TW202413556A - Coating composition, process for preparing the same, and laminate prepared by using the same - Google Patents

Abstract

The present invention provides a coating composition, a process for preparing the same, and a laminate prepared by using the same. Specifically, according to an embodiment of the present invention, the coating composition comprises a polyhydroxyalkanoate (PHA) and an acrylic binder, wherein the weight ratio of the polyhydroxyalkanoate (PHA) to the acrylic binder is adjusted to 3:7 to 7:3. Thus, it is not only environmentally friendly by increasing the content of biocarbon and reducing the carbon (carbon dioxide) emissions, but also can enhance dispersibility, coatability, water resistance, processability, and productivity at the same time.

Description

Coating composition, method for preparing the same and coating prepared by using the same

Invention Field

The present invention relates to coating compositions, methods for preparing the same, and laminates prepared by using the same.

Invention Background

In recent years, with the increasing concern about environmental issues, research on the treatment and recycling of various domestic wastes has been actively carried out.

In particular, in order to improve the recyclability and marine biodegradability of packaging materials, it is desired to develop coating compositions prepared from biodegradable plastics, thereby expanding the utilization of environmentally friendly materials and increasing the demand for environmentally friendly materials.

In particular, coating compositions prepared from biodegradable plastics and containing large amounts of bioplastics are being developed to reduce carbon emissions and respond to global environmental regulations.

For example, a coating composition is developed by mixing polyhydroxyalkanoate (PHA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate terephthalate (PBST), polybutylene succinate adipate (PBSA) or the like with a dispersion. This is used to develop a paper packaging material by laminating paper and a biodegradable film.

However, when the coating composition is bonded to a paper substrate to produce a paper packaging material, there is a problem of weak water resistance, which allows moisture to penetrate from the food, thereby tearing the packaging material, causing food contamination or shortening the service life. There are still limitations in simultaneously satisfying the adhesion with the paper substrate, processability, productivity (using a mass production system), and carbon emission reduction effect. [Prior technical document] [Patent document] (Patent document 1) Korean Patent Publication No. 2012-0103158

Summary of the invention Technical problem

One object of the present invention is to provide a coating composition and a preparation method thereof, wherein the coating composition is environmentally friendly due to its excellent biodegradability and biocompatibility, and can simultaneously enhance dispersibility, coatability, water resistance, processability and productivity.

Another object of the present invention is to provide a laminate prepared using the coating composition and a method for preparing the same .

According to one embodiment of the present invention, a coating composition is provided, which comprises polyhydroxyalkanoate (PHA) and acrylic adhesive, wherein the weight ratio of polyhydroxyalkanoate (PHA) to acrylic adhesive is 3:7 to 7:3.

According to another embodiment, when the coating composition is applied to ^a paper substrate having a basis weight of 20 to 400 g/m ^{2 at a coating amount of 1 to 100 g/m 2 and} then dried at 170° C. or less, the drying time may be less than 200 seconds.

According to another embodiment, the content of biochar can be 25% or more based on the total weight of the coating composition.

According to another embodiment, the polyhydroxyalkanoate (PHA) may have a weight average molecular weight (Mw) of 200,000 g/mol to 900,000 g/mol, an average particle size of 5 μm or less, and a polydispersity index (PDI) of 3 or less.

According to another embodiment, the polyhydroxyalkanoate (PHA) may have a glass transition temperature (Tg) of -10°C to 10°C, a crystallization temperature (Tc) of 70°C to 120°C, and a melting temperature (Tm) of 100°C to 170°C.

According to another embodiment, the polyhydroxyalkanoate (PHA) may comprise repeating units derived from at least one monomer selected from the group consisting of 4-hydroxybutyrate (4-HB), 3-hydroxybutyrate (3-HB), 3-hydroxypropionate (3-HP), 3-hydroxyvalerate (3-HV), 3-hydroxyhexanoate (3-HH), 4-hydroxyvalerate (4-HV), 5-hydroxyvalerate (5-HV) and 6-hydroxyhexanoate (6-HH).

According to another embodiment, the polyhydroxyalkanoate (PHA) may be a PHA copolymer comprising repeating units derived from 3-hydroxybutyrate (3-HB) monomers and repeating units derived from 4-hydroxybutyrate (4-HB) monomers, wherein the repeating units derived from 4-hydroxybutyrate (4-HB) monomers may be 0.1 mol % to 60 mol % based on the total molar number of the repeating units derived from 3-hydroxybutyrate (3-HB) monomers and the repeating units derived from 4-hydroxybutyrate (4-HB) monomers.

According to another embodiment, the acrylic adhesive may include an acrylic monomer, a copolymer including an acrylic monomer and at least one monomer selected from the group consisting of a silicone monomer and a styrene monomer, or a combination thereof, and have an average particle size of 1 μm or less and a polydispersity index (PDI) of 2 or less.

According to another embodiment, the coating composition may further comprise at least one additive selected from the group consisting of a dispersant, a thickener, a preservative, a defoaming agent, and a pH adjuster, and the additive may be used in an amount of 0.1 wt % to 30 wt % based on the total weight of the solid content of the coating composition.

According to another embodiment of the present invention, a method for preparing a coating composition is provided, the method comprising preparing a polyhydroxyalkanoate (PHA) dispersion containing polyhydroxyalkanoate (PHA); and mixing the polyhydroxyalkanoate (PHA) dispersion with an acrylic emulsion containing an acrylic binder, wherein the weight ratio of the polyhydroxyalkanoate (PHA) to the acrylic binder is 3:7 to 7:3.

According to another embodiment, the polyhydroxyalkanoate (PHA) dispersion may include polyhydroxyalkanoate (PHA), a dispersant and a solvent, and the polyhydroxyalkanoate (PHA) may be used in an amount of 10 wt % to 60 wt % based on the total weight of the polyhydroxyalkanoate (PHA) dispersion.

According to another embodiment, the polyhydroxyalkanoate (PHA) dispersion may have a pH of 5 to 8 and a viscosity of 50 to 1,000 cPs measured at 25°C.

According to another embodiment, the acrylic emulsion may have a pH of 8 or less and a viscosity of 1,000 cPs or less measured at 25°C.

According to one embodiment of the present invention, a laminate is provided, which includes a substrate layer and a coating layer, wherein the coating layer includes polyhydroxyalkanoate (PHA) and an acrylic adhesive, and the weight ratio of the polyhydroxyalkanoate (PHA) to the acrylic adhesive is 3:7 to 7:3.

According to another embodiment, the coating may have a thickness of 5 to 30 g/m ² and a water absorption index (WAI) of 30 g/m ² ·10 minutes or less when measured using the Cobb water absorption test according to the TAPPI T441 standard.

According to another embodiment of the present invention, a method for preparing a laminate is provided, which includes (1) preparing a coating composition, and (2) coating the coating composition on a substrate and drying it to form a coating.

According to another embodiment, drying may be performed at 100°C to 250°C for less than 200 seconds.

According to another embodiment, the coating composition can be applied to the substrate in an amount of 1 to 100 g/m ^2. Advantageous Effects of the Invention

The coating composition according to one embodiment of the present invention comprises polyhydroxyalkanoate (PHA) and acrylic binder, wherein the weight ratio of polyhydroxyalkanoate (PHA) to acrylic binder is adjusted to 3:7 to 7:3. Therefore, it is not only environmentally friendly by increasing the biochar content, but also can enhance dispersibility, coatability, water resistance, processability and productivity at the same time.

In addition, the method for preparing a coating composition according to one embodiment of the present invention can prepare a coating composition having excellent characteristics in a simple and effective method.

In addition, the laminate using the coating composition according to one embodiment of the present invention is environmentally friendly because it has excellent biodegradability and biocompatibility, and carbon (carbon dioxide) emissions can be reduced by increasing the biocarbon content, and it has excellent water resistance. Therefore, when it is applied to products that require water resistance, such as packaging materials or food containers for packaging foods with a large amount of water, it exhibits excellent characteristics and can further enhance the service life characteristics and recyclability.

In addition, since the method for preparing a laminate according to an embodiment of the present invention uses a coating composition, the drying time after coating can be significantly reduced, thereby improving productivity. Specifically, when it is dried at 140° C. to 170° C., the production rate and water resistance of the coating can be optimally enhanced.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the present invention will be described in detail. The present invention is not limited to the disclosure given below, but can be modified into various forms as long as the gist of the present invention is not changed.

Throughout the present specification, unless specifically stated otherwise, when a part is referred to as “comprising” an element, it should be understood that other elements may be included rather than excluded.

Unless otherwise indicated, all numbers and expressions relating to quantities of components, reaction conditions, and the like used herein are to be understood as being modified by the term "about."

In the present specification, when it is mentioned that an element is formed “on” or “under” another element, it not only means that one element is directly formed “on” or “under” another element, but also means that one element is indirectly formed on or under another element with other elements interposed therebetween.

Throughout this specification, the terms first, second and similar terms are used to describe various components. However, these components should not be limited by these terms. These terms are only used to distinguish one component from another.

In this specification, reference numerals of "one side" or "above" and "below" of each component are explained based on the accompanying drawings. These terms are only used to distinguish components and can be interchanged with each other in actual applications.

In addition, for the purpose of description, the size of individual components may be exaggeratedly depicted in the accompanying drawings and does not indicate the actual size. In addition, throughout the specification, the same component symbols refer to the same components.

The present invention relates to a coating composition in which PHA and an acrylic adhesive satisfy a specific weight ratio; a method for preparing the same; a laminate prepared by using the coating composition; and a method for preparing the same (which will be described in detail).

The coating composition according to one embodiment of the present invention comprises polyhydroxyalkanoate (PHA) and acrylic adhesive, wherein the weight ratio of PHA to acrylic adhesive is 3:7 to 7:3.

The coating composition according to one embodiment of the present invention comprises PHA and an acrylic binder, wherein the weight ratio of PHA to acrylic binder is adjusted to 3:7 to 7:3. Therefore, it is not only environmentally friendly, because carbon (carbon dioxide) emissions can be reduced by increasing the biocarbon content, but also can enhance dispersibility, coatability, water resistance, processability and productivity at the same time. Specifically, the layer or product formed using the coating composition has excellent water resistance, which can further enhance the service life characteristics and recyclability, and it has a biocarbon content within a specific range, which is very beneficial in terms of environmental friendliness.

