Biodegradable coating compositions, methods of making, and biodegradable articles 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 copolymer polyhydroxyalkanoate (PHA) resin including a PHA resin, a surfactant, inorganic particles, and a rheology modifier, and includes 4-hydroxybutyrate (4-HB) repeating units. By using a PHA resin having a weight average molecular weight of 10,000 g / mol to 12,000,000 g / mol, the biodegradable coating composition is environmentally friendly due to excellent biodegradability and biocompatibility, and can have improved dispersibility, coating properties, oil resistance, and processability.

Description

Technical Field

[0001] This invention relates to biodegradable coating compositions, methods for preparing said biodegradable coating compositions, and biodegradable articles using said biodegradable coating compositions. Background Technology

[0002] In recent years, with increasing attention to environmental issues, research on the treatment and recycling of various types of household waste is being actively conducted. Specifically, although inexpensive and highly processable polymer materials are widely used to manufacture various products (such as paper, films, fibers, packaging materials, bottles, and containers), when these products reach the end of their lifespan, their incineration may release harmful substances, and depending on the type of harmful substances, it can take hundreds of years for them to completely decompose naturally.

[0003] Therefore, research on biodegradable polymers continues, which can decompose in a short time to improve environmental friendliness, while also improving mechanical properties, oil resistance, water resistance and processability, and extending the product's lifespan, thereby reducing waste or improving its recyclability.

[0004] Polyhydroxyalkanoates (PHAs) are biodegradable polymers composed of various types of hydroxycarboxylic acids produced by numerous microorganisms and used as intracellular storage materials. PHAs possess similar physical properties to conventional petroleum-derived synthetic polymers such as polybutylene terephthalate (PBAT), polybutylene succinate (PBS), polybutylene terephthalate (PBST), and polybutylene adipate (PBSA), exhibiting complete biodegradability and excellent biocompatibility.

[0005] At the same time, in order to improve the service life and recyclability of various products (such as paper, film, fiber, packaging materials, bottles, containers, etc.), it is important to improve mechanical properties such as strength, water resistance, and oil resistance. In particular, food packaging materials used for packaging foods rich in moisture or oil (such as fruits, vegetables, bread, biscuits, ice cream, etc.) have the problem of the packaging material being torn by moisture or oil from the food, thus contaminating the food, or having a short service life.

[0006] To improve mechanical properties, water resistance, and oil resistance, methods are used to form coatings on the surface of products. However, there is a problem that the coating may reduce biodegradability and recyclability. Specifically, additional steps may be required to remove the coating, or the product's biodegradability and recyclability may be compromised due to the coating. Therefore, there is a need to develop biodegradable coating compositions that are excellent in terms of dispersibility, coating performance, oil resistance, water resistance, and processability, while being environmentally friendly due to their excellent biodegradability and biocompatibility.

[0007] [Existing technical documents]

[0008] [Patent Literature]

[0009] (Patent Document 1) Korean Patent Publication No. 2012-0103158. Summary of the Invention

[0010] Technical issues

[0011] Therefore, the present invention aims to provide a biodegradable coating composition, a method for preparing the same, and a biodegradable article using the same, wherein the biodegradable coating composition improves dispersibility, coating performance, oil resistance, and processability, while being environmentally friendly due to its excellent biodegradability and biocompatibility.

[0012] Solution to the problem

[0013] The biodegradable coating composition according to an embodiment of the present invention comprises a polyhydroxyalkanoate (PHA) resin, a surfactant, inorganic particles, and a rheology modifier, wherein the PHA resin is a copolymeric polyhydroxyalkanoate resin comprising repeating units of 4-hydroxybutyrate (4-HB) and has a weight-average molecular weight of 10,000 g / mol to 1,200,000 g / mol.

[0014] According to another embodiment of the present invention, a method for preparing a biodegradable coating composition includes (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, and the polyhydroxyalkanoate resin is a copolymer polyhydroxyalkanoate resin containing repeating 4-hydroxybutyrate (4-HB) units and has a weight-average molecular weight of 10,000 g / mol to 1,200,000 g / mol.

[0015] According to another embodiment of the invention, a biodegradable article comprises a substrate and a biodegradable coating, wherein the biodegradable coating comprises a polyhydroxyalkanoate (PHA) resin, a surfactant, inorganic particles, and a rheology modifier, and the PHA resin is a copolymer polyhydroxyalkanoate resin comprising repeating 4-hydroxybutyrate (4-HB) units and has a weight-average molecular weight of 10,000 g / mol to 1,200,000 g / mol.

[0016] Advantages of the present invention

[0017] Since the biodegradable coating composition according to embodiments of the present invention contains specific polyhydroxyalkanoate (PHA) resins, surfactants, inorganic particles, and rheology modifiers, it can improve dispersibility, dispersion stability, storage stability, coating performance, oil resistance, and processability.

[0018] In particular, since the biodegradable coating composition contains inorganic particles that do not contain hydrophilic functional groups as inorganic particles, oil resistance can be further improved.

[0019] In addition, the biodegradable coating composition contains a copolymerized polyhydroxyalkanoate resin with specific repeating units and weight-average molecular weight as the polyhydroxyalkanoate resin, and it has excellent dispersibility, despite containing a small amount of surfactant.

[0020] Therefore, coatings formed using biodegradable coating compositions are environmentally friendly due to their excellent biodegradability and biocompatibility, as well as their excellent dispersibility and coating properties. In particular, biodegradable articles including coatings exhibit excellent oil resistance, thus demonstrating superior properties when used in articles requiring oil resistance (e.g., food packaging materials for packaging oily foods). Attached Figure Description

[0021] Figure 1 A biodegradable article according to an embodiment of the present invention is shown.

[0022] Figure 2 A biodegradable article according to another embodiment of the present invention is shown.

[0023] Figure 3 Photographs of the surfaces of the biodegradable articles of Example 2-1, Comparative Example 2-2, and Comparative Example 2-4 are shown.

[0024] [Explanation of reference numerals in the attached figures]

[0025] 1: Biodegradable products

[0026] 100: Base

[0027] 200: Biodegradable coating. Detailed Implementation

[0028] The present invention will be described in detail below. The present invention is not limited to the disclosure given below, but can be modified in various forms without altering the spirit of the invention.

[0029] In this specification, unless otherwise expressly stated, when a component is referred to as a “comprising” element, it is understood to include other elements rather than exclude other elements.

[0030] Unless otherwise stated, all numerical values ​​and expressions relating to the amount of components, reaction conditions, etc., used herein should be understood to be modified by the term “about”.

[0031] In this specification, when referring to an element being formed "on" or "below" another element, it means not only that an element is formed directly "on" or "below" another element, but also that an element is formed indirectly on or below another element, with other elements inserted between them.

[0032] In this specification, the terms first, second, etc., are used to describe individual components. However, components should not be limited by these terms. These terms are only used to distinguish one component from another.

