Biodegradable coating composition, method for preparing the same, and biodegradable article using the same

Abstract

The present invention relates to a biodegradable coating composition, a method for preparing the same, and a biodegradable article using the same. In particular, according to an embodiment of the present invention, the biodegradable coating composition is a copolymerized polyhydroxyalkanoate (PHA) resin comprising a PHA resin, a surfactant, inorganic particles, and a rheology modifier, and comprising 4-hydroxybutyrate (4-HB) repeat units. By using a PHA resin having a weight average molecular weight of 10,000 to 1,200,000 g / mol, the biodegradable coating composition is environmentally compatible due to its excellent biodegradability and biocompatibility, and can have improved dispersibility, coatability, oil resistance, and processability.

Description

[Technical Field]

[0001] The present invention relates to a biodegradable coating composition, a method for preparing the same, and a biodegradable article using the same. [Background technology]

[0002] In recent years, with the increasing concern about environmental issues, research into the treatment and recycling of various household wastes has been actively conducted. Specifically, polymer materials, which are inexpensive and have excellent processability, are widely used to manufacture various products such as paper, films, fibers, packaging materials, bottles, and containers. However, at the end of their lifespan, these products may emit harmful substances when incinerated, and depending on the type of product, they may take hundreds of years to completely decompose naturally.

[0003] Therefore, research continues into biodegradable polymers that can be decomposed in a short time to improve environmental compatibility while improving mechanical properties, oil resistance, water resistance, and processability, and extending the life of the product itself, thereby reducing the amount of waste or improving the recyclability of the product.

[0004] Polyhydroxyalkanoates (PHAs) are biodegradable polymers composed of several hydroxylcarboxylic acids that are produced by many microorganisms and used as intracellular storage materials. Polyhydroxyalkanoates have physical properties similar to those of 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 highly biocompatible.

[0005] On the other hand, it is important to improve mechanical properties such as strength, water resistance, and oil resistance in order to improve the service life and recyclability of various products such as paper, film, fiber, packaging material, bottles, containers, etc. In particular, food packaging materials for packaging foods with high moisture or oil content, such as fruits, vegetables, bread, cookies, ice cream, etc., are problematic in that the packaging materials are easily torn by moisture or oil from the food, thereby contaminating the food or shortening its service life.

[0006]

[0003] In order to improve mechanical properties, water resistance, and oil resistance, a method of forming a coating layer on the surface of a product is used. However, there is a problem in that the coating layer impairs biodegradability and recyclability. Specifically, an additional step may be required to remove the coating layer, or the coating layer may impair the biodegradability and recyclability of the product. Therefore, there is a need for the development of a biodegradable coating composition that is environmentally friendly due to its excellent biodegradability and biocompatibility, yet has excellent dispersibility, coatability, oil resistance, water resistance, and processability. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent Publication No. 2012-0103158 Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, an object of the present invention is to provide a biodegradable coating composition that is environmentally friendly due to its excellent biodegradability and biocompatibility, and that can improve dispersibility, coatability, oil resistance, and processability, a method for preparing the composition, and a biodegradable article using the composition. [Means for solving the problem]

[0009] A biodegradable coating composition according to an embodiment of the present invention includes a polyhydroxyalkanoate (PHA) resin; a surfactant; inorganic particles; and a rheology modifier, wherein the polyhydroxyalkanoate resin is a copolymerized polyhydroxyalkanoate resin containing 4-hydroxybutyrate (4-HB) repeat units and has a weight average molecular weight of 10,000 g / mol to 1,200,000 g / mol.

[0010] Another embodiment of the present invention provides a method for preparing a biodegradable coating composition, comprising the steps of: (1) stirring a polyhydroxyalkanoate (PHA) resin; (2) adding a surfactant; (3) adding a rheology modifier; and (4) adding inorganic particles, wherein steps (2) to (4) are performed simultaneously, sequentially, or randomly selected, and the polyhydroxyalkanoate resin is a copolymerized polyhydroxyalkanoate resin containing 4-hydroxybutyrate (4-HB) repeating units and has a weight average molecular weight of 10,000 g / mol to 1,200,000 g / mol.

[0011] A biodegradable article according to another embodiment of the present invention includes a substrate; and a biodegradable coating layer, wherein the biodegradable coating layer includes a polyhydroxyalkanoate (PHA) resin; a surfactant; inorganic particles; and a rheology modifier, wherein the polyhydroxyalkanoate resin is a copolymerized polyhydroxyalkanoate resin including 4-hydroxybutyrate (4-HB) repeat units and has a weight average molecular weight of 10,000 g / mol to 1,200,000 g / mol. [Effects of the Invention]

[0012] When the biodegradable coating composition according to an embodiment of the present invention contains a specific polyhydroxyalkanoate (PHA) resin, a surfactant, inorganic particles, and a rheology modifier, it is possible to improve dispersibility, dispersion stability, storage stability, coatability, oil resistance, and processability.

[0013] In particular, when the biodegradable coating composition contains inorganic particles that do not contain a hydrophilic functional group as inorganic particles, it is possible to further improve oil resistance.

[0014] Furthermore, the biodegradable coating composition contains a copolymerized polyhydroxyalkanoate resin having a specific repeating unit and weight-average molecular weight as the polyhydroxyalkanoate resin, and has excellent dispersibility despite containing only a small amount of surfactant.

[0015] Therefore, the coating layer formed using the biodegradable coating composition has excellent dispersibility and coatability, as well as excellent biodegradability and biocompatibility, making it environmentally friendly. In particular, the biodegradable article including the coating layer has excellent oil resistance, and therefore can exhibit excellent properties when applied to articles requiring oil resistance, such as food packaging materials for packaging oily foods. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram of a biodegradable article according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram of a biodegradable article according to another embodiment of the present invention. [Figure 3] 1 is a photograph of the surface of the biodegradable articles of Example 2-1, Comparative Example 2-2, and Comparative Example 2-4. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described in detail below. The present invention is not limited to the disclosure shown below, and may be modified in various forms as long as the gist of the present invention is not changed.

[0018] Throughout this specification, when an article is referred to as "comprising" certain elements, it is understood that other elements may be included rather than excluding other elements, unless specifically stated otherwise.

[0019] All numbers and expressions relating to quantities of ingredients, reaction conditions, and the like used herein should be understood as being modified by the term "about" unless otherwise specified.

[0020] In this specification, when it is said that an element is 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 via an intervening element(s).

[0021] Throughout this specification, terms such as first, second, etc. are used to describe various components, but the components should not be limited by the terms. The terms are used only to distinguish one component from another.

[0022] In this specification, the references to "one side" and "the other side" or "upper side" and "lower side" of each component are explained based on the drawings. These terms are merely used to distinguish the components, and may be interchangeable in actual use.

[0023] Additionally, for illustrative purposes, the size of individual elements in the accompanying figures may be exaggerated and not depicted to scale. Further, like reference numerals refer to like elements throughout the specification.

[0024] Biodegradable coating composition A biodegradable coating composition according to an embodiment of the present invention includes a polyhydroxyalkanoate (PHA) resin; a surfactant; inorganic particles; and a rheology modifier, wherein the polyhydroxyalkanoate resin is a copolymerized polyhydroxyalkanoate resin containing 4-hydroxybutyrate (4-HB) repeat units and has a weight average molecular weight of 10,000 g / mol to 1,200,000 g / mol.

