Polyhydroxyalkanoate (PHA) dispersion and method for preparing the same

Abstract

This invention provides a polyhydroxyalkanoate (PHA) dispersion that is environmentally friendly due to its excellent biodegradability and biocompatibility, while also offering improved dispersibility, coating properties, productivity, and processability. [Solution] A polyhydroxyalkanoate (PHA) dispersion is provided, comprising polyhydroxyalkanoate (PHA) particles, wherein the average particle size of the polyhydroxyalkanoate (PHA) particles is 0.5 μm to 5 μm, and the particle size deviation is within ±0.3 μm.

Description

Detailed description of the invention

[0001] [Technical field] The present invention relates to a polyhydroxyalkanoate (PHA) dispersion and a method for preparing the same dispersion.

[0002] [Background technology] In recent years, with increasing concerns about environmental issues, research into the treatment and recycling of various types of household waste has become more active. Specifically, polymer materials, which are inexpensive and have excellent processability, are widely used to manufacture a variety of products such as paper, film, textiles, packaging materials, bottles, and containers. However, when these products reach the end of their lifespan, they can release harmful substances when incinerated, and depending on the type of product, they can take hundreds of years to completely decompose naturally.

[0003] Therefore, research will continue on biodegradable polymers that can improve mechanical properties, oil resistance, water resistance, and processability, extend the lifespan of the product itself, thereby reducing the amount of waste or improving the recyclability of the product, while also improving environmental compatibility by decomposing quickly.

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

[0005] On the other hand, improving the mechanical properties such as strength, water resistance, and oil resistance is important to enhance the service life and recyclability of various products such as paper, film, textiles, packaging materials, bottles, and containers. While methods for forming a coating layer on the surface of products are sometimes used to improve physical properties, this presents the problem of impaired biodegradability and recyclability. Therefore, there is a need for the development of environmentally friendly biodegradable dispersions with excellent dispersibility, coating properties, processability, and biodegradability and biocompatibility, as well as methods for preparing them.

[0006] [Prior art document] [Patent] [Patent Document 1] Korean Published Patent No. 2012-0103158

[0007] [Detailed description of the invention] [Technical issues] Therefore, the present invention aims to provide a polyhydroxyalkanoate (PHA) dispersion that is environmentally friendly thanks to its excellent biodegradability and biocompatibility, while also improving dispersibility, coating properties, productivity, and processability, as well as a method for preparing the same dispersion.

[0008] [Solutions to the problem] The polyhydroxyalkanoate (PHA) dispersion according to the embodiment of the present invention contains polyhydroxyalkanoate (PHA) particles, the average particle size of the polyhydroxyalkanoate (PHA) particles is 0.5 μm to 5 μm, and the particle size deviation is within ±0.3 μm.

[0009] A method for preparing a polyhydroxyalkanoate (PHA) dispersion according to another embodiment of the present invention comprises the step of dispersing polyhydroxyalkanoate (PHA) in a solvent using a particle dispersion method, a melt dispersion method, or a solvent extraction method, wherein the average particle size of the dispersed polyhydroxyalkanoate (PHA) particles is 0.5 μm to 5 μm, and the particle size deviation is within ±0.3 μm.

[0010] [Advantageous effects of the invention] When a method for preparing a polyhydroxyalkanoate (PHA) dispersion according to an embodiment of the present invention includes a step of dispersing polyhydroxyalkanoate (PHA) in a solvent using a particle dispersion method, a melt dispersion method, or a solvent extraction method, a polyhydroxyalkanoate (PHA) dispersion excellent in dispersibility and processability can be effectively prepared.

[0011] Specifically, by this method for preparing a polyhydroxyalkanoate (PHA) dispersion, a polyhydroxyalkanoate (PHA) dispersion containing polyhydroxyalkanoate (PHA) particles with an average particle size of 0.5 μm to 5 μm and a particle size deviation within ±0.3 μm can be prepared, so that the dispersibility, dispersion stability, and processability can be improved.

Brief Description of the Drawings

[0012] [Figure 1] It is a photograph of PHA prepared in step (1) of Examples 1 to 10. [Figure 2] It is a photograph of the PHA dispersion prepared in Examples 1 to 10. [Figure 3] It is a photograph of the PHA dispersion prepared in Comparative Examples 1 to 3. [Figure 4] It is a diagram of a biodegradable article according to an embodiment of the present invention. [Figure 5] It is a diagram of a biodegradable article according to another embodiment of the present invention.

[0013] [Best Mode for Carrying Out the Invention] Hereinafter, the present invention will be described in detail. The present invention is not limited to the disclosure shown below, and may be modified in various forms without changing the gist of the present invention.

[0014] Throughout this specification, when referring to a member "including" an element, it is understood that other elements may be included rather than excluded unless specifically stated otherwise.

[0015] All figures and expressions relating to the quantities of ingredients, reaction conditions, etc., used herein should be understood to be modified by the term "approximately" unless otherwise specified.

[0016] In this specification, when it is stated that one element is formed "on top of" or "below" another element, it means not only that one element is directly formed "on top of" or "below" another element, but also that one element is indirectly formed on top of or below another element with other elements (maybe more than one) in between.

[0017] Throughout this specification, terms such as "1," "2," etc., are used to describe various components. However, the components should not be limited by these terms. The terms are used solely for the purpose of distinguishing one component from another.

[0018] In this specification, references to "one" and "the other" or "upper" and "lower" of each component are explained based on the drawings. These terms are merely for distinguishing components and may be interchangeable in practice.

[0019] Furthermore, for illustrative purposes, the sizes of individual elements in the attached drawings may be exaggerated and do not represent their actual sizes. Additionally, the same reference number refers to the same element throughout the specification.

[0020] Polyhydroxyalkanoate (PHA) dispersion The polyhydroxyalkanoate (PHA) dispersion according to the embodiment of the present invention contains polyhydroxyalkanoate (PHA) particles, the average particle size of the polyhydroxyalkanoate (PHA) particles is 0.5 μm to 5 μm, and the particle size deviation is within ±0.3 μm.

[0021] The polyhydroxyalkanoate (PHA) dispersion may have a solid content of 10% to 60% by weight. For example, the solid content of the PHA dispersion may be 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.

[0022] The polyhydroxyalkanoate (PHA) dispersion may have a viscosity of 100 mPa·s to 1,000 mPa·s. For example, the viscosity of the PHA dispersion may be 100 mPa·s to 1,000 mPa·s, 100 mPa·s to 900 mPa·s, 100 mPa·s to 650 mPa·s, 105 mPa·s to 500 mPa·s, 105 mPa·s to 400 mPa·s, 110 mPa·s to 350 mPa·s, or 115 mPa·s to 315 mPa·s.

[0023] Polyhydroxyalkanoate (PHA) dispersions may have a haze of 100% to 400%. For example, the haze of a PHA dispersion may be 100% to 400%, 150% to 380%, 180% to 360%, 200% to 350%, 215% to 345%, 233% to 338%, 235% to 335%, or 236% to 331%.

[0024] Furthermore, the polyhydroxyalkanoate (PHA) dispersion may have an L* of 40 or more, an a* of less than 0.44, and a b* of 6 or less. For example, the L* of the PHA dispersion may be 40 or more, 42 or more, 45 or more, 48 or more, 40 to 60, 42 to 58, 45 to 55, or 48 to 55, and a* may be less than 0.44, 0.43 or less, 0.42 or less, 0.4 or less, 0.01 to less than 0.44, 0.05 to 0.42, or 0.08 to 0.4, and b* may be 6 or less, 5.8 or less, 5.6 or less, 3 to 6, 3.3 to 5.8, 3.5 to 5.6, or 3.7 to 5.6.

[0025] L*, a*, and b* are color coordinates defined by the International Commission on Illumination (CIE), where color is represented by L (lightness), a (complementary color from green to red), and b (complementary color from yellow to blue). L*, a*, and b* may be measured using a spectrophotometer CM-5 (manufacturer: Konica Minolta).