[0033] In this specification, references to "one side" and "the other side" or "upper" and "lower" for each component are explained based on the accompanying drawings. These terms are used only to distinguish components and are interchangeable in practical application.

[0034] Furthermore, for descriptive purposes, the dimensions of the various elements in the accompanying drawings may be exaggerated and do not represent actual dimensions. Additionally, in the specification, the same reference numerals denote the same elements.

[0035] Biodegradable coating composition

[0036] The biodegradable coating composition according to an embodiment of the present invention comprises a polyhydroxyalkanoate (PHA) resin, a surfactant, inorganic particles, and a rheology modifier, wherein the PHA resin is a copolymeric polyhydroxyalkanoate resin comprising repeating units of 4-hydroxybutyrate (4-HB) and has a weight-average molecular weight of 10,000 g / mol to 1,200,000 g / mol.

[0037] The solids content of the biodegradable coating composition can be from 10% to 60% by weight. For example, the solids content of the biodegradable coating composition can be from 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.

[0038] The viscosity of the biodegradable coating composition can be from 130 mPa·s to 1000 mPa·s. For example, the viscosity of the biodegradable coating composition can be from 130 mPa·s to 1000 mPa·s, 130 mPa·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.

[0039] Polyhydroxyalkanoate (PHA) resin

[0040] Polyhydroxyalkanoate (PHA) resins have similar physical properties to conventional petroleum-derived synthetic polymers such as polybutylene terephthalate (PBAT), polybutylene succinate (PBS), polybutylene terephthalate (PBST), and polybutylene adipate (PBSA), exhibiting complete biodegradability and excellent biocompatibility.

[0041] Specifically, PHA resin is a natural thermoplastic polyester polymer that accumulates in microbial cells. As it is a biodegradable material, it can be composted and eventually decomposes into carbon dioxide, water, and organic waste without producing toxic waste. In particular, because PHA is biodegradable (even in soil and ocean), when biodegradable coating compositions and biodegradable articles prepared using said biodegradable coating compositions contain PHA resin, they can possess environmentally friendly properties. Therefore, a significant advantage of biodegradable coating compositions and biodegradable articles using said biodegradable coating compositions is their applicability across a wide range of fields due to their biodegradability and environmental friendliness.

[0042] Since the biodegradable coating composition according to embodiments of the present invention contains polyhydroxyalkanoate (PHA) resin, biodegradability can be improved without compromising mechanical properties.

[0043] PHA resins can be formed by the enzymatic polymerization of one or more monomer repeating units in living cells.

[0044] PHA resin can be a copolymer polyhydroxy fatty acid ester resin (hereinafter referred to as PHA copolymer resin), specifically a copolymer in which different repeating units are randomly distributed in the polymer chain.

[0045] Examples of repeating units that may be included 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-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). PHA resins may contain one or more repeating units selected from the repeating units described above.

[0046] Specifically, the PHA resin may contain one or more repeating units selected from 3-HB, 4-HB, 3-HP, 3-HH, 3-HV, 4-HV, 5-HV, and 6-HH.

[0047] More specifically, the PHA resin may contain 4-HB repeating units. That is, the PHA resin may be a PHA copolymer resin containing 4-HB repeating units.

[0048] Furthermore, PHA resins may contain isomers. For example, PHA resins may contain structural isomers, enantiomers, or geometric isomers. Specifically, PHA resins may contain structural isomers.

[0049] Furthermore, the PHA resin can be a PHA copolymer resin containing 4-HB repeating units, and also containing a repeating unit different from the 4-HB repeating units, or containing two, three, four, five, six or more repeating units that are different from each other. For example, the PHA resin can be poly-3-hydroxybutyrate-co-4-hydroxybutyrate (hereinafter referred to as 3HB-co-4HB).

[0050] According to an embodiment of the present invention, it is important to adjust the content of 4-HB repeating units in the PHA copolymer resin.

[0051] Specifically, in order to achieve the desired physical properties of the present invention, and particularly in order to improve biodegradability in soil and ocean and obtain excellent dispersibility, dispersion stability, storage stability, coating performance, water resistance, processability and productivity without impairing mechanical properties, it is very important to adjust the content of 4-HB repeating units contained in the PHA copolymer resin.

[0052] More specifically, based on the total weight of the PHA copolymer resin, the PHA copolymer resin may contain 0.1 wt% to 60 wt% of 4-HB repeating units. For example, based on the total weight of the PHA copolymer resin, the content of 4-HB repeating units 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 9% by weight, 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.

[0053] Since the content of 4-HB repeating units meets the above range, biodegradability in soil and ocean can be improved, and properties such as dispersibility, dispersion stability, storage stability, coating performance, oil resistance, processability and productivity can be further improved without impairing mechanical properties.

[0054] According to embodiments of the present invention, the PHA resin can be a PHA copolymer resin with adjustable crystallinity. Specifically, the PHA resin contains one or more 4-HB repeating units, and the content of the 4-HB repeating units can be controlled to adjust the crystallinity of the PHA resin.

[0055] In addition, the PHA resin can be a copolyhydroxy fatty acid ester (PHA) resin, wherein the copolyhydroxy fatty acid ester (PHA) resin contains at least one repeating unit selected from 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).

[0056] Specifically, the PHA copolymer resin may contain 4-HB repeating units, and further contain one or more repeating units selected from 3-HB repeating units, 3-HP repeating units, 3-HH repeating units, 3-HV repeating units, 4-HV repeating units, 5-HV repeating units, and 6-HH repeating units. More specifically, the PHA resin may contain both 4-HB repeating units and 3-HB repeating units.

[0057] For example, based on the total weight of the PHA copolymer resin, the PHA copolymer resin may contain 20% or more, 35% or more, 40% or more, 50% or more, 60% or more, 70% or more, or 75% or more 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 of 3-HB repeating units.

[0058] PHA resins with adjustable crystallinity are those in which the crystallinity and amorphous state are adjusted by increasing the irregularity in their molecular structure. Specifically, the type or ratio of monomers or the type or content of isomers can be adjusted.

[0059] According to embodiments of the present invention, the PHA resin may comprise two or more types of PHA resins with different degrees of crystallinity. Specifically, the PHA resin may be prepared by mixing two or more types of PHA resins with different degrees of crystallinity to ensure that the content of 4-HB repeating units is within a specific range.

[0060] Specifically, the PHA resin may include a first PHA resin, wherein the first PHA resin is a semi-crystalline PHA resin.

[0061] As a semi-crystalline PHA (hereinafter referred to as scPHA) resin with controlled crystallinity, the first PHA resin may contain 0.1 wt% to 30 wt% of 4-HB repeating units. For example, the first PHA resin may contain 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 15 wt%, 2 wt% to 25 wt%, 3 wt% to 25 wt%, 3 wt% to 24 wt%, 5 wt% to 24 wt%, 7 wt% to 20 wt%, 10 wt% to 20 wt%, 15 wt% to 25 wt%, or 15 wt% to 24 wt% of 4-HB repeating units.