[0025] The solids content of the biodegradable coating composition may be 10% to 60% by weight, for example, 10% to 60% by weight, 15% to 55% by weight, 20% to 55% by weight, 25% to 50% by weight, 30% to 45% by weight, or 35% to 45% by weight.

[0026] The biodegradable coating composition may have a viscosity of 130 mPa·s to 1,000 mPa·s. For example, the viscosity of the biodegradable coating composition may be 130 Pa·s to 1,000 Pa·s, 130 Pa·s to 900 mPa·s, 130 mPa·s to 800 mPa·s, 140 mPa·s to 750 mPa·s, 150 mPa·s to 600 mPa·s, 155 mPa·s to 550 mPa·s, 160 mPa·s to 400 mPa·s, 165 mPa·s to 350 mPa·s, or 165 mPa·s to 300 mPa·s.

[0027] Polyhydroxyalkanoate (PHA) resin Polyhydroxyalkanoate (PHA) resins have physical properties similar to those of 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.

[0028] Specifically, PHA resin is a natural thermoplastic polyester polymer that accumulates within microbial cells. Because PHA resin is a biodegradable substance, it can be decomposed and ultimately broken down into carbon dioxide, water, and organic waste without producing toxic waste. In particular, since PHA is biodegradable even in soil and the sea, biodegradable coating compositions and biodegradable articles prepared using the same can have environmentally friendly properties when they contain PHA resin. Therefore, biodegradable coating compositions and biodegradable articles using the same have significant advantages in that they can be used in a variety of fields due to their biodegradability and environmental compatibility.

[0029] When the biodegradable coating composition according to an embodiment of the present invention contains a polyhydroxyalkanoate (PHA) resin, the biodegradability can be improved without deteriorating the mechanical properties.

[0030] PHA resins can be formed by enzyme-catalyzed polymerization of one or more monomer repeat units within living cells.

[0031] The PHA resin may be a copolymerized polyhydroxyalkanoate resin (hereinafter referred to as a PHA copolymer resin), specifically a copolymer in which different repeating units are randomly distributed in the polymer chain.

[0032] Examples of repeating units that can be contained in PHA resins 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-HV), and 2-hydroxybutyrate (hereinafter referred to as 2-hydroxybutanoate). Examples of repeating units include 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 repeating units selected from the above.

[0033] 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.

[0034] More specifically, the PHA resin may include 4-HB repeat units, i.e., the PHA resin may be a PHA copolymer resin that includes 4-HB repeat units.

[0035] Furthermore, 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.

[0036] Additionally, the PHA resin may be a PHA copolymer resin that contains 4-HB repeat units and further contains one type of repeat unit different from the 4-HB repeat unit, or two, three, four, five, six, or more types of repeat units that are different from each other. For example, the PHA resin may be poly-3-hydroxybutyrate-co-4-hydroxybutyrate (hereinafter referred to as 3HB-co-4HB).

[0037] According to embodiments of the present invention, it is important to control the content of 4-HB repeat units in the PHA copolymer resin.

[0038] Specifically, in order to achieve the physical properties desired in the present invention, particularly to enhance biodegradability in soil and sea and to achieve excellent dispersibility, dispersion stability, storage stability, coatability, water resistance, processability, and productivity without deteriorating mechanical properties, it is extremely important to adjust the content of 4-HB repeating units contained in the PHA copolymer resin.

[0039] More specifically, the PHA copolymer resin 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 resin. For example, the 4-HB repeat unit content may be 0.1 wt% to 60 wt%, 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 2 wt%, based on the total weight of the PHA copolymer resin. It may be 9% by weight, 1% by weight to 25% by weight, 1% by weight to 24% by weight, 2% by weight to 20% by weight, 2% by weight to 23% by weight, 3% by weight to 20% by weight, 3% by weight to 15% by weight, 4% by weight to 18% by weight, 5% by weight to 15% by weight, 8% by weight to 12% by weight, 9% by weight to 12% by weight, 15% by weight to 55% by weight, 15% by weight to 50% by weight, 20% by weight to 55% by weight, 20% by weight to 50% by weight, 25% by weight to 55% by weight, 25% by weight to 50% by weight, 35% by weight to 60% by weight, 40% by weight to 55% by weight, or 45% by weight to 55% by weight.

[0040] When the content of 4-HB repeating units satisfies the above range, it is possible to enhance biodegradability in soil and in the sea, and to further improve properties such as dispersibility, dispersion stability, storage stability, coatability, oil resistance, processability, and productivity without reducing mechanical properties.

[0041] According to an embodiment of the present invention, the PHA resin may be a PHA copolymer resin having a controlled crystallinity. Specifically, the PHA resin includes one or more 4-HB repeat units, and the content of the 4-HB repeat units may be controlled to control the crystallinity of the PHA resin.

[0042] Furthermore, the PHA resin may be a copolymerized polyhydroxyalkanoate (PHA) resin containing at least one repeat unit selected from the group consisting of 3-hydroxybutyrate (3-HB), 4-hydroxybutyrate (4-HB), 3-hydroxypropionate (3-HP), 3-hydroxyhexanoate (3-HH), 3-hydroxyvalerate (3-HV), 4-hydroxyvalerate (4-HV), 5-hydroxyvalerate (5-HV), and 6-hydroxyhexanoate (6-HH).

[0043] Specifically, the PHA copolymer resin may include 4-HB repeat units and may further include 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 include 4-HB repeat units and 3-HB repeat units.

[0044] For example, the PHA copolymer resin may comprise 3-HB repeat units in an amount of 20% or more, 35% or more, 40% or more, 50% or more, 60% or more, 70% or more, or 75% or more by weight, and 99% or less, 98% or less, 97% or less, 96% or less, 95% or less, 93% or less, 91% or less, 90% or less, 80% or less, 70% or less, 60% or less, or 55% or less by weight, based on the total weight of the PHA copolymer resin.

[0045] The crystallinity-controlled PHA resin may have its crystallinity and amorphous nature controlled by increasing the disorder in its molecular structure, specifically by controlling the type or ratio of monomers or the type or content of isomers.

[0046] According to an embodiment of the present invention, the PHA resin may contain two or more PHA resins having different crystallinity levels. Specifically, the PHA resin may be prepared by mixing two or more PHA resins having different crystallinity levels so as to have a 4-HB repeat unit content within a specific range.

[0047] In particular, the PHA resin may include a first PHA resin that is a semi-crystalline PHA resin.

[0048] As a controlled-crystallinity semi-crystalline PHA (hereinafter referred to as scPHA) resin, the first PHA resin may contain 4-HB repeat units in an amount of 0.1 to 30% by weight. For example, the first PHA resin may contain 4-HB repeat units in an amount of 0.1 to 30% by weight, 0.5 to 30% by weight, 1 to 30% by weight, 3 to 30% by weight, 1 to 28% by weight, 1 to 25% by weight, 1 to 24% by weight, 1 to 15% by weight, 2 to 25% by weight, 3 to 25% by weight, 3 to 24% by weight, 5 to 24% by weight, 7 to 20% by weight, 10 to 20% by weight, 15 to 25% by weight, or 15 to 24% by weight.

[0049] The glass transition temperature (Tg) of the first PHA resin may be -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. The crystallization temperature (Tc) of the first PHA resin may be 70°C to 120°C, 75°C to 120°C, or 75°C to 115°C. The melting point (Tm) of the first PHA resin may be 105°C to 165°C, 110°C to 160°C, 115°C to 155°C, or 120°C to 150°C.