[0026] A polyhydroxyalkanoate (PHA) dispersion may have a Yellow Index (YI) of 5 to 20, which can be measured in accordance with the ASTM E313 standard. For example, the Yellow Index (YI) of a PHA dispersion may be 5 to 20, 6 to 18, 7 to 15, 9 to 13, 9.1 to 12.99, or 9.1 to 12.95.

[0027] When the color characteristics of the PHA dispersion, such as haze, L*, a*, and b*, as well as the yellow index, meet the above ranges, the PHA dispersion has excellent color characteristics and can improve its anti-yellowing effect.

[0028] Furthermore, the polyhydroxyalkanoate (PHA) dispersion may have a zeta potential of -10mV or less. For example, the zeta potential of the PHA dispersion may be -10mV or less, -15mV or less, -20mV or less, -25mV or less, or -30mV or less, and may be -150mV or more, -125mV or more, -100mV or more, or -80mV or more. When the zeta potential of the PHA dispersion satisfies the above range, the interparticle dispersion stability within the PHA dispersion and the dispersibility of high-content PHA dispersions can be further improved.

[0029] Zeta potential (or interfacial potential) refers to the potential difference between the charge of the ions surrounding a particle and the charge of the dispersion. Specifically, there are two types of liquid layers surrounding a particle: an internal region (stem layer: electron layer) where ions form a strong boundary, and an external region (diffuse) where ions form relatively weak bonds. The external region (diffuse) is the theoretical boundary region where ions and particles exist stably. For example, when a particle moves, the ions in the internal region move within a given boundary. On the other hand, ions outside a given boundary move independently, like a giant dispersion medium, regardless of the particle. The potential at this boundary is the zeta potential.

[0030] Zeta potential may be measured using, but is not limited to, a ZetaPlus Zeta Potential Analyzer (manufacturer: Brookhaven Instruments) or a Zeta Sizer (manufacturer: Melbourne Instruments).

[0031] The polyhydroxyalkanoate (PHA) dispersion may have a pH of 3 to 11 or 4 to 10.

[0032] Furthermore, the polyhydroxyalkanoate (PHA) dispersion may have a light transmittance of 10% to 99%. For example, the light transmittance of the PHA dispersion may be the light transmittance of the biodegradable coating layer formed from the PHA dispersion, and may be 10% to 99%, 10% to 90%, 15% to 95%, 20% to 90%, or 25% to 85%.

[0033] Polyhydroxyalkanoate (PHA) Polyhydroxyalkanoates (PHAs) possess physical properties similar to conventional petroleum-derived synthetic polymers, such as polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate terephthalate (PBST), and polybutylene succinate adipate (PBSA), exhibit complete biodegradability, and have excellent biocompatibility.

[0034] Specifically, PHA is a natural thermoplastic polyester polymer that accumulates within microbial cells. Since PHA is a biodegradable substance, it can be broken down, ultimately into carbon dioxide, water, and organic waste without producing toxic waste. In particular, because PHA is biodegradable even in soil and seawater, dispersions containing PHA and biodegradable articles prepared using PHA can possess environmentally friendly properties. Thus, dispersions containing PHA and biodegradable articles prepared using PHA dispersions have the significant advantage of being biodegradable and environmentally friendly, making them applicable in a variety of fields.

[0035] When a polyhydroxyalkanoate (PHA) dispersion according to an embodiment of the present invention contains polyhydroxyalkanoate (PHA) particles, its biodegradability can be improved without reducing its mechanical properties.

[0036] PHA can be formed by the enzymatic polymerization of one or more monomer repeating units within living cells.

[0037] PHA may be a polyhydroxyalkanoate (PHA) copolymer (hereinafter referred to as PHA copolymer), specifically a copolymer in which different repeating units are randomly dispersed in the polymer chain.

[0038] Examples of repeating units that may be contained in PHA include 2-hydroxybutyrate, lactic acid, glycolic acid, 3-hydroxybutyrate (hereinafter referred to as 3-HB), 3-hydroxypropionate (hereinafter referred to as 3-HP), 3-hydroxyvalerate (hereinafter referred to as 3-HV), 3-hydroxyhexanoate (hereinafter referred to as 3-HH), 3-hydroxyheptanoate (hereinafter referred to as 3-HHep), 3-hydroxyoctanoate (hereinafter referred to as 3-HO), 3-hydroxynonanoate (hereinafter referred to as 3-HN), 3-hydroxydecanoate (hereinafter referred to as 3-HD), 3-hydroxydodecanoate (hereinafter referred to as 3-HDd), 4-hydroxybutyrate (hereinafter referred to as 4-HB), 4-hydroxyvalerate (hereinafter referred to as 4-HV), 5-hydroxyvalerate (hereinafter referred to as 5-HV), and 6-hydroxyhexanoate (hereinafter referred to as 6-HH). PHA may include one or more repeating units selected from the above.

[0039] Specifically, PHA may include one or more repeating units selected from the group consisting of 3-HB, 4-HB, 3-HP, 3-HH, 3-HV, 4-HV, 5-HV, and 6-HH.

[0040] More specifically, PHA may contain 4-HB repeating units. That is, PHA may be a PHA copolymer containing 4-HB repeating units.

[0041] Furthermore, PHA may contain isomers. For example, PHA may contain structural isomers, enantiomers, or geometric isomers. Specifically, PHA may contain structural isomers.

[0042] Furthermore, PHA may be a PHA copolymer containing a 4-HB repeating unit, and further containing one repeating unit different from the 4-HB repeating unit, or two, three, four, five, six, or more repeating units that are different from each other. For example, PHA may be poly-3-hydroxybutyrate-co-4-hydroxybutyrate (hereinafter referred to as 3HB-co-4HB).

[0043] According to embodiments of the present invention, it is important to adjust the content of 4-HB repeating units contained in the PHA copolymer.

[0044] Specifically, in order to achieve the desired physical properties in the present invention, it is extremely important to adjust the content of 4-HB repeating units contained in the PHA copolymer, in particular to enhance biodegradability in soil and seawater, and to achieve excellent dispersibility, dispersion stability, storage stability, coating properties, water resistance, processability, and productivity without reducing mechanical properties.

[0045] More specifically, the PHA copolymer may contain 4-HB repeating units in an amount of 0.1% to 60% by weight based on the total weight of the PHA copolymer. For example, the content of 4-HB repeating units is 0.1% to 60% by weight, 0.1% to 55% by weight, 0.5% to 60% by weight, 0.5% to 55% by weight, 1% to 60% by weight, 1% to 55% by weight, 1% to 50% by weight, 2% to 55% by weight, 3% to 55% by weight, 3% to 50% by weight, 5% to 55% by weight, 5% to 50% by weight, 10% to 55% by weight, 10% to 50% by weight, 1% to 40% by weight, 1% to 30% by weight, and 1% to 29% by weight based on the total weight of the PHA copolymer. It may also be % 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.

[0046] When the content of 4-HB repeating units meets the above range, it is possible to enhance biodegradability in soil and seawater, and further improve properties such as dispersibility, dispersion stability, storage stability, coating properties, processability, and productivity without reducing mechanical properties.

[0047] According to embodiments of the present invention, the PHA may be a PHA copolymer whose crystallinity is controlled. Specifically, the PHA comprises one or more 4-HB repeating units, and the content of the 4-HB repeating units may be controlled to adjust the crystallinity of the PHA.

[0048] Furthermore, PHA may be a polyhydroxyalkanoate (PHA) copolymer comprising at least one repeating 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).

[0049] Specifically, the PHA copolymer may contain 4-HB repeating units, and may further contain one or more repeating units selected from the group consisting of 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 copolymer may contain 4-HB repeating units and 3-HB repeating units.

[0050] For example, the PHA copolymer may contain 3-HB repeating units in amounts of 20% or more by weight, 35% or more by weight, 40% or more by weight, 50% or more by weight, 60% or more by weight, 70% or more by weight, or 75% or more by weight, and 99% or less by weight, 98% or less by weight, 97% or less by weight, 96% or less by weight, 95% or less by weight, 93% or less by weight, 91% or less by weight, 90% or less by weight, 80% or less by weight, 70% or less by weight, 60% or less by weight, or 55% or less by weight, based on the total weight of the PHA copolymer.