Specifically, the weight ratio of PHA to acrylic adhesive may be 3:7 to 6:4, 4:6 to 7:3, 4:6 to 6:4, 3:7 to 5:5, or 5:5 to 7:3.

If the weight ratio of PHA to acrylic binder satisfies the above range, the effect of the present invention is more advantageously achieved, and the coating composition may have a biocarbon content of 25% or more (25% modern carbon (pMC) or more), 30% or more, 35% or more, 40% or more, 50% or more, 60% or more, or 70% or more based on the total weight of the coating composition. Here, biocarbon may refer to recyclable carbon, and the content of biocarbon may refer to a value measured according to ASTM D6866. That is, the content of biocarbon may refer to a value expressed as a percentage of the radioactive carbon isotope content.

When the content of biochar in the coating composition satisfies the above range, carbon dioxide emissions can be minimized when the coating composition is used to form a laminate.

At the same time, according to one embodiment of the present invention, when the coating composition is coated on a substrate, the drying time after coating can be significantly reduced, thereby improving productivity. Specifically, when the PHA coating composition without an acrylic binder is coated on a substrate, a coating film can be formed only when it is dried for a long time at a high temperature. In contrast, for the PHA coating composition containing an acrylic binder, a coating film can be formed in a short period of time. In addition, a coating film is easily formed even at a relatively low temperature.

Specifically, when the coating composition is applied to a paper substrate having a basis weight of 20 to 400 g/m ² at a coating amount of 1 g/m ² to 100 g/m ² , and then dried at 170° C. or less, the drying time may be shorter than 200 seconds, 190 seconds or less, 180 seconds or less, 170 seconds or less, 160 seconds or less, 150 seconds or less, shorter than 150 seconds, 140 seconds or less, 130 seconds or less, 125 seconds or less, 120 seconds or less, 100 seconds or less, 90 seconds or less, 80 seconds or less, 75 seconds or less, or 60 seconds or less, and 30 seconds or more, 31 seconds or more, 35 seconds or more, or 40 seconds or more. Here, the drying completion point may be checked visually. For example, it might refer to the point at which a coating becomes transparent.

Specifically, when the coating composition is applied to a paper substrate having a basis weight of 20 to 400 g/m ² at a coating amount of 1 to 100 g/m ² and then dried at about 120° C. to less than 170° C., the drying time may be 190 seconds or less, 180 seconds or less, 170 seconds or less, shorter than 150 seconds, 140 seconds or less, 130 seconds or less, 125 seconds or less or 120 seconds or less, and 31 seconds or more, 35 seconds or more or 50 seconds or more.

In addition, for example, when the coating composition is applied to a paper substrate having a basis weight of 20 to 400 g/m ² at a coating amount of 2 to 100 g/m ² and then dried at 170° C., the drying time may be 90 seconds or less, 85 seconds or less, 80 seconds or less, 78 seconds or less, or 75 seconds or less, and 31 seconds or more, 33 seconds or more, or 35 seconds or more.

For example, when the coating composition is applied to a paper substrate having a basis weight of 180 g/m ² at a coating amount of 8 g/m ² to 10 g/m ² and then dried at 170° C., the drying time may be 90 seconds or less, 85 seconds or less, 80 seconds or less, 78 seconds or less, 75 seconds or less, or 70 seconds or less, for example, 35 seconds to 90 seconds, 37 seconds to 90 seconds, 50 seconds to 90 seconds, 53 seconds to 90 seconds, or 50 seconds to 85 seconds.

In addition, for example, when the coating composition is applied to a paper substrate having a basis weight of 20 to 400 g/m ² at a coating amount of 1 to 100 g/m ² and then dried at 140° C., the drying time may be shorter than 200 seconds, 190 seconds or shorter, 180 seconds or shorter, 170 seconds or shorter, 160 seconds or shorter, 150 seconds or shorter, shorter than 150 seconds, 140 seconds or shorter, 130 seconds or shorter, 125 seconds or shorter or 120 seconds or shorter, and 40 seconds or longer, 45 seconds or longer or 50 seconds or longer.

In addition, for example, when the coating composition is applied to a paper substrate having a basis weight of 180 g/m ² at a coating amount of 8 g/m ² to 10 g/m ² and then dried at 140° C., the drying time may be shorter than 150 seconds, 140 seconds or less, 130 seconds or less, 125 seconds or less, or 120 seconds or less, for example, 50 seconds to 140 seconds, 50 seconds to 130 seconds, or 50 seconds to 120 seconds.

Meanwhile, the coating composition according to one embodiment of the present invention may further contain a solvent.

The solvent may include distilled water, deionized water or a hydrophilic solvent. The solvent may be distilled water or deionized water, or a mixture of distilled water or deionized water and a hydrophilic solvent.

The hydrophilic solvent may be at least one selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, di-butanol, tertiary butanol, n-pentanol, isopentanol, di-pentanol, tertiary pentanol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, and cyclohexanol.

The solvent may be used in an amount of 20 wt % to 69.5 wt %, 30 wt % to 60 wt %, 35 wt % to 55 wt %, or 40 wt % to 55 wt %, based on the total weight of the coating composition.

If the solvent is used within the above content range, it is possible to easily achieve the physical properties of the coating composition required in the present invention. Therefore, it is more conducive to achieving the effect of the present invention.

The solid content of the coating composition may be 10% to 80% by weight. For example, the solid content of the coating composition may be 10% to 75% by weight, 10% to 70% by weight, 15% to 70% by weight, 20% to 60% by weight, 25% to 60% by weight, 30% to 55% by weight, or 35% to 55% by weight.

The coating composition may have an acidity of 6 to 11. For example, the acidity of the coating composition may be 6 to 10, 6 to 8, 7 to 11, 7.5 to 11, or 8 to 11. If the acidity is less than 6, aggregates may be formed.

Additionally, the coating composition may have a viscosity of 100 cPs to 1,000 cPs measured at 25°C. For example, the viscosity of the coating composition may be 110 cPs to 1,000 cPs, 115 cPs to 1,000 cPs, 130 cPs to 1,000 cPs, 155 cPs to 1,000 cPs, 200 cPs to 1,000 cPs, 155 cPs to 850 cPs, 155 cPs to 800 cPs, 200 cPs to 800 cPs, 300 cPs to 800 cPs, 400 cPs to 800 cPs, 155 cPs to 700 cPs, 160 cPs to 700 cPs, 200 cPs to 700 cPs, 300 cPs to 700 cPs, 400 cPs to 700 cPs, 160 cPs to 450 cPs, 160 cPs to 300 cPs, 165 cPs to 250 cPs, or 165 cPs to 230 cPs. Viscosity can be measured using a DVE-RV viscometer that uses shear stress to measure viscosity. For example, measurements can be made at about 25°C using a #63 spindle at a shear rate of 12 rpm.

If the coating composition satisfies the above ranges of solid content, acidity and/or viscosity, dispersibility, dispersion stability and storage stability can be enhanced. Since it can have a viscosity suitable for coating, coatability, productivity and processability can be further enhanced.

In the following, each component of the coating composition will be described in detail. Polyhydroxyalkanoate (PHA )

Polyhydroxyalkanoates (hereinafter referred to as PHAs) exhibit complete biodegradability and excellent biocompatibility while having physical properties similar to those of known petroleum-derived synthetic polymers such as polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate terephthalate (PBST), and polybutylene succinate adipate (PBSA).

Specifically, PHA is a natural thermoplastic polyester polymer accumulated in microbial cells. Since it is biodegradable, it can be composted and eventually decomposed into carbon dioxide, water, and organic waste without generating toxic waste. Specifically, since PHA is biodegradable even in soil and ocean, when a coating composition and a laminate using the same (biodegradable product) include PHA, it can be environmentally friendly. Therefore, the coating composition and the laminate using the same have great advantages because they are extremely biodegradable and environmentally friendly, so they can be used in various fields.

Specifically, since the coating composition according to one embodiment of the present invention includes PHA, biodegradability can be enhanced without deteriorating mechanical properties.

PHA can be formed by enzyme-catalyzed polymerization of one or more monomers in living cells.

PHA may be a PHA homopolymer composed of one monomer and having the same repeating units, or a PHA copolymer comprising repeating units derived from two or more different monomers. Alternatively, PHA may include a PHA homopolymer and a PHA copolymer.

When the PHA is a copolymer, it may be, for example, a copolymeric PHA comprising repeating units derived from two or more different monomers, wherein the repeating units derived from the different monomers are randomly distributed in the polymer chain.

Examples of monomers that may be included 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-HV), 3-hydroxyhexanoate (hereinafter referred to as 3-HH), 3-hydroxyoctanoate (hereinafter referred to as 3-HHep), 3-hydroxyoctanoate (hereinafter referred to as 3-HV), 3-hydroxyhexanoate (hereinafter referred to as 3-HH), 3-hydroxyoctanoate (hereinafter referred to as 3-HH), 3-hydroxyhexanoate (hereinafter referred to as 3-HHep), 3-hydroxyoctanoate (hereinafter referred to as 3-HV), 3-hydroxyhexanoate (hereinafter referred to as 3-HH), 3-hydroxyoct ... The PHA may contain repeating units derived from one or more monomers selected from the above.

In addition, the PHA may be a PHA homopolymer composed of repeating units derived from monomers selected from the group consisting of 4-HB, 3-HB, 3-HP, 3-HV, 3-HH, 4-HV, 5-HV and 6-HH, or a PHA copolymer comprising repeating units derived from one or more monomers selected from the group consisting of 4-HB, 3-HB, 3-HP, 3-HV, 3-HH, 4-HV, 5-HV and 6-HH.

For example, the polyhydroxyalkanoate (PHA) may comprise repeating units derived from at least one monomer selected from the group consisting of 4-hydroxybutyrate (4-HB), 3-hydroxybutyrate (3-HB), 3-hydroxypropionate (3-HP), 3-hydroxyvalerate (3-HV), 3-hydroxyhexanoate (3-HH), 4-hydroxyvalerate (4-HV), 5-hydroxyvalerate (5-HV), and 6-hydroxyhexanoate (6-HH).

Specifically, the PHA may be a PHA homopolymer composed of monomers selected from the group consisting of 4-HB and 3-HB, or a PHA copolymer comprising one or more monomers selected from the group consisting of 4-HB and 3-HB.