[0050] The first PHA resin may have a weight average molecular weight of 10,000 g / mol to 1,200,000 g / mol, 50,000 g / mol to 1,100,000 g / mol, 100,000 g / mol to 1,000,000 g / mol, 100,000 g / mol to 900,000 g / mol, 200,000 g / mol to 800,000 g / mol, 200,000 g / mol to 600,000 g / mol, or 200,000 g / mol to 400,000 g / mol.

[0051] Additionally, the PHA resin may include a second PHA, which is an amorphous PHA resin with controlled crystallinity.

[0052] As an amorphous PHA (hereinafter referred to as aPHA) resin with controlled crystallinity, the second PHA resin may contain 4-HB repeat units in an amount of 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.

[0053] The glass transition temperature (Tg) of the second PHA resin may be -45°C to -10°C, -35°C to -15°C, -35°C to -20°C, or -30°C to -20°C.

[0054] Furthermore, the crystallization temperature (Tc) of the second PHA resin may not be measured, or may be 60°C to 120°C, 60°C to 110°C, 70°C to 120°C, or 75°C to 115°C. The melting point (Tm) of the second PHA resin may not be measured, or may be 100°C to 170°C, 100°C to 160°C, 110°C to 160°C, or 120°C to 150°C.

[0055] The second PHA resin may have a weight average molecular weight of 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, 200,000 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.

[0056] The first PHA resin and the second PHA resin can be distinguished based on the content of 4-HB repeating units, and may have at least one property selected from the group consisting of the glass transition temperature (Tg), crystallization temperature (Tc), and melting point (Tm) described above. Specifically, the first PHA resin and the second PHA resin can be distinguished based on the content of 4-HB repeating units, glass transition temperature (Tg), crystallization temperature (Tc), melting point (Tm), etc.

[0057] According to embodiments of the present invention, the PHA resin may include a first PHA resin, or both a first PHA resin and a second PHA resin.

[0058] Specifically, when the PHA resin contains a first PHA resin that is a semi-crystalline PHA resin, or both a first PHA resin that is a semi-crystalline PHA resin and a second PHA resin that is an amorphous PHA resin, more specifically, when the contents of the first PHA resin and the second PHA resin are adjusted, it is possible to further improve dispersibility, dispersion stability, storage stability, coatability, and processability.

[0059] Furthermore, the glass transition temperature (Tg) of the PHA resin may be -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.

[0060] Furthermore, the crystallization temperature (Tc) of the PHA resin may not be measured, or may be 60°C to 120°C, 60°C to 110°C, 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.

[0061] The melting point (Tm) of the PHA resin may not be measured, or may be 100°C to 170°C, 105°C to 170°C, 105°C to 165°C, 110°C to 160°C, 115°C to 155°C, 110°C to 150°C, 120°C to 150°C, or 120°C to 140°C.

[0062] Furthermore, the PHA resin may have a weight average molecular weight of 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. mol, 250,000g / mol to 1,150,000g / mol, 300,000g / mol to 1,100,000g / mol, 350,000g / mol to 1,000,000g / mol, 350,000g / mol to 950,000g / mol, 100,000g / mol to 900,000g / mol, 200,000g / mol to 800 ,000 g / mol, 200,000 g / mol to 700,000 g / mol, 250,000 g / mol to 650,000 g / mol, 200,000 g / mol to 400,000 g / mol, 300,000 g / mol to 800,000 g / mol, 300,000 g / mol to 600,000 g / mol, 500,000 g / mol to 1,2 The molecular weight may be 50,000 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, 600,000 g / mol to 900,000 g / mol, or 500,000 g / mol to 900,000 g / mol.

[0063] The PHA resin may have a crystallinity of 90% or less as measured by differential scanning calorimetry (DSC). For example, the crystallinity of the PHA resin may be 90% or less, 85% or less, 80% or less, 75% or less, or 70% or less as measured by differential scanning calorimetry.

[0064] Furthermore, the PHA resin may have an average particle size of 0.5 μm to 5 μm. For example, the PHA resin may have an average particle size of 0.5 μm to 5 μm, 0.5 μm to 4.5 μm, 0.7 μm to 4 μm, 1 μm to 3.5 μm, or 1.2 μm to 3.5 μm.

[0065] The average particle size of the PHA resin may be measured using a nanoparticle size analyzer (e.g., Zetasizer Nano ZS). Specifically, the average particle size of the PHA resin is measured by dynamic light scattering (DLS) using a Zetasizer Nano ZS (manufacturer: Marven) at a temperature of 25°C and a measurement angle of 175°. In such cases, the peak value obtained by the polydispersity index (PDI) within a confidence interval of 0.5 was considered to be the particle size.

[0066] The PHA resin may have a polydispersity index (PDI) of less than 2.5. For example, the polydispersity index of the PHA resin may be less than 2.5, 2.3 or less, 2.1 or less, or 2.0 or less.

[0067] When the average particle size and polydispersity index of the PHA resin satisfy the above ranges, the dispersibility, dispersion stability, storage stability, coatability, and processability can be further improved.

[0068] Furthermore, PHA resins can be obtained by cell disruption using non-mechanical or chemical methods. Specifically, since PHA resins are natural thermoplastic polyester polymers that accumulate within microbial cells and have relatively large average particle sizes, they may be obtained by a disruption process to improve dispersibility, coatability, and processability.

[0069] According to another embodiment of the present invention, the biodegradable coating composition may further comprise a biodegradable polymer.

[0070] Specifically, the biodegradable polymer may include at least one selected from the group consisting of polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), thermoplastic starch (TPS), polybutylene succinate terephthalate (PBST), polyethylene terephthalate (PET), polybutylene succinate adipate (PBSA), polybutylene adipate (PBA), polypropylene (PP), polyethylene (PE), and polycaprolactone (PCL). When the biodegradable coating composition further includes a biodegradable polymer, it may be more advantageous to control properties such as mechanical properties.

[0071] Furthermore, the biodegradable coating composition may contain the PHA resin in an amount of 10% to 70% by weight based on the total weight of the biodegradable coating composition on a solids basis. For example, the PHA resin content may be 10% to 70% by weight, 20% to 65% by weight, 25% to 55% by weight, 30% to 45% by weight, or 35% to 40% by weight based on the total weight of the biodegradable coating composition on a solids basis.

[0072] surfactants According to an embodiment of the present invention, the biodegradable coating composition includes a surfactant. When the biodegradable coating composition includes a surfactant, dispersibility, dispersion stability, storage stability, coatability, and processability can be further improved.

[0073] Specifically, the surfactant may be at least one selected from the group consisting of cationic surfactants, anionic surfactants, phosphate surfactants, fatty acid surfactants, acrylic surfactants, urethane surfactants, epoxy surfactants, and nonionic surfactants. The surfactant may be a polymer surfactant containing at least one selected from the group consisting of carboxylic acids, amines, isocyanates, and derivatives thereof.

[0074] For example, the surfactant may be at least one selected from the group consisting of polyvinyl alcohol, sodium dodecylbenzenesulfonate, polyvinylpyrrolidone, methyl polyethylene alkyl ether, alkylbenzenesulfonate, nonylphenol ether sulfate, sodium lauryl sulfate, lithium dodecyl sulfate, alkyl phosphate, glyceryl ester, and polypropylene glycol ester.

