Biodegradable multilayer film, method for manufacturing the same, and environmentally friendly packaging material containing the same

Abstract

To provide a biodegradable multilayer film, a method for producing the same, and an environmentally friendly packaging material containing the same.SOLUTION: The biodegradable multilayer film includes a base layer and a biodegradable polymer layer, wherein the biodegradable polymer layer includes a polyhydroxyalkanoate (PHA) polymer, and the biodegradable polymer layer has a thermal bond strength of 0. 5kgf / 15mm to 15kgf / 15mm, a WVTR of 3g / m2 atm day or less, and an OTR of 10cc / m2 atm day or less. The biodegradable multilayer film can biodegrade in natural conditions, such as soil and ocean, can improve barrier properties to moisture and oxygen without including aluminum or nylon materials, and can further improve adhesion properties. Thus, the biodegradable multilayer film can be used in various fields as a packaging material, and a high-quality and environment-friendly packaging material is provided.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a biodegradable multilayer film, a method for producing the same, and environmentally friendly packaging materials comprising the same. [Background technology]

[0002] Commonly used packaging materials consist of a base layer for printing and surface protection, a barrier layer (barrier film) to block moisture and oxygen, and an inner layer for heat-sealing lamination and preserving the contents.

[0003] Packaging materials are designed to suit their purpose, with a substrate layer typically consisting of polyethylene terephthalate (PET) or polypropylene (PP) film, which functions for packaging printing applications such as gravure, flexography, and screen printing and acts as a support layer to maintain film strength in multi-layer structures; a barrier layer, which includes an aluminum foil or nylon layer, which functions as a barrier layer; and an inner layer, consisting of a low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or cast polypropylene (CPP) layer for heat-seal lamination, which functions to store food or objects and maintain their shape.

[0004] However, recycling these packaging materials is difficult. Depending on the type of packaging material, these packaging materials are difficult to completely decompose naturally during the landfill process or take hundreds of years to decompose. In particular, these packaging materials hardly decompose in the soil or ocean, causing problems of not only marine pollution but also air pollution.

[0005] To solve these problems, there has been an increasing need in recent years for environmentally friendly packaging materials that do not use non-degradable plastics, such as PET and nylon, which are both environmentally unfriendly, or aluminum as a metal component, can easily maintain the life and storage stability of the contents, and can be completely decomposed naturally or by landfilling after use without damaging the natural environment.

[0006] Various biodegradable materials, such as paper and biodegradable polymers, such as polylactic acid (PLA), have been studied as environmentally friendly packaging materials. However, these materials have a problem in that they are hardly usable as packaging materials due to their low barrier properties against oxygen or moisture, along with their biodegradability.

[0007] Therefore, there is a need to develop biodegradable films and environmentally friendly packaging materials that are biodegradable in soil and sea and have excellent barrier properties against oxygen and moisture. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Korean Patent Publication No. 2012-0103158 [Invention Disclosure]

[0009] [Technical issues] An object of the present invention is to provide a biodegradable multilayer film that is biodegradable under natural conditions, such as in soil and sea, does not contain aluminum or nylon materials, has excellent barrier properties against moisture and oxygen, and has excellent adhesive properties.

[0010] Another object of the present invention is to provide a method for efficiently producing a biodegradable multilayer film having the above properties.

[0011] Another object of the present invention is to provide an environmentally friendly packaging material that contains the above multilayer film and has excellent shelf life properties, allowing for the safe preservation of perishable goods.

[0012] [How to solve the problem] The present invention relates to a biodegradable multilayer film comprising a substrate layer and a biodegradable resin layer, wherein the biodegradable resin layer comprises a polyhydroxyalkanoate (PHA) resin, the biodegradable resin layer has a heat seal strength of 0.5 to 15 kgf / 15 mm, and the biodegradable multilayer film has a heat seal strength of 3 g / m 2Water vapor transmission rate of 10cc / m or less 2 To provide a biodegradable multilayer film having an oxygen permeability of 1000 ppm or less.

[0013] Additionally, the present invention provides a method for producing a biodegradable multilayer film, the method comprising the step of melt-extruding a polyhydroxyalkanoate (PHA) resin onto a substrate layer to form a biodegradable resin layer, the biodegradable resin layer having a heat seal strength of 0.5 to 15 kgf / 15 mm, and the biodegradable multilayer film having a heat seal strength of 3 g / m 2 Water vapor transmission rate of 10cc / m or less 2 The present invention provides a method for producing an oxygen permeability of 1000 ppm or less.

[0014] In addition, the present invention provides an environmentally friendly packaging material comprising the above-mentioned biodegradable multilayer film.

[0015] The biodegradable multilayer film according to one embodiment of the present invention has a specific structure including a substrate layer and a biodegradable resin layer, and contains specific biodegradable components, so that the biodegradable multilayer film is biodegradable in natural conditions, such as soil and the sea, and has enhanced barrier properties against moisture and oxygen and further enhanced adhesive properties without containing aluminum or nylon materials.

[0016] Meanwhile, the method for producing a biodegradable multilayer film according to one embodiment of the present invention can provide a method for efficiently producing a biodegradable multilayer film having the above-mentioned properties.

[0017] In addition, various structures can be designed according to the purpose by easily combining a biodegradable resin layer with a barrier layer having various functions. In particular, when the co-extrusion method according to one embodiment of the present invention is adopted, a single material or different materials can be extruded at once to combine materials having various functions, which further improves processability and productivity.

[0018] Furthermore, the biodegradable multilayer film is environmentally friendly because it decomposes completely in both soil and the sea and can safely preserve fresh produce. Therefore, it can be used in a variety of fields as a packaging material, and a high-quality, environmentally friendly packaging material can be provided. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view of a biodegradable multilayer film according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of a biodegradable multilayer film according to another embodiment of the present invention. [Figure 3] FIG. 2 is a cross-sectional view of a biodegradable multilayer film according to another embodiment of the present invention. [Figure 4] FIG. 2 is a cross-sectional view of a biodegradable multilayer film according to another embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

[0020] The present invention will now be described in more detail.

[0021] The embodiments are not limited to those described below, but rather may be modified in various ways without departing from the spirit of the present invention.

[0022] Throughout this specification, when a part is referred to as "comprising" certain elements, it is understood that other elements may be included, rather than being excluded, unless otherwise specified.

[0023] As used herein, the singular forms "a," "an," and "the" are to be construed as including the singular or plural number as the context dictates, unless otherwise indicated.

[0024] Additionally, all numbers expressing physical properties of elements, dimensions, reaction conditions, and the like used herein are to be understood as being modified by the term "about" unless otherwise specified.

[0025] Throughout this specification, terms such as "first resin layer," "second resin layer," "first adhesive layer," "second adhesive layer," "first," and "second" are used to describe various components. However, the components should not be limited by the terms. The terms are used only to distinguish one component from another.

[0026] In this specification, when an element is said to be formed "on" or "under" another element, it means not only that the element is directly formed "on" or "under" the other element, but also that the element is indirectly formed on or under the other element with one or more other elements interposed therebetween.

[0027] In addition, the terms "one side" and "opposite side" or "upper" and "lower" of each component are described based on the drawings. These terms are merely used to distinguish the components, and may be interchangeable in actual applications.

[0028] Additionally, for illustrative purposes, the size of particular elements in the accompanying figures may be exaggerated and not intended to represent actual size. Additionally, like reference numerals refer to like elements throughout the specification.

[0029] [Biodegradable multilayer film] The biodegradable multilayer film according to one embodiment of the present invention comprises a substrate layer and a biodegradable resin layer, the biodegradable resin layer comprising a polyhydroxyalkanoate (PHA) resin, the biodegradable resin layer having a heat seal strength of 0.5 to 15 kgf / 15 mm, and the biodegradable multilayer film having a heat seal strength of 3 g / m 2 Water vapor transmission rate of 10cc / m or less 2 ·Has an oxygen permeability of less than ·atm·days.

[0030] Because the biodegradable multilayer film according to one embodiment of the present invention has the specific structure described above and contains specific biodegradable components, the biodegradable multilayer film and environmentally friendly packaging materials containing the same are biodegradable in natural conditions, such as soil and sea, and have enhanced barrier properties against moisture and oxygen without containing aluminum or nylon materials, thereby enabling the safe preservation of fresh produce, and have excellent adhesive properties. Therefore, the biodegradable multilayer film is of technological importance in that it can provide high-quality, environmentally friendly packaging materials.

[0031] Additionally, according to one embodiment of the present invention, the biodegradable multilayer film may further include a barrier layer, and the barrier layer may include an ethylene vinyl alcohol (EVOH) resin.

[0032] Specifically, the biodegradable multilayer film includes a substrate layer, a barrier layer, and a biodegradable resin layer, the biodegradable resin layer includes a polyhydroxyalkanoate (PHA) resin, the barrier layer includes an ethylene vinyl alcohol (EVOH) resin, the biodegradable resin layer has a heat seal strength of 0.5 to 15 kgf / 15 mm, and the biodegradable multilayer film has a heat seal strength of 3 g / m 2 Water vapor transmission rate of 10cc / m or less 2 ·Has an oxygen permeability of less than ·atm·days.

[0033] When a biodegradable multilayer film comprises a barrier layer containing an ethylene vinyl alcohol (EVOH) resin and a biodegradable resin layer containing a polyhydroxyalkanoate (PHA) resin, not only can the heat seal strength of each of the barrier layer and the biodegradable resin layer be increased, but also interlayer delamination can be minimized because both the barrier layer and the biodegradable resin layer contain hydroxy (OH) functional groups. Therefore, the barrier layer and the biodegradable resin layer have excellent compatibility with each other, further improving the adhesive properties.

[0034] Each layer of the biodegradable multilayer film will now be described in detail.

[0035] Base material layer The biodegradable multilayer film of the present invention may include a substrate layer.

[0036] Because the biodegradable multilayer film includes a substrate layer, it is easy to print product information and designs on it, which can be advantageous for protecting the surface.

[0037] The substrate layer may include at least one selected from the group consisting of paper, polyethylene terephthalate (PET) film, polyimide (PI) film, polypropylene (PP) film, and polyethylene (PE) film. Specifically, the substrate layer may include paper.

[0038] When the substrate layer comprises paper, it may be more advantageous to provide an environmentally friendly packaging material, since paper has better biodegradability than other plastic materials.

[0039] The substrate layer, for example, the paper layer, is 30 to 200 g / m 2 The substrate layer may have a thickness that varies depending on the thickness of the biodegradable multilayer film, but the thickness may be, for example, 30 to 1000 μm, for example, 30 to 500 μm, or for example, 40 to 300 μm.

[0040] On the other hand, the barrier layer or the biodegradable resin layer may be disposed on at least one surface of the substrate layer.

