KR102658352B1 - Biodegradable multilayer film - Google Patents

Abstract

The present invention relates to a biodegradable film with a multi-layer structure comprising a first layer and a second layer, and specifically, the first layer is a first biodegradable resin containing polybutylene adipate terephthalate (PBAT) 25 to 25. 70wt%; 15 to 60 wt% of first thermoplastic starch; 5 to 20 wt% of a mixture of rice husk and calcium carbonate; and 1 to 20 wt% of an additive containing at least one selected from the group consisting of ester compounds, oxidation accelerators, antioxidants, slip agents, pigments and UV stabilizers, and the second layer is poly. 25 to 70 wt% of a second biodegradable resin comprising lactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), and polypropylene carbonate (PPC); 15 to 60 wt% of second thermoplastic starch; 5 to 20 wt% of a mixture of rice husk ash and calcium carbonate; Illite 3 to 10 wt%; and 1 to 20 wt% of the additive; and a biodegradable film having excellent biodegradability, mechanical properties, deodorizing performance, and antibacterial performance.

Description

Biodegradable multilayer film {BIODEGRADABLE MULTILAYER FILM}

The present invention relates to a biodegradable film, and specifically, to a first layer formed of a composition containing polybutylene adipate terephthalate (PBAT); and a second layer formed of a composition containing polylactic acid (PLA) and illite.

Biodegradable resin refers to a resin that is decomposed into water and carbon dioxide or water and methane gas by microorganisms that exist in nature, such as bacteria, algae, and mold. In general, biodegradable resins are required to decompose by more than 90% compared to cellulose, a standard material, within 6 months under industrial composting conditions. Global standards generally follow EN13432 or ASTM D6400, and in Korea, EL721, EL721, and EL721 depending on the material. It largely follows EL724 or EL727.

Currently, biodegradable film materials are mainly made of poly(butylene adipate terephthalate) (PBAT), but their commercial use is somewhat limited due to their high price. Accordingly, the use of polylactic acid (PLA), the cheapest of the biodegradable resins, is increasing in order to secure price competitiveness against existing polyethylene films. However, polylactic acid itself has low impact strength and heat resistance, and is used as a film. When molded, a problem arises where the manufactured film is easily torn due to lack of stretchability. Accordingly, there is a movement to use a mixture of polybutylene adipate terephthalate and polylactic acid. However, there is a problem that compatibility needs to be improved when mixing protons, and in order to be effective, more than 80% of polybutylene adipate terephthalate must be used, so there is still a problem with price competitiveness.

Biodegradable films are widely used in various industrial fields where existing polyethylene-based and polyester-based films are used. For example, it is used for general packaging or food packaging. In the case of food packaging materials, it is required to exhibit an effect that can inhibit bacterial growth in order to improve food preservation.

Illite is commonly recognized as one of the minerals belonging to the mica group. Compared to muscovite, which is one of the other minerals of the mica family, the tetrahedral Al is relatively small, the water content is high, and some of the interlayer cations K are replaced with Ca ions. It is in the spotlight in many industrial fields because it has various effects such as antibacterial, deodorizing, heavy metal adsorption, pest control, and plant growth promotion. It is especially popular in the agricultural field as a fertilizer because it contains K.

KR 102326756 B1

The present invention provides a multi-functional biodegradable film that has excellent mechanical properties, has excellent biodegradation speed, is inexpensive to manufacture, has antibacterial and deodorizing effects, and can create an environment favorable for strength improvement and recovery by being buried in the soil and decomposing. The purpose is to provide

According to one aspect of the present invention, it is a multi-layered biodegradable film comprising a first layer and a second layer, wherein the first layer is a first biodegradable resin 25 containing polybutylene adipate terephthalate (PBAT). to 40wt%; 40 to 60 wt% of first thermoplastic starch; 5 to 20 wt% of a mixture of rice husk and calcium carbonate; and 1 to 20 wt% of an additive containing at least one selected from the group consisting of ester compounds, oxidation accelerators, antioxidants, slip agents, pigments and UV stabilizers, wherein the second layer is 50 to 70 wt% of a second biodegradable resin comprising polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), and polypropylene carbonate (PPC); 15 to 25 wt% of second thermoplastic starch; 5 to 20 wt% of a mixture of rice husk ash and calcium carbonate; Illite 1 to 10 wt%; A biodegradable film formed of a second composition containing 1 to 20 wt% of the additive may be provided.