[0051] PHAs with adjusted crystallinity may have their crystallinity and amorphous properties adjusted when the irregularity within their molecular structure increases. Specifically, the type or ratio of monomers, or the type or content of isomers, may be adjusted.

[0052] According to embodiments of the present invention, the PHA may comprise two or more PHAs having different degrees of crystallinity. Specifically, the PHA may be prepared by mixing two or more PHAs having different degrees of crystallinity so as to have a content of 4-HB repeating units within a specific range.

[0053] Specifically, the PHA may include a first PHA which is a semi-crystalline PHA.

[0054] As a semi-crystalline PHA with controlled crystallinity (hereinafter referred to as scPHA), the first PHA may contain 4-HB repeating units in amounts of 0.1% to 30% by weight. For example, the first PHA may contain 4-HB repeating units in amounts 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.

[0055] The glass transition temperature (Tg) of the first PHA 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 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 may be 105°C to 165°C, 110°C to 160°C, 115°C to 155°C, or 120°C to 150°C.

[0056] The first PHA 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.

[0057] Furthermore, the PHA may also include a second PHA, which is an amorphous PHA resin with controlled crystallinity.

[0058] As amorphous PHA with controlled crystallinity (hereinafter referred to as aPHA), the second PHA may contain 4-HB repeating units in amounts 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.

[0059] The glass transition temperature (Tg) of the second PHA tree may be -45°C to -10°C, -35°C to -15°C, -35°C to -20°C, or -30°C to -20°C.

[0060] Furthermore, the crystallization temperature (Tc) of the second PHA does not need to 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 does not need to 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.

[0061] 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.

[0062] The first PHA and the second PHA can be distinguished with respect to 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). Specifically, the first PHA and the second PHA can be distinguished with respect to the content of 4-HB repeating units, glass transition temperature (Tg), crystallization temperature (Tg), melting point (Tm), etc.

[0063] According to embodiments of the present invention, the PHA may include a first PHA, or it may include both the first PHA and the second PHA.

[0064] Specifically, when the PHA includes either a first PHA that is semi-crystalline, or both a first PHA that is semi-crystalline and a second PHA that is amorphous, or more specifically, when the content of the first and second PHAs is adjusted, it is possible to further improve dispersibility, dispersion stability, storage stability, coating properties, and processability.

[0065] Furthermore, the glass transition temperature (Tg) of PHA 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.

[0066] The crystallization temperature (Tc) of PHA does not need to be measured, or it 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.

[0067] The melting point (Tm) of PHA does not need to be measured, or it may be in the range of 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.

[0068] Furthermore, PHA 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 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, 200,000 g / mol to 1,200,000 g / mol Moles, 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 1,000g / mol, 200,000g / mol~700,000g / mol, 250,000g / mol~650,000g / mol, 200,000g / mol~400,000g / mol, 300,000g / mol~800,000g / mol, 300,000g / mol~600,000g / mol, 500,000g / mol~1,2 It may also be 00,000 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.

[0069] PHA may have a crystallinity of 90% or less, as measured by differential scanning calorimetry (DSC). For example, the crystallinity of PHA may be measured by differential scanning calorimetry and may be 90% or less, 85% or less, 80% or less, 75% or less, or 70% or less.

[0070] According to embodiments of the present invention, the PHA dispersion contains PHA particles. Specifically, the PHA dispersion may contain PHA particles obtained from PHA.

[0071] The PHA particles may have an average particle size of 0.5 μm to 5 μm. For example, the average particle size of the PHA particles may be 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.

[0072] Furthermore, the PHA particles may have a particle size deviation of ±0.3 μm or less. For example, the particle size deviation of the PHA particles may be within ±0.2 μm, ±0.15 μm, ±0.1 μm, or ±0.05 μm.

[0073] The average particle size and particle size deviation of PHA particles may be measured using a nanoparticle size analyzer (e.g., Zetasizer Nano ZS). Specifically, the average particle size and particle size deviation of PHA particles are 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°. Here, the peak value obtained by the polydispersity index (PDI) with a confidence interval of 0.5 is considered to be the particle size.

[0074] A PHA may have a multivariance index (PDI) of less than 3. For example, the multivariance index of a PHA may be less than 3, 2.8 or less, 2.5 or less, less than 2.5, 2.1 or less, or 2 or less.

[0075] If the average particle size, particle size deviation, and polydispersity index of PHA meet the above ranges, dispersibility, dispersion stability, storage stability, coating properties, and processability can be further improved.

[0076] Furthermore, PHA can be obtained by cell disruption using mechanical or physical methods, or by cell disruption using non-mechanical or chemical methods. Specifically, since PHA is a naturally occurring thermoplastic polyester polymer that accumulates in microbial cells and has a relatively large average particle size, PHA may be obtained by a disruption process to improve its dispersibility, coating properties, and processability.

[0077] According to another embodiment of the present invention, the PHA dispersion may further contain a biodegradable polymer.

[0078] 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). If the PHA dispersion further contains biodegradable polymers, it may be more advantageous to control properties such as mechanical properties.

[0079] According to another embodiment of the present invention, the PHA dispersion may contain a surfactant. When the PHA dispersion contains a surfactant, its dispersibility, dispersion stability, storage stability, coating properties, and processability can be further improved.

[0080] Specifically, the surfactant may be a cationic surfactant, anionic surfactant, phosphate-based surfactant, fatty acid-based surfactant, acrylic surfactant, urethane-based surfactant, epoxy-based surfactant, and nonionic surfactant, or a polymeric surfactant comprising at least one selected from the group consisting of carboxylic acids, amines, isocyanates, and their derivatives.

[0081] For example, the surfactant may be at least one selected from the group consisting of polyvinyl alcohol, sodium dodecylbenzenesulfonate, polyvinylpyrrolidone, methyl polyethylene alkyl ether, alkylbenzene sulfonate, nonylphenol ether sulfate, sodium lauryl sulfate, lithium dodecyl sulfate, alkyl phosphate, glyceryl ester, and polypropylene glycol ester.

[0082] The PHA dispersion may contain a surfactant in an amount of 0.01% to 10% by weight on a solids basis, based on the total weight of the PHA dispersion. For example, the surfactant content may be 0.01% to 10% by weight, 0.01% to 8% by weight, 0.05% to 5% by weight, 0.07% to 3.5% by weight, 0.1% to 5% by weight, 1% to 5% by weight, 1.5% to 5% by weight, 0.1% to 2.5% by weight, or 0.01% to 3% by weight, based on the total weight of the PHA dispersion on a solids basis.

[0083] Despite containing significantly less surfactant than conventional solutions, the PHA dispersion exhibits excellent dispersibility, dispersion stability, storage stability, coating properties, and processability.

[0084] The PHA dispersion may further contain at least one additive selected from the group consisting of rheological modifiers, antioxidants, stabilizers, antimicrobial agents, defoaming agents, preservatives, and pH adjusters.

[0085] The rheological modifier may be at least one selected from the group consisting of gum, clay mineral, cellulose derivative, cellulose-based modifier, acrylic-based modifier, and urethane-based modifier. For example, the rheological modifier may be one of gum, clay mineral, or cellulose-based modifier, or a mixture of the two, such as gum and clay mineral, or gum and cellulose-based modifier.

[0086] 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, ghati gum, tara gum, tamarind gum, and tragacanth gum. The clay mineral may be at least one selected from the group consisting of bentonite, smectite, etherpulgite, montmorillonite, kaolinite, sericite, and illite.

[0087] The cellulose derivative may be at least one selected from the group consisting of casein, sodium caseate, and sodium alginate. The cellulose-based modifier may be at least one selected from the group consisting of methylcellulose, hydroxypropylcellulose, and methylhydroxypropylcellulose.

[0088] Furthermore, the rheological modifier may have branched, linear, plate-like, irregular, spherical, or rod-like shapes. When the rheological modifier has any of the above shapes, its coating properties, processability, and productivity can be further improved.