[0041] In addition, an environmentally friendly blocking layer may be coated on the surface of the substrate layer to have moisture and / or oxygen barrier properties, or a functional coating layer having antistatic or adhesive properties may be further formed.

[0042] The functional coating layer may include a primer coating layer and an adhesive coating layer, and these may have commonly used materials and physical properties as long as they do not impair the effects desired in the present invention.

[0043] For example, the functional coating layer may include a primer coating layer. In this case, the barrier properties against moisture and / or oxygen can be further improved, adhesion with the barrier layer or biodegradable resin layer can be enhanced, and antistatic performance can be improved. In addition, if another layer, such as an adhesive coating layer or a release layer, is used on the opposite side of the primer coating layer, it is possible to prevent these coating liquids from penetrating the surface of the substrate (liquid penetration phenomenon).

[0044] The primer coating layer may contain at least one type of antistatic material selected from the group consisting of ammonium-based compounds, phosphoric acid-based compounds, and polymers such as acrylic resins and urethane-based resins.

[0045] The adhesive coating layer is a coating layer for enhancing adhesion, and contains, for example, at least one selected from the group consisting of polyhydroxyalkanoate (PHA), polysilicone-based compounds, polyvinyl alcohol (PVA), ethylene vinyl acetate (EVA), acrylic resins, and urethane-based resins.

[0046] The thickness of the functional coating layer may be adjusted appropriately depending on the use and purpose of the biodegradable multilayer film, and may be specifically, but is not limited to, 15 nm to 50 nm, 20 nm to 45 nm, 25 nm to 40 nm, or 30 nm to 35 nm.

[0047] biodegradable resin layer The biodegradable multilayer film of the present invention may include a biodegradable resin layer containing a polyhydroxyalkanoate (hereinafter referred to as PHA) resin.

[0048] PHA resins have similar physical properties to conventional petroleum-derived synthetic polymers, such as polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate terephthalate (PBST), and polybutylene succinate adipate (PBSA), and are completely biodegradable and have excellent biocompatibility.

[0049] Specifically, PHA resin is a natural thermoplastic polyester polymer that accumulates in microbial cells. Because PHA resin is a biodegradable material, it can be composted without generating toxic waste and ultimately decomposes into carbon dioxide, water, and organic waste. In particular, PHA resin is biodegradable in soil and the ocean. Therefore, when a biodegradable resin layer contains a PHA resin, the biodegradable resin layer is biodegradable under any environmental conditions, for example, in soil and the ocean, and has environmentally friendly properties. Therefore, when a multilayer film contains a biodegradable resin layer containing a PHA resin, the multilayer film has the great advantage of being usable as an environmentally friendly packaging material in various fields.

[0050] PHA resins may be formed by enzyme-catalyzed polymerization of one or more monomer repeat units in living cells.

[0051] The PHA resin may be a polyhydroxyalkanoate copolymer resin (hereinafter referred to as a PHA copolymer), specifically a copolymer containing two or more different repeat units, the different repeat units being randomly distributed in the polymer chain.

[0052] Examples of repeating units that may be contained in PHA include 2-hydroxybutyrate, lactic acid, glycolic acid, 3-hydroxybutyrate (hereinafter referred to as 3-HB), 3-hydroxypropionate (hereinafter referred to as 3-HP), 3-hydroxyvalerate (hereinafter referred to as 3-HV), 3-hydroxyhexanoate (hereinafter referred to as 3-HH), 3-hydroxyheptanoate (hereinafter referred to as 3-HHep), 3-hydroxyoctanoate (hereinafter referred to as 3-HO), 3-hydroxynonanoate (hereinafter referred to as 3-HN), 3-hydroxydecanoate (hereinafter referred to as 3-HD), 3-hydroxydodecanoate (hereinafter referred to as 3-HDd), 4-hydroxybutyrate (hereinafter referred to as 4-HB), 4-hydroxyvalerate (hereinafter referred to as 4-HV), 5-hydroxyvalerate (hereinafter referred to as 5-HV), and 6-hydroxyhexanoate (hereinafter referred to as 6-HH). The PHA resin may contain one or more repeat units selected from those listed above.

[0053] Specifically, the PHA resin may include one or more repeat units selected from the group consisting of 3-HB, 4-HB, 3-HP, 3-HH, 3-HV, 4-HV, 5-HV, and 6-HH.

[0054] More specifically, the PHA resin may contain 4-HB repeating units, i.e., the PHA resin may be a PHA copolymer containing 4-HB repeating units.

[0055] In addition, the PHA resin may include isomers. For example, the PHA resin may include structural isomers, enantiomers, or geometric isomers. Specifically, the PHA resin may include structural isomers.

[0056] Additionally, the PHA resin may be a PHA copolymer that contains 4-HB repeat units and further contains one type of repeat unit different from the 4-HB repeat units, or two, three, four, five, six or more types of repeat units that are different from each other.

[0057] According to one embodiment of the present invention, the PHA resin may comprise a polyhydroxyalkanoate copolymer resin comprising at least one repeat unit selected from the group consisting of 3-HB, 3-HP, 3-HH, 3-HV, 4-HV, 5-HV, and 6-HH, and 4-HB repeat units.

[0058] Specifically, the PHA copolymer may contain 4-HB repeat units and further contain one or more repeat units selected from the group consisting of 3-HB repeat units, 3-HP repeat units, 3-HH repeat units, 3-HV repeat units, 4-HV repeat units, 5-HV repeat units, and 6-HH repeat units. More specifically, the PHA resin may be a polyhydroxyalkanoate copolymer resin containing 3-HB repeat units and 4-HB repeat units.

[0059] For example, the PHA resin may be poly-3-hydroxybutyrate-co-4-hydroxybutyrate (hereinafter referred to as 3HB-co-4HB).

[0060] According to one embodiment of the present invention, it is important to control the 4-HB repeat unit content of the PHA copolymer.

[0061] That is, the content of 4-HB repeat units in the PHA copolymer can be important to achieve the physical properties desired in the present invention, particularly to increase biodegradability in soil and sea, and to achieve superior physical properties, such as enhanced optical, thermal, and mechanical properties.

[0062] More specifically, the PHA copolymer may contain 4-HB repeat units in an amount of 0.1 wt% to 60 wt%, based on the total weight of the PHA copolymer. For example, the 4-HB repeat unit content may be 0.1 wt% to 55 wt%, 0.5 wt% to 60 wt%, 0.5 wt% to 55 wt%, 1 wt% to 60 wt%, 1 wt% to 55 wt%, 1 wt% to 50 wt%, 2 wt% to 55 wt%, 3 wt% to 55 wt%, 3 wt% to 50 wt%, 5 wt% to 55 wt%, 5 wt% to 50 wt%, 10 wt% to 55 wt%, 10 wt% to 50 wt%, 1 wt% to 40 wt%, 1 wt% to 30 wt%, 1 wt% to 29 wt%, 1 wt% to 10 ... The amount may be 1% to 25% by weight, 1% to 24% by weight, 2% to 20% by weight, 2% to 23% by weight, 3% to 20% by weight, 3% to 15% by weight, 4% to 18% by weight, 5% to 15% by weight, 8% to 12% by weight, 9% to 12% by weight, 15% to 55% by weight, 15% to 50% by weight, 20% to 55% by weight, 20% to 50% by weight, 25% to 55% by weight, 25% to 50% by weight, 35% to 60% by weight, 40% to 55% by weight, or 45% to 55% by weight.

[0063] When the content of 4-HB repeating units satisfies the above range, biodegradability in soil and sea can be increased, excellent optical properties can be maintained, the thermal properties of the material can be improved, and mechanical properties such as flexibility and strength can be further enhanced.

[0064] In addition, the PHA resin may contain at least one or more 4-HB repeat units, and the crystallinity of the PHA resin may be adjusted by controlling the content of the 4-HB repeat units, i.e., the PHA resin may be a PHA copolymer with controlled crystallinity.

[0065] The crystallinity of the PHA resin may be adjusted by increasing the disorder in its molecular structure, such as by adjusting the type and ratio of monomers or the type and / or content of isomers.

[0066] The PHA resin may comprise a combination of two or more PHA resins with different degrees of crystallinity, i.e., by mixing two or more PHA resins with different degrees of crystallinity, the PHA resin may be adjusted to have a specific range of 4-HB repeat unit content.

[0067] For example, the PHA resin may comprise a mixed resin of a first PHA resin and a second PHA resin having different contents of 4-HB repeating units, and the PHA resin may be adjusted so that the content of 4-HB repeating units is 0.1 to 60 wt% relative to the total weight of the PHA resin. Specific properties of the first and second PHA resins are described below.

[0068] Alternatively, the PHA copolymer may comprise 3-HB repeat units in an amount of, for example, 20% by weight or more, 35% by weight or more, 40% by weight or more, 50% by weight or more, 60% by weight or more, 70% by weight or more, or 75% by weight or more, and 99% by weight or less, 98% by weight or less, 97% by weight or less, 96% by weight or less, 95% by weight or less, 93% by weight or less, 91% by weight or less, 90% by weight or less, 80% by weight or less, 70% by weight or less, 60% by weight or less, or 55% by weight or less, based on the total weight of the PHA copolymer.

[0069] On the other hand, the PHA resin may have a glass transition temperature (Tg) of, for example, -45°C to 80°C, -35°C to 80°C, -30°C to 80°C, -25°C to 75°C, -20°C to 70°C, -35°C to 5°C, -25°C to 5°C, -35°C to 0°C, -25°C to 0°C, -30°C to -10°C, -35°C to -15°C, -35°C to -20°C, -20°C to 0°C, -15°C to 0°C, or -15°C to -5°C.

[0070] The crystallization temperature (Tc) of the PHA resin may not be measured, or may be, for example, 70°C to 120°C, 75°C to 120°C, 75°C to 115°C, 75°C to 110°C, or 90°C to 110°C.

[0071] The melting temperature (Tm) of the PHA resin may not be measured, or may be, for example, 100°C to 170°C, for example, 110°C to 150°C, or for example, 120°C to 140°C.

[0072] The PHA resin may have a weight average molecular weight (Mw) of, for example, 10,000 g / mol to 1,200,000 g / mol. For example, the weight average molecular weight of the PHA resin may be 50,000 g / mol to 1,200,000 g / mol, 100,000 g / mol to 1,200,000 g / mol, 50,000 g / mol to 1,000,000 g / mol, 100,000 g / mol to 1,000,000 g / mol, or 200,000 g / mol to 1,200,000 g / mol. 0,000 g / mol, 250,000 g / mol to 1,150,000 g / mol, 300,000 g / mol to 1,100,000 g / mol, 350,000 g / mol to 1,000,000 g / mol, 350,000 g / mol to 950,000 g / mol, 100,000 g / mol to 900,000 g / mol, 20 0,000g / mol to 800,000g / mol, 200,000g / mol to 700,000g / mol, 250,000g / mol to 650,000g / mol, 200,000g / mol to 400,000g / mol, 300,000g / mol to 800,000g / mol, 300,000g / mol to 600,000g The molecular weight may be 500,000 g / mol to 1,200,000 g / mol, 500,000 g / mol to 1,000,000 g / mol, 550,000 g / mol to 1,050,000 g / mol, 550,000 g / mol to 900,000 g / mol, or 600,000 g / mol to 900,000 g / mol.