Additionally, in the first composition, the calcium carbonate may be surface-modified with at least one selected from the group consisting of acetyl acetonate and benzophenone-based compounds.

Additionally, the calcium carbonate may be manufactured by calcining at least one selected from the group consisting of oyster shells and cockle shells at 300 to 550°C and then pulverizing them to a particle size of 0.5 to 50 μm.

In addition, the rice husk ash may be prepared by first firing rice husk at 300 to 550°C, grinding it to a particle size of 0.5 to 50㎛, and secondary firing at 550 to 700°C.

Additionally, the second composition may further include at least one selected from the group consisting of perlite and deep ocean water.

The biodegradable film according to one aspect of the present invention has excellent mechanical properties and water resistance, so it can be used as a replacement for conventional polyethylene-based films in various industrial fields. At the same time, it has excellent biodegradability, so it is easy to decompose naturally, reducing environmental pollution and being eco-friendly. There are benefits that the product can provide.

In addition, because it has excellent antibacterial, antiviral and deodorizing effects, when applied as a food packaging material, it can improve the preservability of packaged food.

In addition, when it is processed and decomposed in the soil after use, it has the effect of adding compost and has an excellent soil improvement function that can improve soil quality, which has the advantage of improving and restoring soil strength.

In addition, the manufacturing cost is reduced compared to conventional biodegradable films, so productivity can be further improved.

The present invention relates to a biodegradable film with a multilayer structure comprising a first layer and a second layer.

Hereinafter, the present invention will be described in more detail.

Unless otherwise defined, technical and scientific terms used in this specification can be interpreted as commonly understood by a person of ordinary skill in the technical field to which this invention belongs. Additionally, singular expressions include plural expressions unless the context clearly dictates otherwise. In addition, terms such as 'include' or 'have' are intended to designate the presence of features, numbers, steps, components, or a combination thereof described in the specification, but are not intended to indicate the presence of one or more other features, numbers, steps, or components. It should not be understood as excluding the possibility of the presence or addition of elements or combinations thereof.

Additionally, in various embodiments of the present specification, terms such as first, second, and third are used to describe various components, but these components should not be limited by these terms. These terms are merely used to distinguish one component from another. Accordingly, what is referred to as a first component in one embodiment may be referred to as a second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiment.

According to one aspect of the invention, a first layer; And a second layer; a multi-layered biodegradable film including a biodegradable film can be provided. The biodegradable film can be used as packaging material, especially food packaging material. The biodegradable film of a preferred embodiment of the present invention is described as being composed of a double film including a first layer film and a second layer film, but the biodegradable film according to one aspect of the present invention includes the first layer and the second layer film. It is natural that in addition to the second layer, other layers may be added as needed.

The first layer is a first biodegradable resin; a first thermoplastic starch; A mixture of rice husk and calcium carbonate; and additives.

The first biodegradable resin is a soft polymer and refers to a resin that decomposes on its own in a natural environment such as soil. The first biodegradable resin includes poly(butylene adipate terephthalate) (PBAT), and in order to maintain excellent strength and extensibility of the produced film, the polybutylene adipate terephthalate (PBAT) is used. Pate terephthalate is preferably selected with a number average molecular weight (Mn) of 80,000 to 200,000 g/mol.

The first biodegradable resin may be contained in an amount of 25 to 40 wt% based on 100 wt% of the first composition. If the content of the first biodegradable resin in the first composition is less than 25wt%, it is difficult to exhibit physical properties as a synthetic resin, and if it is more than 40wt%, the content of the other components contained in the composition is sufficient to provide a sufficient effect. Because it is difficult to contain, the physical properties of products using the composition may deteriorate and manufacturing costs may increase.