[0062] The glass transition temperature (Tg) of the first PHA resin can 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 can be 70°C to 120°C, 75°C to 120°C, or 75°C to 115°C. The melting temperature (Tm) of the first PHA resin can be 105°C to 165°C, 110°C to 160°C, 115°C to 155°C, or 120°C to 150°C.

[0063] The weight-average molecular weight of the first PHA resin can be from 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.

[0064] In addition, the PHA resin may contain a second PHA, which is an amorphous PHA resin with controlled crystallinity.

[0065] As an amorphous PHA (hereinafter referred to as aPHA) resin with controlled crystallinity, the second PHA resin may contain 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 of 4-HB repeating units.

[0066] The glass transition temperature (Tg) of the second PHA resin can be -45℃ to -10℃, -35℃ to -15℃, -35℃ to -20℃, or -30℃ to -20℃.

[0067] Furthermore, the crystallization temperature (Tc) of the second PHA resin is not measurable, but 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 temperature (Tm) of the second PHA resin is not measurable, but may be 100°C to 170°C, 100°C to 160°C, 110°C to 160°C, or 120°C to 150°C.

[0068] The weight-average molecular weight of the second PHA resin can be 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.

[0069] The first PHA resin and the second PHA resin can be distinguished based on the content of 4-HB repeating units, and can have at least one characteristic selected from the above-mentioned glass transition temperature (Tg), crystallization temperature (Tc), and melting temperature (Tm). 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 (Tg), melting temperature (Tm), etc.

[0070] According to an embodiment of the present invention, the PHA resin may comprise a first PHA resin or comprise a first PHA resin and a second PHA resin.

[0071] Specifically, since the PHA resin contains a first PHA resin (which is a semi-crystalline PHA resin) or contains a first PHA resin (which is a semi-crystalline PHA resin) and a second PHA resin (which is an amorphous PHA resin), and more specifically, since the content of the first PHA resin and the second PHA resin can be adjusted, the dispersibility, dispersion stability, storage stability, coating performance and processability can be further improved.

[0072] In addition, the glass transition temperature (Tg) of PHA resin can be -45℃ to 80℃, -35℃ to 80℃, -30℃ to 80℃, -25℃ to 75℃, -20℃ to 70℃, -35℃ to 5℃, -25℃ to 5℃, -35℃ to 0℃, -25℃ to 0℃, -30℃ to -10℃, -35℃ to -15℃, -35℃ to -20℃, -20℃ to 0℃, -15℃ to 0℃, or -15℃ to -5℃.

[0073] In addition, the crystallization temperature (Tc) of PHA resin is not measurable, or it can 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.

[0074] The melting temperature (Tm) of PHA resin is not measurable, or it can 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.

[0075] In addition, the weight-average molecular weight of PHA resin can range from 10,000 g / mol to 1,200,000 g / mol. For example, the weight-average molecular weight of PHA resin can be from 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, 200,000 g / mol to 1,200,000 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, and 200,000 g / mol to 80 0000 g / mol, 200000 g / mol to 700000 g / mol, 250000 g / mol to 650000 g / mol, 200000 g / mol to 400000 g / mol, 300000 g / mol to 800000 g / mol, 300000 g / mol to 600000 g / mol, 500000 g / mol to 1200000 g / mol, 500000 g / mol to 1000000 g / mol, 550000 g / mol to 1050000 g / mol, 550000 g / mol to 900000 g / mol, 600000 g / mol to 900000 g / mol or 500000 g / mol to 900000 g / mol.

[0076] The crystallinity of PHA resin, as measured by differential scanning calorimetry (DSC), can be 90% or less. For example, the crystallinity of PHA resin can be measured by differential scanning calorimetry and can be 90% or less, 85% or less, 80% or less, 75% or less, or 70% or less.

[0077] Furthermore, the average particle size of the PHA resin can be from 0.5 μm to 5 μm. For example, the average particle size of the PHA resin can be from 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.

[0078] The average particle size of PHA resin can be measured using a nanoparticle size analyzer (e.g., Zetasizer Nano ZS). Specifically, the average particle size of PHA resin was 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 this case, the peak value obtained by using the polydispersity index (PDI) with a confidence interval of 0.5 was taken as the particle size.

[0079] The polydispersity index (PDI) of PHA resin can be less than 2.5. For example, the polydispersity index of PHA resin can be less than 2.5, 2.3 or less, 2.1 or less, or 2.0 or less.

[0080] Since the average particle size and polydispersity index of PHA resin meet the above range, its dispersibility, dispersion stability, storage stability, coating performance, and processability can be further improved.

[0081] Furthermore, PHA resin can be obtained through cell disruption using non-mechanical or chemical methods. Specifically, since PHA resin is a natural thermoplastic polyester polymer that accumulates in microbial cells and has a relatively large average particle size, it can be obtained through disruption methods, thereby improving dispersibility, coating performance, and processability.

[0082] According to another embodiment of the invention, the biodegradable coating composition may further comprise a biodegradable polymer.

[0083] Specifically, the biodegradable polymer may include at least one selected from polylactic acid (PLA), polybutylene terephthalate (PBAT), polybutylene succinate (PBS), thermoplastic starch (TPS), polybutylene terephthalate (PBST), polyethylene terephthalate (PET), polybutylene adipate (PBSA), polybutylene adipate (PBA), polypropylene (PP), polyethylene (PE), and polycaprolactone (PCL). Because the biodegradable coating composition also contains a biodegradable polymer, it may be more advantageous for controlling properties such as mechanical properties.

[0084] Furthermore, based on the total weight of the biodegradable coating composition based on solids content, the biodegradable coating composition may contain 10% to 70% by weight of PHA resin. Specifically, based on the total weight of the biodegradable coating composition based on solids content, the content of PHA resin 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.

[0085] surfactants

[0086] According to embodiments of the present invention, the biodegradable coating composition comprises a surfactant. Because the biodegradable coating composition comprises a surfactant, its dispersibility, dispersion stability, storage stability, coating performance, and processability can be further improved.

[0087] Specifically, the surfactant may be at least one selected from cationic surfactants, anionic surfactants, phosphate surfactants, fatty acid surfactants, acrylic surfactants, urethane surfactants, epoxy surfactants, and nonionic surfactants. The surfactant may also be a polymeric surfactant comprising at least one selected from carboxylic acids, amines, isocyanates, and their derivatives.

[0088] For example, the surfactant may be at least one selected from polyvinyl alcohol, sodium dodecylbenzene sulfonate, polyvinylpyrrolidone, methyl polyvinyl alkyl ether, alkylbenzene sulfonate, nonylphenol ether sulfate, sodium dodecyl sulfate, lithium dodecyl sulfate, alkyl phosphate ester, glycerol ester and polypropylene glycol ester.