[0073] On the other hand, the biodegradable resin layer may be a single layer, or may include two or more biodegradable resin layers.

[0074] When the biodegradable resin layer has two or more layers, it may include a first resin layer and a second resin layer.

[0075] When the biodegradable resin layer is a single layer, the thickness of the biodegradable resin layer may be 10 to 200 μm, for example, 15 to 150 μm, 20 to 100 μm, or 25 to 50 μm. When the biodegradable resin layer has two or more layers, the thickness of the first resin layer and the second resin layer may each be 5 to 100 μm, for example, 7 to 80 μm, 10 to 50 μm, or 12 to 25 μm.

[0076] The first and second resin layers may comprise a first and second PHA resin, respectively, which can be distinguished with respect to their 4-HB repeat unit content, glass transition temperature (Tg), crystallization temperature (Tc), and melting temperature (Tm).

[0077] Specifically, the first resin layer includes a first PHA resin, which may contain 4-HB repeat units in an amount of, for example, 15% to 60% by weight, 15% to 55% by weight, 20% to 55% by weight, 25% to 55% by weight, 30% to 55% by weight, 35% to 55% by weight, 20% to 50% by weight, 25% to 50% by weight, 30% to 50% by weight, 35% to 50% by weight, or 20% to 40% by weight, based on the total weight of the first PHA resin.

[0078] The glass transition temperature (Tg) of the first PHA resin may be -45°C to -10°C, -35°C to -10°C, -35°C to -15°C, -35°C to -20°C, or -30°C to -20°C.

[0079] The crystallization temperature (Tc) of the first PHA resin may not be measured, or may be, for example, 60°C to 120°C, 60°C to 110°C, 70°C to 120°C, or 75°C to 115°C.

[0080] The melting temperature (Tm) of the first PHA resin may not be measured, or may be, for example, 100°C to 170°C, 100°C to 160°C, 110°C to 160°C, or 120°C to 150°C.

[0081] The first PHA resin may be, for example, 10,000 g / mol to 1,200,000 g / mol, 10,000 g / mol to 1,000,000 g / mol, 50,000 g / mol to 1,000,000 g / mol, 50,000 g / mol to 1,200,000 g / mol, for example, 70,000 g / mol to 1,000,000 g / mol, 50,000 g / mol to 1,000,000 g / mol, 2 The polymer may have a weight average molecular weight (Mw) of 00,000 g / mol to 1,200,000 g / mol, 300,000 g / mol to 1,000,000 g / mol, 100,000 g / mol to 900,000 g / mol, 500,000 g / mol to 900,000 g / mol, 200,000 g / mol to 800,000 g / mol, or 200,000 g / mol to 400,000 g / mol.

[0082] On the other hand, the second resin layer contains a second PHA resin, which may contain 4-HB repeating units in an amount of 0.1% by weight to 30% by weight based on the total weight of the second PHA resin. The second PHA resin may comprise 4-HB repeat units in an amount of, for example, 0.1 wt % to 30 wt %, 0.5 wt % to 30 wt %, 1 wt % to 30 wt %, 3 wt % to 30 wt %, 1 wt % to 28 wt %, 1 wt % to 25 wt %, 1 wt % to 24 wt %, 1 wt % to 20 wt %, 1 wt % to 15 wt %, 2 wt % to 25 wt %, 3 wt % to 25 wt %, 3 wt % to 24 wt %, 5 wt % to 20 wt %, greater than 5 wt % to less than 20 wt %, 7 wt % to 20 wt %, 10 wt % to 20 wt %, 15 wt % to 25 wt %, or 15 wt % to 24 wt %.

[0083] The first and second PHA resins may differ from each other with respect to their content of 4-HB repeat units.

[0084] The second PHA resin may have a glass transition temperature (Tg) of, for example, -30°C to 80°C, -30°C to 10°C, -25°C to 5°C, -25°C to 0°C, -20°C to 0°C, or -15°C to 0°C.

[0085] The glass transition temperature (Tg) of the first PHA resin and the glass transition temperature (Tg) of the second PHA resin may be different from each other.

[0086] The second PHA resin may have a crystallization temperature (Tc) of, for example, 70°C to 120°C, such as 75°C to 115°C, or may for example not be determined.

[0087] The second PHA resin may have a melting temperature (Tm) of, for example, 100°C to 170°C, for example, 105°C to 165°C, for example, 110°C to 160°C, for example, 100°C to 150°C, for example, 115°C to 155°C, or for example, 120°C to 150°C.

[0088] The second PHA resin may be 10,000 g / mol to 1,200,000 g / mol, 50,000 g / mol to 1,200,000 g / mol, 70,000 g / mol to 1,000,000 g / mol, 50,000 g / mol to 1,100,000 g / mol, 100,000 g / mol to 1,000,000 g / mol, 300 The polymer may have a weight average molecular weight (Mw) of from 2,000 g / mol to 1,000,000 g / mol, from 100,000 g / mol to 900,000 g / mol, from 200,000 g / mol to 800,000 g / mol, from 200,000 g / mol to 600,000 g / mol, from 200,000 g / mol to 400,000 g / mol, or from 400,000 g / mol to 700,000 g / mol.

[0089] Specifically, the first PHA resin has a glass transition temperature (Tg) of -35°C to -15°C, and the second PHA resin satisfies at least one characteristic selected from a glass transition temperature (Tg) of -15°C to 0°C, a crystallization temperature (Tc) of 80°C to 110°C, and a melting temperature (Tm) of 120°C to 160°C, and the glass transition temperatures (Tg) of the first PHA resin and the second PHA resin may be different from each other. In addition, the crystallization temperature (Tc) and melting temperature (Tm) of the first PHA resin do not need to be measured.

[0090] It may be more advantageous to achieve the desired effects of the present invention if the first PHA resin and the second PHA resin each satisfy at least one of the above-mentioned ranges for the content of 4-HB repeating units, glass transition temperature (Tg), crystallization temperature (Tc), and melting temperature (Tm).

[0091] Additionally, the first PHA resin and the second PHA resin may each be a PHA resin with controlled crystallinity.

[0092] For example, the first PHA resin may comprise an amorphous PHA resin (hereinafter referred to as an aPHA resin), and the second PHA resin may comprise a semi-crystalline PHA resin (hereinafter referred to as an scPHA resin).

[0093] aPHA resins and scPHA resins can be distinguished with respect to the content of 4-HB repeating units, glass transition temperature (Tg), crystallization temperature (Tc), melting temperature (Tm), and the like.

[0094] The aPHA resin may contain 4-HB repeat units in an amount of, for example, 25 to 50% by weight based on the total weight of the PHA resin.

[0095] The aPHA resin may have a glass transition temperature (Tg) of, for example, -35°C to -20°C.

[0096] The crystallization temperature (Tc) of the aPHA resin does not need to be measured.

[0097] The melting temperature (Tm) of the aPHA resin does not need to be measured.

[0098] The scPHA resin may contain 4-HB repeat units in an amount of, for example, 1 to less than 25% by weight based on the total weight of the PHA resin.

[0099] The scPHA resin may have a glass transition temperature (Tg) of -20°C to 0°C.

[0100] The scPHA resin may have a crystallization temperature (Tc) of 75°C to 115°C.

[0101] The scPHA resin may have a melting temperature (Tm) of 110°C to 160°C.

[0102] When a biodegradable multilayer film according to one embodiment of the present invention includes two or more layers, including a first resin layer and a second resin layer, it may be more advantageous to provide various properties compared to a single layer.

[0103] Specifically, a first resin layer containing a first PHA resin may be advantageous for enhancing interlayer adhesion, and a second resin layer containing a second PHA resin may be more advantageous for enhancing printability.

[0104] Additionally, the first PHA resin and the second PHA resin can be distinguished with respect to the content of 4-HB repeat units contained in the PHA, the glass transition temperature (Tg), the crystallization temperature (Tc), and the melting temperature (Tm) of the PHA.

[0105] Additionally, the PHA of the first resin layer may contain more or less 4-HB repeat units than the PHA of the second resin layer, and preferably contains more 4-HB repeat units than the PHA of the second resin layer.

[0106] On the other hand, the biodegradable resin layer may further contain at least one biodegradable resin selected from the group consisting of polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene succinate-adipate (PBSA), polybutylene succinate-terephthalate (PBST), polyhydroxybutyrate-valerate (PHBV), polycaprolactone (PCL), polybutylene succinate adipate terephthalate (PBSAT), and thermoplastic starch (TPS).

[0107] In addition, the biodegradable resin layer may further contain at least one additive selected from the group consisting of slip agents, antioxidants, crosslinking agents, nucleating agents, fillers, stabilizers, and compatibilizers. For example, the additive may be used in an amount of 0.5 to 30 wt % based on the total weight of the biodegradable resin layer.

[0108] Slip agents are additives that enhance slip properties during extrusion and prevent film surfaces from sticking to each other.

[0109] The slip agent may be any commonly used slip agent as long as it does not impair the effects of the present invention, for example, at least one selected from the group consisting of erucamide, oleamide, and stearamide.

[0110] The slip agent may be used in an amount of, for example, 0.01 to 20 wt %, 0.01 to 15 wt %, 0.01 to 12 wt %, 0.01 to 10 wt %, 0.01 to 8 wt %, 0.01 to 5 wt %, 0.2 to 4.5 wt %, 0.2 to 4 wt %, or 0.5 to 3 wt %, based on the total weight of the biodegradable resin layer.

[0111] When the content of the slip agent satisfies the above range, the processability, productivity, and moldability can be further improved, which may be more advantageous in achieving the desired effects of the present invention.

[0112] The antioxidant is an additive that prevents decomposition by ozone or oxygen, prevents oxidation during storage, and prevents deterioration of the physical properties of the film.

[0113] The antioxidant may be any commonly used antioxidant as long as it does not impair the effects of the present invention.

[0114] Specifically, the antioxidant may include at least one selected from the group consisting of hindered phenol-based antioxidants and phosphite-based (phosphorus-based) antioxidants.

[0115] The hindered phenol antioxidant may include, for example, at least one selected from the group consisting of 4,4′-methylene-bis(2,6-di-t-butylphenol), octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate), and 3,9-bis[2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane.