The first thermoplastic starch (TPS) is included to improve the biodegradability and processing properties of the produced film, and to create a soil environment suitable for plant growth by supplying organic matter to the soil after decomposition. The first thermoplastic starch has a melting point (DSC) of 110 to 120°C, a density (at 23°C) of 1.2 to 1.3 g/cm ³ , a melt flow rate of 4 to 5, and a moisture content of 1 to 1 according to Karl Fischer Titration. It is recommended to use one that satisfies the 3% condition. In addition, a breaking load of 30 to 40 MPa according to the ASTM D882 test method, an elongation at break of 375 to 385%, a longitudinal (MD) tear resistance of 55 to 65 N/mm and a transverse direction (TD) tear resistance of 105 according to the ASTM D1922 test method. to 115N/mm, and a water vapor permeation point (38°C 90%ΔRH) of 380 to 410g*30μm/m ² according to the ASTM E96 test method. When the first thermoplastic starch has the above-mentioned physical properties, it can exhibit excellent processability during film processing, and the produced film decomposes at an appropriate rate, which has the advantage of being suitable for functioning as a biodegradable film.

The first thermoplastic starch may be contained in an amount of 40 to 60 wt% based on 100 wt% of the first composition. If the content is less than 40wt%, biodegradability may be reduced and problems may arise where it is difficult to show the effect of improving processability due to addition, and if it is more than 60wt%, the mechanical strength of the produced film may be significantly reduced.

The mixing ratio of the first biodegradable resin and the first thermoplastic starch included in the first composition may be 1:0.95 to 2 by weight, but is not limited thereto. When the mixing ratio of the biodegradable polymer and the thermoplastic starch contained in the first composition is within the above-mentioned range, the advantage is that the produced film exhibits excellent processability, strength, and elongation while decomposing at an appropriate rate that is not too fast. there is.

The mixture of rice husk and calcium carbonate may be added to reduce the manufacturing cost of the first composition and improve strength when manufactured into a film.

The rice husk may be used powdered to a particle size of 100 to 400 μm. If the particle size is greater than 400㎛, problems may arise where processability decreases when processed into a film form and the strength of the manufactured film decreases. The rice husk may be surface-treated with a basic material in order to improve the interfacial bonding force with the resin and increase the strength of the produced film. Preferably, one that has been sequentially surface treated with a basic compound and a silane compound is selected. The basic compound may be, for example, at least one selected from the group consisting of sodium hydroxide, magnesium oxide, calcium oxide, and aluminum oxide, but is not limited thereto. The silane-based compound may be at least one selected from the group consisting of aminosilane and alkylsilane, but is not limited thereto. The surface treatment can be performed by known methods.

The calcium carbonate may be used in powder form with a particle size of 0.5 to 50㎛. If the particle size is less than 0.5㎛, handling is difficult when mixed into the composition, and if it is more than 50㎛, the processability may be reduced when processed into a film type. The calcium carbonate is at least one selected from the group consisting of acetyl acetonate-based compounds and benzophenone-based compounds in order to improve the interfacial bonding force with the resin and increase the strength of the produced film, while improving the decomposability of the first layer. One with surface treatment can be used.

The calcium carbonate may be derived from oyster shells or cockle shells. In detail, the calcium carbonate may be manufactured by calcining at least one selected from the group consisting of oyster shells and cockle shells at 300 to 550°C and then pulverizing them to a particle size of 0.5 to 50㎛. When firing at least one selected from the group consisting of oyster shells and cockle shells, if the firing temperature is less than 300℃, it is difficult to produce calcium carbonate, and if it exceeds 550℃, highly reactive calcium oxide is produced, reducing the suitability for use in food packaging. Problems may arise. When the calcium carbonate is derived from at least one selected from the group consisting of oyster shells and cockle shells, there is an advantage in improving the nature compatibility of the produced biodegradable film and reducing manufacturing costs.

The mixture of rice husk and calcium carbonate may be contained in an amount of 5 to 20 wt%, preferably 5 to 15 wt%, based on 100 wt% of the first composition. If the content is less than 5wt%, it is difficult to achieve the purpose of addition, and if it is more than 20wt%, the softness and processability of the produced film may be reduced. The mixing ratio of the rice husk and the calcium carbonate included in the first composition may be 1:0.8 to 1.2 by weight, but is not limited thereto.

If necessary, the composition may further include additives to improve the physical properties or functionality of the product being manufactured. The additive may be included in an amount of 1 to 20 wt%, preferably 1 to 15 wt%, and more preferably 3 to 8 wt%, based on a total of 100 wt% of the biodegradable resin composition.