[0089] The rheological modifier may be used in amounts 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, 0.01% to 4% by weight, 0.01% to 3% by weight, 0.02% to 2% by weight, 0.02% to 1.5% by weight, or 0.03% to 1% by weight, based on the total weight of the PHA dispersion.

[0090] Antioxidants are additives used to prevent decomposition by ozone or oxygen, to prevent oxidation during storage, and to prevent deterioration of physical properties. Any commonly used antioxidant may be used as long as the effects of the present invention are not impaired.

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

[0092] For example, the hindered phenol antioxidant may include at least one selected from the group consisting of, for example, 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-based (phosphorus-based) 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]dioxyphosfepin-6-yl]oxy]-ethyl]ethaneamine.

[0094] The antioxidant may be used in amounts 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 PHA dispersion.

[0095] Stabilizers are additives that protect against oxidation and heat, and prevent color changes. Any commonly used stabilizer may be used as a stabilizer, as long as the effects of the present invention are not impaired.

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

[0097] The stabilizer may be used in amounts 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 PHA dispersion.

[0098] The antimicrobial agent may be at least one natural antimicrobial agent selected from the group consisting of organic acids, bacteriocins, and calcium preparations or colloids, or compounds containing elements such as silver. The antimicrobial agent may also be at least one selected from the group consisting of polylysine, benzoisothiazolinone, vinegar powder, chito-oligosaccharides, 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 amounts 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 PHA dispersion, on a solid content basis.

[0100] Furthermore, the defoaming agent is an additive used to prevent or reduce foaming. Any commonly used defoaming agent may be used as the defoaming agent, as long as the effects of the present invention are 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 particulate defoaming agents, and silicone-based defoaming agents, or it 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 waxes.

[0102] The defoaming agent may be used in amounts 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 PHA dispersion, on a solid content 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 to these.

[0104] The preservative may be used in amounts 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 PHA dispersion.

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

[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 amounts 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 PHA dispersion.

[0108] Method for preparing polyhydroxyalkanoate (PHA) dispersion A method for preparing a polyhydroxyalkanoate (PHA) dispersion according to another embodiment of the present invention comprises the step of dispersing polyhydroxyalkanoate (PHA) in a solvent using a particle dispersion method, a melt dispersion method, or a solvent extraction method, wherein the average particle size of the dispersed polyhydroxyalkanoate (PHA) particles is 0.5 μm to 5 μm, and the particle size deviation is within ±0.3 μm.

[0109] Polyhydroxyalkanoates (PHAs) can be obtained by cell disruption using mechanical or physical methods, or by cell disruption using non-mechanical or chemical methods.

[0110] The average particle size of PHA destroyed by mechanical or physical cell disruption is larger than that of PHA destroyed by non-mechanical or chemical cell disruption, resulting in lower dispersibility. However, the method for preparing a PHA dispersion according to the present invention can achieve excellent dispersibility even when cells are destroyed by mechanical or physical methods.

[0111] Furthermore, the preparation of the polyhydroxyalkanoate (PHA) dispersion may be carried out using at least one apparatus selected from the group consisting of a stirrer, homogenizer, high-pressure homogenizer, microfluidizer, and colloid mill, or by at least one method selected from the group consisting of high shear, sonication, and membrane emulsification.

[0112] Particle dispersion method A method for preparing a polyhydroxyalkanoate (PHA) dispersion according to another embodiment of the present invention may include the steps of (1-1) preparing polyhydroxyalkanoate (PHA) obtained by cell disruption using physical or chemical methods; and (1-2) dispersing the polyhydroxyalkanoate (PHA) in a solvent using a particle dispersion method.

[0113] First, polyhydroxyalkanoates (PHAs) obtained by cell disruption using physical or chemical methods may be prepared (Step (1-1)).

[0114] Details regarding cell disruption and PHA are as described above.

[0115] Furthermore, the PHA prepared in step (1-1) may be in the form of fine particles. Specifically, the PHA obtained by cell disruption using mechanical or chemical methods in step (1-1) may be a powder in the form of fine particles.

[0116] Subsequently, the polyhydroxyalkanoate (PHA) can be dispersed in the solvent using a particle dispersion method (step (1-2)).

[0117] Specifically, step (1-2) may include adding a surfactant to the PHA prepared in step (1-1). For example, step (1-2) may include adding the surfactant in amounts of 0.01% to 10% by weight, 0.01% to 8% by weight, 0.05% to 5% by weight, 0.07% to 3.5% by weight, 0.1% to 5% by weight, 1% to 5% by weight, 1.5% to 5% by weight, 0.1% to 2.5% by weight, or 0.01% to 3% by weight, based on the total weight of the PHA dispersion.

[0118] The surfactant may be 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 polymeric surfactant containing at least one selected from the group consisting of carboxylic acids, amines, isocyanates, and their derivatives.

[0119] For example, the surfactant may be at least one selected from the group consisting of polyvinyl alcohol, sodium dodecylbenzenesulfonate, polyvinylpyrrolidone, methyl polyethylene alkyl ether, alkylbenzene sulfonate, nonylphenol ether sulfate, sodium lauryl sulfate, lithium dodecyl sulfate, alkyl phosphate, glyceryl ester, and polypropylene glycol ester. In particle dispersion methods, polyvinyl alcohol surfactants are preferred because they have high solubility, a fast reaction rate, reduced toxicity, and improved productivity and processability, but are not limited thereto.

[0120] Furthermore, the dispersion step may be carried out by a high-speed dispersion process using a homogenizer at a rate of 60% to 80% of the maximum rotational speed per minute (rpm) for 20 to 60 minutes. For example, the dispersion step may be carried out by a high-speed dispersion process using a homogenizer at a rate of 60% to 80%, 65% to 75%, or 60% to 70% of the maximum rotational speed per minute (rpm) for 20 to 60 minutes, 25 to 55 minutes, 25 to 45 minutes, or 25 to 40 minutes.

[0121] Alternatively, the dispersion step may be performed by ultrasonic treatment at an energy level of 20 Hz or higher for 1 hour or less. For example, the dispersion step may be performed by ultrasonic treatment at an energy level of 20 Hz or higher, 25 Hz or higher, 30 Hz or higher, 40 Hz or higher, or 50 Hz or higher for 1 hour or less, 55 minutes or less, 50 minutes or less, or 45 minutes or less, or 5 minutes or more, 10 minutes or more, 15 minutes or more, or 20 minutes or more.

[0122] When the dispersion step is performed under the above conditions, dispersibility, dispersion stability, storage stability, coating properties, and processability can be further improved.

[0123] According to another embodiment of the present invention, the distribution step may include a step of performing a first distribution process; and a step of performing a second distribution process.

[0124] Specifically, the dispersion step may be carried out by filtering, washing, and a second dispersion treatment of the first aqueous dispersion that has undergone the first dispersion treatment.

[0125] More specifically, in the dispersion step, the PHA obtained by cell disruption using a physical method in step (1-1), a mixture of PHA and a surfactant, or a mixture of PHA, a surfactant and a solvent may be subjected to a first dispersion treatment to produce a first aqueous dispersion; the first aqueous dispersion may be filtered and washed, a solvent may be added thereto, and a second dispersion treatment may be performed to prepare a PHA dispersion.

[0126] The filtration step may be carried out using a filter material such as paper, woven fabric, nonwoven fabric, screen, polymer membrane, or wedge wire, and may be carried out using a suction filter, pressure filter, membrane separator, vacuum filter, reduced pressure vacuum filter, industrial filter press, tube press, plate press, gauge press, belt press, screw press, disc press, pressure function press, or centrifuge.

[0127] The washing step may be carried out using a solvent. Specifically, the solvent used in the washing step may be water, distilled water, 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.

[0128] Furthermore, the solvent added to the filtered and washed first aqueous dispersion may be water, distilled water, or a hydrophilic solvent. For example, the solvent added to the first aqueous dispersion may be the same as the solvent used in the washing step.