[0116] The phosphite (phosphorus) antioxidant may include, for example, at least one selected from the group consisting of tris-(2,4-di-t-butylphenyl)phosphite, bis-(2,4-di-t-butylphenyl)pentaerythritol-diphosphite, bis-(2,6-di-t-butyl-4-methylphenyl)pentaerythritol-diphosphite, distearyl-pentaerythritol-diphosphite, [bis(2,4-di-t-butyl-5-methylphenoxy)phosphino]biphenyl, and N,N-bis[2-[[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f][1,3,2]dioxyphosphepin-6-yl]oxy]-ethyl]ethanamine.

[0117] The antioxidant may be used in an amount of, for example, 0.01 to 20 wt %, 0.01 to 15 wt %, 0.01 to 12 wt %, 0.01 to 10 wt %, 0.01 to 8 wt %, 0.01 to 5 wt %, 0.2 to 4.5 wt %, 0.2 to 4 wt %, or 0.5 to 3 wt %, relative to the total weight of the biodegradable resin layer.

[0118] When the content of the antioxidant satisfies the above range, the physical properties of the film can be improved, which may be more advantageous in achieving the desired effects of the present invention.

[0119] The crosslinking agent is an additive for modifying the properties of the PHA and increasing the molecular weight of the resin. Any common crosslinking agent may be used as long as it does not impair the effects of the present invention.

[0120] For example, the crosslinking agent may be at least one selected from the group consisting of fatty acid esters, epoxy group-containing (epoxidized) natural oils, diallyl phthalate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol pentaacrylate, diethylene glycol dimethacrylate, and bis(2-methacryloxyethyl)phosphate.

[0121] The crosslinking agent may be used in an amount of, for example, 0.01 to 20 wt %, 0.01 to 15 wt %, 0.01 to 12 wt %, 0.01 to 10 wt %, 0.01 to 8 wt %, 0.01 to 5 wt %, 0.2 to 4.5 wt %, 0.2 to 4 wt %, or 0.5 to 3 wt %, relative to the total weight of the biodegradable resin layer.

[0122] When the content of the crosslinking agent satisfies the above range, the physical properties of the film can be improved, which is more advantageous in achieving the desired effects of the present invention.

[0123] Nucleating agents are additives that assist or change the crystallization morphology of polymers and increase the crystallization (solidification) rate when the polymer melt is cooled. In particular, the PHA resin used in the present invention has a low crystallization rate, so it remains viscous for a long time, making the process difficult. To solve this problem, the use of a nucleating agent can increase the crystallization rate, further improving processability, moldability, and productivity, and effectively achieving the desired physical properties.

[0124] The nucleating agent may be any commonly used nucleating agent as long as it does not impair the effects of the present invention.

[0125] Specifically, the nucleating agent may be a simple substance (pure substance), a metal compound including a complex oxide, such as carbon black, calcium carbonate, synthetic silicic acid and salt, silica, zinc white, clay, kaolin, basic magnesium carbonate, mica, talc, quartz powder, diatomaceous earth, dolomite powder, titanium oxide, zinc oxide, antimony oxide, barium sulfate, calcium sulfate, alumina, calcium silicate, metal salts of organic phosphorus, and boron nitride; a low molecular weight organic compound having a metal carboxylate group, such as octylic acid, toluic acid, heptanoic acid, pelargonic acid, lauric acid, myristic acid, palmitic acid, or the like. metal salts of benzoic acid, stearic acid, behenic acid, cerotic acid, montanic acid, melissic acid, benzoic acid, p-tert-butylbenzoic acid, terephthalic acid, terephthalic acid monomethyl ester, isophthalic acid, and isophthalic acid monomethyl ester; polymeric organic compounds having metal carboxylate groups, such as carboxyl group-containing polyethylene obtained by oxidation of polyethylene, carboxyl group-containing polypropylene obtained by oxidation of polypropylene, copolymers of acrylic acid or methacrylic acid with olefins (e.g., ethylene, propylene, and butene-1); Polymers, copolymers of acrylic acid or methacrylic acid with styrene, copolymers of olefins with maleic anhydride, and salts of copolymers of styrene with maleic anhydride; polymeric organic compounds, such as polyolefins of alpha-olefins having five or more carbon atoms branched at the third carbon atom (e.g., 3,3-dimethylbutene-1,3-methylbutene-1,3-methylpentene-1,3-methylhexene-1 and 3,5,5-trimethylhexene-1), polyvinylcycloalkanes (e.g., vinylcyclopentane, vinylcyclohexane, and vinylnorbornane). mers, polyalkylene glycols (e.g., polyethylene glycol and polypropylene glycol), poly(glycolic acid), cellulose, cellulose esters, and cellulose ethers; phosphoric or phosphorous acids and their metal salts, such as diphenyl phosphate, diphenyl phosphite, metal salts of bis(4-tert-butylphenyl)phosphate, and methylene bis-(2,4-tert-butylphenyl)phosphate; sorbitol derivatives, such as bis(p-methylbenzylidene)sorbitol and bis(p-ethylbenzylidene)sorbitol;and thioglycolic anhydride, p-toluenesulfonic acid, and metal salts thereof. The nucleating agents may be used alone or in combination.

[0126] The nucleating agent may be used in an amount of, for example, 0.01 to 20 wt%, 0.01 to 15 wt%, 0.01 to 12 wt%, 0.01 to 10 wt%, 0.01 to 8 wt%, 0.01 to 5 wt%, 0.2 to 4.5 wt%, 0.2 to 4 wt%, or 0.5 to 3 wt%, relative to the total weight of the biodegradable resin layer.

[0127] When the content of the nucleating agent satisfies the above range, the crystallization rate can be increased to improve moldability, and the productivity and processability of the film can be further improved.

[0128] The filler is an additive for increasing the crystallization rate during the molding process, thereby increasing moldability. Any commonly used filler may be used as long as it does not impair the effects of the present invention. The filler may include at least one selected from the group consisting of calcium carbonate (e.g., light or ground calcium carbonate), silica, talc, kaolin, barium sulfate, clay, calcium oxide, magnesium hydroxide, titanium oxide, carbon black, and glass fiber.

[0129] The filler, particularly the inorganic filler, may have an average particle size of 0.5 μm to 5 μm. If the average particle size of the inorganic filler is less than 0.5 μm, it becomes difficult to disperse the particles. If the average particle size exceeds 5 μm, the particle size becomes excessively large, which may impair the effects of the present invention. The filler may be used in an amount of, for example, 0.01 to 20 wt %, 0.01 to 15 wt %, 0.01 to 12 wt %, 0.01 to 10 wt %, 0.01 to 8 wt %, 0.01 to 5 wt %, 0.2 to 4.5 wt %, 0.2 to 4 wt %, or 0.5 to 3 wt %, based on the total weight of the biodegradable resin layer.

[0130] When the content of the filler satisfies the above range, it may be more advantageous to achieve the desired effects of the present invention.

[0131] The stabilizer is an additive for protecting against oxidation and heat and preventing discoloration. The stabilizer may be any commonly used stabilizer as long as it does not impair the effects of the present invention.

[0132] Specifically, the stabilizer may be one selected from the group consisting of trimethyl phosphate, triphenyl phosphate, trimethylphosphine, phosphoric acid, and phosphorous acid.

[0133] The stabilizer may be used in an amount of, for example, 0.01 to 20 wt%, 0.01 to 15 wt%, 0.01 to 12 wt%, 0.01 to 10 wt%, 0.01 to 8 wt%, 0.01 to 5 wt%, 0.2 to 4.5 wt%, 0.2 to 4 wt%, or 0.5 to 3 wt%, relative to the total weight of the biodegradable resin layer.

[0134] When the content of the stabilizer satisfies the above range, it may be more advantageous to achieve the desired effects of the present invention.

[0135] In addition, a compatibilizer is an additive that provides compatibility by eliminating heterogeneity between resins.

[0136] The compatibilizer may be any commonly used compatibilizer as long as it does not impair the effects of the present invention.

[0137] Specifically, the compatibilizer may include at least one selected from the group consisting of polyvinyl acetate (PVAc), isocyanate, polypropylene carbonate, glycidyl methacrylate, ethylene vinyl alcohol, polyvinyl alcohol (PVA), ethylene vinyl acetate, and maleic anhydride.

[0138] The compatibilizer may be used in an amount of, for example, 0.01 to 20 wt %, 0.01 to 15 wt %, 0.01 to 12 wt %, 0.01 to 10 wt %, 0.01 to 8 wt %, 0.01 to 5 wt %, 0.2 to 4.5 wt %, 0.2 to 4 wt %, or 0.5 to 3 wt %, relative to the total weight of the biodegradable resin layer.

[0139] When the content of the compatibilizer satisfies the above range, the compatibility between the resins used can be increased, thereby improving the physical properties of the film, which can be more advantageous in achieving the desired effects of the present invention.

[0140] Barrier layer The biodegradable multilayer film of the present invention may include a barrier layer to block moisture and oxygen.

[0141] Additionally, the barrier layer can provide benefits such as reduced permeability to moisture and oxygen, good resistance to oil, and stiffness to the article substrate.

[0142] The barrier layer may include an ethylene vinyl alcohol (hereinafter referred to as EVOH) resin, which may be an ethylene vinyl alcohol copolymer resin.

[0143] The barrier layer contains EVOH resin, which can form a layer for blocking moisture and oxygen. The biodegradable multilayer film has a film thickness of 3 g / m 2 Water vapor transmission rate of 10cc / m or less 2 It may be more advantageous to have an oxygen transmission rate of 0.1 atm / day or less.

[0144] In particular, one embodiment of the present invention is characterized in that the barrier layer does not contain aluminum or nylon material, but rather uses EVOH resin as an environmentally friendly material with excellent barrier properties against moisture and oxygen.

[0145] Furthermore, because EVOH resin contains hydroxy (OH) functional groups, it has excellent compatibility with biodegradable resin layers containing PHA resins that also contain OH functional groups, which can minimize delamination between the barrier layer and the biodegradable resin layer and improve adhesion properties. In addition, the barrier layer containing EVOH resin and the biodegradable resin layer containing PHA resin can be easily co-extruded in a process, which can further improve processability and productivity.

[0146] On the other hand, when the ethylene group content and molecular weight of the EVOH resin are controlled, the EVOH resin can further improve the physical properties of the biodegradable multilayer film.

[0147] The ethylene group content of the EVOH resin may be, for example, 10 to 70% by weight, for example, 20 to 60% by weight, or for example, 25 to 50% by weight. When the ethylene group content of the EVOH resin satisfies the above range, the barrier properties that block moisture and oxygen can be improved.

[0148] The barrier layer may be located on the substrate layer.