The additive may include an ester compound of a long-chain fatty acid with more than 12 carbon atoms and an ester compound of a short-chain fatty acid with less than 6 carbon atoms. At this time, the mixing ratio of the ester compound of long-chain fatty acids and the ester compound of short-chain fatty acids may be 1:0.5 to 0.8. Preferred esters include, but are not limited to, ester compounds of long-chain fatty acids having 14 carbon atoms and ester compounds of short-chain fatty acids having 4 carbon atoms.

The additive may include an autooxidizing agent containing a double bond to improve biodegradability. The auto-oxidizing agent may be at least one selected from the group consisting of ALA (α-Linolenic acid), GLA (γ-Linolenic acid), and unsaturated fatty acids, but is not limited thereto. The unsaturated fatty acid may be at least one selected from the group consisting of oleic acid, linoleic acid, linolenic acid, and palmitoleic acid, but is not limited thereto.

The additive may include an oxidation promoter or antioxidant to adjust the decomposition rate. As the oxidation accelerator, a compound containing a divalent transition metal cation may be used. The transition metal cation may include, but is not limited to, at least one selected from the group consisting of Fe ²⁺ , Co ²⁺ , Ni ²⁺ and Cu ²⁺ . The antioxidant may include at least one selected from the group consisting of phenol-based antioxidants and phosphorus-based antioxidants.

The additive may include a slip agent to improve processability during film production. The slip agent may be at least one selected from the group consisting of calcium stearate, zinc stearate, erucamide, oleamide, and stearamide, but is not limited thereto.

The additive may include pigment. As the pigment, known pigments showing various colors such as black, red, and green can be used.

The additive may include a UV stabilizer. The UV stabilizer may include at least one selected from the group consisting of hydroxy benzophenone, hydroxyphenyl benzotriazole, aryl ester, and oxanilide.

The additive may include a compatibilizer or chain extender to improve resin strength. Monoethanolamine (MEA) may be used as the compatibilizer, but is not limited thereto. The chain extender is at least one selected from the group consisting of methylene diphenyl diisocyanate, hexamethylene diisocyanate, and epoxy-based styrene-acrylic oligomer (multifunctional epoxy-based styrene-acrylic oligomer) may be used, but is not limited to this.

The second layer is a second biodegradable resin; secondary thermoplastic starch; A mixture of rice husk ash and calcium carbonate; illite; and additives. In explaining the second layer, detailed descriptions of parts that overlap with the above-described first layer will be omitted.

The second biodegradable resin is a soft polymer that decomposes on its own in a natural environment such as soil, and has a different composition from the first biodegradable resin. The second biodegradable resin is polylactic acid (PLA), poly(butylene succinate); PBS, and poly(butylene succinate-co-butylene adipate). ; PBSA) and polypropylene carbonate (PPC). In order to maintain excellent processability and stretchability of the produced film, the polylactic acid is selected to have a number average molecular weight (Mn) of 10,000 to 50,000 g/mol, and the polybutylene succinate and the polybutylene Succinate adipate is preferably selected to have a number average molecular weight (Mn) of 80,000 to 200,000 g/mol.

In the second biodegradable resin, polylactic acid, polybutylene succinate, polybutylene succinate adipate, and polypropylene carbonate may be included in a weight ratio of 1:0.5 to 1:0.1 to 0.3:0.1 to 0.3. . Pure polylactic acid resin has excellent tensile strength and processability, but has a problem of being easily torn and damaged due to its very low elongation. However, the second biodegradable resin is polylactic acid, polybutylene succinate, polybutylene succinate adipate, and By including the polypropylene carbonate component in the above content range, there is an advantage of maintaining excellent strength and exhibiting significantly better elongation than pure polylactic acid.

The second biodegradable resin may be contained in an amount of 50 to 70 wt% based on 100 wt% of the second composition. In the second composition, if the content of the second biodegradable resin is less than 50wt%, it is difficult to exhibit physical properties as a synthetic resin, and if it is more than 70wt%, the content of the other components contained in the composition is sufficient to provide a sufficient effect. Because it is difficult to contain, the physical properties of products using the composition may deteriorate and manufacturing costs may increase.