[0075] Furthermore, the biodegradable coating composition may contain a surfactant in an amount of less than 0.3 wt % based on the total weight of the biodegradable coating composition on a solids basis. For example, the surfactant content may be less than 0.3 wt %, less than 0.2 wt %, or less than 0.15 wt %, or may be 0.01 wt % to less than 0.3 wt %, 0.01 wt % to 0.25 wt %, 0.03 wt % to 0.2 wt %, or 0.05 wt % to 0.15 wt %, based on the total weight of the biodegradable coating composition on a solids basis.

[0076] Although the biodegradable coating composition contains a smaller amount of surfactant than conventional compositions, it still has excellent dispersibility, dispersion stability, storage stability, coatability, and processability.

[0077] inorganic particles According to an embodiment of the present invention, the biodegradable coating composition comprises inorganic particles.

[0078] Specifically, the inorganic particles may not contain hydrophilic functional groups, or may contain hydrophobic functional groups. When the biodegradable coating composition contains inorganic particles that do not contain hydrophilic functional groups or inorganic particles that contain hydrophobic functional groups, the oil resistance can be further improved.

[0079] More specifically, when the biodegradable coating composition contains inorganic particles, the oil resistance can be improved by adjusting the contact angle on the surface of the coating layer formed using the composition.

[0080] The inorganic particles may be at least one selected from the group consisting of talc, clay, silica, titanium oxide, montmorillonite, boron nitride, calcium carbonate, titanium dioxide, antimony trioxide, and zinc oxide.

[0081] Furthermore, the inorganic particles may be spherical, irregular, branched, rod-like, bead-like, ellipsoidal, or plate-like. Specifically, the inorganic particles may have different shapes depending on their types. When the biodegradable coating composition contains inorganic particles of specific types and shapes, the oil resistance can be further improved.

[0082] The biodegradable coating composition may contain inorganic particles in an amount of 0.1 wt % to 10 wt % based on the total weight of the biodegradable coating composition on a solids basis. For example, the content of the inorganic particles may be 0.1 wt % to 10 wt %, 0.2 wt % to 8 wt %, 0.5 wt % to 4 wt %, 0.7 wt % to 2 wt %, or 0.9 wt % to 1.5 wt % based on the total weight of the biodegradable coating composition on a solids basis.

[0083] Rheology Modifiers According to an embodiment of the present invention, the biodegradable coating composition includes a rheology modifier. When the biodegradable coating composition includes a rheology modifier, the coatability, processability, and productivity can be further improved.

[0084] The rheology modifier may be at least one selected from the group consisting of gums, clay minerals, cellulose derivatives, cellulose-based modifiers, acrylic modifiers, and urethane-based modifiers. For example, the rheology modifier may be one of gums, clay minerals, or cellulose-based modifiers, or may be a mixture of two types, such as gums and clay minerals, or gums and cellulose-based modifiers.

[0085] The gum may be at least one selected from the group consisting of xanthan gum, guar gum, gellan gum, locust gum, gum arabic, carrageenan, karaya gum, gum ghatti, tara gum, tamarind gum, and tragacanth gum. The clay mineral may be at least one selected from the group consisting of bentonite, smectite, ether pulgite, montmorillonite, kaolinite, sericite, and illite.

[0086] The cellulose derivative may be at least one selected from the group consisting of casein, sodium caseinate, and sodium alginate. The cellulose-based modifier may be at least one selected from the group consisting of methyl cellulose, hydroxypropyl cellulose, and methylhydroxypropyl cellulose.

[0087] Furthermore, the rheology modifier may have a branched, linear, plate-like, irregular, spherical, or rod-like shape, which can further improve the coatability, processability, and productivity.

[0088] The rheology modifier may be used in an amount of 0.01 wt % to 20 wt %, 0.01 wt % to 15 wt %, 0.01 wt % to 12 wt %, 0.01 wt % to 10 wt %, 0.01 wt % to 8 wt %, 0.01 wt % to 5 wt %, 0.01 wt % to 4 wt %, 0.01 wt % to 3 wt %, 0.02 wt % to 2 wt %, 0.02 wt % to 1.5 wt %, or 0.03 wt % to 1 wt %, based on the total weight of the biodegradable coating composition on a solids basis.

[0089] Additionally, the biodegradable coating composition may further comprise at least one additive selected from the group consisting of antioxidants, stabilizers, antibacterial agents, antifoaming agents, preservatives, and pH adjusters.

[0090] The antioxidant is an additive for preventing decomposition by ozone or oxygen, preventing oxidation during storage, and preventing deterioration of physical properties. Any commonly used antioxidant may be used as long as it does not impair the effects of the present invention.

[0091] Specifically, the antioxidant may include at least one selected from the group consisting of hindered phenol-based antioxidants and phosphite-based (phosphorus-based) antioxidants.

[0092] For example, the hindered phenolic antioxidant may include 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.

[0093] Furthermore, 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.

[0094] The antioxidant may be used in an amount of 0.01% to 20% by weight, 0.01% to 15% by weight, 0.01% to 12% by weight, 0.01% to 10% by weight, 0.01% to 8% by weight, 0.01% to 5% by weight, 0.2% to 4.5% by weight, 0.2% to 4% by weight, or 0.5% to 3% by weight, based on the total weight of the biodegradable coating composition on a solids basis.

[0095] The stabilizer is an additive for protecting the composition from oxidation and heat and preventing color change. Any commonly used stabilizer may be used as the stabilizer as long as the effect of the present invention is not impaired.

[0096] Specifically, the stabilizer may be at least one selected from the group consisting of trimethyl phosphate, triphenyl phosphate, trimethylphosphine, phosphoric acid, and phosphorous acid.

[0097] The stabilizer may be used in an amount of 0.01% to 20% by weight, 0.01% to 15% by weight, 0.01% to 12% by weight, 0.01% to 10% by weight, 0.01% to 8% by weight, 0.01% to 5% by weight, 0.2% to 4.5% by weight, 0.2% to 4% by weight, or 0.5% to 3% by weight, based on the total weight of the biodegradable coating composition on a solids basis.

[0098] The antibacterial agent may be at least one natural antibacterial agent selected from the group consisting of organic acids, bacteriocins, and compounds containing elements such as calcium agents or colloids, or silver. The antibacterial agent may be at least one selected from the group consisting of polylysine, benzisothiazolinone, vinegar powder, chitooligosaccharide, hydrogen peroxide, ethylenediaminetetraacetic acid, potassium sorbate, sorbic acid, propionic acid, potassium propionate, sodium benzoate, 1,2-hexanediol, and 1,2-octanediol.

[0099] The antimicrobial agent may be used in an amount of 0.01% to 5% by weight, 0.01% to 3% by weight, 0.01% to 1% by weight, 0.1% to 1% by weight, 0.2% to 1% by weight, or 0.3% to 1% by weight, based on the total weight of the biodegradable coating composition on a solids basis.

[0100] Furthermore, the antifoaming agent is an additive for preventing or reducing foaming. Any commonly used antifoaming agent may be used as the antifoaming agent as long as the effect of the present invention is not impaired.