[0149] In addition, a barrier layer may be located on at least one side of the biodegradable resin layer.

[0150] The weight of the barrier layer may be 10% by weight or less of the total weight of the biodegradable multilayer film. The barrier layer has excellent barrier properties against moisture and oxygen even at a low weight (content).

[0151] The barrier layer may have a thickness of 5 to 50 μm. For example, the thickness of the barrier layer may be 5 μm to 40 μm, 5 μm to 35 μm, or 5 μm to 30 μm. When the thickness of the barrier layer satisfies the above range, the barrier properties against moisture and oxygen and productivity can be further improved. When the thickness of the barrier layer is thinner than the above range, it is difficult to obtain sufficient barrier properties. When the thickness of the barrier layer is thicker than the above range, problems such as high process costs and low productivity can occur.

[0152] The barrier layer and the biodegradable resin layer may be formed by co-extrusion onto the substrate layer, or may be formed by lamination onto the substrate layer.

[0153] adhesive layer The biodegradable multilayer film of the present invention may further comprise an adhesive layer.

[0154] According to one embodiment of the present invention, when the barrier layer and the biodegradable resin layer are formed by laminating them onto the base layer, an adhesive layer may be interposed between the base layer, the biodegradable resin layer, and the barrier layer.

[0155] For example, referring to Figure 4, the biodegradable multilayer film (1) includes a substrate layer (13), a barrier layer (12) disposed on the substrate layer, and a biodegradable resin layer (11) disposed on the barrier layer (12). The biodegradable multilayer film (1) may include a first adhesive layer (16) between the substrate layer (13) and the barrier layer (12), and a second adhesive layer (17) between the barrier layer (12) and the biodegradable resin layer (11).

[0156] In addition, the biodegradable multilayer film may include a substrate layer, a biodegradable resin layer disposed on the substrate layer, and a barrier layer disposed on the biodegradable resin layer, with a first adhesive layer and a second adhesive layer respectively interposed therebetween.

[0157] In addition, when the biodegradable multilayer film includes a first resin layer and a second resin layer as biodegradable resin layers and the first resin layer and the second resin layer are formed by laminating them to a substrate layer, the adhesive layer may also be formed on at least one side of each of the first resin layer and the second resin layer.

[0158] The adhesive layer has excellent adhesive strength and can be selected from various materials within a range that does not impair the effects of the present invention. For example, the adhesive layer may contain at least one selected from the group consisting of polyhydroxyalkanoate (PHA), polysilicone-based compounds, polyvinyl alcohol (PVA), ethylene vinyl acetate (EVA), acrylic resins, and urethane-based resins.

[0159] The adhesive layer may have a thickness of 5 μm to 20 μm, 5 μm to 15 μm, or 5 μm to 10 μm.

[0160] Polymer resin layer The biodegradable multilayer film of the present invention may further comprise a polymer resin layer.

[0161] The biodegradable multilayer film may further comprise at least one polymer resin layer comprising at least one selected from the group consisting of polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene succinate-adipate (PBSA), polybutylene succinate-terephthalate (PBST), polyhydroxybutyrate-valerate (PHBV), polycaprolactone (PCL), polybutylene succinate adipate terephthalate (PBSAT), thermoplastic starch (TPS), polypropylene (PP), polyethylene terephthalate (PET), and polyethylene (PE).

[0162] Specifically, the biodegradable multilayer film may further include at least one polymer resin layer containing at least one selected from the group consisting of polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), thermoplastic starch (TPS), polypropylene (PP), polyethylene terephthalate (PET), and polyethylene (PE).

[0163] The polymer resin layer may be formed on the barrier layer, the biodegradable resin layer, or both.

[0164] For example, a polymer resin layer may be formed on the barrier layer, and the polymer resin layer may be selected from the group consisting of polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), thermoplastic starch (TPS), and polypropylene (PP). Specifically, the polymer resin layer may be selected from the group consisting of polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), and polypropylene (PP). In addition, from the viewpoint of biodegradability, the polymer resin layer may be selected from the group consisting of polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), and thermoplastic starch (TPS).

[0165] In addition, when the biodegradable multilayer film includes a first resin layer and a second resin layer as biodegradable resin layers, the polymer resin layer may be formed on at least one side of each of the first resin layer and the second resin layer.

[0166] The polymer resin layer may have a thickness of 5 to 50 μm. For example, the thickness of the polymer resin layer may be 5 μm to 40 μm, 5 μm to 35 μm, or 5 μm to 30 μm.

[0167] Various structures of biodegradable multilayer films 1 to 4 show cross-sectional views of biodegradable multilayer films of various structures according to embodiments of the present invention.

[0168] First, a biodegradable multilayer film (1) according to one embodiment of the present invention may include a substrate layer (13) and a biodegradable resin layer (11) disposed on the substrate layer (13).

[0169] In addition, the biodegradable multilayer film (1) may further comprise a barrier layer (12).

[0170] Specifically, the barrier layer (12) may be disposed on the base layer (13), for example, interposed between the base layer (13) and the biodegradable resin layer (11).

[0171] In addition, a barrier layer (12) may be disposed on the biodegradable resin layer (11).

[0172] Referring to FIG. 1, a biodegradable multilayer film (1) according to one embodiment of the present invention may include a substrate layer (13), a barrier layer (12) disposed on the substrate layer (13), and a biodegradable resin layer (11) disposed on the barrier layer (12).

[0173] A biodegradable multilayer film according to another embodiment may include a substrate layer, a biodegradable resin layer disposed on the substrate layer, and a barrier layer disposed on the biodegradable resin layer.

[0174] The barrier layer (12) and the biodegradable resin layer (11) may be formed by co-extrusion onto the base layer (13) or by lamination onto the base layer (13).

[0175] According to one embodiment, when the barrier layer (12) and the biodegradable resin layer (11) are formed by laminating them to the substrate layer (13), referring back to Figure 4, the biodegradable multilayer film (1) includes the substrate layer (13), the barrier layer (12) disposed on the substrate layer, and the biodegradable resin layer (11) disposed on the barrier layer (12). The biodegradable multilayer film (1) may include a first adhesive layer (16) between the substrate layer (13) and the barrier layer (12), and a second adhesive layer (17) between the barrier layer (12) and the biodegradable resin layer (11).

[0176] According to another embodiment, the biodegradable multilayer film comprises a substrate layer, a biodegradable resin layer disposed on the substrate layer, and a barrier layer disposed on the biodegradable resin layer, and may comprise a first adhesive layer and a second adhesive layer respectively interposed therebetween.

[0177] In addition, referring to Figure 2, when the biodegradable multilayer film (1) includes a biodegradable resin layer (11) including a first resin layer and a second resin layer, the biodegradable multilayer film (1) may include a substrate layer (13), a barrier layer (12) disposed on the substrate layer, a first resin layer (14) disposed on the barrier layer (12), and a second resin layer (15) disposed on the first resin layer (14).

[0178] For example, the biodegradable multilayer film may have a structure of substrate layer / barrier layer / first resin layer / second resin layer, substrate layer / barrier layer / second resin layer / first resin layer, substrate layer / first resin layer / barrier layer / second resin layer, substrate layer / second resin layer / barrier layer / first resin layer, substrate layer / first resin layer / second resin layer / barrier layer, or substrate layer / second resin layer / first resin layer / barrier layer.

[0179] More specifically, referring to FIG. 3, the substrate layer (13) comprises paper, and the biodegradable multilayer film may have a structure of substrate layer (13) / first resin layer (14) / barrier layer (12) / second resin layer (15), or substrate layer / second resin layer / barrier layer / first resin layer.

[0180] The biodegradable multilayer film may, for example, include three or more layers, for example, 3 to 11 layers, and may have a total thickness of 30 μm to 350 μm, for example, 30 μm to 150 μm.

[0181] The barrier layer may occupy 10% or less of the thickness of the biodegradable multilayer film.

[0182] The ratio of the total thickness of the biodegradable resin layer and the base layer to the thickness of the barrier layer may be 90:10 to 99:1.

[0183] The thickness ratio of the biodegradable resin layer to the barrier layer may be 1:0.1 to 0.5.

[0184] Additionally, the thickness ratio of the paper layer and the biodegradable resin layer to the barrier layer may be 1:0.01 to 0.1.

[0185] The biodegradable resin layer may have a thickness of 10 to 100 μm.

[0186] On the other hand, the thickness ratio of the first resin layer to the second resin layer may be 1:0.5 to 1.5. When the thickness ratio of the first resin layer to the second resin layer satisfies the above range, it can be advantageous in terms of controlling the adhesive strength and film strength.

[0187] Physical properties of biodegradable multilayer films The multilayer film according to one embodiment of the present invention is characterized by being biodegradable by any one of microorganisms, moisture, oxygen, light, and heat, having low water vapor permeability and oxygen permeability, and excellent adhesive properties.

[0188] Specifically, the biodegradable multilayer film is, for example, 3 / m 2 ·atm·days or less, 2.5 / m2 ·atm·days or less, 2 / m 2 ·atm·day or less, 1 / m 2 ·atm·day or less, 0.8 / m 2 ·atm·day or less, 0.7 / m 2 ·atm·day or less, 0.6 / m 2 ·atm·days or less, or 0.5 / m 2 It may have a water vapor transmission rate (WVTR) of less than 1000 ppm.

[0189] The water vapor transmission rate can be measured, for example, using a Mocon Permatran-w3 / 33 water vapor transmission rate meter at 38±0.5° C. and a relative humidity of 90±2%.

[0190] In addition, the biodegradable multilayer film has a viscosity of, for example, 10 cc / m 2 ·atm·day or less, 5cc / m 2 ·atm·day or less, 3cc / m 2 ·atm·day or less, 2cc / m 2 ·atm·day or less, 1cc / m 2 ·atm·day or less, 0.5cc / m 2 ·atm·day or less, 0.4cc / m 2 ·atm·day or less, 0.3cc / m 2 atm·days or less, or 0.2cc / m 2 It may have an oxygen transmission rate (OTR) of less than 1 atm.

[0191] Oxygen transmission rate (OTR) can be measured at 23±0.5°C using a Labthink OX2 / 230 oxygen transmission rate meter.

[0192] Additionally, the biodegradable multilayer film may have a tensile strength of, for example, 10 to 50 MPa, or for example, 20 to 40 MPa.

[0193] The biodegradable multilayer film is cut into test pieces 100 mm long and 15 mm wide, and mounted on an INSTRON universal testing machine (UTM; model 5966) with a chuck spacing of 50 mm in accordance with ASTM-D882. The test is carried out at room temperature of 25°C and a tensile speed of 200 mm / min, and the tensile strength is measured using a program installed on the machine.