More specifically, PHA may comprise repeating units derived from a 4-HB monomer.

PHA may be a PHA homopolymer composed of repeating units derived from 4-HB monomers.

Alternatively, the PHA resin may be a PHA copolymer comprising repeating units derived from a 4-HB monomer.

For example, the PHA may be a PHA copolymer comprising repeating units derived from a 4-HB monomer and further comprising repeating units derived from a monomer different from 4-HB, or further comprising repeating units derived from two, three, four, five, six or more repeating units that are different from each other.

According to one embodiment of the present invention, PHA may include repeating units derived from 4-HB monomers and repeating units derived from one or more monomers selected from the group consisting of 3-HB, 3-HP, 3-HV, 3-HH, 4-HV, 5-HV and 6-HH. More specifically, PHA may include a PHA copolymer comprising repeating units derived from 3-HB monomers and repeating units derived from 4-HB monomers.

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

In addition, the PHA may include isomers. For example, the PHA may include structural isomers, mirror isomers, or geometric isomers. Specifically, the PHA may include structural isomers.

According to one embodiment of the present invention, it is important to adjust the content of repeating units derived from 4-HB monomers contained in the PHA copolymer.

Specifically, in order to achieve the physical properties required by the present invention, especially to improve biodegradability in soil and ocean, and to achieve excellent dispersibility, dispersion stability, storage stability, coatability, water resistance, processability and productivity without deteriorating mechanical properties, it is very important to adjust the content of repeating units derived from 4-HB monomers contained in the PHA copolymer.

More specifically, the PHA copolymer may include recurring units derived from 4-HB monomers in an amount of 0.1 mol % to 60 mol % based on the total moles of recurring units derived from monomers contained in the PHA copolymer. For example, based on the total moles of repeating units derived from monomers contained in the PHA copolymer, the content of repeating units derived from 4-HB monomers may be 0.1 mol% to 55 mol%, 0.5 mol% to 60 mol%, 0.5 mol% to 55 mol%, 1 mol% to 60 mol%, 1 mol% to 55 mol%, 1 mol% to 50 mol%, 2 mol% to 55 mol%, 3 mol% to 55 mol%, 3 mol% to 50 mol%, 5 mol% to 55 mol%, 5 mol% to 50 mol%, 10 mol% to 55 mol%, 10 mol% to 50 mol%, 1 mol% to 40 mol%, 1 mol% to 3 ... % to 29 mole%, 1 mole% to 25 mole%, 1 mole% to 24 mole%, 2 mole% to 20 mole%, 2 mole% to 23 mole%, 3 mole% to 20 mole%, 3 mole% to 15 mole%, 4 mole% to 18 mole%, 5 mole% to 15 mole%, 8 mole% to 12 mole%, 9 mole% to 12 mole%, 15 mole% to 55 mole%, 15 mole% to 50 mole%, 20 mole% to 55 mole%, 20 mole% to 50 mole%, 25 mole% to 55 mole%, 25 mole% to 50 mole%, 35 mole% to 60 mole%, 40 mole% to 55 mole%, or 45 mole% to 55 mole%.

In addition, the PHA may be a PHA copolymer comprising repeating units derived from 3-hydroxybutyrate (3-HB) monomers and repeating units derived from 4-hydroxybutyrate (4-HB) monomers, wherein the repeating units derived from the 4-HB monomer may be 0.1 mol % to 60 mol % based on the total molar number of the repeating units derived from the 3-HB monomer and the repeating units derived from the 4-HB monomer. For example, the repeating units derived from the 4-HB monomer may be 0.1 mol% to 55 mol%, 0.5 mol% to 60 mol%, 0.5 mol% to 55 mol%, 1 mol% to 60 mol%, 1 mol% to 55 mol%, 1 mol% to 50 mol%, 2 mol% to 55 mol%, 3 mol% to 55 mol%, 3 mol% to 50 mol%, 5 mol% to 55 mol%, 5 mol% to 50 mol%, 10 mol% to 55 mol%, 10 mol% to 50 mol%, 1 mol% to 40 mol%, 1 mol% to 30 mol%, based on the total moles of repeating units derived from the 3-HB monomer and the repeating units derived from the 4-HB monomer. %, 1 mol % to 29 mol %, 1 mol % to 25 mol %, 1 mol % to 24 mol %, 2 mol % to 20 mol %, 2 mol % to 23 mol %, 3 mol % to 20 mol %, 3 mol % to 15 mol %, 4 mol % to 18 mol %, 5 mol % to 15 mol %, 8 mol % to 12 mol %, 9 mol % to 12 mol %, 15 mol % to 55 mol %, 15 mol % to 50 mol %, 20 mol % to 55 mol %, 20 mol % to 50 mol %, 25 mol % to 55 mol %, 25 mol % to 50 mol %, 35 mol % to 60 mol %, 40 mol % to 55 mol %, or 45 mol % to 55 mol %.

If the content of the repeating unit derived from the 4-HB monomer satisfies the above range, it is possible to increase biodegradability in soil and ocean and further enhance dispersibility, dispersion stability, storage stability, coatability, water resistance, processability and productivity without deteriorating mechanical properties.

According to one embodiment of the present invention, the PHA may be a PHA copolymer with adjusted crystallinity. Specifically, the PHA may include at least one repeating unit derived from a 4-HB monomer, and the content of the repeating unit derived from the 4-HB monomer may be controlled to adjust the crystallinity of the PHA.

In addition, the PHA copolymer may include repeating units derived from 3-HB monomers in an amount of 20 mol% or more, 35 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, or 75 mol% or more, and 99 mol% or less, 98 mol% or less, 97 mol% or less, 96 mol% or less, 95 mol% or less, 93 mol% or less, 91 mol% or less, 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, or 55 mol% or less, based on the total moles of repeating units derived from monomers contained in the PHA copolymer.

The crystallinity-adjusted PHA may be a resin in which the crystallinity and amorphous property are adjusted as the irregularity of the molecular structure increases. Specifically, the crystallinity and amorphous property may be determined by the type or ratio of monomers or the type or content of isomers.

According to one embodiment of the present invention, PHA may include two or more types of PHAs having different crystallinity. Specifically, PHA may be prepared by preparing a mixture of two or more types of PHAs having different crystallinity so as to have a repeating unit content derived from a 4-HB monomer within a specific range.

Specifically, the PHA may include a first PHA that is a semi-crystalline PHA.

The first PHA is a semi-crystalline PHA (hereinafter referred to as scPHA) resin having controlled crystallinity, and may include 0.1 mol% to 30 mol% of repeating units derived from 4-HB monomers based on the total molar number of repeating units derived from monomers contained in the first PHA resin. The first PHA may include repeating units derived from 4-HB monomers in an amount of 0.1 mol% to 30 mol%, 0.5 mol% to 30 mol%, 1 mol% to 30 mol%, 3 mol% to 30 mol%, 1 mol% to 28 mol%, 1 mol% to 25 mol%, 1 mol% to 24 mol%, 1 mol% to 15 mol%, 2 mol% to 25 mol%, 3 mol% to 25 mol%, 3 mol% to 24 mol%, 5 mol% to 24 mol%, 7 mol% to 20 mol%, 10 mol% to 20 mol%, 15 mol% to 25 mol%, or 15 mol% to 24 mol%, based on the total moles of repeating units derived from monomers contained in the first PHA resin.

The glass transition temperature (Tg) of the first PHA may be -30°C to 80°C, -30°C to 10°C, -10°C to 10°C, -25°C to 5°C, -25°C to 0°C, -20°C to 0°C, -15°C to 0°C, or -10°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. Its melting temperature (Tm) may be 105°C to 165°C, 110°C to 160°C, 115°C to 160°C, or 120°C to 160°C.

The weight average molecular weight of the first PHA may be 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 900,000 g/mol, 200,000 g/mol to 800,000 g/mol, 200,000 g/mol to 600,000 g/mol, 200,000 g/mol to 400,000 g/mol, 400,000 g/mol to 800,000 g/mol, 300,000 g/mol to 500,000 g/mol, 300,000 g/mol to 500,000 g/mol, g/mol to 400,000 g/mol, 400,000 g/mol to 600,000 g/mol, 500,000 g/mol to 900,000 g/mol, 600,000 g/mol to 900,000 g/mol, 500,000 g/mol to 850,000 g/mol, or 600,000 g/mol to 800,000 g/mol.

Additionally, the PHA may include a second PHA that is an amorphous PHA resin having a controlled degree of crystallinity.

The second PHA is an amorphous PHA (hereinafter referred to as aPHA) resin having controlled crystallinity. Based on the total mole number of repeating units derived from monomers contained in the second PHA resin, it may include repeating units derived from 4-HB monomers in an amount of 15 mol% to 60 mol%, 15 mol% to 55 mol%, 20 mol% to 55 mol%, 25 mol% to 55 mol%, 30 mol% to 55 mol%, 35 mol% to 55 mol%, 20 mol% to 50 mol%, 25 mol% to 50 mol%, 30 mol% to 50 mol%, 35 mol% to 50 mol%, 20 mol% to 40 mol%.

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

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

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/mole 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.

The first PHA and the second PHA can be distinguished according to the content of repeating units derived from 4-HB monomers and can have at least one characteristic selected from the group consisting of: glass transition temperature (Tg), crystallization temperature (Tc), and melting temperature (Tm). Specifically, the first PHA and the second PHA can be distinguished according to the content of repeating units derived from 4-HB monomers, glass transition temperature (Tg), crystallization temperature (Tg), melting temperature (Tm), and similar characteristics.

According to one embodiment of the present invention, the PHA may include a first PHA, or it may include both a first PHA and a second PHA.

Specifically, since the PHA includes a first PHA that is a semi-crystalline PHA or both a first PHA that is a semi-crystalline PHA and a second PHA that is an amorphous PHA, more specifically, since the contents of the first PHA and the second PHA are adjusted, the dispersibility, dispersion stability, storage stability, coatability and processability can be further enhanced.

In addition, 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, -10°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.

The crystallization temperature (Tc) of PHA may not be measured or may be 60°C to 120°C, 60°C to 110°C, 70°C to 120°C, 75°C to 120°C, 75°C to 115°C, 75°C to 110°C, or 90°C to 110°C.