[0129] The first and second dispersion steps may be carried out by a dispersion process using a homogenizer at a rate of 60% to 80% of the maximum rotational speed per minute (rpm) for 20 to 60 minutes. For example, the first and second dispersion steps may each be carried out by a dispersion process using a homogenizer at a rate of 60% to 80%, 65% to 75%, or 60% to 70% of the maximum rotational speed per minute (rpm) for 20 to 60 minutes, 25 to 55 minutes, 25 to 45 minutes, or 25 to 40 minutes, respectively.

[0130] Furthermore, the dispersion step may be carried out by dispersing the PHA obtained by cell disruption using a chemical method. Specifically, in the dispersion step, the PHA obtained by cell disruption using a chemical method in step (1-1), a mixture of this PHA and a surfactant, or a mixture of this PHA, a surfactant and a solvent may be subjected to a dispersion treatment to prepare a PHA dispersion.

[0131] More specifically, the average particle size of the disrupted PHA obtained by cell disruption using mechanical or physical methods is larger and less dispersible than the average particle size of the disrupted PHA obtained by cell disruption using non-mechanical or chemical methods; therefore, it may be preferable to further perform filtration, washing, and a second dispersion treatment. However, since the average particle size of the PHA obtained by cell disruption using non-mechanical or chemical methods in step (1-1) is relatively small and highly dispersible, filtration, washing, and a second dispersion treatment may be performed optionally.

[0132] Melting dispersion method A method for preparing a polyhydroxyalkanoate (PHA) dispersion according to another embodiment of the present invention may include the steps of (2-1) preparing the polyhydroxyalkanoate (PHA) and (2-2) dispersing the polyhydroxyalkanoate (PHA) in a solvent using a melt-dispersion method.

[0133] First, a polyhydroxyalkanoate (PHA) may be prepared (Step (2-1)).

[0134] Further details about PHA are as described above.

[0135] Unlike the particle dispersion method, the melt-dispersion method does not require that the PHA prepared in step (2-1) be obtained by cell disruption using non-mechanical or chemical methods. Specifically, since the melt-dispersion method includes a step of melting the PHA, it is possible to further improve dispersibility even when using PHA obtained by cell disruption using mechanical or physical methods, which has an average particle size relatively larger than that of PHA obtained by cell disruption using non-mechanical or chemical methods.

[0136] For example, even if the PHA obtained by cell disruption using mechanical or physical methods in step (2-1) is in a form with a large average particle size, such as granules or pellets, its dispersibility can be further improved.

[0137] Subsequently, the polyhydroxyalkanoate (PHA) may be dispersed in the solvent using a melt-dispersion method (step (2-2)).

[0138] Specifically, the dispersion step includes the steps of: melting polyhydroxyalkanoate (PHA); mixing the melted polyhydroxyalkanoate with a surfactant; and dispersing the mixture of the melted polyhydroxyalkanoate and surfactant in the solvent under high pressure.

[0139] More specifically, the PHA prepared in step (2-1) may be melted, and the melt or a mixture of the melt and a surfactant may be subjected to a first dispersion treatment to produce a first aqueous dispersion, and further, the first aqueous dispersion may be subjected to a second high-pressure dispersion treatment in a solvent to prepare a PHA dispersion.

[0140] The melting step may be carried out at 100°C to 220°C. For example, the melting step may be carried out at 100°C to 220°C, 110°C to 200°C, 120°C to 170°C, or 130°C to 160°C.

[0141] Furthermore, the content of the surfactant mixed with the melt may be 0.01% to 10% by weight, 0.01% to 8% by weight, 0.05% to 5% by weight, 0.07% to 3.5% by weight, 0.1% to 5% by weight, 1% to 5% by weight, 1.5% to 5% by weight, 0.1% to 2.5% by weight, or 0.01% to 3% by weight, based on the total weight of the PHA dispersion.

[0142] Specifically, the surfactant may be 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 polymeric surfactant containing at least one selected from the group consisting of carboxylic acids, amines, isocyanates, and their derivatives.

[0143] For example, the surfactant may be at least one selected from the group consisting of polyvinyl alcohol, sodium dodecylbenzenesulfonate, polyvinylpyrrolidone, methyl polyethylene alkyl ether, alkylbenzene sulfonate, nonylphenol ether sulfate, sodium lauryl sulfate, lithium dodecyl sulfate, alkyl phosphate, glyceryl ester, and polypropylene glycol ester. In the melt-dispersion method, sodium dodecylbenzenesulfonate surfactant may be preferred because it efficiently forms a core-shell and controls the zeta potential within a desired range, but it is not limited to this.

[0144] The first dispersion process may be carried out using a homogenizer at a rate of 60% to 80% of the maximum rotational speed per minute (rpm) for 20 to 60 minutes. For example, the first dispersion step may be carried out using a homogenizer at a rate of 60% to 80%, 65% to 75%, or 60% to 70% of the maximum rotational speed per minute (rpm) for 20 to 60 minutes, 25 to 55 minutes, 25 to 45 minutes, or 25 to 40 minutes.

[0145] Furthermore, the second high-pressure dispersion process may be carried out using a homogenizer at a rate of 60% to 80% of the maximum rotational speed per minute (rpm) for 20 to 60 minutes. For example, the second high-pressure dispersion step may be carried out using a homogenizer at a rate of 60% to 80%, 65% to 75%, or 60% to 70% of the maximum rotational speed per minute (rpm) for 20 to 60 minutes, 25 to 55 minutes, 25 to 45 minutes, or 25 to 40 minutes.

[0146] The solvent used for the second dispersion treatment under high pressure may be water, distilled water, or a hydrophilic solvent. Specifically, the solvent may be water, distilled water, 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.

[0147] Solvent extraction method A method for preparing a polyhydroxyalkanoate (PHA) dispersion according to another embodiment of the present invention may include the steps of (3-1) preparing a polyhydroxyalkanoate (PHA) and (3-2) dispersing the polyhydroxyalkanoate (PHA) in a solvent using a solvent extraction method.

[0148] First, a polyhydroxyalkanoate (PHA) may be prepared (step (3-1)).

[0149] Further details about PHA are as described above.

[0150] Unlike the particle dispersion method, the solvent extraction method does not require that the PHA prepared in step (3-1) be PHA obtained by cell disruption using non-mechanical or chemical methods. Specifically, since the solvent extraction method includes a step of mixing the PHA with a specific first solvent to prepare a first solution, it is possible to further improve dispersibility even when using PHA obtained by cell disruption using mechanical or physical methods, which has an average particle size relatively larger than that of PHA obtained by cell disruption using non-mechanical or chemical methods.

[0151] For example, the dispersibility of the PHA obtained in step (3-1) by cell disruption using mechanical or physical methods can be further improved even if it is in a form with a large average particle size, such as granules or pellets.

[0152] Subsequently, the polyhydroxyalkanoate (PHA) may be dispersed in a solvent using a solvent extraction method (step (3-2)).

[0153] Specifically, the dispersion step may include: preparing a first solution by mixing a polyhydroxyalkanoate (PHA) with a first solvent; preparing a second solution by mixing a surfactant with a second solvent; mixing the first solution and the second solution; and performing ultrasonic dispersion on the mixture.

[0154] The first solvent may be at least one selected from the group consisting of chloroform, ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, isoamyl acetate, propyl propionate, butyl propionate, isobutyl propionate, ethyl butyrate, isobutyl isobutyrate, dichloromethane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, methyl ethyl ketone, methylene chloride, tetrahydrofuran, toluene, and acetone.

[0155] Dispersibility can be improved by using a solvent with high solubility for PHA as the first solvent. Chloroform is sometimes preferred because of its high solubility for PHA, but it is not the only solvent that can be used.

[0156] In the first solution preparation step, the weight ratio of the first solvent to PHA may be 1:9, 1.5:8.5, 2:8, or 3:7.

[0157] The second solvent may be water, distilled water, or a hydrophilic solvent. Specifically, the solvent may be water, distilled water, 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.