[0194] When the tensile strength satisfies the above range, it is possible to simultaneously improve the productivity, processability, and moldability of the biodegradable multilayer film.

[0195] On the other hand, the biodegradable resin layer may have a heat seal strength of 0.5 to 15 kgf / 15 mm, 1 to 10 kgf / 15 mm, 3 to 10 kgf / 15 mm, or 4 to 8 kgf / 15 mm.

[0196] When the biodegradable resin layer includes a first resin layer and a second resin layer, the heat seal strength of the first resin layer may be 1 to 15 kgf / 15 mm, 3 to 10 kgf / 15 mm, 3 to 8 kgf / 15 mm, or 4 to 8 kgf / 15 mm, and the heat seal strength of the second resin layer may be 1 to 12 kgf / 15 mm, 1 to 10 kgf / 15 mm, 3 to 10 kgf / 15 mm, or 3 to 7 kgf / 15 mm.

[0197] Additionally, the barrier layer may have a heat seal strength of 0.5 to 10 kgf / 15 mm, 0.8 to 8 kgf / 15 mm, 1 to 8 kgf / 15 mm, or 1 to 5 kgf / 15 mm.

[0198] The heat seal strength can be measured, for example, using a LLOYD LD5 universal tensile tester at a grip distance of 50 mm, a speed of 100 mm / min, and a sample width of 15 mm.

[0199] When the heat seal strength of the biodegradable resin layer and the heat seal strength of the barrier layer each satisfy the above range, the interlayer adhesion properties are excellent, which prevents peeling of the layers and further improves processability and productivity.

[0200] On the other hand, biodegradable multilayer films can have excellent optical properties.

[0201] Specifically, the biodegradable multilayer film may have a haze of 20% or less, 15% or less, 10% or less, 7% or less, 6% or less, or 5% or less. If the haze exceeds the above range, the transparency of the biodegradable multilayer film will be significantly reduced, which may limit the use of the biodegradable multilayer film for packaging purposes where the contents inside the packaging material are visible, for example.

[0202] Additionally, the biodegradable multilayer film may have a light transmittance of 85% or more, 88% or more, or 90% or more.

[0203] Furthermore, the biodegradable multilayer film is characterized by a biodegradability of 90% or more in soil and sea. Biodegradability indicates the rate of decomposition compared to a standard material (e.g., cellulose) over the same period. The Korean Ministry of Environment defines a biodegradable material as one that is 90% or more biodegradable in 180 days or 60% or more biodegradable in 45 days compared to a standard material. Specifically, this is based on biodegradability measured according to composting conditions (ISO 14855-1).

[0204] [Method for producing a biodegradable multilayer film] A method for producing a biodegradable multilayer film according to one embodiment of the present invention includes the step of melt-extruding a polyhydroxyalkanoate (PHA) resin onto a substrate layer to form a biodegradable resin layer, the biodegradable resin layer having a heat seal strength of 0.5 to 15 kgf / 15 mm, and the biodegradable multilayer film having a heat seal strength of 3 g / m 2 Water vapor transmission rate of 10cc / m or less 2 ·Has an oxygen permeability of less than ·atm·days.

[0205] In addition, the method for producing a biodegradable multilayer film further includes a step of melt-extruding an ethylene vinyl alcohol (EVOH) resin to form a barrier layer, and the biodegradable resin layer and the barrier layer may be formed by melt-co-extruding a polyhydroxyalkanoate (PHA) resin and an ethylene vinyl alcohol (EVOH) resin onto the substrate layer, or by melt-extruding each of them and laminating them onto the substrate layer.

[0206] Specifically, a method for producing a biodegradable multilayer film may include melt-co-extruding a polyhydroxyalkanoate (PHA) resin and an ethylene vinyl alcohol (EVOH) resin onto a substrate layer to form a biodegradable resin layer and a barrier layer.

[0207] According to another embodiment of the present invention, a method for producing a biodegradable multilayer film may include melt-extruding a polyhydroxyalkanoate (PHA) resin and an ethylene vinyl alcohol (EVOH) resin, respectively, and laminating them onto a substrate layer to form a biodegradable resin layer and a barrier layer.

[0208] The method for producing a biodegradable multilayer film allows for the efficient combination of materials with various functions as well as multilayer film structures, allowing for the design of various structures according to the purpose. In particular, when a co-extrusion method according to one embodiment of the present invention is adopted, it is more advantageous for producing a multilayer film by combining materials with various functions by simultaneously extruding a single material or different materials. Therefore, it is possible to further efficiently improve processability and productivity.

[0209] The method for producing the biodegradable multilayer film is described in detail below.

[0210] A method for producing a biodegradable multilayer film may include melt-extruding a PHA resin onto a substrate layer to form a biodegradable resin layer.

[0211] Additionally, a method for producing a biodegradable multilayer film may include melt co-extruding a PHA resin and an EVOH resin onto a substrate layer to form a biodegradable resin layer and a barrier layer.

[0212] The PHA resin and EVOH resin are as described above.

[0213] The PHA resin and the EVOH resin may each be in the form of powder, granules, or pellets. Specifically, the PHA resin and the EVOH resin may each be in the form of pellets.

[0214] When the PHA resin and the EVOH resin are each in the form of pellets, each resin may be cooled to, for example, 75°C or less, 30°C or less, or 5°C or less, and the cooled resin may then be cut to form pellets.

[0215] The cutting step can be performed using a pellet cutter, including, without limitation, any commonly used in the art, and the pellets can have a variety of shapes.

[0216] Additionally, a step of drying the pellets may be carried out. Drying may be carried out at 30°C to 100°C for 2 to 12 hours. Specifically, drying may be carried out at 35°C to 95°C, 40°C to 90°C, or 45°C to 85°C for 3 to 12 hours or 4 to 10 hours. When the conditions for the step of drying the pellets satisfy the above ranges, the quality can be further improved.

[0217] During the melt co-extrusion, the extrusion temperatures of the PHA resin and the EVOH resin may be controlled individually. The melt co-extrusion may be carried out at a temperature of 120°C to 250°C.

[0218] Specifically, the extrusion temperature of the PHA resin and the extrusion temperature of the EVOH resin may be the same or different.

[0219] The extrusion temperature of the PHA resin may be, for example, 120°C to 250°C, 120°C to 200°C, 140°C to 200°C, 140°C to 190°C, 140°C to 180°C, or 140°C to 170°C.

[0220] The extrusion temperature of the EVOH resin may be, for example, 120°C to 250°C, 140°C to 250°C, 140°C to 240°C, 140°C to 230°C, or 140°C to 220°C.

[0221] When the extrusion temperature of the PHA resin and the extrusion temperature of the EVOH resin are different from each other, the difference in extrusion temperature may be 50°C or less, 40°C or less, or 30°C or less.

[0222] In addition, according to one embodiment of the present invention, when the substrate layer includes paper and the biodegradable resin layer and the barrier layer are formed on the substrate layer, it may be necessary to carefully control the temperature during melt co-extrusion so that extrusion bonding can be performed in the lowest melting temperature range. Otherwise, deformation and partial incineration of the paper substrate layer may make it difficult to achieve the object of the present invention.

[0223] In addition, the melt coextrusion may be followed by stretching, heat setting, and / or drying. The process conditions for these steps may be any process conditions commonly used in the art, as long as they do not impair the desired effects of the present invention.

[0224] Meanwhile, according to one embodiment of the present invention, the PHA resin may include a first PHA resin and a second PHA resin. In such a case, the first PHA resin, the second PHA resin, and the EVOH resin may be melt-coextruded. That is, three types of resins may be melt-coextruded onto the substrate layer to form a first resin layer, a second resin layer, and an EVOH resin layer. In such a case, the arrangement and order of each resin layer may be variously designed depending on the desired purpose.

[0225] The types and specific properties of the first PHA resin and the second PHA resin are as described above.

[0226] Additionally, at least one polymer resin selected from the group consisting of polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene succinate-adipate (PBSA), polybutylene succinate-terephthalate (PBST), polyhydroxybutyrate-valerate (PHBV), polycaprolactone (PCL), polybutylene succinate adipate terephthalate (PBSAT), thermoplastic starch (TPS), polypropylene (PP), polyethylene terephthalate (PET), and polyethylene (PE) may be melt-extruded with the first PHA resin, second PHA resin, and EVOH resin to form the first resin layer, second resin layer, EVOH resin layer, and polymer resin layer. In such cases, the arrangement and order of the resin layers may be varied depending on the desired purpose.

[0227] Additionally, the biodegradable resin layer, the polymer resin layer, and / or the EVOH resin layer may further contain at least one additive selected from the group consisting of slip agents, antioxidants, crosslinking agents, nucleating agents, fillers, stabilizers, and compatibilizers, the specific types and contents of which are as described above.

[0228] In a method for producing a biodegradable multilayer film, when the biodegradable resin layer and the barrier layer are formed by melt co-extrusion, it is possible to minimize the weight (content) of the barrier layer in the biodegradable multilayer film while simultaneously achieving excellent barrier properties against moisture and oxygen. In particular, when paper is used as the substrate layer and the biodegradable resin layer and the barrier layer are melt co-extruded onto the paper, it is possible to provide an effective biodegradable multilayer film that has optimal barrier properties (shielding effect) against moisture and oxygen and can be biodegraded in soil or the sea.

[0229] Meanwhile, a method for producing a biodegradable multilayer film according to another embodiment of the present invention may include melt-extruding a PHA resin and an EVOH resin to produce a PHA film and an EVOH film, respectively, and laminating them onto a substrate layer to form a biodegradable resin layer and a barrier layer.

[0230] In the method, a PHA resin and an EVOH resin are melt-extruded to produce a PHA film and an EVOH film, respectively, which are then laminated to a substrate layer to form a biodegradable resin layer and a barrier layer, wherein the lamination may be performed by forming an adhesive layer between the substrate layer, the biodegradable resin layer, and the barrier layer. The type, thickness and placement of the adhesive layer are as described above.

[0231] During melt extrusion, the extrusion temperatures of the PHA resin and the EVOH resin may be controlled independently.

[0232] Specifically, the extrusion temperature of the PHA resin and the extrusion temperature of the EVOH resin may be the same or different.

[0233] The extrusion temperature of the PHA resin may be, for example, 120°C to 250°C, for example, 120°C to 200°C, for example, 140°C to 200°C, for example, 140°C to 190°C, for example, 140°C to 180°C, or for example, 140°C to 170°C.

[0234] The extrusion temperature of the EVOH resin may be, for example, 120°C to 250°C, for example, 140°C to 250°C, for example, 140°C to 240°C, for example, 140°C to 230°C, or for example, 140°C to 220°C.

[0235] When the extrusion temperatures of the PHA resin and the EVOH resin are different from each other, the difference in extrusion temperature may be 50°C or less, 40°C or less, or 30°C or less.

