechanical properties and thermal properties, a biodegradability lower than that of natural polymer substances, and a production cost, which is at least 7-8 times as high as that of the existing general purpose resins due to high raw material cost, even though they can be produced in large quantities.

[6] Among the natural polymer substances, those promising for use as resin materials are divided into 3-4 categories. They are broadly divided, according to production sources, into microorganism-derived polymers PHB (polyhydroxybutyrate) and PHV (polyhydroxy valerate), plant-derived polymers starch and lignin, and animal-derived polymer chitin-chitosan. [7] The greatest advantages of these natural polymers are that they have very excellent biodegradability and do not cause hazardous substances unlike the case of the synthetic polymers, and mostly have very excellent mechanical and thermal properties.

[8] In brief, with respect to the degradation mechanism of degradable resins containing such natural polymers, the natural polymers are first degraded by microorganisms in soil to form fine pores, the carbon-carbon bonds of the resins are then broken by auto- oxidants, and ultimately, the resins are completely degraded into water and carbon dioxide, so that they are reduced to nature.

[9] However, most of these natural polymers have problems in that it is not easy to construct a mass production system, their processability is low compared to the existing synthesized resins, and the diversity of physical properties and the flexibility of improvement in physical properties are insufficient for coping with various applications. Thus, these natural polymers cannot be easily used.

[10] Among such natural polymers, natural polymers such as starch and chitosan have been studied and some thereof are already commercialized. Starch is advantageous in terms of cost, but has reduced workability or physical properties, and chitosan is expensive, but has good formability or physical properties.

[11] Chitosan is a deacetylated product of chitin (C H NO ) , an abundant natural glucosamine polysaccharide found in the ecosystem. In particular, chitin is found in the shells of crustaceans, such as crabs, lobsters and shrimp. The compound is also found in the exoskeletons of marine zooplankton, in the wings of certain insects, such as butterflies and ladybugs, and in the cell wall of yeasts, mushrooms and other fungi.

[12] On the structural level, chitosan is predominantly poly glucosamine, and is generally prepared by the alkaline hydrolysis of chitin. The degree of deacetylation normally ranges from 70-98%. The deacetylated amino groups, at a pH below about 6 are protonated, and therefore are responsible for positive charges, which make the chitosan polymer soluble in water. This characteristic also leads to high positive charge density in the chitosan compound.

[13] Also, chitosan can be solubilized by acid hydrolysis of chitin and used as a polymer material. Currently, it is used as a medium for medical drugs, or a support, and receives a lot of attention for use as polymer resin, because the component thereof is a polymer.

[14] However, this class of chitosan, which is currently used, employs only some of the functionalities of chitosan, including biocompatibility or degradability, and does not use excellent mechanical performance of chitosan. The reason is that, although films or molded articles prepared from chitosan, which is a cellulose polymer derivative having a high molecular weight ranging from hundreds of thousands to millions, have very excellent physical properties compared to the existing synthesized polymer substances, chitosan has no melting point, is dissolved only in an acidic aqueous solution, and furthermore, does not show good solubility even in an acetic acid aqueous solution, which is a unique solvent for chitosan. For this reason, chitosan is used only in the form of powder obtained by the deacetylation of natural chitin, or in the form of films or fibers, and is impossible to use in other forms, particularly in the form of structural materials.

Disclosure of Invention Technical Problem

[15] Accordingly, the present invention has been made in order to solve the above-desc ribed problems occurring in the prior art, and it is an object of the present invention to provide a large quantity of biodegradable resin, which contains, as a natural polymer substance, chitosan waste powder processed from industrial waste remaining after extracting chitosan, instead of chitosan extract, and thus has low cost and excellent physical properties and biodegradability.

[16] Another object of the present invention is to provide a biodegradable resin composition comprising chitosan waste powder compounded with resin.