[0158] The surfactant content mixed in the second solution preparation step may be 0.01% to 10% by weight, 0.01% to 8% by weight, 0.05% to 5% by weight, 0.07% to 3.5% by weight, 0.1% to 5% by weight, 1% to 5% by weight, 1.5% to 5% by weight, 0.1% to 2.5% by weight, or 0.01% to 3% by weight, based on the total weight of the PHA dispersion and on a solids basis.

[0159] Specifically, the surfactant may be 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 polymeric surfactant containing at least one selected from the group consisting of carboxylic acids, amines, isocyanates, and their derivatives.

[0160] For example, the surfactant may be at least one selected from the group consisting of polyvinyl alcohol, sodium dodecylbenzenesulfonate, polyvinylpyrrolidone, methyl polyethylene alkyl ether, alkylbenzene sulfonate, nonylphenol ether sulfate, sodium lauryl sulfate, lithium dodecyl sulfate, alkyl phosphate, glyceryl ester, and polypropylene glycol ester. In solvent extraction methods, polyvinyl alcohol surfactants may be preferred because they have rapid and high solubility in the second solvent, particularly water or distilled water, thus improving miscibility, but the method is not limited to this.

[0161] Furthermore, the step of preparing the second solution may further include a dispersion step. For example, the dispersion step may be carried out using a homogenizer by dispersion at a rate of 60% to 80%, 65% to 75%, or 60% to 70% of the maximum rotational speed per minute (rpm) for 20 to 60 minutes, 25 to 55 minutes, 25 to 45 minutes, or 25 to 40 minutes.

[0162] Subsequently, the mixed solution of the first solution and the second solution may be subjected to ultrasonic dispersion treatment at an energy level of 20 Hz or higher for a period of 1 hour or less. For example, the ultrasonic dispersion treatment may be performed at an energy level of 20 Hz or higher, 25 Hz or higher, 30 Hz or higher, 40 Hz or higher, for a period of 1 hour or less, 55 minutes or less, 50 minutes or less, or 45 minutes or less, or for 5 minutes or more, 10 minutes or more, 15 minutes or more, or 20 minutes or more.

[0163] Furthermore, after the ultrasonic dispersion step, an additional step may be performed in which the mixed solution of the first and second solutions is subjected to vacuum distillation. For example, the residual solvent may be removed from the mixed solution by vacuum distillation at a temperature of 60°C or lower, 50°C or lower, or 40°C or lower.

[0164] Furthermore, after the ultrasonic dispersion step, an additional step may be performed in which the mixed solution of the first and second solutions is filtered, washed, and redispersed. Specifically, the mixture from which the residual solvent has been removed by vacuum distillation may be filtered, washed, and then redispersed.

[0165] The filtration step may be carried out using a filter material such as paper, woven fabric, nonwoven fabric, screen, polymer membrane, or wedge wire, and may be carried out using a suction filter, pressure filter, membrane separator, vacuum filter, reduced pressure vacuum filter, industrial filter press, tube press, plate press, gauge press, belt press, screw press, disc press, pressure function press, or centrifuge.

[0166] The washing and redispersion steps may be carried out using a second solvent. Specifically, the solvent used in the washing step may be water, distilled water, a hydrophilic solvent, or a mixture of water, distilled water, and a hydrophilic solvent.

[0167] Furthermore, using a homogenizer, redispersion may be carried out by a dispersion process of 20 to 60 minutes, 25 to 55 minutes, 25 to 45 minutes, or 25 to 40 minutes at a rate of 60% to 80%, 65% to 75%, or 60% to 70% of the maximum rotational speed per minute (rpm).

[0168] Method for preparing biodegradable articles A method for preparing a biodegradable article according to another embodiment of the present invention comprises the steps of: preparing a polyhydroxyalkanoate (PHA) dispersion; and forming a biodegradable coating layer from the polyhydroxyalkanoate (PHA) dispersion.

[0169] Details regarding the preparation of the PHA dispersion are as described above.

[0170] Subsequently, a biodegradable coating layer is formed on one side of the substrate using a PHA dispersion.

[0171] According to an embodiment of the present invention, the step of forming the biodegradable coating layer may be performed by coating a PHA dispersion liquid on a substrate and drying it.

[0172] The substrate is not limited as long as a biodegradable coating layer can be formed 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, non-woven 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.

[0173] Specifically, from the viewpoint of enhancing the coating property of the substrate, the substrate may preferably be a single-material substrate. The substrate may be paper, kraft paper, cloth, or non-woven fabric, but is not limited thereto. Furthermore, when the substrate contains paper or kraft paper, it has better biodegradability than other plastic materials, so it can be more advantageous for providing an environmentally compatible packaging material.

[0174] The substrate may have a thickness of 20 μm or more. For example, the thickness of the substrate may be 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.

[0175] Furthermore, the substrate may have a basis weight of 30 g / m 2 , 2 , 2 , 2 , 2 , 2 ~500 g / 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 is 30 g / m 2 ~500 g / m 2 、30 g / m 2 ~350 g / m 2 、30 g / m 2 ~200 g / m 2 、50 g / m 2 ~200 g / m 280g / m 2 ~200g / m 2 100g / m 2 ~200g / m 2 130g / m 2 ~190g / m 2 150g / m 2 ~185g / m 2 , or 120g / m 2 ~320g / m 2 That's fine.

[0176] On the other hand, the 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 have moisture barrier 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, which may have commonly used materials and physical properties as long as they do not impair the effects desired in the present invention.

[0177] Furthermore, the PHA dispersion is 5 g / m². 2 ~100g / m 2 The coating may be applied to the substrate in the amount specified. For example, the coating amount may be 5 g / m². 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 , or 10g / m 2 ~40g / m 2 This is also acceptable. If the coating amount meets the above range, coating properties, productivity, and processability can be further improved.

[0178] Furthermore, the coating may be applied once to form a single coating layer, or it may be applied two or more times to form multiple coating layers. The amount of coating can be adjusted within the above range depending on the desired number of coating layers. Specifically, the amount of coating may be the total amount used for multiple coating layers.

[0179] Once the PHA dispersion is applied to the substrate, it may be dried at 100°C to 200°C for 5 seconds to 30 minutes. 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.

[0180] The formation of the biodegradable coating layer may be carried out without particular limitations, as long as it is a coating process commonly used in the art. For example, the formation of the biodegradable coating layer may be carried out by gravure printing coating, slot coating, doctor blade coating, spray coating, bar coating, spin coating, or in-line coating, but is not limited to these.

[0181] biodegradable articles A biodegradable article according to another embodiment of the present invention comprises a substrate and a biodegradable coating layer, wherein the biodegradable coating layer contains polyhydroxyalkanoate (PHA) particles, the average particle size of the dispersed polyhydroxyalkanoate (PHA) particles is 0.5 μm to 5 μm, and the particle size deviation is within ±0.3 μm.

[0182] Figure 4 shows a biodegradable article according to an embodiment of the present invention. Figure 5 shows a biodegradable article according to another embodiment of the present invention.

[0183] Specifically, Figure 4 shows a biodegradable article (1) in which a biodegradable coating layer (200) is formed on one side of a substrate (100). Figure 5 shows a biodegradable article (1) in which a biodegradable coating layer (200) is formed on both sides of a substrate (100).

[0184] When a biodegradable article includes a biodegradable coating layer on one or both sides of a substrate, and the biodegradable coating layer contains PHA particles with an average particle size of 0.5 μm to 5 μm and a particle size deviation of ±0.3 μm or less, the biodegradable article is environmentally compatible due to its excellent biodegradability and biocompatibility, and can have excellent dispersibility, coating properties, productivity, and processability.

[0185] Details regarding the base material are as described above.

[0186] 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, but is not limited to these.

[0187] Biodegradable articles containing a biodegradable coating layer may be, but are not limited to, packaging materials, cardboard boxes, shopping bags, disposable tableware, packaging containers, or paper straws.

[0188] [Embodiments for carrying out the invention] The present invention will be described in more detail below with reference to the following examples. However, the following examples are intended to illustrate the present invention, and the scope of the examples is not limited to them.