[0101] For example, the defoaming agent may be at least one selected from the group consisting of alcohol-based defoaming agents, polar compound-based defoaming agents, inorganic particle-based defoaming agents, and silicone-based defoaming agents, or may be at least one selected from the group consisting of ethyl alcohol, 2-ethylhexanol, polysiloxane, dimethylpolysiloxane, silicone paste, silicone emulsion, silicone-treated powder, fluorosilicone, distearic acid, ethylene glycol, and natural wax.

[0102] The antifoaming agent may be used in an amount of 0.0001% to 5% by weight, 0.0001% to 3% by weight, 0.0001% to 1% by weight, 0.001% to 1% by weight, or 0.001% to 0.5% by weight, based on the total weight of the biodegradable coating composition on a solids basis.

[0103] Furthermore, the preservative may be at least one natural preservative selected from the group consisting of hydroxyacetophenone, Centella asiatica extract, 1,2-hexanediol, and 1,3-butanediol, or at least one preservative selected from the group consisting of 1,2-benzisothiazolin-3-one and potassium benzoate, but is not limited thereto.

[0104] The preservative may be used in an amount of 0.01% to 20% by weight, 0.01% to 15% by weight, 0.01% to 12% by weight, 0.01% to 10% by weight, 0.01% to 8% by weight, 0.01% to 5% by weight, 0.2% to 4.5% by weight, 0.2% to 4% by weight, or 0.5% to 3% by weight, based on the total weight of the biodegradable coating composition on a solids basis.

[0105] Furthermore, a pH adjuster refers to a substance added to a solution to adjust the pH. The pH adjuster may include both a pH-lowering agent for lowering the pH and a pH-elevating agent for raising the pH. Specifically, the pH-lowering agent may be a strong acidic substance such as sulfuric acid and hydrochloric acid or an aqueous ammonium salt solution, and the pH-elevating agent may be a basic substance such as aqueous ammonia, sodium hydroxide, lithium hydroxide, potassium hydroxide, or an aqueous acetate solution, but is not limited thereto.

[0106] For example, the pH-raising agent may be at least one selected from the group consisting of acetic acid, lactic acid, hydrochloric acid, phosphoric acid, sodium hydroxide, citric acid, malic acid, fumaric acid, potassium phosphate, sodium bicarbonate, and sodium phosphate.

[0107] The pH adjuster may be used in an amount of 0.01% to 20% by weight, 0.01% to 15% by weight, 0.01% to 12% by weight, 0.01% to 10% by weight, 0.01% to 8% by weight, 0.01% to 5% by weight, 0.2% to 4.5% by weight, 0.2% to 4% by weight, or 0.5% to 3% by weight, based on the total weight of the biodegradable coating composition on a solids basis.

[0108] Method for preparing a biodegradable coating composition Another embodiment of the present invention provides a method for preparing a biodegradable coating composition, comprising the steps of: (1) stirring a polyhydroxyalkanoate (PHA) resin; (2) adding a surfactant; (3) adding a rheology modifier; and (4) adding inorganic particles, wherein steps (2) to (4) are performed simultaneously, sequentially, or randomly selected, and the polyhydroxyalkanoate resin is a copolymerized polyhydroxyalkanoate resin containing 4-hydroxybutyrate (4-HB) repeating units and has a weight average molecular weight of 10,000 g / mol to 1,200,000 g / mol.

[0109] First, the polyhydroxyalkanoate (PHA) resin is stirred (step (1)).

[0110] Specifically, the first aqueous dispersion may be prepared by stirring a PHA resin, the details of which are as described above.

[0111] Stirring may be performed at 3,000 rpm or less for 5 to 150 minutes, for example, using a mixer that utilizes uniaxial shear stress (product name: Homo-disper, manufacturer: Premix, maximum rotation speed per minute: 8,000 rpm). Stirring may be carried out at 3,000 rpm or less, 2,500 rpm or less, 2,000 rpm or less, 1,500 rpm or less, 1,000 rpm or less, 800 rpm or less, 650 rpm or less, 500 rpm to 3,000 rpm, 550 rpm to 2,500 rpm, or 600 rpm to 2,000 rpm for 5 to 150 minutes, 20 to 130 minutes, 25 to 110 minutes, 30 to 100 minutes, 60 to 120 minutes, 70 to 140 minutes, 5 to 70 minutes, 10 to 60 minutes, 20 to 80 minutes, or 30 to 60 minutes.

[0112] When the stirring is carried out under the above conditions, the dispersibility, dispersion stability, storage stability, coatability, and processability can be further improved.

[0113] Additionally, the stirring may be carried out in a solvent.

[0114] Specifically, the solvent used in the stirring may be water, distilled water, or a hydrophilic solvent. Specifically, the solvent may be water, distilled water, or a hydrophilic solvent, or a mixture of water, distilled water, and a hydrophilic solvent. For example, the hydrophilic solvent may be at least one selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, tert-amyl alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, and cyclohexanol.

[0115] The solids content of the first aqueous dispersion may be 10% to 60% by weight, for example, 10% to 60% by weight, 15% to 55% by weight, 20% to 55% by weight, 25% to 50% by weight, 30% to 45% by weight, or 35% to 45% by weight.

[0116] Steps (2)-(4) may then be performed simultaneously, sequentially, or in a randomly selected manner.

[0117] Specifically, step (2) is a step of adding a surfactant, step (3) is a step of adding a rheology modifier, and step (4) is a step of adding inorganic particles.

[0118] Details regarding the surfactant, rheology modifier, and inorganic particles are as described above.

[0119] More specifically, steps (2) to (4) may be performed simultaneously or sequentially. Steps (2) to (4) may be randomly selected and performed one at a time. For example, steps (2) to (4) may be performed in the order of steps (2), (3), and (4); steps (3), (2), and (4); steps (4), (2), and (3); or steps (2), (4), and (3).

[0120] According to an embodiment of the present invention, steps (2) to (4) may be performed sequentially.

[0121] Specifically, a surfactant and a rheology modifier can be added to a first aqueous dispersion to prepare a second aqueous dispersion, and inorganic particles can be added to the second aqueous dispersion to prepare a biodegradable coating composition.

[0122] Furthermore, stirring may be further carried out in one or more steps selected from steps (2) to (4). Details of stirring are as described above.

[0123] Specifically, the surfactant may be added to the first aqueous dispersion prepared in step (1) while stirring, the rheology modifier may be further added thereto while stirring to prepare a second aqueous dispersion, and the inorganic particles may be added to the second aqueous dispersion while stirring to prepare the biodegradable coating composition.

[0124] Method for preparing biodegradable articles A method for preparing a biodegradable article according to another embodiment of the present invention includes the steps of preparing a biodegradable coating composition; and forming a biodegradable coating layer from the biodegradable coating composition.

[0125] Details regarding the preparation of the biodegradable coating composition are described above.

[0126] A biodegradable coating layer is then formed on at least one surface of the substrate using a biodegradable coating composition.

[0127] According to an embodiment of the present invention, the step of forming a biodegradable coating layer may be carried out by coating a biodegradable coating composition on a substrate and drying it.

[0128] The substrate is not limited as long as it can form a biodegradable coating layer on the surface of the substrate. For example, the substrate may be at least one selected from the group consisting of paper, kraft paper, cloth, nonwoven fabric, polyethylene terephthalate (PET) film, polyester film such as polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene adipate terephthalate (PBAT), and polybutylene succinate terephthalate (PBST), and polyimide (PI) film.