[17] Still another object of the present invention is to provide a plastic product made of biodegradable resin, which generates little or no hazardous substance and has excellent mechanical and thermal properties. Technical Solution

[18] To achieve the above objects, the present invention provides a biodegradable resin composition, which is biodegraded by microorganisms and naturally degraded by oxidation, the composition comprising, based on 100 parts by weight of resin, 1-50 parts by weight of chitosan waste powder and 0.001-30 parts by weight of an additives.

[19] The resin composition according to the present invention preferably further comprises, based on 100 parts by weight of the resin, 1-60 parts by weight of calcium carbonate and 1-20 parts by weight of titanium dioxide.

[20] The resin is preferably one or more selected from the group consisting of polyvinyl acetate (PVAC), polystyrene (PS), unsaturated polyester (UP), polymethyl methacrylate (PMMA), polyurethane (PUR), polyvinyl chloride (PVC), phenol resin (PF), polyvinylidene chloride (PVDC), urea resin (UF), ABS resin, melamine resin (MF), SAN, SBS, nylon, ASA, EPS, IPA, ALPHALAC, alcohol, epoxy resin, polyethylene (PE), polypropylene (PP), high isotactic polypropylene (HIPP), butene random polypropylene, and high-melt- strength polypropylene(HMSPP).

[21] The additive preferably includes at least one selected from among a heat stabilizer, a UV stabilizer and an auto-oxidant.

[22] The heat stabilizer is preferably one or more selected from the group consisting of zinc (Zn)-based, cadmium (Cd)-based, barium-cadmium-based, barium - cadmium- zinc-based, tin or organo-tin complex-based, calcium- zinc-based, zinc-sulfur (Zn-S)-based, zinc- strontium (Zn-St)-based, lead-strontium (Pb-St)-based, barium strontium (Ba-St)-based, and calcium- strontium (Ca-St)-based heat stabilizers.

[23] The UV stabilizer is preferably one or more selected from the group consisting of hydroxybenzophenone-based, hydroxyphenylbenzotriazole-based, and hindered amine- based UV stabilizers.

[24] The auto-oxidant is preferably one or more selected from the group consisting of oleic acid, linoleic acid, linolenic acid, stearic acid, oleic acid ester, linoleic acid ester, linolenic acid ester and stearic acid ester.

[25] In another aspect, the present invention provides a biodegradable plastic product made of said biodegradable resin composition.

[26] The plastic product is preferably a film or a packaging container.

Advantageous Effects

[27] The biodegradable resin composition according to the present invention, and the biodegradable plastic product made thereof, have the following effects.

[28] The biodegradable resin composition according to the present invention can be used as a raw material for plastic products, particularly films and packaging containers. Also, the biodegradable plastic product prepared using the composition can be degraded by microorganisms when it is wasted after use.

[29] The biodegradable resin composition according to the present invention contains chitosan waste powder (including chitosan, chitin, and derivatives thereof) obtained by drying and grinding crustacean sludge as industrial waste. Thus, the resin composition is a natural polymer, which is advantageous in that it has very excellent degradability, does not cause hazardous substances during degradation unlike a synthetic polymer, and shows very excellent mechanical and thermal properties.

[30] The biodegradable resin composition of the present invention contains recycled industrial waste, overcomes the disadvantage of the prior biodegradable resin having a price 1.6-4 times higher than that of the existing synthetic resin, and can provide a reduction of at least 30% in production cost. This makes it possible to construct a mass production system for biodegradable plastic products and films, which are prepared using the composition. As a result, it is possible to greatly reduce environmental pollution.

[31] The biodegradable resin composition of the present invention has excellent formability, low production cost, excellent tensile strength compared to the prior resin due to calcium carbonate contained therein, and particularly a very excellent antibacterial activity of inhibiting the deterioration of food, caused by the proliferation of harmful microbes.