The melting temperature (Tm) of the PHA may not be measured or may be 100°C to 170°C, 105°C to 170°C, 105°C to 165°C, 110°C to 160°C, 115°C to 160°C, 120°C to 160°C, 130°C to 160°C, or 140°C to 160°C.

In addition, the 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 the PHA resin may be 50,000 g/mol to 1,200,000 g/mol, 100,000 g/mol to 1,200,000 g/mol, 50,000 g/mol to 1,000,000 g/mol, 100,000 g/mol to 1,000,000 g/mol, 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, g/mol, 200,000 g/mol to 900,000 g/mol, 200,000 g/mol to 800,000 g/mol, 200,000 g/mol to 700,000 g/mol, 250,000 g/mol to 650,000 g/mol, 200,000 g/mol to 400,000 g/mol, 300,000 g/mol to 800,000 g/mol, 300,000 g/mol to 600,000 g/mol, 500,000 g/mol to 1,200,000 g/mol, 500,000 g/mol to 1,000,000 g/mol 550,000 g/mol to 1,050,000 g/mol, 550,000 g/mol to 900,000 g/mol, 600,000 g/mol to 900,000 g/mol, 500,000 g/mol to 900,000 g/mol, or 400,000 g/mol to 800,000 g/mol.

In addition, the PHA can have a crystallinity of 90% or less as measured by differential scanning calorimetry (DSC). For example, the crystallinity of the PHA 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.

In addition, the PHA may have an average particle size of 5 μm or less. For example, the average particle size of the PHA may be less than 5 μm, 4.8 μm or less, 4.6 μm or less, or 4.5 μm or less, such as 0.5 μm to 5 μm, 1 μm to 5 μm, 1.5 μm to 5 μm, 1 μm to 4 μm, 1.5 μm to 4 μm, or 1.5 μm to 3.5 μm. Specifically, the PHA may have an average particle size of 1 μm to 4 μm.

The average particle size of PHA can be measured using a laser particle size diffraction instrument. For example, the average particle size of PHA is measured by dynamic light scattering (DLS) using a laser particle size diffraction instrument at a temperature of 25°C and a measurement angle of 175°. In such cases, the peak value derived through the polydispersity index (PDI) in a confidence interval of 0.5 is regarded as the particle size.

The PHA may have a polydispersity index (PDI) of 3 or less. For example, the PHA may have a polydispersity index of less than 3, 2.9 or less, 2.7 or less, or 2.65 or less. Specifically, the PHA may have a polydispersity index of 1 to 3, 1 to less than 3, or 1.5 to 2.5.

When the average particle size and polydispersity index of PHA meet the above ranges, the dispersibility, dispersion stability, storage stability, coatability, water resistance and processability can be further enhanced.

Specifically, the PHA may have a weight average molecular weight (Mw) of 200,000 g/mol to 900,000 g/mol, an average particle size of 5 μm or less, and a polydispersity index (PDI) of 3 or less.

In addition, PHA may have a glass transition temperature (Tg) of -10°C to 10°C, a crystallization temperature (Tc) of 70°C to 120°C, and a melting temperature (Tm) of 100°C to 170°C.

In addition, PHA can be obtained by disrupting cells using mechanical methods or physical methods. Specifically, since PHA is a natural thermoplastic polyester polymer accumulated in microbial cells and has a relatively large average particle size, it can be obtained through a disruption process to enhance dispersibility, spreadability, and processability.

For example, PHA may be in the form of microparticles. Specifically, PHA obtained by disrupting cells using a mechanical method or a physical method may be a powder in the form of microparticles.

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

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

In addition, the coating composition may include 5 wt % to 90 wt % of PHA solids, based on the total weight of the coating composition. For example, the content of PHA solids may be 5 wt % to 80 wt %, 10 wt % to 70 wt %, 15 wt % to 70 wt %, 15 wt % to 65 wt %, 20 wt % to 60 wt %, 25 wt % to 55 wt %, or 30 wt % to 50 wt %, based on the total weight of the coating composition. Acrylic Adhesive

According to one embodiment of the present invention, the coating composition may include an acrylic adhesive.

The acrylic adhesive can act as an adhesive to increase the adhesion between the PHA and the substrate. Specifically, the acrylic adhesive can act as a physical bridge between the PHA particles or between the substrate and the PHA particles to enhance the adhesion between the PHA particles and the substrate. Therefore, productivity, processability and water resistance can be enhanced.

According to another embodiment of the present invention, the acrylic adhesive may include an acrylic monomer, a copolymer including an acrylic monomer and at least one monomer selected from the group consisting of a silicone monomer and a styrene monomer, or a combination thereof.

For example, the acrylic adhesive may include an acryl-polysiloxane copolymer. In addition, the acrylic adhesive may include an acrylic-styrene copolymer. The acrylic monomer may include at least one selected from the group consisting of methyl acrylate, ethyl acrylate, hydroxyethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyethyl methacrylate, propyl methacrylate, methacrylic acid, and butyl acrylate.

Polysiloxane-based monomers can be prepared from groups containing siloxane groups such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane.

The acrylic adhesive may have an average particle size of 1 μm or less, 950 nm or less, 900 nm or less, 850 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 500 nm or less, or 400 nm or less, and 1 nm or more, 5 nm or more, 10 nm or more, 15 nm or more, or 20 nm or more.

The acrylic adhesive may have a polydispersity index (PDI) of 2 or less, 1.5 or less, 1 or less, 0.8 or less, or 0.6 or less.

The average particle size of the acrylic adhesive can be measured using a laser particle size diffraction instrument. For example, the average particle size of the acrylic adhesive is measured by dynamic light scattering (DLS) using a laser particle size diffraction instrument at a temperature of 25°C and a measurement angle of 175°. In such cases, the peak value derived from the polydispersity index (PDI) in a confidence interval of 0.5 is regarded as the particle size.

If the acrylic adhesive satisfies the above ranges of average particle size and polydispersity index (PDI), it will be more conducive to achieving the desired effect of the present invention.

Specifically, the acrylic adhesive may include an acrylic monomer, a copolymer including an acrylic monomer and at least one monomer selected from the group consisting of a silicone monomer and a styrene monomer, or a combination thereof, and have an average particle size of 1 μm or less and a polydispersity index (PDI) of 2 or less.

The coating composition may include an acrylic binder in an amount of 10% to 70% by weight based on the total weight of the solid content of the coating composition. For example, the acrylic binder may be present in an amount of 15% to 70% by weight, 15% to 65% by weight, 20% to 60% by weight, 25% to 55% by weight, or 30% to 50% by weight based on the total weight of the solid content of the coating composition.

If the content of the acrylic adhesive satisfies the above range, the effect of the present invention can be more advantageously achieved while optimally increasing the adhesion between the PHA and the substrate.

The coating composition may further comprise at least one additive selected from the group consisting of a dispersant, a thickener, a preservative, a defoaming agent and a pH adjuster.

Specifically, the dispersant may be an additive for further enhancing dispersibility, dispersion stability, storage stability, coatability, water resistance, and processability.

The dispersant may be at least one selected from the group consisting of phosphoric acid-based dispersants, fatty acid-based dispersants, acrylic acid-based dispersants, urethane-based dispersants, and epoxy-based dispersants. It may be a polymeric dispersant comprising at least one selected from the group consisting of carboxylic acids, amines, isocyanates, and derivatives thereof.

For example, the dispersant may be at least one selected from the group consisting of polyvinyl alcohol, sodium dodecylbenzenesulfonate, polyvinylpyrrolidone, methyl polyvinyl alkyl ether, alkylbenzenesulfonate, nonylphenol ether sulfate, sodium lauryl sulfate, lithium dodecyl sulfate, alkyl phosphate, glycerol ester and propylene glycol ester.

According to one embodiment of the present invention, the dispersant may be polyvinyl alcohol.

Polyvinyl alcohol can be obtained by polymerizing polyvinyl acetate (PVAc) and then replacing the hydrophobic CH ₃ COO- with the hydrophilic -OH via a hydrolysis reaction. In such cases, the -OH substitution degree relative to the total substitution degree, i.e., the ratio of CH ₃ COO- to -OH, is the degree of saponification or hydration. The degree of saponification can vary depending on the molecular weight of the polyvinyl alcohol or its distribution characteristics in the -OH substitution reaction and can have an impact on the physical properties of the final resins, compositions and laminates.

In addition, the coating composition may contain, for example, a dispersant having a saponification degree of 40 mol% or more. When the coating composition contains a dispersant, dispersibility, dispersion stability, storage stability, coatability, water resistance, and processability may be enhanced.

For example, the degree of saponification of the dispersant can be 42 mol% or greater, 55 mol% or greater, 65 mol% or greater, 80 mol% or greater, 85 mol% or greater, or 90 mol% or greater, and 42 mol% to 99 mol%, 75 mol% to 99 mol%, or 80 mol% to 98 mol%.

If the saponification degree satisfies the above range, dispersibility, dispersion stability and storage stability can be enhanced. Since it can have a viscosity suitable for coating, it can enhance the coating property, productivity and processability. Specifically, if the saponification degree exceeds the above range, the solubility or dispersibility of the dispersant is extremely low, and thus it may not be possible to form a coating using the coating composition.

In addition, the degree of polymerization refers to the number of monomers bonded to one chain of a polymer. The average degree of polymerization of the dispersant may be 200 or less. For example, the average degree of polymerization of the dispersant may be 200 or less, 180 or less, or 150 or less, and may be 80 to 200, 90 to 200, or 100 to 200. When the average degree of polymerization satisfies the above range, dispersibility, dispersion stability, storage stability, coatability, water resistance, and processability may be enhanced.

When the saponification degree and polymerization degree of the dispersant satisfy the above ranges, the dispersibility, dispersion stability, storage stability, coatability, water resistance and processability can be enhanced. Specifically, since the dispersant having the saponification degree and polymerization degree satisfying the above ranges has excellent compatibility with the PHA having the above-mentioned characteristics, the dispersibility, dispersion stability, storage stability, coatability, water resistance and processability can be further enhanced.