[0089] Furthermore, based on the total weight of the biodegradable coating composition based on solid content, the biodegradable coating composition may contain less than 0.3% by weight of surfactant. For example, based on the total weight of the biodegradable coating composition based on solid content, the surfactant content may be less than 0.3% by weight, less than 0.2% by weight, or less than 0.15% by weight, and may be from 0.01% by weight to less than 0.3% by weight, from 0.01% by weight to 0.25% by weight, from 0.03% by weight to 0.2% by weight, or from 0.05% by weight to 0.15% by weight.

[0090] Although biodegradable coating compositions contain less surfactant than conventional coating compositions, they exhibit excellent dispersibility, dispersion stability, storage stability, coating performance, and processability.

[0091] Inorganic particles

[0092] According to an embodiment of the present invention, the biodegradable coating composition comprises inorganic particles.

[0093] Specifically, the inorganic particles may not contain hydrophilic functional groups. Alternatively, the inorganic particles may contain hydrophilic functional groups. Since the biodegradable coating composition contains inorganic particles that do not contain hydrophilic functional groups or inorganic particles that contain hydrophobic functional groups, oil resistance can be further improved.

[0094] More specifically, since the biodegradable coating composition contains inorganic particles, oil resistance can be improved by adjusting the contact angle of the surface of the coating formed using the biodegradable coating composition.

[0095] The inorganic particles can be at least one selected from talc, clay, silica, titanium dioxide, montmorillonite, boron nitride, calcium carbonate, titanium dioxide, antimony trioxide, and zinc oxide.

[0096] Furthermore, the inorganic particles can be spherical, irregular, branched, rod-shaped, bead-shaped, elliptical, or plate-shaped. Specifically, the inorganic particles can have different shapes depending on their type. Because the biodegradable coating composition contains specific types and shapes of inorganic particles, it can further improve oil resistance.

[0097] Based on the total weight of the biodegradable coating composition based on solid content, the biodegradable coating composition may contain an amount of inorganic particles from 0.1 wt% to 10 wt%. For example, based on the total weight of the biodegradable coating composition based on solid content, the content of inorganic particles may be from 0.1 wt% to 10 wt%, from 0.2 wt% to 8 wt%, from 0.5 wt% to 4 wt%, from 0.7 wt% to 2 wt%, or from 0.9 wt% to 1.5 wt%.

[0098] rheology modifiers

[0099] According to embodiments of the present invention, the biodegradable coating composition includes a rheology modifier. Because the biodegradable coating composition includes a rheology modifier, coating performance, processability, and productivity can be further improved.

[0100] The rheology modifier may be at least one selected from gums, clay minerals, cellulose derivatives, cellulose modifiers, acrylic modifiers, and urethane modifiers. For example, the rheology modifier may be one of gums, clay minerals, or cellulose modifiers, or may be a mixture of two types (e.g., gums and clay minerals or gums and cellulose modifiers).

[0101] The gum may be selected from at least one of xanthan gum, guar gum, gellan gum, locust bean gum, gum arabic, carrageenan, carrageenan, solanum, tara gum, tamarind gum, and astragalus gum. The clay mineral may be selected from at least one of bentonite, montmorillonite, ether clay, montmorillonite, kaolinite, sericite, and illite.

[0102] Cellulose derivatives may be at least one selected from casein, sodium caseinate, and sodium alginate. Cellulose modifiers may be at least one selected from methylcellulose, hydroxypropylcellulose, and methylhydroxypropylcellulose.

[0103] Furthermore, rheology modifiers can have branched, linear, plate-like, irregular, spherical, or rod-like shapes. Because rheology modifiers can have these shapes, coating performance, processability, and productivity can be further improved.

[0104] Based on the total weight of solids content in the biodegradable coating composition, the rheology modifier can be used in amounts 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%.

[0105] In addition, the biodegradable coating composition may also contain at least one additive selected from antioxidants, stabilizers, antibacterial agents, defoamers, preservatives, and pH adjusters.

[0106] Antioxidants are additives used to prevent decomposition by ozone or oxygen, oxidation during storage, and deterioration of physical properties. Any commonly used antioxidant can be used, as long as it does not impair the effectiveness of the invention.

[0107] Specifically, antioxidants may include at least one selected from hindered phenolic antioxidants and phosphite (phosphorus) antioxidants.

[0108] For example, hindered phenolic antioxidants may include at least one selected from 4,4'-methylene-bis(2,6-di-tert-butylphenol), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis[3-(3,5-di-tert-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.

[0109] In addition, phosphite (phosphorus) antioxidants may include, for example, at least one selected from tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol-diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol-diphosphite, pentaerythritol distearate, [bis(2,4-di-tert-butyl-5-methylphenoxy)phosphino]biphenyl, and N,N-bis[2-[[2,4,8,10-tetra(1,1-dimethylethyl)dibenzo[d,f][1,3,2]dioxaphosphazenecycloheptane-6-yl]oxy]ethyl]ethylamine.

[0110] Based on the total weight of solids content in the biodegradable coating composition, the antioxidant may be used in amounts 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%, 0.2 wt% to 4.5 wt%, 0.2 wt% to 4 wt%, or 0.5 wt% to 3 wt%.

[0111] A stabilizer is an additive used to protect against oxidation and heating and to prevent color changes. Any commonly used stabilizer can be used as a stabilizer, as long as it does not impair the effectiveness of the invention.

[0112] Specifically, the stabilizer may be at least one selected from trimethyl phosphate, triphenyl phosphate, trimethylphosphine, phosphoric acid, and phosphorous acid.

[0113] Based on the total weight of solids content in the biodegradable coating composition, the stabilizer may be used in amounts 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%, 0.2 wt% to 4.5 wt%, 0.2 wt% to 4 wt%, or 0.5 wt% to 3 wt%.

[0114] The antibacterial agent may be at least one natural antibacterial agent selected from organic acids, bacteriocins, and calcium preparations or colloids, or compounds containing elements such as silver. The antibacterial agent may be at least one selected from polylysine, benzisothiazolinone, acetic acid powder, chitosan oligosaccharide, hydrogen peroxide, ethylenediaminetetraacetic acid, potassium sorbate, sorbic acid, propionic acid, potassium propionate, sodium benzoate, 1,2-hexanediol, and 1,2-octanediol.

[0115] Based on the total weight of solids content in the biodegradable coating composition, the antimicrobial agent can be used in amounts of 0.01 wt% to 5 wt%, 0.01 wt% to 3 wt%, 0.01 wt% to 1 wt%, 0.1 wt% to 1 wt%, 0.2 wt% to 1 wt%, or 0.3 wt% to 1 wt%.