[0236] After this, the PHA resin and EVOH resin may each be extruded and then bonded to the laminate using an adhesive layer.

[0237] Eco-friendly packaging materials According to one embodiment of the present invention, there is provided an environmentally friendly packaging material comprising the above-described biodegradable multilayer film.

[0238] Specifically, according to one embodiment of the present invention, the environmentally friendly packaging material may include a biodegradable multilayer film, the biodegradable multilayer film including a substrate layer and a biodegradable resin layer, the biodegradable resin layer including a polyhydroxyalkanoate (PHA) resin, the biodegradable resin layer having a heat seal strength of 0.5 to 15 kgf / 15 mm, and the biodegradable multilayer film having a heat seal strength of 3 g / m 2 Water vapor transmission rate of 10cc / m or less 2 ·Has an oxygen permeability of less than ·atm·days.

[0239] According to another embodiment of the present invention, an environmentally friendly packaging material may include a biodegradable multilayer film, the biodegradable multilayer film including a substrate layer, a barrier layer, and a biodegradable resin layer, the biodegradable resin layer including a polyhydroxyalkanoate (PHA) resin, the biodegradable resin layer having a heat seal strength of 0.5 to 15 kgf / 15 mm, the barrier layer including an ethylene vinyl alcohol (EVOH) resin, and the biodegradable multilayer film having a heat seal strength of 3 g / m 2 Water vapor transmission rate of 10cc / m or less 2 ·Has an oxygen permeability of less than ·atm·days.

[0240] The environmentally friendly packaging may be in the form of a film that can be used, for example, as general purpose disposable packaging and food packaging. The environmentally friendly packaging may include bubble wrap.

[0241] In addition, the eco-friendly packaging material can be used in a variety of applications, including pet food packaging, seaweed packaging, nut packaging, dry food packaging, mask pack packaging, feed packaging, and coffee pouches.

[0242] Environmentally friendly packaging materials may be produced by further processing the biodegradable multilayer film into a desired shape for a desired use, which may be accomplished by any method known in the art, such as extrusion, injection molding, compression molding, pressure molding, blowing (e.g., blown film, blown foam), calendar molding, rotational molding, casting (e.g., cast sheet, cast film), or thermoforming.

[0243] The environmentally friendly packaging material can be disposed of in landfills, and therefore, even when used in large quantities, the risk of environmental pollution is very low compared to conventional packaging materials. The environmentally friendly packaging material has excellent formability and flexibility, which makes it possible to provide a high-quality, biodegradable, environmentally friendly packaging material with excellent physical properties and quality.

[0244] [Embodiments of the present invention] The present invention will be described in detail below with reference to examples. However, the following examples are intended to illustrate the present invention, and the scope of the present invention is not limited thereto. [Example]

[0245] Example 1: Multilayer film having a structure of paper / second resin layer (scPHA) / first resin layer (aPHA) / barrier layer (EVOH) Step 1: Preparation of PHA and EVOH resins As polyhydroxyalkanoate (PHA) resins, a first PHA resin (3-HB-co-4-HB, aPHA) (manufacturer: CJ Corporation, Korea) and a second PHA resin (3-HB-co-4-HB, scPHA) (manufacturer: CJ Corporation, Korea) shown in Table 1 were prepared. As an EVOH resin, an ethylene vinyl alcohol (EVOH) resin (H171B, manufacturer: Kuraray Co., Ltd.) with an ethylene group content of 38 mol% was prepared in the form of pellets.

[0246] [Table 1]

[0247] Step 2: Formation of the biodegradable resin layer (second resin layer and first resin layer) and the barrier layer on the substrate layer by melt co-extrusion Using a T-die triple coextrusion laminator, the EVOH resin prepared in step 1, the first PHA resin (aPHA), and the second PHA resin (scPHA) were loaded into extruders A, B, and C, respectively, in that order. Paper (manufacturer: Moorem) was used as the substrate layer. The EVOH resin, the first PHA resin (aPHA), and the second PHA resin (scPHA) were melt-coextruded (triple extrusion) so that the second resin layer containing the second PHA resin (scPHA) was in contact with the substrate layer. The melt-coextrusion temperatures were set to 240°C, 160°C, and 160°C for the EVOH resin, the first PHA resin (aPHA), and the second PHA resin (scPHA), respectively.

[0248] The biodegradable multilayer film had a structure of paper (83 μm) / second resin layer (scPHA) (15 μm) / first resin layer (aPHA) (15 μm) / barrier layer (EVOH) (8 μm), with a total thickness of 121 μm.

[0249] Example 2: Multilayer film having a structure of paper / first resin layer (aPHA) / second resin layer (scPHA) / barrier layer (EVOH) A multilayer film having a structure of paper (83 μm) / first resin layer (aPHA) (15 μm) / second resin layer (scPHA) (15 μm) / barrier layer (EVOH) (8 μm) and a total thickness of 121 μm was obtained in the same manner as in Example 1, except that in step 2 of Example 1, the EVOH resin, second PHA resin (scPHA), and first PHA resin (aPHA) were loaded into extruders A, B, and C in that order, and melt co-extrusion was carried out so that the first resin layer containing the first PHA resin (aPHA) was in contact with the substrate layer.

[0250] Example 3: Multilayer film having a structure of paper / barrier layer (EVOH) / first resin layer (aPHA) / second resin layer (scPHA) A multilayer film having a structure of paper (83 μm) / barrier layer (EVOH) (8 μm) / first resin layer (aPHA) (15 μm) / second resin layer (scPHA) (15 μm) and a total thickness of 121 μm was obtained in the same manner as in Example 1, except that in step 2 of Example 1, the second PHA resin (scPHA), the first PHA resin (aPHA), and the EVOH resin were charged in this order into extruders A, B, and C, and melt co-extrusion was carried out so that the barrier layer containing the EVOH resin was in contact with the substrate layer.

[0251] Example 4: Multilayer film having a structure of paper / first resin layer (aPHA) / barrier layer (EVOH) / second resin layer (scPHA) A multilayer film having a structure of paper (83 μm) / first resin layer (aPHA) (15 μm) / barrier layer (EVOH) (8 μm) / second resin layer (scPHA) (15 μm) and a total thickness of 121 μm was obtained in the same manner as in Example 1, except that in step 2 of Example 1, the second PHA resin (scPHA), EVOH resin, and first PHA resin (aPHA) were loaded into extruders A, B, and C in that order, and melt co-extrusion was carried out so that the first resin layer containing the first PHA resin (aPHA) was in contact with the substrate layer.

[0252] Example 5: Paper / EVOH / Second Resin Layer (scPHA) A multilayer film having a structure of paper (83 μm) / barrier layer (EVOH) (8 μm) / second resin layer (scPHA) (15 μm) and a total thickness of 106 μm was obtained in the same manner as in Example 1, except that in step 2 of Example 1, the second PHA resin (scPHA) and the EVOH resin were charged in this order into extruders A and B, and melt co-extrusion was carried out so that the barrier layer containing the EVOH resin was in contact with the substrate layer.

[0253] Example 6: Multilayer film (laminate) having a structure of paper / first resin layer (aPHA) / barrier layer (EVOH) / second resin layer (scPHA) In step 2 of Example 1, the EVOH resin was melt-extruded at 240°C using an extruder to form a barrier film (barrier layer), the second PHA resin (scPHA) was melt-extruded at 160°C to form a second resin film (second resin layer), and the first PHA resin (aPHA) was melt-extruded at 160°C to form a first resin film (first resin layer).

[0254] Paper (manufacturer: Moorim) was used as the substrate layer. Each of the films prepared above was laminated onto the substrate layer to form a paper / first resin layer (aPHA) / barrier layer (EVOH) / second resin layer (scPHA) structure. In this case, each layer was bonded using an adhesive solution. As a result, a multilayer film was obtained with a paper (83 μm) / first resin layer (aPHA) (15 μm) / barrier layer (EVOH) (8 μm) / second resin layer (scPHA) (15 μm) structure.

[0255] Example 7: Multilayer film (laminate) having a structure of paper / barrier layer (EVOH) / first resin layer (aPHA) / second resin layer (scPHA) A multilayer film was obtained in the same manner as in Example 6, except that the layering order in Example 6 was changed so that the film had a structure of paper (83 μm) / barrier layer (EVOH) (8 μm) / first resin layer (aPHA) (15 μm) / second resin layer (scPHA) (15 μm).

[0256] Comparative Example 1: Multilayer film (laminate) having a structure of polyethylene terephthalate (PET) / thin aluminum layer / nylon layer / cast polypropylene (CPP) layer A multilayer film was obtained in the same manner as in Example 6, except that the multilayer film was formed to have a structure of polyethylene terephthalate (PET) / thin aluminum layer / nylon layer / cast polypropylene (CPP) layer.

[0257] Comparative Example 2: Multilayer film having a substrate layer / CPP layer structure A multilayer film was obtained in the same manner as in Example 1, except that a cast polypropylene (CPP) resin was used to form the multilayer film so as to have a structure of a substrate layer and a CPP layer.

[0258] Comparative Example 3: Multilayer film having a substrate layer / LDPE layer structure A multilayer film was obtained in the same manner as in Comparative Example 2, except that a low-density polyethylene (LDPE) resin was used instead of a cast polypropylene (CPP) resin to form a multilayer film having a structure of a substrate layer and an LDPE layer.

[0259] Comparative Example 4: Multilayer film having a structure of substrate layer / LLDPE layer A multilayer film was obtained in the same manner as in Comparative Example 2, except that a LLDPE resin was used instead of a cast polypropylene (CPP) resin to form a multilayer film having a structure of a substrate layer and a linear low-density polyethylene (LLDPE) layer.

[0260] Comparative Example 5: Multilayer film having a structure of paper / EVOH / PBAT layers A multilayer film having a structure of paper (83 μm) / barrier layer (EVOH) (8 μm) / polybutylene adipate terephthalate (PBAT) layer (15 μm) was obtained in the same manner as in Example 5, except that PBAT resin (Ankor Bioplastics) was used instead of the second PHA resin (scPHA) in Example 5.

[0261] Evaluation example Evaluation example 1 The heat-sealing method was used to examine the thermal adhesive properties of the multilayer films obtained in the examples and comparative examples. The heat-sealing strength was measured to evaluate the peeling of the thermally bonded portions.

[0262] The heat seal strength was measured using a LLOYD LD5 universal tensile tester at a grip spacing of 50 mm, a speed of 100 mm / min, and a sample width of 15 mm, and the results are shown in Table 2 below.

[0263] [Table 2]

[0264] As can be seen from Table 2 above, the heat seal strength of the first resin layer (aPHA layer) and the second resin layer (scPHA layer) were approximately 6.5 kgf / 15 mm and approximately 5.5 kgf / 15 mm, respectively, and the heat seal strength of the EVOH layer was approximately 2.2 kgf / 15 mm. The heat seal strength of each layer was excellent.