[0129] Specifically, from the viewpoint of enhancing the coatability of the substrate, the substrate may preferably be a substrate made of a single material. The substrate may be, but is not limited to, paper, kraft paper, cloth, or nonwoven fabric. Furthermore, when the substrate includes paper or kraft paper, it has better biodegradability than other plastic materials, which may be more advantageous for providing environmentally friendly packaging materials.

[0130] The substrate may have a thickness of 15 μm or more. For example, the thickness of the substrate may be 15 μm or more, 20 μm or more, 50 μm or more, 70 μm or more, 100 μm or more, 130 μm or more, 150 μm or more, 200 μm or more, 300 μm or more, or 500 μm or more.

[0131] Furthermore, the base material is 30 g / m 2 ~500g / m 2 For example, if the substrate is paper, kraft paper, woven fabric, knitted fabric, or nonwoven fabric, the basis weight of the substrate may be 30 g / m 2 ~500g / m 2 , 30g / m 2 ~350g / m2 , 30g / m 2 ~200g / m 2 , 50g / m 2 ~200g / m 2 , 80g / m 2 ~200g / m 2 , 100g / m 2 ~200g / m 2 , 130g / m 2 ~190g / m 2 , 150g / m 2 ~185g / m 2 , or 120 g / m 2 ~320g / m 2 may be.

[0132] Alternatively, a barrier layer may be disposed on at least one surface of the substrate. An environmentally compatible barrier film may be coated on the surface of the substrate to provide moisture and / or oxygen barrier properties, or a functional coating layer having antistatic or adhesive properties may be further formed. 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 desired effects of the present invention.

[0133] Furthermore, the biodegradable coating composition is 5 g / m 2 ~100g / m 2 For example, the coating amount may be 5 g / m 2 ~100g / m 2 , 5g / m 2 ~85g / m 2 , 5g / m 2 ~70g / m 2 , 8g / m 2 ~60g / m 2 , 9g / m 2 ~50g / m 2 , 5g / m 2 ~50g / m 2 , 6g / m 2 ~40g / m 2 , 7g / m 2 ~30g / m 2 , 8g / m 2~20g / m 2 , or 10 g / m 2 ~40g / m 2 When the coating amount satisfies the above range, the coating properties, productivity, and processability can be further improved.

[0134] Furthermore, coating may be performed once to form one coating layer, or may be performed twice or more to form multiple coating layers. The coating amount can be adjusted within the above range depending on the desired number of coating layers. Specifically, the coating amount may be the total amount used for multiple coating layers.

[0135] Once the biodegradable coating composition has been applied to the substrate, it may be dried for 5 seconds to 30 minutes at 100° C. to 200° C. For example, drying may be carried out at 100° C. to 200° C., 110° C. to 185° C., 120° C. to 180° C., or 130° C. to 175° C. for 5 seconds to 30 minutes, 10 seconds to 25 minutes, 20 seconds to 20 minutes, 30 seconds to 15 minutes, or 40 seconds to 10 minutes.

[0136] The formation of the biodegradable coating layer may be carried out by any coating process commonly used in the art, without particular limitation, including, but not limited to, gravure printing coating, slot coating, doctor blade coating, spray coating, bar coating, spin coating, or in-line coating.

[0137] biodegradable articles A biodegradable article according to another embodiment of the present invention includes a substrate; and a biodegradable coating layer, wherein the biodegradable coating layer includes a polyhydroxyalkanoate (PHA) resin; a surfactant; inorganic particles; and a rheology modifier, wherein the polyhydroxyalkanoate resin is a copolymerized polyhydroxyalkanoate resin including 4-hydroxybutyrate (4-HB) repeat units and has a weight average molecular weight of 10,000 g / mol to 1,200,000 g / mol.

[0138] Figure 1 shows a biodegradable article according to an embodiment of the present invention, and Figure 2 shows a biodegradable article according to another embodiment of the present invention.

[0139] Specifically, Figure 1 shows a biodegradable article (1) in which a biodegradable coating layer (200) is formed on one side of a substrate (100), and Figure 2 shows a biodegradable article (1) in which a biodegradable coating layer (200) is formed on both sides of a substrate (100).

[0140] When a biodegradable article includes a biodegradable coating layer on one or both sides of a substrate, and the biodegradable coating layer includes a PHA resin, a surfactant, inorganic particles, and a rheology modifier, the excellent biodegradability and biocompatibility make it environmentally compatible and it can have excellent coatability, productivity, and processability. In particular, a biodegradable article including a biodegradable coating layer has excellent oil resistance, and therefore can exhibit excellent properties when used as an article requiring oil resistance, such as a food packaging material for packaging oily foods.

[0141] Details regarding the substrate are as described above.

[0142] Furthermore, the biodegradable coating layer may have a contact angle of 30° to 150°. For example, the contact angle of the biodegradable coating layer may be 30° to 150°, 40° to 140°, 40° to 130°, or 50° to 120°. When the contact angle of the biodegradable coating layer satisfies the above range, it may have excellent oil resistance.

[0143] The contact angle can be measured at room temperature (25° C.) using a contact angle meter (product name: DSA100, manufacturer: KRUSS).

[0144] Furthermore, the biodegradable coating layer may have a thickness of 5 μm to 50 μm, 5 μm to 40 μm, or 6 μm to 30 μm.

[0145] The biodegradable article may have a kit rating of 5 or greater as measured by TAPPI UM 557. For example, the kit rating may be 5 or greater or 6 or greater. When the kit rating of the biodegradable article satisfies the above range, the biodegradable article has excellent oil resistance.

[0146] Specifically, the kit evaluation can be measured by an oil resistance kit evaluation test in accordance with TAPPI UM 557 "Repellency of Paper and Board to Grease, Oil, and Waxes (Kit Test)."

[0147] More specifically, the kit evaluation test reagent is dropped from a specific height onto the surface of a biodegradable article (5 cm wide and 15 cm long), i.e., onto the coating layer formed on the biodegradable article. Then, after a specific time has passed, the excess kit evaluation test reagent is wiped off with a clean tissue or cotton pad, and the surface is immediately visually inspected to determine the oil resistance kit rating.

[0148] In this test, if the surface of the biodegradable article becomes significantly darker in color compared to a surface on which the test reagent has not been dropped, it is determined to have failed; otherwise, it is determined to have passed. The above test is repeated using kit evaluation test reagents with higher scores until a kit evaluation test reagent is found to fail. The oil resistance kit rating can be determined as the average of the kit evaluation test reagents with the highest score that passed.

[0149] The biodegradable article comprising the biodegradable coating layer may be, but is not limited to, packaging material, cardboard boxes, shopping bags, disposable tableware, packaging containers, or paper straws.

[0150] The present invention will now be described in more detail with reference to the following examples, which are intended to illustrate the present invention and are not intended to limit the scope of the invention. [Example]

[0151] Preparation of Biodegradable Coating Compositions Example 1-1 (1) Preparation of PHA resin A polyhydroxyalkanoate (PHA) resin with a solid content of 10 wt% (4-hydroxybutyrate (4-HB) content: 10 wt%, weight average molecular weight (Mw): 340,000 g / mol, average particle size: 2 μm, polydispersity index (PDI): 1.9, manufacturer: CJ) was prepared. The PHA resin was obtained by chemical powdering using sodium dodecylbenzenesulfonate.