[0116] Furthermore, a defoamer is an additive used to prevent or reduce foaming. Any commonly used defoamer can be used as a defoamer, as long as it does not impair the effectiveness of the invention.

[0117] For example, the defoamer may be at least one selected from alcohol-based defoamers, polar compound defoamers, inorganic particulate defoamers, and silicone defoamers, or may be at least one selected from ethanol, 2-ethylhexanol, polysiloxane, dimethylpolysiloxane, silicone paste, silicone emulsion, silicone-treated powder, fluorosilicone, distearate, ethylene glycol, and natural waxes.

[0118] Based on the total weight of solids content in the biodegradable coating composition, the defoamer can be used in amounts of 0.0001 wt% to 5 wt%, 0.0001 wt% to 3 wt%, 0.0001 wt% to 1 wt%, 0.001 wt% to 1 wt%, or 0.001 wt% to 0.5 wt%.

[0119] In addition, the preservative may be at least one natural preservative selected from p-hydroxyacetophenone, centella asiatica extract, 1,2-hexanediol and 1,3-butanediol, or at least one preservative selected from 1,2-benzisothiazolin-3-one and potassium benzoate, but is not limited thereto.

[0120] Based on the total weight of solids content in the biodegradable coating composition, the preservative may be used in amounts 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%, 0.2 wt% to 4.5 wt%, 0.2 wt% to 4 wt%, or 0.5 wt% to 3 wt%.

[0121] Furthermore, pH adjusters refer to materials added to a solution to adjust the pH. This can include pH lowering agents for reducing pH and pH increasing agents for increasing pH. Specifically, pH lowering agents can be strong acids (e.g., sulfuric acid and hydrochloric acid) or aqueous solutions of ammonium salts, and pH increasing agents can be alkaline substances (e.g., ammonia, sodium hydroxide, lithium hydroxide, and potassium hydroxide) or aqueous solutions of acetates, but are not limited to these.

[0122] For example, the pH increaser may be at least one selected from acetic acid, lactic acid, hydrochloric acid, phosphoric acid, sodium hydroxide, citric acid, malic acid, fumaric acid, potassium phosphate, sodium bicarbonate, and sodium phosphate.

[0123] Based on the total weight of solids content in the biodegradable coating composition, the pH adjuster can be used in amounts 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%, 0.2 wt% to 4.5 wt%, 0.2 wt% to 4 wt%, or 0.5 wt% to 3 wt%.

[0124] Method for preparing biodegradable coating compositions

[0125] According to another embodiment of the present invention, a method for preparing a biodegradable coating composition includes (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, and the polyhydroxyalkanoate resin is a copolymer polyhydroxyalkanoate resin containing repeating 4-hydroxybutyrate (4-HB) units and has a weight-average molecular weight of 10,000 g / mol to 1,200,000 g / mol.

[0126] First, stir the polyhydroxyalkanoate (PHA) resin (step (1)).

[0127] Specifically, the PHA resin can be stirred to prepare a first aqueous dispersion. Details regarding the PHA resin are as described above.

[0128] Mixing can be performed at 3000 rpm or less for 5 to 150 minutes. For example, mixing can be performed using a mixer that utilizes uniaxial shear stress (product name: Homo-disper, manufacturer: Premix, maximum speed: 8000 rpm). Stirring can be performed at 3000 rpm or less, 2500 rpm or less, 2000 rpm or less, 1500 rpm or less, 1000 rpm or less, 800 rpm or less, 650 rpm or less, 500 rpm to 3000 rpm, 550 rpm to 2500 rpm, or 600 rpm to 2000 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.

[0129] Since the stirring is carried out under the above conditions, the dispersibility, dispersion stability, storage stability, coating performance and processability can be further improved.

[0130] In addition, stirring can be carried out in a solvent.

[0131] Specifically, the solvent used in stirring can be water, distilled water, or a hydrophilic solvent. Specifically, the solvent can be water, distilled water, or a hydrophilic solvent, or a mixture of water, distilled water, and a hydrophilic solvent. For example, the hydrophilic solvent can be at least one selected from methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-pentanol, isopentanol, sec-pentanol, tert-pentanol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, and cyclohexanol.

[0132] The solids content of the first aqueous dispersion may be from 10% to 60% by weight. For example, the solids content of the first aqueous dispersion may be from 10% to 60% by weight, from 15% to 55% by weight, from 20% to 55% by weight, from 25% to 50% by weight, from 30% to 45% by weight, or from 35% to 45% by weight.

[0133] Then, steps (2) to (4) can be performed simultaneously, sequentially, or randomly.

[0134] Specifically, step (2) involves adding a surfactant, step (3) involves adding a rheology modifier, and step (4) involves adding inorganic particles.

[0135] Details regarding surfactants, rheology modifiers, and inorganic particles are as described above.

[0136] More specifically, steps (2) through (4) can be performed simultaneously or sequentially. Steps (2) through (4) can be randomly selected and performed one by one. For example, they can be performed in the order of steps (2), (3), and (4), in the order of steps (3), (2), and (4), in the order of steps (4), (2), and (3), or in the order of steps (2), (4), and (3).

[0137] According to an embodiment of the present invention, steps (2) to (4) can be performed sequentially.

[0138] Specifically, surfactants and rheology modifiers can be added to the 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.

[0139] In addition, stirring may be performed in one or more steps selected from steps (2) to (4). Details regarding stirring are as described above.

[0140] Specifically, a surfactant can be added to the first aqueous dispersion prepared in step (1) under stirring, and a rheology modifier can be further added to it under stirring to prepare a second aqueous dispersion. Inorganic particles can be added to the second aqueous dispersion under stirring to prepare a biodegradable coating composition.

[0141] Methods for preparing biodegradable products

[0142] A method for preparing a biodegradable article according to another embodiment of the present invention includes preparing a biodegradable coating composition and forming a biodegradable coating from the biodegradable coating composition.

[0143] Details regarding the preparation of the biodegradable coating composition are described above.

[0144] Then, a biodegradable coating is formed on at least one side of the substrate using a biodegradable coating composition.

[0145] According to an embodiment of the present invention, the step of forming a biodegradable coating can be performed by applying a biodegradable coating composition to a substrate and drying it.

[0146] There are no restrictions on the substrate, as long as a biodegradable coating can be formed on its surface. For example, the substrate can be at least one selected from paper, kraft paper, fabric, non-woven fabric, polyethylene terephthalate (PET) film, polyester film (e.g., polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene adipate terephthalate (PBAT) and polybutylene terephthalate terephthalate (PBST)), and polyimide (PI) film.

[0147] Specifically, from the perspective of improving the coating performance of the substrate, the substrate can preferably be a single-material substrate. The substrate can be paper, kraft paper, fabric, or non-woven fabric, but is not limited to these. In addition, when the substrate includes paper or kraft paper, it may be more advantageous to provide environmentally friendly packaging materials because paper has better biodegradability than other plastic materials.