Mode for the Invention

[32] The present inventors have found that natural polymers such as chitosan-chitin have very excellent degradability, do not generate hazardous substances during degradation unlike a synthetic polymer, have very excellent mechanical and thermal properties, but are difficult to use for general applications, because they are highly expensive and it is not easy to construct a system for the mass production of the natural polymers, and that a waste, which is disposed of as industrial waste after preparing chitin/chitosan from crustaceans, still contains a large amount of chitin/chitosan, and, as a result, completing the present invention relating to a biodegradable resin having excellent biodegradability.

[33] Hereinafter, the present invention will be described in further detail with reference to examples. It is to be understood, however, that these examples are illustrative purposes, and the scope of the present invention are not limited thereto.

[34] The inventive biodegradable resin composition, which is biodegraded by microorganisms and naturally degraded by oxidation, comprises chitin/chitosan waste powder, resin and an additive.

[35] In the present invention, in order to develop a biodegradable resin usable in plastic products and films, which have at least the same physical properties as those of the prior products and, at the same time, are completely degraded by soil microorganisms or sunlight when they are disposed of, chitin/chitosan waste powder having excellent degradability compared to starch is used as a natural polymer.

[36] Generally, chitin is a substance contained in the exoskeletons of crustaceans, such as crabs and shrimp, and the cell wall of fungi or higher plants, such as seaweeds, in large amounts, and is a natural polymer substance abundant next to cellulose in nature. It is extracted by treating the exoskeletons of crustaceans, such as crabs and shrimp, with acid and alkali. Also, chitosan is synthesized by deacetylating the extracted chitin with an aqueous sodium hydroxide solution.

[37] In the present invention, waste remaining after extracting chitosan, that is, crustacean sludge (which is disposed of as industrial waste after a chitosan preparation process comprising immersing crustacean exoskeletons in hydrochloric acid to dissolve calcium carbonate, heating the solution together with alkali to remove proteins, and washing and drying the precipitate) is powdered for use in the present invention.

[38] Specifically, the present invention is characterized in that, in order to provide a large amount of biodegradable resin, which is inexpensive and has excellent physical properties and biodegradability, crustacean sludge is used which is disposed of as industrial waste after preparing chitin/chitosan from crustacean exoskeletons.

[39] Herein, crustacean sludge, which is disposed of as industrial waste after preparing chitosan, contains a large amount of water, and thus the crustacean sludge itself cannot be formed into a given shape. For this reason, in a preferred embodiment, the crustacean sludge is naturally dried for 2-5 days or is dried for 30 minutes to 2 hours using a drier to remove more than 95% of water, and the dried material is powdered using known means, such as a grinder or a millstone.

[40] Also, the size of powder particles is preferably in a range from nanometer size to fine particle size approximately equal to the size of wheat flour, such that the particles can be uniformly dispersed and distributed in plastic products and films during the preparation of the plastic products, and the completed plastic products can be easily degraded while maintaining their tensile strength.

[41] Thus, the term chitosan waste powder as used herein should be interpreted as a concept of a mixture, which is obtained by drying and then powdering crustacean sludge and includes a powder of chitosan, chitin and/or derivatives thereof remaining in the crustacean sludge.

[42] The chitosan waste powder prepared as described above is preferably used in an amount of 1-50 parts by weight, and more preferably 25-30 parts by weight, based on 100 parts by weight of the resin. If the chitosan waste powder is used in an amount of more than 50 parts by weight, it will reduce physical properties and lead to a significant increase in production cost, and if it is used in an amount of less than 1 part by weight, biodegradability will be reduced.

[43] Among resins used in the present invention, as thermoplastic resin polyethylene, it is preferable to use high-density polyethylene, low-density polyethylene or linear low- density polyethylene as it is or after it is grafted with α,β-unsaturated carboxylic acids, such as acrylic acid, methylmethacrylic acid and maleic anhydride, in order to increase compatibility with natural polymers, dispers ability and degradability.

[44] Also, HIPP (high isotactic PP) is a polypropylene (PP) having a crystallinity higher than that of existing polypropylene. It has excellent mechanical properties, including high rigidity and high impact resistance.