[0152] (2) Preparation of biodegradable coating composition A first aqueous dispersion having a solids content of 40% by weight was prepared by centrifuging the PHA resin in an aqueous system.

[0153] Then, 97 parts by weight of the first aqueous dispersion and 1 part by weight of polyvinyl alcohol (PVA, manufacturer: Kuraray, hydrolysis rate: 80%) having a surfactant concentration of 10% were charged into a 1-liter glass beaker and stirred at 1,500 rpm for 60 minutes using a mixer (product name: Homo-disper, manufacturer: Premix, maximum rotation speed: 8,000 rpm). Then, 1 part by weight of xanthan gum (manufacturer: Dyne Materials) having a concentration of 5% as a rheology modifier (Rr) was added to the mixture, followed by stirring at 600 rpm for 10 minutes to prepare a second aqueous dispersion having a solids content of 39% by weight.

[0154] Then, 1 part by weight of spherical silica having hydrophobic functional groups (product name: R202, manufacturer: Evonik) as inorganic particles was added to the second aqueous dispersion, followed by stirring at 2,000 rpm for 30 minutes to prepare a biodegradable coating composition having a solids content of 39.95% by weight.

[0155] Example 1-2 In step (2), a biodegradable coating composition was prepared in the same manner as in Example 1-1, except that irregular talc (manufacturer: Kotz) having no hydrophilic functional groups was used as the inorganic particles.

[0156] Examples 1-3 In step (2), a biodegradable coating composition was prepared in the same manner as in Example 1-1, except that platelet-type montmorillonite (manufacturer: Sigma-Aldrich) not having hydrophilic functional groups was used as the inorganic particles.

[0157] Examples 1-4 In step (2), a biodegradable coating composition was prepared in the same manner as in Example 1-1, except that platelet-shaped boron nitride (manufacturer: IWsolution) not having hydrophilic functional groups was used as the inorganic particles.

[0158] Examples 1-5 In step (2), a biodegradable coating composition was prepared in the same manner as in Example 1-1, except that 0.5 parts by weight of spherical silica having hydrophobic functional groups (product name: R202, manufacturer: Evonik) was used as the inorganic particles.

[0159] Examples 1-6 In step (2), a biodegradable coating composition was prepared in the same manner as in Example 1-1, except that 3 parts by weight of spherical silica having hydrophobic functional groups (product name: R202, manufacturer: Evonik) was used as the inorganic particles.

[0160] Examples 1-7 A biodegradable coating composition was prepared in the same manner as in Example 1-1, except that in step (1), a polyhydroxyalkanoate (PHA) resin having a solids content of 10 wt % (4-hydroxybutyrate (4-HB) content: 8 wt %, weight average molecular weight (Mw): 300,000 g / mol, average particle size: 3 μm, polydispersity index (PDI): 1.9, manufacturer: CJ) was prepared.

[0161] Comparative Example 1-1 A biodegradable coating composition was prepared in the same manner as in Example 1-1, except that in step (2), the addition of inorganic particles was not carried out together with stirring.

[0162] Comparative Example 1-2 In step (1), a polyhydroxyalkanoate (PHA) resin having a solid content of 5 wt% (4-hydroxybutyrate (4-HB) content: 10 wt%, weight average molecular weight (Mw): 600,000 g / mol, average particle size: 2 μm, polydispersity index (PDI): 1.9, manufacturer: CJ) was prepared; and in step (2), a biodegradable coating composition was prepared in the same manner as in Example 1-1, except that no inorganic particles were added during stirring.

[0163] Comparative Examples 1-3 A biodegradable coating composition was prepared in the same manner as in Example 1-1, except that in step (1), a polyhydroxyalkanoate (PHA) resin having a solids content of 5 wt % (4-hydroxybutyrate (4-HB) content: 10 wt %, weight average molecular weight (Mw): 600,000 g / mol, average particle size: 2 μm, polydispersity index (PDI): 1.9, manufacturer: CJ) was prepared.

[0164] Comparative Examples 1-4 In step (1), a polyhydroxyalkanoate (PHA) resin having a solid content of 10 wt% (4-hydroxybutyrate (4-HB) content: 10 wt%, weight average molecular weight (Mw): 190,000 g / mol, average particle size: 2 μm, polydispersity index (PDI): 2.1, manufacturer: CJ) was prepared; and in step (2), a biodegradable coating composition was prepared in the same manner as in Example 1-1, except that no inorganic particles were added during stirring.

[0165] Comparative Examples 1-5 A biodegradable coating composition was prepared in the same manner as in Example 1-1, except that in step (1), a polyhydroxyalkanoate (PHA) resin having a solids content of 10 wt % (4-hydroxybutyrate (4-HB) content: 10 wt %, weight average molecular weight (Mw): 190,000 g / mol, average particle size: 2 μm, polydispersity index (PDI): 2.1, manufacturer: CJ) was prepared.

[0166] Comparative Examples 1-6 In step (2), a biodegradable coating composition was prepared in the same manner as in Example 1-1, except that talc (manufacturer: Kotz) was used as the inorganic particles in an amount of 30 parts by weight.

[0167] Comparative Examples 1-7 A biodegradable coating composition was prepared in the same manner as in Example 1-1, except that in step (2), the rheology modifier was not added together with stirring.

[0168] [Table 1]

[0169] Preparation of biodegradable articles Example 2-1 15.4 g / m using a Mayer bar coater (manufacturer: RDS) 2The biodegradable coating composition prepared in Example 1-1 was applied to a substrate in a coating amount of 180 g / m and dried at 170°C for 10 minutes to prepare a biodegradable article having a biodegradable coating layer. 2 Uncoated kraft paper (manufacturer: Hansol Paper) having a basis weight of 100g was used as the substrate.

[0170] Examples 2-2 to 2-7 and Comparative Examples 2-1 to 2-7 Biodegradable articles were prepared in the same manner as in Example 2-1, except that the biodegradable coating compositions prepared in Examples 1-2 to 1-7 and Comparative Examples 1-1 to 1-7 were used, respectively. The coating amounts of the biodegradable coating compositions were varied as shown in Table 2 below.

[0171] [Test Example] Test Example 1: Dispersion Stability The biodegradable coating compositions prepared in Examples 1-1 to 1-7 and Comparative Examples 1-1 to 1-7 were each placed in a test tube and left to stand for 2 weeks at 50° C. The dispersion stability was then visually evaluated according to the following evaluation criteria. ◎: No phase separation or precipitation occurred ○: Slight phase separation occurred but no precipitation occurred △: Some phase separation and precipitation occurred ×: Significant phase separation and precipitation occurred

[0172] Test Example 2: Viscosity The viscosity of each of the biodegradable coating compositions prepared in Examples 1-1 to 1-7 and Comparative Examples 1-1 to 1-7 was measured using a DVE-RV viscometer (manufacturer: Brookfield), which measures viscosity using shear stress at a shear rate of approximately 23°C and 12 rpm.

[0173] Test Example 3: Kit Evaluation Test The biodegradable articles prepared in Examples 2-1 to 2-7 and Comparative Examples 2-1 to 2-7 were each measured for oil resistance kit evaluation test in accordance with TAPPI UM 557 "Repellency of Paper and Board to Grease, Oil, and Waxes (Kit Test)."