The second thermoplastic starch (TPS) is included to improve the biodegradability and processing properties of the produced film, and to create a soil environment suitable for plant growth by supplying organic matter to the soil after decomposition. The second thermoplastic starch can be used to satisfy the same conditions as the first thermoplastic starch, except for the condition of a moisture content of 4 to 7% according to the Karl Fischer Titration, so a detailed description thereof will be omitted. . The second thermoplastic starch is selected to have a higher moisture content than the first thermoplastic starch, so that the biodegradation rate of the second layer can be adjusted to be faster than that of the first layer.

The second thermoplastic starch may be contained in an amount of 15 to 25 wt% based on 100 wt% of the second composition. If the content is less than 15wt%, biodegradability may be reduced and problems may arise where it is difficult to show the effect of improving processability due to addition, and if it is more than 25wt%, the mechanical strength of the produced film may be significantly reduced.

The mixing ratio of the second biodegradable resin and the second thermoplastic starch included in the second composition may be 1:0.2 to 0.5 by weight, but is not limited thereto. When the mixing ratio of the biodegradable polymer and the thermoplastic starch included in the second composition is within the above-mentioned range, there is an advantage in that the produced film can be decomposed at an appropriate rate considering the period of use.

The mixture of rice husk ash and calcium carbonate may be added to reduce the manufacturing cost of the second composition, improve strength when manufactured as a film, and enhance antibacterial, harmful substance adsorption and deodorization effects. Additionally, as the film biodegrades, it can be added to prevent acidification of the soil and improve soil quality.

The rice husk ash may be obtained by calcining rice husk. The firing treatment may be performed by first firing at 300 to 550°C, then going through a process of controlling the particle size through pulverization, and then performing additional secondary firing at 550 to 700°C. Through this firing, it is possible to obtain rice husk ash containing silicon oxide in high purity. The rice husk ash content can be adjusted to have a particle size of 0.5 to 50 ㎛, preferably 5 to 50 ㎛, and this particle size adjustment is performed between the first and second calcinations. In order to obtain the desired rice husk ash with a high silicon oxide content, it is necessary to sinter at a temperature of 550°C or higher. However, if the processing calcination temperature exceeds 550°C, handling of the resulting rice husk ash becomes rapidly difficult and grinding becomes difficult. may occur. The physical stability of the resin composition is improved by lowering and controlling the porosity and hygroscopicity of the rice husk ash obtained through primary firing through grinding, and then secondary firing is used to control the composition and physical properties, rice husk with optimized applicability for films. Ash can be obtained.

The mixture of rice husk ash and calcium carbonate may be contained in an amount of 5 to 20 wt%, preferably 5 to 15 wt%, based on 100 wt% of the second composition. If the content is less than 5wt%, it is difficult to achieve the purpose of addition, and if it is more than 20wt%, the softness and processability of the produced film may be reduced. The mixing ratio of the rice husk ash and the calcium carbonate included in the second composition may be 1:0.8 to 1.2 by weight, but is not limited thereto.

The illite is included as a filler, which not only reduces the manufacturing cost of resin, but also improves the strength of products such as films made of resin, and has far-infrared ray radiation, harmful substance adsorption and removal, deodorization, antibacterial and antiviral effects. On the other hand, since it contains silicic acid, it can provide an effect of improving mental strength if biodegraded later. Additionally, it can provide the effect of preventing acidification of the soil. The price of illite is 20 to 30% lower than the price of calcium carbonate, which is widely used as a typical filler, and therefore it is included to replace at least a portion of the calcium carbonate contained in the biodegradable resin composition according to one aspect of the present invention. In this case, there is an advantage of increasing productivity by reducing the manufacturing cost of the film being manufactured.

The illite may be added in powder form with a particle size of 0.5 to 50 μm. In addition, it is recommended to use one containing 5 to 10 wt% of potassium oxide (K ₂ O) based on 100 wt% of illite, preferably 5 to 7 wt%.

If necessary, the illite may be added to the biodegradable resin composition according to one aspect of the present invention in a state in which the surface of the illite is treated with additive components for improving performance. At this time, the surface treatment of the additive component to the illite may be performed by a known method, for example, by immersing the illite in a mixture of the additive component for a certain period of time and coating the illite. It may also be performed by spray coating a mixture of added ingredients.