[0265] Evaluation example 2 The water vapor permeability and oxygen permeability of the multilayer films obtained in the examples and comparative examples were measured under the following conditions.

[0266] Water vapor transmission rates (WVTR) were measured using a Mocon Permatran-w3 / 33 water vapor transmission rate meter at 38±0.5°C and 90±2% relative humidity.

[0267] Oxygen transmission rates (OTR) were measured at 23±0.5°C using a Mocon OX2-TRAN 2 / 12 oxygen transmission rate meter.

[0268] The water vapor permeability, oxygen permeability, and biodegradability of the multilayer films obtained in the Examples and Comparative Examples are summarized in Table 3 below.

[0269] [Table 3]

[0270] As can be seen from Table 3 above, the multilayer films of Examples 1 to 7, unlike the multilayer films of Comparative Examples 1 to 5, were biodegradable in both soil and sea, and had significantly low water vapor permeability and oxygen permeability.

[0271] Specifically, the multilayer films of Examples 1 to 7 have a water vapor permeability of 0.38 to 2.55 g / m 2 ·atm·day, and oxygen permeability is 0.17~0.39cc / m 2 ·atm·day.

[0272] In contrast, the multilayer films of Comparative Examples 2 to 4 had a water vapor transmission rate of 4.5 g / m 2 atm·days or more, and oxygen permeability is 1,000cc / m 2 The water vapor permeability and oxygen permeability were significantly increased compared to the multilayer films of Examples 1 to 7.

[0273] In addition, the multilayer film of Comparative Example 1 had a water vapor permeability and an oxygen permeability of 0.09 g / m 2 atm·day and 0.10cc / m 2 ·atm· days, but was not biodegradable in both soil and the ocean.

[0274] Furthermore, in the multilayer film of Comparative Example 5, the biodegradable resin layer contained only PBAT resin without containing PHA resin. Therefore, the water vapor permeability was 4.5 g / m 2 ·atm·day, which was increased compared to the water vapor transmission rates of the multilayer films of Examples 1 to 7. The multilayer film of Comparative Example 5 was not biodegradable in either soil or the sea.

[0275] Furthermore, it was confirmed that the water vapor permeability and oxygen permeability of the multilayer films of Examples 1 to 7 changed significantly depending on the layering order.

[0276] In particular, the multilayer film of Example 4, which has a structure of paper / first resin layer (aPHA layer) / barrier layer (EVOH layer) / second resin layer (scPHA layer), has a water vapor permeability of 0.38 g / m 2 ·atm·day, and oxygen permeability is 0.17cc / m 2 The water vapor permeability and oxygen permeability were significantly lower than those of the multilayer films of Comparative Examples 2 to 5, and the films were biodegradable in both soil and the sea. [Explanation of symbols]

[0277] 1: Biodegradable multilayer film 11: Biodegradable resin layer 12: Barrier layer 13: Base material layer 14: First resin layer 15: Second resin layer 16: First adhesive layer 17: Second adhesive layer

Claims

1. A biodegradable multilayer film comprising a substrate layer and a biodegradable resin layer, wherein the biodegradable resin layer comprises a polyhydroxyalkanoate (PHA) resin, the biodegradable resin layer has a heat seal strength of 0.5 to 15 kgf / 15 mm, and the biodegradable multilayer film has a heat seal strength of 3 g / m ２ Water vapor transmission rate of 10 cc / m or less atm / day ２ A biodegradable multilayer film having an oxygen permeability of atm-days or less.

2. 10. The biodegradable multilayer film of claim 1, further comprising a barrier layer, said barrier layer comprising an ethylene vinyl alcohol (EVOH) resin.

3. 2. The biodegradable multilayer film of claim 1, wherein the polyhydroxyalkanoate (PHA) resin is a polyhydroxyalkanoate copolymer resin containing 4-hydroxybutyrate (4-HB) repeat units, and the polyhydroxyalkanoate copolymer resin contains the 4-hydroxybutyrate (4-HB) repeat units in an amount of 0.1 to 60 wt %, based on the total weight of the polyhydroxyalkanoate copolymer resin.

4. the biodegradable resin layer includes a first resin layer and a second resin layer, the first resin layer comprises a first PHA resin comprising 4-hydroxybutyrate (4-HB) repeat units in an amount of 15% to 60% by weight; the second resin layer comprises a second PHA resin comprising 4-hydroxybutyrate (4-HB) repeat units in an amount of 0.1 wt % to 30 wt %; 3. The biodegradable multilayer film according to claim 2, wherein the first PHA resin and the second PHA resin differ from each other in terms of their content of 4-HB repeating units.

5. the first PHA resin has a glass transition temperature (Tg) of −45° C. to −10° C.; the second PHA resin satisfies at least one characteristic selected from a glass transition temperature (Tg) of −30° C. to 80° C., a crystallization temperature (Tc) of 70° C. to 120° C., and a melting point (Tm) of 100° C. to 170° C.; The biodegradable multilayer film according to claim 4 , wherein the glass transition temperature (Tg) of the first PHA resin and the glass transition temperature (Tg) of the second PHA resin are different from each other.

6. The biodegradable multilayer film according to claim 2 , wherein the barrier layer and the biodegradable resin layer are formed by co-extrusion onto the base layer or by lamination onto the base layer.

7. substrate layer / barrier layer / first resin layer / second resin layer, substrate layer / barrier layer / second resin layer / first resin layer, substrate layer / first resin layer / barrier layer / second resin layer, base material layer / second resin layer / barrier layer / first resin layer, substrate layer / first resin layer / second resin layer / barrier layer, or Base layer / second resin layer / first resin layer / barrier layer The biodegradable multilayer film of claim 4, comprising the structure:

8. 8. The biodegradable multilayer film according to claim 7, wherein the substrate layer comprises at least one selected from the group consisting of paper, polyethylene terephthalate (PET) film, polyimide (PI) film, polypropylene (PP) film, and polyethylene (PE) film.

9. 9. The biodegradable multilayer film according to claim 8, wherein the substrate layer comprises paper, and the biodegradable multilayer film has a structure of substrate layer / first resin layer / barrier layer / second resin layer, or substrate layer / second resin layer / barrier layer / first resin layer.

10. 2. The biodegradable multilayer film according to claim 1, further comprising an adhesive layer, wherein the adhesive layer comprises at least one selected from the group consisting of polyhydroxyalkanoate (PHA), a polysilicone-based compound, polyvinyl alcohol (PVA), ethylene vinyl acetate (EVA), an acrylic resin, and a urethane-based resin.

11. 2. The biodegradable multilayer film of claim 1, further comprising at least one polymer resin layer comprising at least one selected from the group consisting of polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene succinate-adipate (PBSA), polybutylene succinate-terephthalate (PBST), polyhydroxybutyrate-valerate (PHBV), polycaprolactone (PCL), polybutylene succinate adipate terephthalate (PBSAT), thermoplastic starch (TPS), polypropylene (PP), polyethylene terephthalate (PET), and polyethylene (PE).

12. 2. The biodegradable multilayer film according to claim 1, wherein the biodegradable resin layer further comprises at least one additive selected from the group consisting of slip agents, antioxidants, crosslinking agents, nucleating agents, fillers, stabilizers, and compatibilizers.

13. 2. The biodegradable multilayer film according to claim 1, wherein the biodegradable resin layer further comprises at least one biodegradable resin selected from the group consisting of polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene succinate-adipate (PBSA), polybutylene succinate-terephthalate (PBST), polyhydroxybutyrate-valerate (PHBV), polycaprolactone (PCL), polybutylene succinate adipate terephthalate (PBSAT), and thermoplastic starch (TPS).

14. 3. The biodegradable multilayer film according to claim 2, having a thickness of 30 μm to 350 μm, wherein the barrier layer accounts for 10% or less of the thickness of the biodegradable multilayer film, and the thickness ratio of the biodegradable resin layer to the barrier layer is 1:0.1 to 0.

5.

15. The biodegradable multilayer film according to claim 4, wherein the thickness ratio of the first resin layer to the second resin layer is 1:0.5 to 1.

5.

16. 5. The biodegradable multilayer film according to claim 4, wherein the barrier layer has a heat seal strength of 0.5 to 10 kgf / 15 mm, the first resin layer has a heat seal strength of 1 to 15 kgf / 15 mm, and the second resin layer has a heat seal strength of 1 to 12 kgf / 15 mm.

17. 1. A method for producing a biodegradable multilayer film, comprising: The method includes melt-extruding a polyhydroxyalkanoate (PHA) resin onto a substrate layer to form a biodegradable resin layer; the biodegradable resin layer has a heat seal strength of 0.5 to 15 kgf / 15 mm; The biodegradable multilayer film has a density of 3 g / m ２ Water vapor transmission rate of 10 cc / m or less atm / day ２ -Having an oxygen transmission rate of atm-day or less.

18. further comprising melt-extruding an ethylene vinyl alcohol (EVOH) resin to form a barrier layer; 18. The method for producing a biodegradable multilayer film according to claim 17, wherein the biodegradable resin layer and the barrier layer are formed by melt co-extruding the polyhydroxyalkanoate (PHA) resin and the ethylene vinyl alcohol (EVOH) resin onto the substrate layer, or by melt-extruding the polyhydroxyalkanoate (PHA) resin and the ethylene vinyl alcohol (EVOH) resin separately and laminating them onto the substrate layer.

19. 19. The method for producing a biodegradable multilayer film according to claim 18, wherein the biodegradable resin layer and the barrier layer are formed on the substrate layer by melt co-extrusion, and the melt co-extrusion is carried out at a temperature of 120°C to 250°C.

20. 20. The method for producing a biodegradable multilayer film according to claim 18, wherein the biodegradable resin layer and the barrier layer are formed on the substrate layer by lamination, and the lamination is performed by forming an adhesive layer between the substrate layer, the biodegradable resin layer, and the barrier layer.

21. the polyhydroxyalkanoate (PHA) resin comprises a first PHA resin and a second PHA resin; the first PHA comprises 4-hydroxybutyrate (4-HB) repeat units in an amount of 15% to 60% by weight, based on the total weight of the first PHA resin; the second PHA comprises 4-hydroxybutyrate (4-HB) repeat units in an amount of 0.1 wt % to 30 wt % based on the total weight of the second PHA resin; 18. The method for producing a biodegradable multilayer film according to claim 17, wherein the first PHA resin and the second PHA resin differ from each other with respect to their content of 4-HB repeat units.

22. An environmentally friendly packaging material comprising the biodegradable multilayer film according to any one of claims 1 to 16.

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