[45] Butene random polypropylene (PP) is a polypropylene prepared by copolymerizing propylene with butane and has excellent transparency and blocking ability, and low seal temperature.

[46] HMS (high melt strength) PP improves the disadvantage of general PP that is difficult to apply to expansion, vacuum molding and hollow molding processes due to its linear structure. It has significantly increased melt strength due to side chains introduced into PP resin, and thus can be applied even to processes to which general PP is impossible to apply. [47] Also, the biodegradable resin composition of the present invention may further comprise, based on 100 parts by weight of the resin, 1-60 parts by weight of calcium carbonate and 1-20 parts by weight of titanium dioxide, in which the calcium carbonate and the titanium dioxide are used to improve the physical properties of the biodegradable resin.

[48] Specifically, although the biodegradable resin composition, comprising the resin, the chitosan waste powder and the additive, can also have the desired physical properties, it has a problem in that the expression of various colors can be restricted by the coloring effect of the chitosan waste powder, which has a natural brown color. To solve this problem, calcium carbonate and titanium dioxide are used.

[49] In other words, when calcium carbonate and titanium dioxide are added in the above-described amounts to the biodegradable resin composition comprising the chitosan waste powder and the additive, a white biodegradable resin composition, from which the coloring effect of the chitosan waste powder was removed, can be obtained. Thus, various colors can be freely expressed by adding a pigment having the desired color to the white biodegradable resin composition. Accordingly, the design of a product, which can be prepared using the inventive biodegradable resin composition, can be made freer.

[50] Herein, the contents of calcium carbonate and titanium dioxide were determined through a number of repeated experiments, and if they are used in amounts deviating from the above-specified ranges, the desired physical properties cannot be obtained.

[51] Also, to the mixture of the chitosan waste powder and the resin, an additive, such as a stabilizer or an auto-oxidant, is preferably added in an amount of 0.001-30 parts by weight based on 100 parts by weight of the resin.

[52] The additive can be various depending on the intended use of the composition. It is preferable to add a heat stabilizer for preventing the thermal degradation of the resin, or a UV stabilizer for preventing photooxidation caused by UV light.

[53] As the heat stabilizer, it is preferable to use at least one selected from the group consisting of zinc (Zn)-based, cadmium (Cd)-based, barium-cadmium-based, barium- cadmium- zinc-based, tin or organo-tin complex-based, calcium- zinc-based, zinc- sulfide (Zn-S)-based, zinc- strontium (Zn-St)-based, lead- strontium (Pb-St)-based, barium-strontium (Ba-St)-based, and calcium- strontium (Ca-St)-based heat stabilizers.

[54] As the UV stabilizer, it is preferable to use hydroxybenzophenone-based, hydrox- yphenylbenzotriazole-based or hindered amine-based UV stabilizers.

[55] The Pb-St is mainly used in soft/hard products, extruded products, injected products and calendered products and has excellent activity and heat stability. The Ba-St has excellent heat resistance, activity, transparency and processability, and when it is used in combination with Cd or Zn, it has an excellent synergistic effect, eliminates initial coloring and shows extended heat resistance. The Ca-St is used as a lubricant for resin processing, has excellent activity and gel activity, is nontoxic, and is used in nontoxic compounds together with Zn-St. The Zn-St is used as a lubricant for nontoxic products and general olefin resins, is nontoxic, and has initial coloring prevention ability and plate-out prevention ability, but causes zinc burring due to low heat stability.

[56] The auto-oxidant is a substance, which can react with transition metal ions such as iron in soil, and thus can be converted into peroxide or hydroperoxide capable of breaking the carbon-carbon bonds of resin. As the auto-oxidant, it is general to use fatty acid or fatty acid ester, having at least one double bond per molecule.

[57] Said fatty acid or fatty acid ester, which are used as the auto-oxidant, is preferably one or more selected from the group consisting of oleic acid, linoleic acid, linolenic acid, stearic acid, oleic acid ester, linoleic acid ester, linolenic acid ester, and stearic acid ester.