In addition, the coating composition may include a dispersant in an amount of 0.01% to 10% by weight, based on the total weight of the coating composition. For example, the dispersant may be present in an amount of 0.01% to 10% by weight, 0.01% to 8% by weight, 0.05% to 7% by weight, 0.1% to 6% by weight, 0.1% to 5% by weight, 1% to 5% by weight, 1.5% to 5% by weight, 0.1% to 3% by weight, 0.5% to 3.5% by weight, 1% to 3% by weight, or 1.5% to 3% by weight, based on the total weight of the coating composition.

Thickeners are additives that give appropriate viscosity.

The thickener may include at least one selected from cellulose and gum. Specifically, the cellulose may include at least one selected from the group consisting of natural cellulose, methylcellulose and microcellulose. The gum may include at least one selected from the group consisting of guar gum, carrageenan and safflower gum.

The thickener can be used in an amount of 0.01 wt % to 20 wt %, 0.01 wt % to 15 wt %, 0.01 wt % to 12 wt %, 0.01 wt % to 10 wt %, 0.01 wt % to 8 wt %, 0.01 wt % to 5 wt %, 0.2 wt % to 4.5 wt %, 0.2 wt % to 4 wt %, or 0.5 wt % to 3 wt %, based on the total weight of the solid content of the coating composition.

In addition, 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-butylene glycol, and may be at least one preservative selected from the group consisting of 1,2-benzoisothiazoline-3-one and potassium benzoate, but is not limited thereto.

The preservative may be used in an amount of 0.01 wt % to 20 wt %, 0.01 wt % to 15 wt %, 0.01 wt % to 12 wt %, 0.01 wt % to 10 wt %, 0.01 wt % to 8 wt %, 0.01 wt % to 5 wt %, 0.2 wt % to 4.5 wt %, 0.2 wt % to 4 wt %, or 0.5 wt % to 3 wt %, based on the total weight of the solid content of the coating composition.

In addition, the defoaming agent is an additive used to prevent or reduce foaming. Any commonly used defoaming agent can be used as the defoaming agent as long as the effect of the present invention is not impaired.

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

The defoaming agent may be used in an amount 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 %, based on the total weight of the solid content of the coating composition.

In addition, the pH adjuster refers to a material added to a solution to adjust the pH value. It may include both a pH lowering agent for lowering the pH value and a pH raising agent for raising the pH value. Specifically, the 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 the pH raising agent may be an alkaline substance such as aqueous ammonia, sodium hydroxide, lithium hydroxide and potassium hydroxide, or an aqueous solution of an acetate salt, but it is not limited thereto.

For example, the pH adjuster 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.

The pH adjuster may be used in an amount of 0.01 wt % to 20 wt %, 0.01 wt % to 15 wt %, 0.01 wt % to 12 wt %, 0.01 wt % to 10 wt %, 0.01 wt % to 8 wt %, 0.01 wt % to 5 wt %, 0.2 wt % to 4.5 wt %, 0.2 wt % to 4 wt %, or 0.5 wt % to 3 wt %, based on the total weight of the solid content of the coating composition.

The additive may be used in an amount of 0.1 wt % to 30 wt %, 0.5 wt % to 30 wt %, 0.5 wt % to 25 wt %, or 1 wt % to 20 wt %, based on the total weight of the solid content of the coating composition.

Specifically, the coating composition may further include at least one additive selected from the group consisting of a dispersant, a thickener, a preservative, a defoaming agent, and a pH adjuster, and the additive may be used in an amount of 0.1 wt % to 30 wt % based on the total weight of the solid content of the coating composition. < Method for preparing coating composition >

The method for preparing a coating composition according to one embodiment of the present invention comprises (1) preparing a polyhydroxyalkanoate (PHA) dispersion containing PHA; and mixing the PHA dispersion with an acrylic emulsion containing an acrylic binder, wherein the weight ratio of PHA to the acrylic binder is 3:7 to 7:3.

Specifically, the method for preparing a coating composition includes preparing a PHA dispersion containing PHA (the first step).

The PHA dispersion includes PHA. Specifically, the PHA dispersion may include PHA, a dispersant, and a solvent.

The types of PHA are described above.

The PHA may be used in an amount of 10 wt % to 60 wt %, 20 wt % to 60 wt %, 30 wt % to 60 wt %, 30 wt % to 55 wt %, 35 wt % to 50 wt %, or 35 wt % to 45 wt %, based on the total weight of the PHA dispersion.

For example, the polyhydroxyalkanoate (PHA) dispersion may include polyhydroxyalkanoate (PHA), a dispersant and a solvent, and the polyhydroxyalkanoate (PHA) may be used in an amount of 10 wt % to 60 wt % based on the total weight of the polyhydroxyalkanoate (PHA) dispersion. If the content of PHA satisfies the above range, it is not only environmentally friendly by increasing the content of biochar, but also can enhance dispersibility, coatability, water resistance, processability and productivity at the same time.

The types of dispersants are as described above.

The dispersant may be used in an amount of 0.5 wt % to 20 wt %, 1 wt % to 15 wt %, 3 wt % to 15 wt %, or 5 wt % to 15 wt %, based on the total weight of the PHA dispersion.

If the content of the dispersant satisfies the above range, the dispersibility, dispersion stability, storage stability, coatability, water resistance and processability can be enhanced.

The solvent may include distilled water, deionized water or a hydrophilic solvent. The solvent may be distilled water or deionized water, or a mixture of distilled water or deionized water and a hydrophilic solvent.

The hydrophilic solvent may be at least one selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, di-butanol, tertiary butanol, n-pentanol, iso-pentanol, di-pentanol, tertiary pentanol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, and cyclohexanol.

The solvent may be used in an amount other than the PHA and the dispersant in the PHA dispersion, and specifically, may be used in an amount of 20 wt % to 69.5 wt %, 30 wt % to 60 wt %, 35 wt % to 55 wt %, or 40 wt % to 55 wt %.

The PHA dispersion can be obtained by mixing and stirring PHA, a dispersant and a solvent.

Agitation can be performed using a homogenizer, a centrifuge, a stirrer, a high shear mixer, a high pressure disperser, a mechanical mixer, a high pressure mixer, a high pressure dispersion device (microfluidizer), a colloid mill, an ultrasonic disperser (ultrasonic wave processor), and membrane emulsification or the like, but is not limited thereto.

When preparing a PHA dispersion, PHA can be physically emulsified using the above method, and a dispersion in which PHA particles are uniformly dispersed can be prepared.

For example, the homogenizer can be used to stir at a rate of 10% to 80% of the maximum speed (rpm) for 10 minutes to 60 minutes. For example, the homogenizer can be used to stir at 10% to 80%, 15% to 75%, 20% to 60%, 20% to 50%, 40% to 80%, 45% to 70%, 60% to 80%, 65% to 75%, or 60% to 70% of the maximum speed (rpm) for 10 minutes to 60 minutes, 20 minutes to 60 minutes, 25 minutes to 55 minutes, 25 minutes to 45 minutes, or 25 minutes to 40 minutes.

As another example, stirring can be performed using a centrifuge, a blender, or a homogenizer at 750 rpm to 10,000 rpm, 1,000 rpm to 10,000 rpm, 2,000 rpm to 10,000 rpm, 4,000 rpm to 10,000 rpm, 750 rpm to 8,000 rpm, 900 rpm to 7,000 rpm, 1,000 rpm to 5,000 rpm, 1,500 rpm to 4,000 rpm, 1,500 rpm to 3,000 rpm, 6,000 rpm to 10,000 rpm, 6,500 rpm to 9,500 rpm, 7,000 rpm to 9,000 rpm, or 7,500 rpm to 8,500 rpm. rpm for 15 to 60 minutes, 20 to 50 minutes, 20 to 40 minutes, or 25 to 35 minutes.

When stirring is carried out under the above conditions, dispersibility, dispersion stability, storage stability, coatability, water resistance, productivity and processability can be further enhanced.

According to another embodiment of the present invention, a filtering step and a washing step can be further performed after the mixing and stirring step. For example, it can be filtered and washed one or more times after the mixing and stirring step.

Alternatively, a further subdivision step may be performed after the filtering step and the washing step.

More specifically, PHA, a dispersant, and a solvent may be mixed and stirred to prepare a first PHA dispersion, the first PHA dispersion may be filtered and washed to prepare a second PHA dispersion, and the second PHA dispersion may be redispersed in a solvent to prepare a final PHA dispersion.

The solid content of the second PHA dispersion may be 10 wt % to 60 wt %. For example, the solid content of the second PHA dispersion may be 12 wt % to 60 wt %, 15 wt % to 55 wt %, 20 wt % to 55 wt %, 25 wt % to 50 wt %, 30 wt % to 60 wt %, 30 wt % to 50 wt %, 30 wt % to 45 wt %, or 35 wt % to 45 wt %.

The filtering step can be performed using a filter medium such as paper, woven fabric, nonwoven fabric, screen, polymer membrane or wedge wire, and can use a suction filter, a pressure filter, a membrane separator, a vacuum filter, a reduced pressure vacuum filter, an industrial filter press, a tubular press, a plate press, a pressure gauge press, a belt press, a screw press, a disc press, a pressure-function press or a centrifuge.

The washing step and the redistribution step can be performed using the above solvents. Specifically, the solvent used in the washing and the redistribution step can be water, such as distilled water or deionized water, or a mixture of the water and a hydrophilic solvent.

The homogenizer can be used at 10% to 80%, 15% to 75%, 20% to 60%, 20% to 50%, 40% to 80%, 45% to 70%, 60% to 80%, 65% to 75%, or 60% to 70% of the maximum rpm and subdivided into steps of 10 minutes to 60 minutes, 20 minutes to 60 minutes, 25 minutes to 55 minutes, 25 minutes to 45 minutes, or 25 minutes to 40 minutes.

The solid content of the final PHA dispersion may be 10 wt % to 60 wt %. For example, the solid content of the final PHA dispersion may be 10 wt % to 60 wt %, 15 wt % to 55 wt %, 20 wt % to 55 wt %, 25 wt % to 50 wt %, 30 wt % to 60 wt %, 30 wt % to 50 wt %, 30 wt % to 45 wt %, or 35 wt % to 45 wt %.

The pH of the final PHA dispersion may be 5 to 8, 5 to 7, 6 to 8, 6 to 7, or 7.