[0148] The thickness of the substrate can be 15 μm or greater. For example, the thickness of the substrate can be 15 μm or greater, 20 μm or greater, 50 μm or greater, 70 μm or greater, 100 μm or greater, 130 μm or greater, 150 μm or greater, 200 μm or greater, 300 μm or greater, or 500 μm or greater.

[0149] In addition, the basis weight of the substrate can be 30 g / m³. 2 Up to 500g / m 2 For example, when the substrate is paper, kraft paper, woven fabric, knitted fabric, or non-woven fabric, the basis weight of the substrate can be 30 g / m³. 2 Up to 500g / m 2 30g / m 2 Up to 350g / m 2 30g / m 2 Up to 200g / m2 50g / m 2 Up to 200g / m 2 80g / m 2 Up to 200g / m 2 100g / m 2 Up to 200g / m 2 130g / m 2 Up to 190g / m 2 150g / m 2 Up to 185g / m 2 Or 120g / m 2 Up to 320g / m 2 .

[0150] Simultaneously, the barrier layer can be disposed on at least one side of the substrate. An environmentally friendly barrier film can be coated onto the surface of the substrate to have moisture and / or oxygen barrier properties, or it can be further formed into a functional coating with antistatic or adhesive properties. The functional coating may include a primer coating and an adhesive coating, which may have commonly used materials and physical properties, provided they do not impair the desired effects of the invention.

[0151] In addition, biodegradable coating compositions can be applied at 5 g / m². 2 Up to 100g / m 2 The coating amount is applied to the substrate. For example, the coating amount can be 5 g / m². 2 Up to 100g / m 2 5g / m 2 Up to 85g / m 2 5g / m 2 Up to 70g / m 2 8g / m 2 Up to 60g / m 2 9g / m 2 Up to 50g / m 2 5g / m 2 Up to 50g / m 2 6g / m 2 Up to 40g / m 2 7g / m 2 Up to 30g / m 2 8g / m 2 Up to 20g / m 2 Or 10g / m 2 Up to 40g / m 2 Since the coating amount meets the above range, coating performance, productivity, and processability can be further improved.

[0152] Furthermore, the coating can be applied in one step to form a single coating, or it can be applied two or more times to form multiple coatings. The coating amount can be adjusted within the range described above, depending on the desired number of coatings. Specifically, the coating amount can be the total amount applied to multiple coatings.

[0153] After the biodegradable coating composition is applied to the substrate, it can be dried at 100°C to 200°C for 5 seconds to 30 minutes. For example, drying can 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.

[0154] There are no particular limitations on the formation of biodegradable coatings, as long as the coating method is commonly used in the art. For example, biodegradable coatings can be formed by concave coating, slotted coating, blade coating, spraying, bar coating, spin coating, or inline coating, but are not limited to these methods.

[0155] Biodegradable products

[0156] According to another embodiment of the invention, a biodegradable article comprises a substrate and a biodegradable coating, wherein the biodegradable coating comprises a polyhydroxyalkanoate (PHA) resin, a surfactant, inorganic particles, and a rheology modifier, and the PHA resin is a copolymer polyhydroxyalkanoate resin comprising repeating 4-hydroxybutyrate (4-HB) units and has a weight-average molecular weight of 10,000 g / mol to 1,200,000 g / mol.

[0157] Figure 1 A biodegradable article according to an embodiment of the present invention is shown. Figure 2 A biodegradable article according to another embodiment of the present invention is shown.

[0158] Specifically, Figure 1 A biodegradable article (1) is shown, wherein a biodegradable coating (200) is formed on one side of a substrate (100). Figure 2 A biodegradable article (1) is shown, wherein a biodegradable coating (200) is formed on both sides of a substrate (100).

[0159] Because biodegradable articles contain a biodegradable coating on one or both sides of the substrate, and the biodegradable coating includes PHA resin, surfactants, inorganic particles, and rheology modifiers, they are environmentally friendly due to their excellent biodegradability and biocompatibility, and can also exhibit excellent coating performance, productivity, and processability. In particular, biodegradable articles including a biodegradable coating have excellent oil resistance, and therefore can exhibit superior properties when used in articles requiring oil resistance (e.g., food packaging materials for packaging oily foods).

[0160] Details regarding the substrate are as described above.

[0161] Furthermore, the contact angle of the biodegradable coating can range from 30° to 150°. For example, the contact angle of the biodegradable coating can be 30° to 150°, 40° to 140°, 40° to 130°, or 50° to 120°. Because the contact angle of the biodegradable coating meets the above range, it can have excellent oil resistance.

[0162] The contact angle can be measured at room temperature (25°C) using a contact angle measuring instrument (product name: DSA100, manufacturer: KRUSS).

[0163] In addition, the thickness of the biodegradable coating can be 5μm to 50μm, 5μm to 40μm, or 6μm to 30μm.

[0164] Biodegradable products can have an oil resistance value of 5 or greater, as measured by TAPPI UM 557. For example, the oil resistance value can be 5 or greater, or 6 or greater. Because biodegradable products meet the above range of oil resistance values, they exhibit excellent oil resistance.

[0165] Specifically, the grease resistance value can be measured by the grease resistance value test according to TAPPI UM 557 "Repellency of paper and paperboard to greases, oils and waxes (grease resistance test)".

[0166] More specifically, the grease resistance test reagent is dropped onto the surface of a biodegradable product (5 cm wide and 15 cm long) from a certain height, i.e., onto the coating formed on the biodegradable product. Then, after a certain period of time, the excess grease resistance test reagent is wiped away with a clean paper towel or cotton sample, and the surface is immediately visually inspected to determine the grease resistance value.

[0167] In this test, if the surface is significantly darker than a surface without test reagent, it is considered a failure; otherwise, it is considered a pass. Repeat the test using a higher grease resistance test reagent until a failed grease resistance test reagent is observed. The grease resistance value can be determined as the average of the highest passing grease resistance values.

[0168] Biodegradable products including biodegradable coatings can be packaging materials, cardboard boxes, shopping bags, disposable tableware, packaging containers, or paper straws, but are not limited to these.

[0169] Scheme of the present invention

[0170] The invention will now be described in more detail with reference to the following embodiments. However, the following embodiments are intended to illustrate the invention, and the scope of the embodiments is not limited thereto.

[0171] [Example]

[0172] Preparation of biodegradable coating compositions

[0173] Example 1-1

[0174] (1) Preparation of PHA resin

[0175] A polyhydroxyalkanoate (PHA) resin with a solids content of 10 wt% (4-hydroxybutyrate (4-HB) content: 10 wt%, weight average molecular weight (Mw): 340000 g / mol, average particle size: 2 μm, polydispersity index (PDI): 1.9, manufacturer: CJ) was prepared. The PHA resin was obtained by chemically crushing using sodium dodecylbenzenesulfonate.