The added ingredient may include at least one selected from the group consisting of fulvic acid and stevia to enhance antibacterial properties. When the added ingredient contains both fulvic acid and stevia, the mixing ratio of the fulvic acid and stevia is preferably 1:0.2 to 1.2 by weight. When the mixing ratio of the fulvic acid and the stevia is within the above-mentioned range, the antibacterial and deodorizing effects of illite surface-treated therewith can be enhanced. The fulvic acid and the stevia can be used for surface treatment of illite in a dissolved state in a solvent. In this case, the solvent is a polar solvent such as water, alcohol with 1 to 4 carbon atoms, and acetone. At least one selected from the group may be used, but it is not limited thereto.

In order to improve the dispersibility of illite in the film and soil improvement properties, the added component may include an amine-based compound. The amine-based compound may be, for example, aminosilane, but is not limited thereto.

The illite may be included in an amount of 1 to 10 wt%, preferably 3 to 10 wt%, based on a total of 100 wt% of the second composition. If the content of illite in the biodegradable resin composition is less than 1 wt%, it is difficult to show the effect of addition, and if it is more than 10 wt%, the manufacturing cost of the produced film may increase and mechanical properties may deteriorate.

The additives included in the second composition may be the same as those included in the first composition. The additive may be included in an amount of 1 to 20 wt%, preferably 1 to 15 wt%, and more preferably 3 to 8 wt%, based on a total of 100 wt% of the biodegradable resin composition.

If necessary, the second composition may further include 1 to 10 wt% of additional additives to improve the soil improvement effect during landfill decomposition. The additional additive may be at least one selected from the group consisting of perlite and deep sea water. The perlite can be added to maximize the effect of improving soil strength, and the deep sea water can be added to replenish mineral components in the soil.

The biodegradable film according to one aspect of the present invention includes the first layer; and the second layer; a film having this structure can be manufactured by co-extruding two or more layers using co-extrusion multilayer casting. The first layer and the second layer may each have a thickness of 3 to 10 μm. The first layer provides high strength, waterproofness, and durability to the film, and the second layer has a relatively higher moisture content, moisture permeability, and biodegradability than the first layer, excellent natural compatibility, and enhanced antibacterial properties. It can provide adsorption and removal of harmful ingredients and deodorizing effects. The biodegradable film according to one aspect of the present invention has the advantage of exhibiting excellent performance that satisfies all mechanical properties, degradability, and functionality through its multi-layer structure. Considering this comprehensive performance, it can be used as a packaging material, especially food packaging. It is suitable to be used as a film for

Hereinafter, more specific and preferred examples are presented to aid understanding of the present invention. However, these examples are merely illustrative of the present invention and do not limit the scope of the appended claims, and are within the scope and technical idea of the present invention. It is obvious to those skilled in the art that various changes and modifications to the embodiments are possible, and it is natural that such changes and modifications fall within the scope of the appended patent claims.

Example

<Manufacture of biodegradable film>

Polybutylene adipate terephthalate, polybutylene succinate, and polybutylene succinate adipate were used with a number average molecular weight of 120,000 g/mol, and polylactic acid was used with a number average molecular weight of 40,000 g/mol.

The thermoplastic starch contained in the first composition has a melting point of 118.5°C, a melt flow rate of 4.5g/10 min, a density (@23°C) of 1.27g/cm ³ , a moisture content of 2%, a breaking load of 35MPa, an elongation at break of 380%, and tear resistance. 60N/mm (MD) and 110N/mm (TD) and water vapor permeability (38℃ 90%ΔRH) of 400g*30μm/m ² were used. The thermoplastic starch contained in the second composition was used with a moisture content of 5%.

Calcium carbonate was prepared by calcining cockle shells at 500°C for 6 hours, pulverizing them, and selecting particles with a particle size of 30㎛ or less through a mesh. A portion of the prepared calcium carbonate was mixed with a solution prepared by stirring benzophenone (0.1 wt%) and stearic acid dissolved in alcohol, and surface treatment was performed using a high-speed kneader. In Table 1 below, calcium carbonate that underwent surface treatment is indicated as calcium carbonate S.

Rice husk pulverized to 300㎛ or less was used. The surface treatment is firstly immersed in an aqueous solution of sodium hydroxide (0.5wt%) for 1 hour and dried, and then secondly immersed in an aqueous solution of aminosilane (3-aminopropyltriethoxysilane; APTES) (0.5wt%) for 30 minutes and dried. It was carried out.