[0189] [Examples] Preparation of PHA dispersion <Particle dispersion method>

[0190] Example 1 (1) Preparation of PHA Polyhydroxyalkanoate (PHA) powder (4-hydroxybutyrate (4-HB) content: 10% by weight, weight-average molecular weight (Mw): 800,000 g / mol, polydispersity index (PDI): 2.0, manufacturer: CJ) was prepared. The PHA powder was obtained by physical grinding using a homogenizer (product name: Homomixer Mark II, manufacturer: Primix).

[0191] (2) Preparation of PHA dispersion A 1-liter glass beaker was filled with 30 parts by weight of PHA powder, 20 parts by weight of polyvinyl alcohol (PVA, manufacturer: Kuraray, hydrolysis rate: 80%) with a concentration of 10% as a surfactant, and 50 parts by weight of distilled water (DI water). A first dispersion treatment was performed using a homogenizer (linear velocity: 1,250 cm / sec, trade name: Homomixer Mark II, manufacturer: Primix, maximum rotation speed per minute: 12,000 rpm) at 70% of the maximum rotation speed per minute for 30 minutes to prepare a first aqueous dispersion.

[0192] Subsequently, the first aqueous dispersion was filtered using a pressure filter, washed with water, and then distilled water was added. A second dispersion treatment was then performed in an aqueous system using a homogenizer (product name: Homomixer Mark II, manufacturer: Primix) to prepare a PHA dispersion with a solid content of 40% by weight.

[0193] Example 2 A PHA dispersion was prepared in the same manner as in Example 1, except that in step (1), a polyhydroxyalkanoate (PHA) powder (containing 4-hydroxybutyrate (4-HB): 10% by weight, weight-average molecular weight (Mw): 380,000 g / mol, polydispersity index (PDI): 1.9, manufacturer: CJ) was prepared.

[0194] Example 3 (1) Preparation of PHA A polyhydroxyalkanoate (PHA) with a solid content of 5% by weight (4-hydroxybutyrate (4-HB) content: 10% by weight, weight-average molecular weight (Mw): 800,000 g / mol, polydispersity index (PDI): 1.9, manufacturer: CJ) was prepared. The PHA was obtained by physical grinding using a homogenizer (product name: Homomixer Mark II, manufacturer: Primix).

[0195] (2) Preparation of PHA dispersion A first aqueous dispersion was prepared by charging a 1-liter glass beaker with 600 parts by weight of PHA and 20 parts by weight of polyvinyl alcohol (PVA, manufacturer: Kuraray, hydrolysis rate: 80%) having a concentration of 10% as a surfactant. A first dispersion treatment was then performed using a homogenizer (linear velocity: 1,250 cm / sec, trade name: Homomixer Mark II, manufacturer: Primix, maximum rotation speed per minute: 12,000 rpm) at 70% of the maximum rotation speed per minute for 30 minutes.

[0196] Subsequently, the first aqueous dispersion was filtered using a pressure filter, washed with water, and then distilled water was added. A second dispersion treatment was then performed in an aqueous system using a homogenizer (product name: Homomixer Mark II, manufacturer: Primix) to prepare a PHA dispersion with a solid content of 40% by weight.

[0197] Example 4 A PHA dispersion was prepared in the same manner as in Example 3, except that in step (1), a polyhydroxyalkanoate (PHA) having 10% by weight solids (4-hydroxybutyrate (4-HB) content: 10% by weight, weight-average molecular weight (Mw): 900,000 g / mol, polydispersity index (PDI): 1.6, manufacturer: CJ) was prepared, and in step (2), 400 parts by weight of PHA were used.

[0198] Example 5 (1) Preparation of PHA Polyhydroxyalkanoate (PHA) powder (4-hydroxybutyrate (4-HB) content: 10% by weight, weight-average molecular weight (Mw): 600,000 g / mol, polydispersity index (PDI): 1.92, manufacturer: CJ) was prepared. The PHA powder was obtained by chemical grinding using sodium dodecylbenzenesulfonate.

[0199] (2) Preparation of PHA dispersion A 1-liter glass beaker was filled with 40 parts by weight of PHA powder, 1 part by weight of polyvinyl alcohol (PVA, manufacturer: Kuraray, hydrolysis rate: 80%) with a concentration of 10% as a surfactant, and 60 parts by weight of distilled water (DI water). A first dispersion treatment was performed using a homogenizer (linear velocity: 1,250 cm / sec, trade name: Homomixer Mark II, manufacturer: Primix, maximum rotation speed per minute: 12,000 rpm) at 70% of the maximum rotation speed per minute for 30 minutes to prepare a first aqueous dispersion.

[0200] Subsequently, the first aqueous dispersion was filtered using a pressure filter, washed with water, and then distilled water was added. A second dispersion treatment was then performed in an aqueous system using a homogenizer (product name: Homomixer Mark II, manufacturer: Primix) to prepare a PHA dispersion with a solid content of 40.1% by weight.

[0201] Example 6 A PHA dispersion was prepared using the PHA powder prepared in step (1) of Example 5, in the same manner as in Example 1.

[0202] Example 7 A PHA dispersion was prepared in the same manner as in Example 3, except that in step (1), a polyhydroxyalkanoate (PHA) having 10% by weight solids (4-hydroxybutyrate (4-HB) content: 10% by weight, weight-average molecular weight (Mw): 600,000 g / mol, polydispersity index (PDI): 1.92, manufacturer: CJ) was prepared.

[0203] <Melting Dispersion Method> Example 8 (1) Preparation of PHA Polyhydroxyalkanoate (PHA) granules (4-hydroxybutyrate (4-HB) content: 10% by weight, weight-average molecular weight (Mw): 800,000 g / mol, polydispersity index (PDI): 1.9, manufacturer: CJ) were prepared. PHA fine particles were obtained by physical grinding using a homogenizer (product name: Homomixer Mark II, manufacturer: Primix).

[0204] (2) Preparation of PHA dispersion 30 parts by weight of PHA granules were melted at 170°C, then mixed with 2 parts by weight of sodium dodecylbenzenesulfonate (SDS), and a first dispersion treatment was performed for 30 minutes at 70% of the maximum rotation speed per minute using a homogenizer (linear velocity: 1,250 cm / sec, trade name: Homomixer Mark II, manufacturer: Primix, maximum rotation speed per minute: 12,000 rpm) to prepare the first aqueous dispersion.

[0205] Subsequently, the first aqueous dispersion was subjected to a second high-pressure dispersion treatment in a solvent for 30 minutes using a high-pressure homogenizer (product name: Homomixer Mark II, manufacturer: Premix, maximum rotation speed per minute: 8,000 rpm) to prepare a PHA dispersion with a solid content of 40% by weight.

[0206] <Solvent extraction method> Example 9 (1) Preparation of PHA and the first solution Polyhydroxyalkanoate (PHA) pellets were prepared (4-hydroxybutyrate (4-HB) content: 10% by weight, weight-average molecular weight (Mw): 800,000 g / mol, polydispersity index (PDI): 2.0, manufacturer: CJ). The PHA pellets were obtained by physical grinding using a homogenizer (product name: Homomixer Mark II, manufacturer: Primix).

[0207] Furthermore, a first solution was prepared by mixing 10 parts by weight of PHA pellets with 90 parts by weight of chloroform.

[0208] (2) Preparation of the second solution A 1-liter glass beaker was filled with 20 parts by weight of polyvinyl alcohol (PVA, manufacturer: Kuraray, hydrolysis rate: 80%) with a concentration of 2% as a surfactant. Distilled water was then added as the second solvent, and the mixture was dispersed using a homogenizer (linear velocity: 1,250 cm / sec, trade name: Homomixer Mark II, manufacturer: Primix, maximum rotation speed per minute: 12,000 rpm) at a speed of 10% of the maximum rotation speed per minute for 5 minutes to prepare the second solution.

[0209] (3) Preparation of PHA dispersion A mixture of the first and second solutions was subjected to ultrasonic dispersion treatment at an energy level of 35 Hz or higher for 30 minutes.