The viscosity of the final PHA dispersion measured at 25° C. may be 1,000 cPs or less, 900 cPs or less, 800 cPs or less, 700 cPs or less, 600 cPs or less, 500 cPs or less, 400 cPs or less, 300 cPs or less, 200 cPs or less, and 50 cPs or more, 60 cPs or more, 70 cPs or more, or 100 cPs or more. The viscosity of the final PHA dispersion measured at 25° C. can be, for example, 50 to 1000 cPs, 50 to 800 cPs, 50 to 700 cPs, 50 to 600 cPs, 50 to 500 cPs, 50 to 400 cPs, 50 to 300 cPs, 100 to 300 cPs, 100 to 250 cPs, 100 to 200 cPs, or 120 to 180 cPs. The viscosity can be measured by a DVE-RV viscometer that uses shear stress to measure viscosity.

If the final PHA dispersion has a solid content, pH value and viscosity that meet the above ranges, the desired effect of the present invention can be more advantageously achieved.

For example, a polyhydroxyalkanoate (PHA) dispersion may have a pH of 5 to 8 and a viscosity of 50 to 1,000 cPs measured at 25°C.

Meanwhile, the method for preparing the coating composition includes mixing the PHA dispersion with an acrylic emulsion including an acrylic binder (second step).

The acrylic emulsion may include an acrylic adhesive. Specifically, the acrylic emulsion may include an acrylic emulsion dispersed in water.

The acrylic emulsion may include an acrylic emulsion dispersed in water, which includes an acrylic binder and water.

The types of acrylic adhesives are described above.

The acrylic adhesive may be used in an amount of 10 wt % to 70 wt %, 15 wt % to 65 wt %, 20 wt % to 60 wt %, 25 wt % to 55 wt %, or 30 wt % to 50 wt %, based on the total weight of the acrylic emulsion.

The water may comprise distilled water or deionized water.

For example, an acrylic emulsion can be obtained by dispersing 40 wt % to 60 wt % of an acrylic binder in 40 wt % to 60 wt % of water.

In addition, an acrylic emulsion can be obtained by dispersing 30 wt % to 60 wt % of an acrylic binder and 10 wt % to 30 wt % of an additive in 40 wt % to 60 wt % of water. The same additive as used in preparing the PHA dispersion can be used as the additive.

The acrylic emulsion may include an acrylic adhesive having an average particle size of 1 μm or less. Specifically, the acrylic adhesive may have an average particle size of 950 nm or less, 900 nm or less, 850 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 500 nm or less, or 400 nm or less, and 1 nm or more, 5 nm or more, 10 nm or more, 15 nm or more, or 20 nm or more.

The acrylic emulsion may include an acrylic adhesive having a polydispersity index (PDI) of 2 or less. Specifically, the acrylic adhesive may have a polydispersity index (PDI) of 1.5 or less, 1 or less, 0.8 or less, or 0.6 or less.

The acrylic emulsion may have a viscosity of 1,000 cPs or less measured at 25°C. Specifically, the viscosity of the acrylic emulsion measured at 25°C may be 1,000 cPs or less, 900 cPs or less, 800 cPs or less, 700 cPs or less, 600 cPs or less, 500 cPs or less, or 450 cPs or less, specifically 100 cPs to 1,000 cPs or less, 110 cPs to 1,000 cPs or less, 115 cPs to 1,000 cPs or less, 130 cPs to 1,000 cPs or less, 155 cPs to 1,000 cPs or less, 200 cPs to 1,000 cPs or less, 155 cPs to 850 cPs or less, 155 cPs to 800 cPs or less, 200 cPs to 800 cPs or less, 300 cPs to 800 cPs or less, 400 cPs to 800 cPs or less, 155 cPs to 700 cPs or less, 160 cPs to 700 cPs or less, 200 cPs to 700 cPs or less, 300 cPs to 700 cPs or less, 300 cPs to 600 cPs or less, or 300 cPs to 500 cPs.

The acrylic emulsion may have a pH of 8 or less. Specifically, the acrylic emulsion may have a pH of 8 or less, specifically, 3 to 8, 4 to 8, 5 to 8, 6 to 8, 7 to 8, or 6 to 7.

The average particle size and polydispersity index (PDI) can be measured using a laser particle size diffraction instrument. The viscosity can be measured using a DVE-RV viscometer (manufacturer: Brookfield) which measures viscosity using shear stress at about 25°C using a #63 spindle at a shear rate of 12 rpm.

For example, an acrylic emulsion may have a pH of 8 or less and a viscosity of 1,000 cPs or less measured at 25°C.

According to one embodiment of the present invention, the emulsion can satisfy at least one of the characteristics of average particle size, dispersion index, viscosity and pH value. If the acrylic emulsion has an average particle size, dispersion index, viscosity and pH value that meet the above ranges, it can be more conducive to achieving the desired effect of the present invention. < Method for preparing a laminate >

The present invention provides a method for preparing a laminate formed using a coating composition.

The method for preparing a laminate includes preparing a coating composition; and coating the coating composition on a substrate and drying it to form a coating.

Since the method for preparing a laminate according to one embodiment of the present invention uses the above coating composition, the drying time after coating can be significantly reduced. Specifically, when it is dried at 140° C. to 170° C., the production rate and water resistance of the coating can be optimally enhanced.

Hereinafter, each step of the method for preparing the laminate will be described in detail.

The method for preparing a laminate may include preparing a coating composition.

The details of the steps for preparing the coating composition (method for preparing the coating composition) are as described above.

The method of preparing a laminate may include applying a coating composition on a substrate and drying it to form a coating.

The substrate is not limited as long as the coating can be formed on the surface of the substrate. For example, the substrate can be at least one selected from the group consisting of paper, fabric, nonwoven fabric, polyethylene terephthalate (PET) film, polyester-based film (such as polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene adipate terephthalate (PBAT) and polybutylene succinate terephthalate (PBST)) and polyimide (PI) film.

Specifically, from the viewpoint of enhancing the coatability of the substrate, the substrate is preferably a substrate of a single material. The substrate may be paper, woven fabric or non-woven fabric.

For example, when the substrate comprises paper, it may be more advantageous to provide an environmentally friendly packaging material because it has better biodegradability than other plastic materials.

The paper may include a paper substrate (paper) made of mechanical pulp, semi-chemical pulp or chemical pulp. Specifically, the paper substrate may include at least one selected from the group consisting of white paper (faux vellum), off-white paper, colored paper, rough paper, heavy paper, velvet paper, coated paper, snow paper, snow white paper, single-sided coated paper, royal coated paper, NCR paper, leather paper, straight grain paper, CCP paper, kraft paper, manila ivory paper, royal ivory paper, tracing paper, kraft paper, fancy paper, cotton paper, label paper, whiteboard paper, photo paper and cup paper.

At the same time, the barrier layer may be disposed on at least one side of the substrate. The environmentally friendly barrier film may be coated on the substrate surface to have moisture and/or oxygen barrier properties, or may further form a functional coating having antistatic properties or adhesive properties. The functional coating may include a base coating layer and an adhesive coating layer, which may have commonly used materials and physical properties as long as they do not impair the desired effect of the present invention.

In addition, the coating composition can be applied to the substrate in an amount of 1 to 100 g/m ^2. That is, the coating composition can be applied to the substrate in ^{an amount of 1 to 100 g/m 2 .} For example, the coating amount may be 2 g/m ² to 100 g/m ² , 1 g/m ² to 80 g/m ² , 1 g/m ² to 70 g/m ² , 1 g/m ² to 50 g/m ² , 5 g/m ² to 100 g/m ² , 5 g/m ² to 85 g/m ² , 5 g/m ² to 70 g/m ² , 8 g/m ² to 60 g/m ² , 9 g/m ² to 50 g/m ² , 5 g/m ² to 50 g/m ² , 5 g/m 2 to 40 g/m 2, 5 g/m ² to 30 g/m ² , 5 g/m ² to 20 g/m ² , 5 g/m ² to 15 g/m ² , or 5 g/m ² to 60 g/m ² . ² to 12 g/m ² . When the coating amount meets the above range, the coatability, productivity and processability can be further enhanced.

In addition, coating may be performed once to form a single coating layer or may be performed two or more times to form a plurality of coating layers.

Once the coating composition has been applied to the substrate, it can be dried at 100° C. to 250° C. for less than 200 seconds. That is, drying can be performed at 100° C. to 250° C. for less than 200 seconds. For example, drying can be performed at 120° C. to 200° C., 120° C. to 185° C., 120° C. to 180° C., 130° C. to 180° C., or 140° C. to 170° C. for 20 seconds to less than 200 seconds, 20 seconds to 180 seconds, 30 seconds to less than 200 seconds, 30 seconds to 180 seconds, 30 seconds to 150 seconds, 30 seconds to 140 seconds, 35 seconds to 140 seconds, 35 seconds to 130 seconds, 35 seconds to 120 seconds, 35 seconds to 100 seconds, or 35 seconds to less than 100 seconds.

For example, once the coating composition has been applied to the substrate, it can be dried at about 170° C. for 30 seconds to 140 seconds, 30 seconds to 130 seconds, 30 seconds to 120 seconds, 30 seconds to 110 seconds, 30 seconds to 100 seconds, 30 seconds to less than 100 seconds, 35 seconds to 95 seconds, or 35 seconds to 90 seconds.

In addition, for example, after the coating composition has been applied to the substrate, it can be dried at about 140° C. for 30 seconds to 200 seconds, 30 seconds to 180 seconds, 30 seconds to 160 seconds, 40 seconds to 160 seconds, 45 seconds to 160 seconds, 45 seconds to 155 seconds, 45 seconds to 150 seconds, or 50 seconds to 150 seconds.

After coating, drying at 140°C to 170°C can best enhance the productivity and water resistance of the coating within a short drying time.

The coating layer can be formed without particular limitation as long as it is a coating method generally used in this technology. For example, the coating layer can be formed using a wet coating method.

Specifically, the coating layer may be formed by gravure coating, slit coating, doctor blade coating, spray coating, rod coating, spin coating, or in-line coating, but is not limited thereto.

For conventional PHA coating compositions that do not contain an acrylic binder, long-term drying at high temperatures is required to form a coating film, under which conditions the coating film is formed once the PHA melts. In contrast, since the coating composition according to one embodiment of the present invention contains an acrylic binder, it can be dried in a short period of time at a relatively low temperature. Therefore, the coating can be formed while maintaining all or part of the particle form, and the particle form of the PHA can serve as a filler.