[0174] Specifically, five drops of the kit evaluation test reagent were dropped from a height of 2.54 cm onto the surface of a biodegradable article (5 cm wide and 15 cm long), specifically onto the coating layer formed on one side of the biodegradable article. After 15 seconds, excess kit evaluation test reagent was wiped off with a clean tissue or cotton pad, and the surface was immediately visually inspected.

[0175] If the surface of the biodegradable article became significantly darker than the coated surface on which the test reagent was not applied, it was determined to have failed; otherwise, it was determined to have passed. The above test was repeated using kit evaluation test reagents with higher scores until a kit evaluation test reagent was found to fail. The oil resistance kit rating was determined as the average of the kit evaluation test reagents with the highest score that passed.

[0176] [Table 2]

[0177] As can be seen from Table 2 above, the biodegradable articles of Examples 2-1 to 2-7 had significantly better oil resistance than the articles of Comparative Examples 2-1 to 2-7.

[0178] Specifically, the biodegradable articles of Examples 2-1 to 2-7 included coating layers prepared using the biodegradable coating compositions of Examples 1-1 to 1-7, which had excellent dispersion stability and viscosity characteristics, and therefore all had excellent oil resistance with a kit rating of 5 or higher. Therefore, when the biodegradable articles are applied as articles requiring oil resistance, such as food packaging materials for packaging oily foods, they can exhibit excellent properties.

[0179] In contrast, when the biodegradable articles of Comparative Examples 2-1 to 2-7 included coating layers prepared using each of the biodegradable coating compositions of Comparative Examples 1-1 to 1-7, which had insufficient dispersion stability and viscosity properties, they all had very poor oil resistance with kit ratings of less than 5, and most were 1. In particular, in Comparative Examples 2-3 and 2-6, the coatability and viscosity properties were insufficient, and it was impossible to form a coating layer by applying each of the coating compositions.

[0180] Furthermore, FIG. 3 shows photographs of the surfaces of the biodegradable articles of Example 2-1, Comparative Example 2-2, and Comparative Example 2-4.

[0181] Specifically, as can be seen from Figure 3, Example 2-1 had excellent coatability and formed a uniform coating layer. In contrast, Comparative Examples 2-2 and 2-4 had insufficient coatability and were unable to form a uniform coating layer, resulting in cracks in the coating layer and exposing the substrate to the outside, resulting in very poor quality. [Explanation of symbols]

[0182] 1···Biodegradable article, 100···Substrate, 200···Biodegradable coating layer.

Claims

1. 1. A biodegradable coating composition comprising a polyhydroxyalkanoate (PHA) resin, a surfactant, inorganic particles, and a rheology modifier, the polyhydroxyalkanoate resin is a copolymerized polyhydroxyalkanoate resin containing 4-hydroxybutyrate (4-HB) repeating units and has a weight average molecular weight of 10,000 g / mol to 1,200,000 g / mol; the biodegradable coating composition has a viscosity of 130 mPa·s to 1,000 mPa·s; The biodegradable coating composition, wherein the polyhydroxyalkanoate resin has an average particle size of 0.5 μm to 5 μm and a polydispersity index (PDI) of 2.0 or less.

2. 2. The biodegradable coating composition of claim 1, wherein the copolymerized polyhydroxyalkanoate resin comprises the 4-hydroxybutyrate (4-HB) repeat unit in an amount of 0.1% to 60% by weight, based on the total weight of the copolymerized polyhydroxyalkanoate resin.

3. the surfactant is used in an amount of less than 0.3 wt. % based on the total weight of the biodegradable coating composition on a solids basis; 2. The biodegradable coating composition according to claim 1, wherein the surfactant is at least one selected from the group consisting of cationic surfactants, anionic surfactants, phosphate-based surfactants, fatty acid-based surfactants, acrylic surfactants, urethane-based surfactants, epoxy-based surfactants, and nonionic surfactants, or a polymer surfactant containing at least one selected from the group consisting of carboxylic acids, amines, isocyanates, and derivatives thereof.

4. The biodegradable coating composition of claim 1 , wherein the inorganic particles do not contain hydrophilic functional groups.

5. 2. The biodegradable coating composition according to claim 1, wherein the inorganic particles are at least one selected from the group consisting of talc, clay, silica, titanium oxide, montmorillonite, boron nitride, calcium carbonate, titanium dioxide, antimony trioxide, and zinc oxide.

6. 2. The biodegradable coating composition according to claim 1, wherein the inorganic particles are used in an amount of 0.1 to 10% by weight based on the total weight of the biodegradable coating composition on a solids basis.

7. 2. The biodegradable coating composition according to claim 1, wherein the rheology modifier is at least one selected from the group consisting of gums, clay minerals, cellulose derivatives, cellulose-based modifiers, acrylic-based modifiers, and urethane-based modifiers.

8. 10. The biodegradable coating composition of claim 1, wherein the rheology modifier has a branched, linear, plate-like, irregular, spherical, or rod-like shape.

9. 10. The biodegradable coating composition of claim 1, wherein the rheology modifier is used in an amount of 0.01% to 5% by weight based on the total weight of the biodegradable coating composition on a solids basis.

10. 2. The biodegradable coating composition according to claim 1, wherein the solids content of the biodegradable coating composition is 10% to 60% by weight.

11. (1) agitating a polyhydroxyalkanoate (PHA) resin; (2) adding a surfactant; (3) adding a rheology modifier; (4) adding inorganic particles; A method for preparing a biodegradable coating composition, comprising: steps (2) to (4) are performed simultaneously, sequentially, or randomly selected, and the polyhydroxyalkanoate resin is a copolymerized polyhydroxyalkanoate resin containing 4-hydroxybutyrate (4-HB) repeat units and has a weight average molecular weight of 10,000 g / mol to 1,200,000 g / mol; the biodegradable coating composition has a viscosity of 130 mPa·s to 1,000 mPa·s; The method of preparing the polyhydroxyalkanoate resin, wherein the polyhydroxyalkanoate resin has an average particle size of 0.5 μm to 5 μm and a polydispersity index (PDI) of 2.0 or less.

12. The method for preparing a biodegradable coating composition according to claim 11, wherein stirring is further carried out in one or more steps selected from steps (2) to (4).

13. The method for preparing a biodegradable coating composition according to claim 12, wherein the stirring is carried out at 3,000 rpm or less for 5 to 150 minutes.

14. A biodegradable article comprising a substrate and a biodegradable coating layer, the biodegradable coating layer is formed from a biodegradable coating composition, the biodegradable coating composition comprising a polyhydroxyalkanoate (PHA) resin, a surfactant, inorganic particles, and a rheology modifier, the polyhydroxyalkanoate resin being a copolymerized polyhydroxyalkanoate resin containing 4-hydroxybutyrate (4-HB) repeating units and having a weight average molecular weight of 10,000 g / mol to 1,200,000 g / mol; the biodegradable coating composition has a viscosity of 130 mPa·s to 1,000 mPa·s; A biodegradable article, wherein the polyhydroxyalkanoate resin has an average particle size of 0.5 μm to 5 μm and a polydispersity index (PDI) of 2.0 or less.

15. 15. The biodegradable article of claim 14, having a kit rating of 5 or greater as measured by TAPPI UM 557.

16. The biodegradable coating layer has a coating weight of 5 g / m ２ ~100g / m ２ The biodegradable article of claim 14 formed with a coating amount of

17. The biodegradable article of claim 14, wherein the biodegradable coating layer has a contact angle of 30° to 150°.

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