[0210] Using a vacuum distillation apparatus (product name: N-21000, manufacturer: Eyela), the residual solvent was removed from the ultrasonically dispersed mixed solution at 40°C, filtered using a pressure filter, washed with water, and then redispersed in an aqueous system to prepare a PHA dispersion with a solid content of 40% by weight.

[0211] Example 10 A PHA dispersion was prepared in the same manner as in Example 9, except that in step (1), polyhydroxyalkanoate (PHA) pellets (4-hydroxybutyrate (4-HB) content: 50% by weight, weight-average molecular weight (Mw): 900,000 g / mol, polydispersity index (PDI): 1.6, manufacturer: CJ) were prepared.

[0212] Comparative Example 1 (1) Preparation of PHA The same PHA powder as in step (1) of Example 1 was prepared.

[0213] (2) Preparation of PHA dispersion 30 parts by weight of PHA powder and 70 parts by weight of distilled water (DI water) were placed in a 1-liter glass beaker, and a first dispersion treatment was performed using a homogenizer (linear velocity: 1,250 cm / sec, product name: Homomixer Mark II, manufacturer: Primix, maximum rotation speed per minute: 12,000 rpm) at 70% of the maximum rotation speed per minute for 30 minutes to prepare a PHA dispersion with a solid content of 30% by weight.

[0214] Comparative Example 2 The PHA dispersion was prepared in the same manner as in Example 5, except that a surfactant was not added in step (2).

[0215] Comparative Example 3 A PHA dispersion was prepared using the same PHA pellet as in step (1) of Example 10, in the same manner as in step (2) of Comparative Example 1.

[0216] Comparative Example 4 In step (2), the PHA dispersion was prepared in the same manner as in Example 1, except that a homogenizer (linear velocity: 1,250 cm / sec, product name: Homomixer Mark II, manufacturer: Primix, maximum rotational speed per minute: 12,000 rpm) was used to perform dispersion processing at 40% of the maximum rotational speed per minute for 30 minutes.

[0217] [Test Examples] Test Example 1: Haze The haze levels of the PHA dispersions in Examples 1-10 and Comparative Examples 1-4 were measured using a haze meter (CM-5, Konica Minolta).

[0218] Test Example 2: Color The color characteristics L*, a*, and b* of the PHA dispersions of Examples 1-10 and Comparative Examples 1-4 were measured using a spectrophotometer CM-5 (manufacturer: Konica Minolta).

[0219] Test Example 3: Yellow Index (YI) The yellow index of the PHA dispersions of Examples 1-10 and Comparative Examples 1-4 was measured using a CM-5 spectrophotometer (manufacturer: Konica Minolta) in accordance with ASTM E313.

[0220] Test Example 4: Zeta Potential The zeta potential of the PHA dispersions of Examples 1-10 and Comparative Examples 1-4 was measured using a ZetaPlus Zeta Potential Analyzer (manufacturer: Brookhaven Instruments).

[0221] Test Example 5: Average particle size and particle size deviation Using a Zetasizer Nano ZS (manufacturer: Marven), the average particle size and particle size deviation of PHA particles contained in each of the PHA dispersions of Examples 1-10 and Comparative Examples 1-4 were measured by dynamic light scattering (DLS) at a temperature of 25°C and a measurement angle of 175°. Here, the peak value derived from the polydispersity index (PDI) with a confidence interval of 0.5 was defined as the particle size.

[0222] Test Example 6: Dispersion Stability The PHA dispersions of Examples 1-10 and Comparative Examples 1-4 were each placed in test tubes and left at 50°C for two weeks. Then, the dispersion stability was 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.

[0223] Test Example 7: Viscosity The viscosity of the PHA dispersions in Examples 1-10 and Comparative Examples 1-4 was measured using a viscometer (manufacturer: Brookfield) that measures viscosity using shear stress at a shear rate of approximately 23°C and 12 rpm.

[0224] [Table 1]

[0225] [Table 2]

[0226] As can be seen from Tables 1 and 2 above, the PHA dispersions of Examples 1 to 10 exhibited significantly superior dispersibility and processability compared to the dispersions of Comparative Examples 1 to 4.

[0227] Specifically, PHA dispersions of Examples 1 to 10 were prepared by particle dispersion, melt dispersion, or solvent extraction according to embodiments of the present invention. Since the average particle size and particle size deviation of the PHA particles contained in the PHA dispersions met specific ranges, they possessed zeta potential, dispersion stability, and viscosity that met desirable ranges, resulting in excellent dispersibility and processability.

[0228] In contrast, the PHA dispersions of Comparative Examples 1-4 had average particle size and particle deviation of contained PHA particles that did not meet the specified range, resulting in zeta potential, dispersion stability, and viscosity that did not meet the desired range, leading to insufficient dispersibility, dispersion stability, and processability. In particular, in Comparative Example 3, the PHA neither dissolved nor dispersed at all.

[0229] [Explanation of reference number] 1 Biodegradable articles 100 Base material 200 Biodegradable coating layer

Claims

1. A polyhydroxyalkanoate (PHA) dispersion containing polyhydroxyalkanoate (PHA) particles, wherein the average particle size of the polyhydroxyalkanoate (PHA) particles is 0.5 μm to 5 μm, and the particle size deviation is within ±0.3 μm. A polyhydroxyalkanoate (PHA) dispersion wherein the polyhydroxyalkanoate (PHA) comprises at least one repeating 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).

2. The polyhydroxyalkanoate (PHA) dispersion according to claim 1, wherein the polyhydroxyalkanoate (PHA) has a weight-average molecular weight of 10,000 g / mol to 1,200,000 g / mol and a polydispersity index (PDI) of less than 2.

5.

3. The polyhydroxyalkanoate (PHA) dispersion according to claim 1, wherein the polyhydroxyalkanoate (PHA) has a crystallinity of 90% or less as measured by differential scanning calorimeter (DSC) and a glass transition temperature (Tg) of -45°C to 80°C.

4. The polyhydroxyalkanoate (PHA) dispersion according to claim 1, wherein the polyhydroxyalkanoate (PHA) is a polyhydroxyalkanoate (PHA) copolymer comprising at least two repeating units 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).

5. The polyhydroxyalkanoate (PHA) dispersion according to claim 4, wherein the polyhydroxyalkanoate (PHA) copolymer contains 4-hydroxybutyrate (4-HB) repeating units in an amount of 0.1% to 60% by weight based on the total weight of the polyhydroxyalkanoate (PHA) copolymer.

6. The polyhydroxyalkanoate (PHA) dispersion further contains a biodegradable polymer, The polyhydroxyalkanoate (PHA) dispersion according to claim 1, wherein the biodegradable polymer comprises 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).

7. The polyhydroxyalkanoate (PHA) dispersion according to claim 1, wherein the polyhydroxyalkanoate (PHA) dispersion has a solid content of 10% to 60% by weight, and the polyhydroxyalkanoate (PHA) dispersion contains a surfactant in an amount of 0.01% to 10% by weight on a solid content basis, based on the total weight of the polyhydroxyalkanoate (PHA) dispersion.

8. The polyhydroxyalkanoate (PHA) dispersion according to claim 7, 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 polymeric surfactant comprising at least one selected from the group consisting of carboxylic acids, amines, isocyanates, and their derivatives.

9. The polyhydroxyalkanoate (PHA) dispersion according to claim 1, wherein the polyhydroxyalkanoate (PHA) dispersion has a haze of 100% to 400% and a yellow index (Y.I.) of 5 to 20.

10. The polyhydroxyalkanoate (PHA) dispersion according to claim 1, wherein the polyhydroxyalkanoate (PHA) dispersion has L* of 40 or more, a* of less than 0.44, and b* of 6 or less.

11. The polyhydroxyalkanoate (PHA) dispersion according to claim 1, wherein the polyhydroxyalkanoate (PHA) dispersion has a zeta potential of -10 mV or less.

12. The polyhydroxyalkanoate (PHA) dispersion according to claim 1, wherein the polyhydroxyalkanoate (PHA) dispersion has a pH of 3 to 11 and a light transmittance of 10% to 99%.

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