[58] Also, the auto-oxidant is preferably added in an amount of 0.1-20 wt%, and more preferably 0.5-5 wt%, based on the total weight of the additives contained in the biodegradable resin.

[59] In addition, a plasticizer, a sensitizer, a colorant, and calcium oxide, for example, can be added to improve the physical performance of the biodegradable resin.

[60] Also, in the present invention, the biodegradable resin composition, comprising the chitosan resin powder and the additives, can be used to prepare various kinds of plastic products, which are naturally degraded and are reduced to nature when they are disposed of after use. In particular, the plastic products prepared according to the present invention have biodegradability and very excellent tensile strength, and thus include various film products, food containers, agricultural/horticultural containers, and packaging containers for various goods.

[61] Example 1 : Preparation of biodegradable resin 1

[62] First, 80 kg of crab sludge (Kuemho Chemical Product Co., Ltd., Hakgok-ri,

Pyeonghae-eup, Ulgin-gun, Gyongsangbuk-do, Korea) disposed of as industrial waste was naturally dried for 3 days, and 50 kg of the dried crab sludge was ground in the form of powder approximately equal to the size of wheat flour, thus preparing chitosan waste powder.

[63] Then, 37.9 kg of LDPE-722 (LG Chemical Co., Ltd., Korea), 37.9 kg of PP-5107

(LG Chemical Co., Ltd.), 12 kg of the chitosan waste powder and 100 g of Zn-S (Dansuk Industrial Co., Ltd., Korea) were placed in a blender equipped with a highspeed stirrer and were stirred at 1200 rpm for 10 minutes.

[64] If the resin used herein is in the form of pellets, but not powder, it is preferable to added wax in an amount of 10 wt% based on the total weight of the composition and to stir the mixture for at least 40 minutes. [65] Then, the biodegradable resin material blended as described above was placed in a single screw extruder and extruded with heating at 170 ⁰C.

[66] The fluid-type mixture extruded from the single screw extruder was received by a

SUS tray, cooled in air and, at the same time, dried so as to be solidified. The solidified material was ground in the form of lumps having a size of less than 5 mm x 5 mm, thus obtaining biodegradable resin 1. Herein, the biodegradable resin 1 had a brown color, because it was slightly colored by the chitosan waste powder (natural brown color) contained therein.

[67] Example 2: Preparation of biodegradable resin 2

[68] Biodegradable resin 2 was obtained in the same manner as in Example 1, except that 16.75 kg of HDPE 7000F (Honam Petrochemical Corp., Korea), 1.25 kg of the chitosan waste powder, 4.5 kg of calcium carbonate, 1.5 kg of titanium dioxide and 1 kg of Zn-S (Dansuk Industrial Co., Ltd., Korea) were placed in a blender equipped with a high-speed stirrer. The biodegradable resin was white in color.

[69] Example 3: Preparation of biodegradable plastic product

[70] 5 kg of each of the biodegradable resins prepared in Examples 1 and 2 was injected into a pressure molding machine preheated to 24O⁰C, and 100 g of pigment cyanine green was added thereto. Then, each of the resins was molded for 15 seconds under a pressure of 7 Pa (N/m2), thus preparing biodegradable container 1 and biodegradable container 2.

[71] It could be seen that the biodegradable container 2 was well colored with the desired color (green).

[72] Test Example 1 : Evaluation of biodegradabilitv

[73] A sheet sample having a size of 10 cm (L) x 10 cm (W) x 0.2 mm (H) was prepared using each of the biodegradable resin composition 1 and the biodegradable resin composition 2 and buried in farming soil. The change in the shape of the samples, caused by the progression of biodegradation, was observed with the passage of time. It could be seen that, after 6 months, the shape of the samples was completely degraded.

[74] Test Example 2: Evaluation of formabilitv

[75] A mold for food container was mounted in an injection molding machine, and each of the biodegradable resin composition 1 and the biodegradable resin composition 2 was injection-molded in the injection molding machine at 24O⁰C. As a result, the molded products had no defect.