In addition, although PHA having a high melting temperature (Tm) is used as described above, the present invention can effectively achieve the desired effect without requiring an additional post-processing step and can maintain the characteristics of the bioplastic material itself.

The present invention provides a laminate formed using a coating composition.

According to one embodiment of the present invention, the laminate comprises a substrate layer and a coating layer, wherein the coating layer comprises polyhydroxyalkanoate (PHA) and an acrylic adhesive, and the weight ratio of PHA to the acrylic adhesive is 3:7 to 7:3.

The laminate according to the present invention includes a base layer, a substrate layer and a coating layer, which will be described in detail below with reference to FIG. 1 and FIG. 2 .

Figure 1 shows a laminate (1) according to one embodiment of the present invention. Figure 2 shows another laminate (1) according to another embodiment of the present invention.

Specifically, Figure 1 shows a laminate (1) in which a coating layer (200) is formed on one side of a substrate layer (100). Figure 2 shows a laminate (1) in which a coating layer (200) is formed on both sides of a substrate layer (100).

The laminate includes a coating on one or both sides of the substrate layer, and the coating includes PHA and acrylic adhesive in a weight ratio of 3:7 to 7:3. Therefore, the laminate using the coating composition according to one embodiment of the present invention is environmentally friendly because it has excellent biodegradability and biocompatibility, and carbon (carbon dioxide) emissions can be reduced by increasing the biocarbon content, and it has excellent water resistance. Therefore, when it is applied to products that require water resistance, such as packaging materials for packaging foods with a large amount of moisture, it can show excellent characteristics. Substrate layer

The substrate layer may serve as a substrate for forming a coating layer in the laminate while ensuring the mechanical strength of the laminate.

The details of the substrate used in the substrate layer are as described above. Specifically, the substrate may include paper.

Specifically, the substrate layer may include a paper layer.

The paper layer may have a biocarbon content (renewable carbon content) of 85% (85% modern carbon (pMC)) or more. Specifically, the paper layer may have a biocarbon content of 85% to 100%, 85% to 99%, 85% to 95%, or 90% to 95%.

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

In addition, the substrate layer may have a basis weight of 30 g/m ² to 500 g/m ^2. For example, when the substrate layer is a paper layer, the basis weight of the paper layer may be 30 g/m ² to 500 g/m ² , 30 g/m ² to 350 g/m ² , 30 g/m ² to 200 g/m ² , 50 g/m ² to 200 g/m ² , 80 g/m ² to 200 g/m ² , 100 g/m ² to 200 g/m ² , 130 g/m ² to 190 g/m ² , 150 g/m ² to 185 g/m ² , or 120 g/m ² to 320 g/m ² . If the basis weight of the substrate layer satisfies the above range, the mechanical strength of the laminate can be ensured, and the processability and productivity can be further enhanced.

The density of the substrate layer may be 0.6 to 1.2 g/cm ³ . Specifically, the density of the substrate layer may be 0.7 to 1.2 g/cm ³ , 0.8 to 1.2 g/cm ³ , or 0.9 to 1.1 g/cm ³ . Coating

The laminate includes a coating layer. The coating layer may be formed on at least one side of the substrate layer to enhance gas barrier properties, sealing properties, biodegradability, and water resistance.

The coating comprises PHA and an acrylic binder, wherein the weight ratio of PHA to acrylic binder is 3:7 to 7:3. The weight ratio of PHA to acrylic binder in the coating may be 3:7 to 7:3, specifically, 3:7 to 6:4, 4:6 to 7:3, 4:6 to 6:4, 3:7 to 5:5, or 5:5 to 7:3.

Details about PHA and acrylic adhesives are as described above.

The coating may have a thickness of 5 to 30 g/ ^m2 and a water absorption index (WAI) of 30 g/ ^m2 ·10 minutes or less when measured using the Cobb water absorption test in accordance with TAPPI T441 standard.

Specifically, the thickness of the coating layer can be 5 to 30 g/m ² , 10 to 30 g/m ² , 10 to 25 g/m ² , 10 to 20 g/m ² , 12 to 18 g/m ² or 13 to 17 g/m ² . If the thickness of the coating layer satisfies the above range, it can be more conducive to achieving the desired effect of the present invention; specifically, the water resistance, processability and productivity of the coating layer can be further enhanced.

Since the coating mainly comprises PHA which is broken down more quickly by microorganisms, it may have a faster biodegradation rate.

In addition, the coating layer is formed by coating the PHA in the form of particles on the substrate layer to ensure uniformity of the coating layer, rather than by melting the PHA having a high melting temperature (Tm). The adhesion between the coating layer (specifically, the PHA particles) and the substrate layer can be enhanced by using an acrylic adhesive. Specifically, since the PHA and the acrylic adhesive are adjusted to a specific content ratio, productivity, processability and water resistance can be enhanced, and environmentally friendly characteristics can be further established through a carbon emission reduction effect.

The water absorption index (WAI) of the coating may be 30 g/m ² ·10 minutes or less. For example, the water absorption index (WAI) of the coating can be less than 30 g/m ² ·10 minutes, 29 g/m ² ·10 minutes or less, 28 g/m ² ·10 minutes or less, 26 g/m ² ·10 minutes or less, 25 g/m ² ·10 minutes or less, 23 g/m ² ·10 minutes or less, 22 g/m ² ·10 minutes or less, 20 g/m ² ·10 minutes or less, or less than 20 g/m ² ·10 minutes, for example, 5 g/m ² ·10 minutes to 30 g/m ² ·10 minutes, 8 g/m ² ·10 minutes to 29 g/m ² ·10 minutes, 8 g/m ² ·10 minutes to 25 g/m ² ·10 minutes, 9 g/m ² ·10 minutes to 25 g/m ² ·10 minutes, 9 g/m ² ·10 minutes to 20 g/m ² ·10 minutes, or 10 g/m ² ·10 minutes to 20 g/m ² ·10 minutes.

If the water absorption index (WAI) is within the above range, the laminate according to the present invention and products made therefrom, such as packaging materials (e.g., food packaging materials) and containers (e.g., food containers), can have excellent waterproofness and high mechanical strength.

The water absorption index (WAI) can be measured by the Cobb water absorption test (test time: 10 minutes) according to TAPPI T441 standard.

For example, the water absorption index (WAI) can be defined as the amount of water (weight) absorbed by a laminate (or packaging material) when 100 ml of water is poured into a laminate (or packaging material) with a width of 10 cm and a length of 10 cm for 10 minutes. Specifically, the water absorption index (WAI) can be calculated according to the following equation 1. [Equation 1] Water absorption index (WAI, g/m ² ·10 minutes) = (laminate weight after water absorption - laminate weight before water absorption, g) / (absorption area, m ² )

The laminate may have a biogenic carbon content of 25% or more, 30% or more, 40% or more, 50% or more, 60% or more, or 70% or more. When the biogenic carbon content of the laminate meets the above range, carbon dioxide emissions can be minimized. Here, the biogenic carbon content may refer to a value measured according to ASTM D6866.

The laminate comprising the coating can be used in various ways, such as packaging materials, cardboard boxes, shopping bags, disposable food containers, packaging containers or paper straws.

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are intended to illustrate the present invention, and the scope of the present invention is not limited thereto. Examples Example 1 Preparation of coating composition (1) Preparation of polyhydroxyalkanoate (PHA) dispersion

Homo Disper (product name: homogenizing dispenser, manufacturer: PRIMIX) was charged with 40 wt% of PHA powder (weight average molecular weight (Mw): 800,000, polydispersity index (PDI): 2.0, 4-HB content: 9 mol%, manufacturer: CJ CheilJedang), 20 wt% of 10% concentration of polyvinyl alcohol (PVA, average molecular weight: 13,000, manufacturer: Kuraray) as a dispersant, and 40 wt% of deionized water (DI water) based on the total weight of the polyhydroxyalkanoate (PHA) dispersion. When calculating the linear velocity, the mixer was operated at a speed of 60-80% of the maximum revolution per minute (rpm) of 1,250 cm/1 second based on a mixer diameter of 3 cm, and then the high-speed dispersion treatment was continued for about 30 minutes to prepare a first PHA dispersion.

The first PHA dispersion was filtered and washed once to prepare a second PHA dispersion.

Distilled water was added to the second PHA dispersion (PHA filter cake) to make the solid content 40 wt%, and then it was redispersed in the aqueous system by a homogenizer to prepare the final PHA dispersion (solid content: 40 wt%, pH: 7, viscosity: 150 cPs). (2) Mixing of PHA dispersion and acrylic emulsion

The PHA dispersion prepared in step (1) above was mixed with an acrylic emulsion (acrylic acid-polysilicone copolymer emulsion dispersed in water) at a weight ratio of 5:5. Then, the Homo Disper (product name: homogenizing disperser, manufacturer: PRIMIX) was operated at a speed of 60-80% of the maximum revolutions per minute, and then the high-speed dispersion treatment was continued for about 20 minutes to prepare a coating composition with reliable uniformity. Preparation of the layer

The coating composition thus prepared was applied at a coating amount of about 8.91 g/m ² on uncoated kraft paper (manufacturer: Hansol Paper) having a basis weight of 180 g/m ² as a substrate using a Mayer rod coater (manufacturer: RDS) so that the coating thickness was about 15 g/m ^2. It was dried at about 170° C. for about 53 seconds to obtain a laminate. Example 2

A coating composition and a laminate were obtained in the same manner as in Example 1, except that, as shown in Tables 1 to 3, the PHA dispersion and the acrylic emulsion dispersed in water were mixed in a weight ratio of 7:3 in the preparation of the coating composition; and the drying time was changed in the preparation of the laminate. Example 3

A coating composition and a laminate were obtained in the same manner as in Example 1, except that, as shown in Tables 1 to 3, the PHA dispersion and the acrylic emulsion dispersed in water were mixed in a weight ratio of 3:7 in the preparation of the coating composition; and the drying time was changed in the preparation of the laminate. Example 4

The coating composition and the laminate were obtained in the same manner as in Example 1, except that, as shown in Tables 1 to 3 , PHAs with different molecular weights and 4-HB contents were used to prepare the coating composition; and the drying time was changed in the manufacture of the laminate.