[0176] (2) Preparation of biodegradable coating composition

[0177] PHA resin was centrifuged in an aqueous system to prepare a first aqueous dispersion with a solid content of 40% by weight.

[0178] Then, 97 parts by weight of the first aqueous dispersion and 1 part by weight of 10% polyvinyl alcohol (PVA, manufacturer: Kuraray, hydrolysis rate: 80%) as a surfactant were added to a 1-liter glass beaker, and the mixture was stirred at 1500 rpm for 60 minutes using a stirrer (product name: Homo-disper, manufacturer: Premix, maximum speed: 8000 rpm). Next, 1 part by weight of 5% xanthan gum (manufacturer: DyneMaterials) as a rheology modifier (Rr) was added, followed by stirring at 600 rpm for 10 minutes to prepare a second aqueous dispersion with a solids content of 39% by weight.

[0179] Then, 1 part by weight of spherical silica with hydrophobic functional groups (product name: R202, manufacturer: Evonik) as inorganic particles was added to the second aqueous dispersion, and the mixture was stirred at 2000 rpm for 30 minutes to prepare a biodegradable coating composition with a solid content of 39.95% by weight.

[0180] Examples 1-2

[0181] The biodegradable coating composition was prepared in the same manner as in Examples 1-1, except that in step (2), irregular talc (manufacturer: Kotz) without hydrophilic functional groups was used as inorganic particles.

[0182] Examples 1-3

[0183] The biodegradable coating composition was prepared in the same manner as in Examples 1-1, except that in step (2), plate-shaped montmorillonite (manufacturer: Sigma-Aldrich) without hydrophilic functional groups was used as inorganic particles.

[0184] Examples 1-4

[0185] The biodegradable coating composition was prepared in the same manner as in Examples 1-1, except that in step (2), plate-shaped boron nitride (manufacturer: IWsolution) without hydrophilic functional groups was used as inorganic particles.

[0186] Examples 1-5

[0187] The biodegradable coating composition was prepared in the same manner as in Examples 1-1, except that in step (2), 0.5 parts by weight of spherical silica (product name: R202, manufacturer: Evonik) with hydrophobic functional groups was used as inorganic particles.

[0188] Examples 1-6

[0189] The biodegradable coating composition was prepared in the same manner as in Examples 1-1, except that in step (2), 3 parts by weight of spherical silica (product name: R202, manufacturer: Evonik) with hydrophobic functional groups were used as inorganic particles.

[0190] Examples 1-7

[0191] The biodegradable coating composition was prepared in the same manner as in Examples 1-1, except that in step (1), a polyhydroxyalkanoate (PHA) resin with a solid content of 10% by weight (4-hydroxybutyrate (4-HB) content: 8% by weight, weight average molecular weight (Mw): 300,000 g / mol, average particle size: 3 μm, polydispersity index (PDI): 1.9, manufacturer: CJ) was prepared.

[0192] Comparative Example 1-1

[0193] The biodegradable coating composition was prepared in the same manner as in Examples 1-1, except that no inorganic particles were added and no stirring was performed in step (2).

[0194] Comparative Examples 1-2

[0195] The biodegradable coating composition was prepared in the same manner as in Examples 1-1, except that in step (1), a polyhydroxyalkanoate (PHA) resin with a solid content of 5% by weight (4-hydroxybutyrate (4-HB) content: 10% by weight, weight average molecular weight (Mw): 600000 g / mol, average particle size: 2 μm, polydispersity index (PDI): 1.9, manufacturer: CJ) was prepared, and in step (2), no inorganic particles were added and no stirring was performed.

[0196] Comparative Examples 1-3

[0197] The biodegradable coating composition was prepared in the same manner as in Examples 1-1, except that in step (1), a polyhydroxyalkanoate (PHA) resin with a solid content of 5% by weight (4-hydroxybutyrate (4-HB) content: 10% by weight, weight average molecular weight (Mw): 600,000 g / mol, average particle size: 2 μm, polydispersity index (PDI): 1.9, manufacturer: CJ) was prepared.

[0198] Comparative Examples 1-4

[0199] The biodegradable coating composition was prepared in the same manner as in Examples 1-1, except that in step (1), a polyhydroxyalkanoate (PHA) resin with a solid content of 10% by weight (4-hydroxybutyrate (4-HB) content: 10% by weight, weight average molecular weight (Mw): 190000 g / mol, average particle size: 2 μm, polydispersity index (PDI): 2.1, manufacturer: CJ) was prepared, and in step (2), no inorganic particles were added and no stirring was performed.

[0200] Comparative Examples 1-5

[0201] The biodegradable coating composition was prepared in the same manner as in Examples 1-1, except that in step (1), a polyhydroxyalkanoate (PHA) resin with a solid content of 10% by weight (4-hydroxybutyrate (4-HB) content: 10% by weight, weight average molecular weight (Mw): 190000 g / mol, average particle size: 2 μm, polydispersity index (PDI): 2.1, manufacturer: CJ) was prepared.

[0202] Comparative Examples 1-6

[0203] The biodegradable coating composition was prepared in the same manner as in Examples 1-1, except that in step (2), 30 parts by weight of talc (manufacturer: Kotz) was used as inorganic particles.

[0204] Comparative Examples 1-7

[0205] The biodegradable coating composition was prepared in the same manner as in Examples 1-1, except that no rheology modifier was added and no stirring was performed in step (2).

[0206] [Table 1]

[0207]

[0208]

[0209] Preparation of biodegradable products

[0210] Example 2-1

[0211] Using a Mayer doctor blade coater (manufacturer: RDS) at 15.4 g / m³ 2 The biodegradable coating composition prepared in Examples 1-1 was applied to a substrate and dried at 170°C for 10 minutes to prepare a biodegradable article with a biodegradable coating. Here, a basis weight of 180 g / m³ was used. 2 Uncoated kraft paper (manufacturer: Hansol Paper) is used as the base.

[0212] Examples 2-2 to 2-7 and Comparative Examples 2-1 to 2-7

[0213] 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. The coating amount of the biodegradable coating compositions varied as shown in Table 2 below.

[0214] [Test Implementation Example]

[0215] Test Example 1: Dispersion Stability

[0216] The biodegradable coating compositions prepared in Examples 1-1 to 1-7 and Comparative Examples 1-1 to 1-7 were placed in test tubes and incubated at 50°C for 2 weeks. The stability of the dispersions was then visually evaluated according to the following criteria.

[0217] ◎: No phase separation or precipitation occurred.

[0218] ○: Slight phase separation occurred, but no precipitation occurred.

[0219] Δ: Partial phase separation and precipitation occur.

[0220] ×: Significant phase separation and precipitation occurred.