[76] Test Example 3

[77] A food container made of the biodegradable composition 1 (chitosan-containing polypropylene) was tested for physical properties, including densit

[78]

[79] y, tensile strength, elongation at break, flexural strength, and flexural modulus (Korea Testing and Research Institute, Yeongdeungpo-gu, Seoul, Korea). The test results are shown in Table 1 below.

[80] Table 1

[81] * : Test velocity is 50 mm/min, test sample is 2A [82] ** : Test velocity is 0.7mm/min, distance between supports is 26mm. [83] From Table 1, it could be seen that the food container made of the biodegradable composition 1 had physical properties suitable for use as a food container.

[84] Test Example 4 [85] A food container made of the biodegradable composition 2 (chitosan-containing polypropylene) was tested for the contents of lead, cadmium, heavy metals and the like (Korea Testing and Research Institute, Yeongdeungpo-gu, Seoul, Korea). The test results are shown in Table 2 below.

[86] Table 2

[87] From Table 2, it could be seen that the food container made of the biodegradable composition 2 had physical properties suitable for use as a food container.

[88] Although the preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Industrial Applicability

[89] The biodegradable resin composition according to the present invention has very excellent biodegradability, excellent formability, low production cost, and excellent strength compared to prior resins due to edible calcium carbonate contained therein. In particularly, it has a very excellent antibiotic activity of inhibiting the deterioration of food caused by microorganisms.

Claims

[1] A biodegradable resin composition, which is biodegraded by microorganisms and naturally degraded by oxidation, the composition comprising, based on 100 parts by weight of resin, 1-50 parts by weight of chitosan waste powder and 0.001-30 parts by weight of an additive.

[2] The composition of Claim 1, which further comprises, based on 100 parts by weight of the resin, 1-60 parts by weight of calcium carbonate and 1-20 parts by weight of titanium dioxide.

[3] The composition of Claim 1 or 2, wherein the resin is one or more selected from the group consisting of polyvinyl acetate (PVAC), polystyrene (PS), unsaturated polyester (UP), polymethyl methacrylate (PMMA), polyurethane (PUR), polyvinyl chloride (PVC), phenol resin (PF), polyvinylidene chloride (PVDC), urea resin (UF), ABS resin, melamine resin (MF), SAN, SBS, nylon, ASA, EPS, IPA, ALPHALAC, alcohol, epoxy resin, polyethylene (PE), polypropylene (PP), high isotactic polypropylene (HIPP), butene random polypropylene, and high- melt-strength polypropylene(HMSPP).

[4] The composition of Claim 1 or 2, wherein the additive includes one or more selected from among a heat stabilizer, a UV stabilizer and an auto-oxidant.

[5] The composition of Claim 4, wherein the heat stabilizer is one or more selected from the group consisting of zinc (Zn)-based, cadmium (Cd)-based, barium- cadmium-based, barium-cadmium-zinc-based, tin or organo-tin complex-based, calcium-zinc-based, zinc-sulfur (Zn-S)-based, zinc-strontium (Zn-St)-based, lead-strontium (Pb-St)-based, barium-strontium (Ba-st)-based and calcium- strontium (Ca-St)-based heat stabilizers.

[6] The composition of Claim 4, wherein the UV stabilizer is one or more selected from the group consisting of hydroxybenzophenone-based, hydroxyphenylben- zotriazole-based, and hindered amine-based UV stabilizers.

[7] The composition of Claim 4, wherein the auto-oxidant is one or more selected from the group consisting of oleic acid, linoleic acid, linolenic acid, stearic acid, oleic acid ester, linoleic acid ester, linolenic acid ester and stearic acid ester.

[8] A biodegradable plastic product prepared using the biodegradable resin composition of any one of Claims 1 to 7.

[9] The biodegradable plastic product of Claim 8, which is a film or a packaging container.