Rice husk ash was prepared by first firing untreated rice husk at 400°C for 4 hours, pulverizing it to less than 30㎛, and secondly firing it at 650°C for 5 hours. For the preparation of comparative examples, some rice husk ash was left in the first firing state without second firing. In Table 1 below, the rice husk ash that underwent only the first firing was classified as 1st, and the rice husk ash that underwent the second firing was classified as 1st. Marked as secondary.

Illite was selected to have a particle size of 5 ㎛ or less and contain 6 wt% of K ₂ O, and surface-treated by immersing it in a mixed aqueous solution of 20 wt % fulvic acid, 10 wt % stevia, and 60 wt % purified water for 2 hours. .

The first composition and the second composition were prepared using the prepared raw materials with the compositions shown in Table 1 below. In Table 1 below, each number means parts by weight. Except for Comparative Examples 1 and 2, each composition was melted and each melted resin composition was extruded through a T-die using two extruders to laminate the two layers to produce a film with a double-layer structure. The thickness of each layer was adjusted to 5㎛ in other examples and comparative examples except Comparative Examples 1 and 2. Comparative Example 1 was a single-layer film using the first composition, and Comparative Example 2 was a single-layer film using the second composition, and the layer thickness was adjusted to 10㎛ to obtain the thickness of the films of all Examples and Comparative Examples. was unified to 10㎛. The size of each film was 1m*1m.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative example 2 Comparative Example 3 Comparative example 4 Composition 1 PBAT 35 35 35 35 35 - 35 35 thermoplastic starch 50 50 50 50 50 - 50 50 chaff 5 5 5 5 5 - 5 5 Calcium Carbonate S 5 - 5 5 5 - 5 5 calcium carbonate - 5 - - - - - - Calcium stearate 2 2 2 2 2 - 2 2 linoleic acid
auto oxidizer 2 2 2 2 2 - 2 2 MEA One One One One One - One One Second composition PLA 30 30 30 30 - 30 20 45 PBS 15 20 15 15 - 15 40 - PBSA 5 5 5 5 - 5 10 5 PPC 5 5 5 5 - 5 10 5 thermoplastic starch 20 15 20 20 - 20 10 25 Rice husk ash (1st) - - 7 - - - - - Rice husk ash (2nd) 7 7 - 7 - 7 One - Calcium Carbonate S 7 - 7 7 - 7 One 14.5 calcium carbonate - 7 - - - - - - Illite S 5.5 5.5 5.5 - - 5.5 2.5 - illite - - - 5.5 - - - - Calcium stearate One One One One - One One One pigment 3 3 3 3 - 3 3 3 MEA One One One One - One One One deep ocean water 0.5 0.5 0.5 0.5 - 0.5 0.5 0.5

<Confirmation of performance of biodegradable film>

A performance confirmation test was performed using the films of Examples and Comparative Examples prepared above.

(1) Check biodegradability

First, the biodegradability of the film was measured. Biodegradability was measured in accordance with the biodegradability measurement method of ISO 14855 and KS M3100-1. The films of the examples and comparative examples prepared above were put into soil mixed with compost and maintained at a humidity of 60%, a temperature of 58±2°C, and a pH of 8.0±1.0. Measurements were performed under the following conditions. After 180 days, the ratio of the biodegradability value of the sample and the biodegradability value of the standard material was calculated and obtained according to Equation 1 below. Tests were performed on three specimens, and the average values are shown in Table 2 below.

(2) Check mechanical properties

Measurements of tensile strength and elongation were performed in accordance with ASTM D882, and the measured results are shown in Table 2 below. Tests were performed on three specimens, and the average values are shown in Table 2 below.

(3) Evaluation of deodorizing power to maintain freshness

After manufacturing plastic bags for food packaging using the films of the above-prepared Examples and Comparative Examples, lettuce was placed in each bag and stored for 7 days. Afterwards, 10 trained panelists (8 women in their 30s, 2 men in their 30s) It was measured and evaluated using a sensory method that allows the subject to smell the inside. It was evaluated on a 5-point scale (the lowest score was 1, the highest was 5), with 1 point being odorless and 5 points being a strong odor that was easily detected. The average value of the sensory evaluation results for each sample was calculated and shown in Table 3 below. The bag was manufactured so that the layer formed from the first composition was on the outside and the layer formed from the second composition was on the inside.