[0221] Test Example 2: Viscosity

[0222] The viscosities of the biodegradable coating compositions prepared in Examples 1-1 to 1-7 and Comparative Examples 1-1 to 1-7 were measured using a DVE-RV viscometer (manufacturer: Brookfield), which measures viscosity using shear stress at a shear rate of 12 rpm at approximately 23°C.

[0223] Test Example 3: Anti-oil value test

[0224] According to TAPPI UM 557 "Repellency of paper and paperboard to greases, oils and waxes (grease resistance test)", the oil resistance values ​​of the biodegradable products prepared in Examples 2-1 to 2-7 and Comparative Examples 2-1 to 2-7 were tested.

[0225] Specifically, drop 5 drops of the grease resistance test reagent onto the surface of a biodegradable product (5 cm wide and 15 cm long) from a height of 2.54 cm, specifically onto the coating formed on one side of the biodegradable product. After 15 seconds, wipe away any excess grease resistance test reagent with a clean paper towel or cotton sample and immediately visually inspect the surface.

[0226] If the surface is significantly darker than the coated surface without test reagent, it is considered a failure; otherwise, it is considered a pass. Repeat the above test using a higher grease resistance test reagent until a failed grease resistance test reagent is observed. The grease resistance value is determined as the average of the highest grease resistance values ​​of the passing reagents.

[0227] [Table 2]

[0228]

[0229]

[0230] As can be seen from Table 2 above, compared with the products of Comparative Examples 2-1 to 2-7, the biodegradable products of Examples 2-1 to 2-7 have excellent oil resistance.

[0231] Specifically, since the biodegradable articles of Examples 2-1 to 2-7 comprise coatings prepared using the biodegradable coating compositions of Examples 1-1 to 1-7, which have excellent dispersion stability and viscosity characteristics, they all exhibit excellent oil resistance (oil resistance value of 5 or greater). Therefore, when used as articles requiring oil resistance (e.g., food packaging materials for packaging oily foods), they can possess excellent properties.

[0232] In contrast, the biodegradable articles of Comparative Examples 2-1 to 2-7, which comprise coatings prepared using the biodegradable coating compositions of Comparative Examples 1-1 to 1-7 with poor dispersion stability and viscosity characteristics, all exhibit very poor oil resistance (oil resistance values ​​less than 5, mostly 1). In particular, the poor coating performance and tackiness characteristics in Comparative Examples 2-3 and 2-6 prevented the application of each coating composition to form a coating.

[0233] also, Figure 3 Photographs of the surfaces of the biodegradable articles of Example 2-1, Comparative Example 2-2, and Comparative Example 2-4 are shown.

[0234] Specifically, from Figure 3 As can be seen, in Example 2-1, the coating performance is excellent, forming a uniform coating. In contrast, in Comparative Examples 2-2 and 2-4, the coating performance is poor, a uniform coating cannot be formed, and the coating cracks, exposing the substrate to the outside, resulting in very poor quality.

Claims

1. A biodegradable coating composition comprising a polyhydroxyalkanoate (PHA) resin, a surfactant, inorganic particles, and a rheology modifier. in, The polyhydroxyalkanoate resin is a copolymer polyhydroxyalkanoate resin containing repeating 4-hydroxybutyrate (4-HB) units, and has a weight-average molecular weight of 10,000 g / mol to 1,200,000 g / mol. 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. Based on the total weight of the copolyhydroxy fatty acid ester resin, the copolyhydroxy fatty acid ester resin contains 0.1% to 60% by weight of 4-hydroxybutyrate (4-HB) repeating units, and Based on the total weight of the solids content in the biodegradable coating composition, the inorganic particles are used in an amount of 0.1% to 10% by weight.

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

3. The biodegradable coating composition according to claim 1, wherein, The inorganic particles do not contain hydrophilic functional groups.

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

5. The biodegradable coating composition according to claim 1, wherein, The rheology modifier is selected from at least one of gums, clay minerals, cellulose derivatives, cellulose modifiers, acrylic modifiers, and urethane modifiers.

6. The biodegradable coating composition according to claim 1, wherein, The rheology modifier has a branched shape, a linear shape, a plate-like shape, an irregular shape, a spherical shape, or a rod-like shape.

7. The biodegradable coating composition according to claim 1, wherein, Based on the total weight of the solids content in the biodegradable coating composition, the rheology modifier is used in an amount from 0.01% to 5% by weight.

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

9. The biodegradable coating composition according to claim 1, wherein, The viscosity of the biodegradable coating composition is from 130 mPa·s to 1000 mPa·s.

10. A method for preparing a biodegradable coating composition, the method comprising: (1) Stir the polyhydroxyalkanoate (PHA) resin; (2) Add surfactant; (3) Add rheology modifier; as well as (4) Add inorganic particles, Steps (2) to (4) are performed simultaneously, sequentially, or randomly, and the polyhydroxyalkanoate resin is a copolymer polyhydroxyalkanoate resin containing repeating 4-hydroxybutyrate (4-HB) units, and has a weight-average molecular weight of 10,000 g / mol to 1,200,000 g / mol. 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. Based on the total weight of the copolyhydroxy fatty acid ester resin, the copolyhydroxy fatty acid ester resin contains 0.1% to 60% by weight of 4-hydroxybutyrate (4-HB) repeating units, and Based on the total weight of the solids content in the biodegradable coating composition, the inorganic particles are used in an amount of 0.1% to 10% by weight.

11. The method for preparing a biodegradable coating composition according to claim 10, wherein, In one or more steps selected from steps (2) to (4), additional stirring is performed.

12. The method for preparing a biodegradable coating composition according to claim 11, wherein, Mix at 3000 rpm or less for 5 to 150 minutes.

13. A biodegradable article, said biodegradable article comprising a substrate and a biodegradable coating, in, The biodegradable coating comprises a polyhydroxyalkanoate (PHA) resin, a surfactant, inorganic particles, and a rheology modifier, wherein the PHA resin is a copolymeric polyhydroxyalkanoate resin containing repeating 4-hydroxybutyrate (4-HB) units and has a weight-average molecular weight of 10,000 g / mol to 1,200,000 g / mol. 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. Based on the total weight of the copolyhydroxy fatty acid ester resin, the copolyhydroxy fatty acid ester resin contains 0.1% to 60% by weight of 4-hydroxybutyrate (4-HB) repeating units, and The amount of inorganic particles is from 0.1% to 10% by weight, based on the total weight of the biodegradable coating.

14. The biodegradable article of claim 13, wherein the biodegradable article has an oil resistance value of 5 or greater as measured by TAPPI UM 557.

15. The biodegradable article according to claim 13, wherein, The biodegradable coating is at 5 g / m 2 Up to 100 g / m 2 The amount of coating is formed.

16. The biodegradable article according to claim 13, wherein, The contact angle of the biodegradable coating is 30° to 150°.

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