(4) Evaluation of antibacterial activity

For the films of the prepared Examples and Comparative Examples, the bacterial reduction rate against Staphylococcus aureus was measured in accordance with KS M ISO 22196 to evaluate the antibacterial activity, and the measured results are shown in Table 3 below.

Tensile strength (Kgf/cm ² ) Elongation (%) Even if it is biodegradable
(%) TD M.D. TD M.D. Example 1 350 572 658 270 95 Example 2 280 501 622 252 90 Example 3 240 476 606 232 90 Example 4 321 533 628 248 92 Comparative Example 1 380 602 680 342 61 Comparative example 2 102 243 562 212 97 Comparative example 3 252 430 342 173 90 Comparative example 4 308 481 325 172 87

Referring to Table 2, the films of Examples of the present invention were found to have excellent tensile strength, elongation, and biodegradability. In the case of Comparative Example 1, which was formed as a single layer of the first composition, mechanical properties such as strength and elongation were excellent, but biodegradability was reduced, and in the case of Comparative Example 2, which was formed as a single layer of the second composition, the biodegradability was excellent but the mechanical properties were reduced. It was found that Comparative Examples 3 and 4, in which the composition of the biodegradable resin contained in the second composition was different from that of the present invention, also showed decreased physical properties.

Deodorizing power evaluation Antibacterial activity evaluation (%) Example 1 1.0 99 Example 3 1.0 99 Example 4 1.0 99 Comparative Example 1 3.1 82 Comparative example 4 3.6 89

Referring to Table 3, the films according to the examples of the present invention were found to have excellent deodorizing and antibacterial properties. Comparative Examples 1 and 4, in which the produced films did not contain illite and bran ash, showed somewhat lower deodorizing and antibacterial effects compared to the Examples.

From the above test examples, the film manufactured with the biodegradable resin composition according to an embodiment of the present invention has an excellent biodegradation rate, can maintain excellent physical properties, and has excellent antibacterial and deodorizing effects, so it is applied as an antibacterial film for food packaging. It was confirmed that it was suitable for use.

Claims (5)

It is a biodegradable film with a multi-layer structure including a first layer and a second layer,
The first layer includes 25 to 40 wt% of a first biodegradable resin containing polybutylene adipate terephthalate (PBAT); 40 to 60 wt% of first thermoplastic starch; 5 to 20 wt% of a mixture of rice husk and calcium carbonate; And, 1 to 20 wt% of an additive containing at least one selected from the group consisting of ester compounds, oxidation accelerators, antioxidants, slip agents, pigments and UV stabilizers,
The second layer is composed of polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), and polypropylene carbonate (PPC) at a ratio of 1:0.5 to 1:0.1 to 0.3:0.1. 50 to 70 wt% of a second biodegradable resin in a weight ratio of 0.3 to 0.3; 15 to 25 wt% of second thermoplastic starch; 5 to 20 wt% of a mixture of rice husk ash and calcium carbonate; Illite 1 to 10 wt%; and 1 to 20 wt% of the additive;
In the first composition, the rice husk is surface-treated with at least one selected from the group consisting of sodium hydroxide, magnesium oxide, calcium oxide, and aluminum oxide,
In the second composition, the rice husk ash is prepared by first calcining rice husk at 300 to 550 ℃, pulverizing the rice husk to a particle size of 0.5 to 50 ㎛, and secondary calcination at 550 to 700 ℃, and the illite is fulvic acid , a biodegradable film surface-treated with at least one selected from stevia and amine-based compounds.
According to clause 1,
In the first composition, the calcium carbonate is surface-modified with at least one selected from the group consisting of acetyl acetonate and benzophenone-based compounds.
According to claim 1 or 2,
The calcium carbonate is a biodegradable film manufactured by calcining at least one selected from the group consisting of oyster shells and cockle shells at 300 to 550°C and then pulverizing them to a particle size of 0.5 to 50 ㎛.
delete According to clause 1,
The second composition is a biodegradable film further comprising at least one selected from the group consisting of perlite and deep ocean water.