A coating composition and a laminate were obtained in the same manner as in Example 4, except that, as shown in Tables 1 to 3, the PHA dispersion and the acrylic emulsion dispersed in water were mixed in a weight ratio of 7:3 in the preparation of the coating composition; and the drying time was changed in the preparation of the laminate. Example 6

A coating composition and a laminate were obtained in the same manner as in Example 4, except that, as shown in Tables 1 to 3, the PHA dispersion and the acrylic emulsion dispersed in water were mixed in a weight ratio of 3:7 in the preparation of the coating composition; and the drying time was changed in the preparation of the laminate. Example 7

The coating composition and the laminate were obtained in the same manner as in Example 1, except that the drying temperature and time were changed in the preparation of the laminate as shown in Tables 1 to 3. Example 8

A coating composition and a laminate were obtained in the same manner as in Example 7, except that, as shown in Tables 1 to 3, the PHA dispersion and the acrylic emulsion dispersed in water were mixed in a weight ratio of 7:3 in the preparation of the coating composition; and the drying time was changed in the preparation of the laminate. Example 9

A coating composition and a laminate were obtained in the same manner as in Example 7, except that, as shown in Tables 1 to 3, the PHA dispersion and the acrylic emulsion dispersed in water were mixed in a weight ratio of 3:7 in the preparation of the coating composition; and the drying time was changed in the preparation of the laminate. Example 10

The coating composition and the laminate were obtained in the same manner as in Example 1, except that, as shown in Tables 1 to 3, PHAs with different molecular weights and 4-HB contents were used to prepare the coating composition; and the drying temperature and time were changed in the manufacture of the laminate.

A coating composition and a laminate were obtained in the same manner as in Example 10, except that, as shown in Tables 1 to 3, the PHA dispersion and the acrylic emulsion dispersed in water were mixed in a weight ratio of 7:3 in the preparation of the coating composition; and the drying time was changed in the preparation of the laminate.

A coating composition and a laminate were obtained in the same manner as in Example 10, except that, as shown in Tables 1 to 3, the PHA dispersion and the acrylic emulsion dispersed in water were mixed in a weight ratio of 3:7 in the preparation of the coating composition; and the drying time was changed in the preparation of the laminate.

A coating composition and a laminate were obtained in the same manner as in Example 1, except that the drying temperature and time were changed in the preparation of the laminate as shown in Tables 1 to 3. Example 14

The coating composition and the laminate were obtained in the same manner as in Example 4, except that the drying temperature and time were changed in the manufacture of the laminate as shown in Tables 1 to 3.

A coating composition and a laminate were obtained in the same manner as in Example 1, except that, as shown in Tables 1 to 3, mixing of the PHA dispersion and the acrylic emulsion was not performed (the second step), and the PHA dispersion as the coating composition was applied onto uncoated kraft paper.

A coating composition and a laminate were obtained in the same manner as in Example 4, except that, as shown in Tables 1 to 3, mixing of the PHA dispersion and the acrylic emulsion was not performed (the second step), and the PHA dispersion as the coating composition was applied onto uncoated kraft paper.

A coating composition and a laminate were obtained in the same manner as in Example 1, except that, as shown in Tables 1 to 3 , the PHA dispersion and the acrylic emulsion dispersed in water were mixed in a weight ratio of 1:9 in the preparation of the coating composition; and the drying time was changed in the preparation of the laminate.

A coating composition and a laminate were obtained in the same manner as in Example 4, except that, as shown in Tables 1 to 3 , the PHA dispersion and the acrylic emulsion dispersed in water were mixed in a weight ratio of 1:9 in the preparation of the coating composition; and the drying time was changed in the preparation of the laminate.

The coating composition and the laminate were obtained in the same manner as in Example 1, except that, as shown in Tables 1 to 3, the PHA dispersion and the acrylic emulsion dispersed in water were mixed in a weight ratio of 2:8 in the preparation of the coating composition; and the drying time was changed in the preparation of the laminate. Test Examples Test Example 1 : Viscosity

The viscosity of the PHA dispersion and acrylic emulsion used in the examples and comparative examples was measured using a DVE-RV viscometer (manufacturer: Brookfield) which uses a #63 spindle at about 25°C and a shear rate of 12 rpm to measure the viscosity using shear stress. Test Example 1 : Average Particle Size

The average particle size of PHA and acrylic adhesive was measured using a laser particle size diffraction instrument.

Specifically, the average particle size of each of the PHA and acrylic emulsions was measured by dynamic light scattering (DLS) at a temperature of 25°C and a measuring angle of 175° using a laser particle size diffraction instrument (particle size analyzer, Beckman Coulter). In such cases, the peak value obtained by the polydispersity index (PDI) in the confidence interval of 0.5 was regarded as the particle size. Test Example 3 : Water resistance

Water resistance is measured according to TAPPI T441 standard via the Cobb water absorption test (test time: 10 minutes).

Specifically, 100 ml of water was poured over 10 minutes onto each of the laminates having a width of 10 cm and a length of 10 cm prepared in Examples 1 to 14 and Comparative Examples 1 to 5. The water absorption index (WAI, g/m ² ·10 minutes) was calculated from the amount of water (weight) absorbed by the laminate according to the following equation 1. [Equation 1] Water absorption index (WAI, g/m ² ·10 minutes) = (weight of laminate after water absorption - weight of laminate before water absorption, g) / (absorption area, m ² )

In Examples 1 to 14 and Comparative Examples 1 to 5, the PHA properties are listed in Table 1, the compositions and properties of the PHA dispersions and acrylic emulsions are listed in Table 2, and the process conditions and physical properties of the coating compositions and laminates are summarized in Tables 3 and 4 below. [Table 1] Average particle size (µm) Mw (g/mol) PDI 4-HB content (mol%) Tg (℃) Tc (℃) Tm (℃) Example 1 2.2 800,000 2.0 9 -5.37 98 157 Example 2 2.2 800,000 2.0 9 -5.37 98 157 Example 3 2.2 800,000 2.0 9 -5.37 98 157 Example 4 3.2 400,000 2.0 11 -9.15 90 159 Example 5 3.2 400,000 2.0 11 -9.15 90 159 Example 6 3.2 400,000 2.0 11 -9.15 90 159 Example 7 2.2 800,000 2.0 9 -5.37 98 157 Example 8 2.2 800,000 2.0 9 -5.37 98 157 Example 9 2.2 800,000 2.0 9 -5.37 98 157 Example 10 3.2 400,000 2.0 11 -9.15 90 159 Example 11 3.2 400,000 2.0 11 -9.15 90 159 Example 12 3.2 400,000 2.0 11 -9.15 90 159 Example 13 2.2 800,000 2.0 9 -5.37 98 157 Example 14 3.2 400,000 2.0 11 -9.15 90 159 Comparison Example 1 2.2 800,000 2.0 9 -5.37 98 157 Comparison Example 2 3.2 400,000 2.0 11 -9.15 90 159 Comparison Example 3 2.2 800,000 2.0 9 -5.37 98 157 Comparison Example 4 3.2 400,000 2.0 11 -9.15 90 159 Comparison Example 5 2.2 800,000 2.0 9 -5.37 98 157 [Table 2] PHA dispersion Acrylic Emulsion PHA (wt%) Dispersant (wt%) Water (wt%) Solid content (weight %) pH Viscosity(cPs) Solid content (weight %) pH Viscosity(cPs) Example 1 40 20 40 40 7 150 40 7 400 Example 2 40 20 40 40 7 150 40 7 400 Example 3 40 20 40 40 7 150 40 7 400 Example 4 40 10 50 40 7 150 40 7 400 Example 5 40 10 50 40 7 150 40 7 400 Example 6 40 10 50 40 7 150 40 7 400 Example 7 40 20 40 40 7 150 40 7 400 Example 8 40 20 40 40 7 150 40 7 400 Example 9 40 20 40 40 7 150 40 7 400 Example 10 40 10 50 40 7 150 40 7 400 Example 11 40 10 50 40 7 150 40 7 400 Example 12 40 10 50 40 7 150 40 7 400 Example 13 40 20 40 40 7 150 40 7 400 Example 14 40 10 50 40 7 150 40 7 400 Comparison Example 1 40 20 40 40 7 150 40 7 400 Comparison Example 2 40 10 50 40 7 150 40 7 400 Comparison Example 3 40 20 40 40 7 150 40 7 400 Comparison Example 4 40 10 50 40 7 150 40 7 400 Comparison Example 5 40 20 40 40 7 150 40 7 400 [table 3] Coating composition Laminate PHA dispersion: acrylic emulsion (weight ratio) PHA: Acrylic Adhesive (weight ratio) Drying temperature(℃) Drying time(s) Coating amount (g/m ² ) Coating thickness (g/m ² ) WAI (g/ ^m2 ·10 min.) Example 1 5:5 5:5 170 53 8.91 15 12.52 Example 2 7:3 7:3 170 75 8.36 15 11.2 Example 3 3:7 3:7 170 35 10.34 15 25.72 Example 4 5:5 5:5 170 55 9.69 15 13.7 Example 5 7:3 7:3 170 90 9.72 15 12.9 Example 6 3:7 3:7 170 37 8.97 15 25.6 Example 7 5:5 5:5 140 75 10.61 15 15.8 Example 8 7:3 7:3 140 150 10.55 15 10.68 Example 9 3:7 3:7 140 60 8.39 15 29.72 Example 10 5:5 5:5 140 80 5.81 15 13.32 Example 11 7:3 7:3 140 120 8.77 15 9.18 Example 12 3:7 3:7 140 53 9.32 15 27.8 Example 13 5:5 5:5 120 180 8.75 15 18.44 Example 14 5:5 5:5 120 180 6.26 15 17.55 Comparison Example 1 10:0 10:0 170 100 8.34 15 25.7 Comparison Example 2 10:0 10:0 170 90 10.32 15 20.6 Comparison Example 3 1:9 1:9 170 30 11.68 15 34.64 Comparison Example 4 1:9 1:9 170 30 8.42 15 33.6 Comparison Example 5 2:8 2:8 170 30 10.8 15 32.2

As shown in Table 3 above, the coating compositions of Examples 1 to 14 each comprised PHA and an acrylic binder in a ratio of 3:7 to 7:3. Therefore, when a laminate is prepared by coating the coating composition onto a substrate, it is possible to enhance coating characteristics and water resistance, and significantly shorten the drying step, thereby further enhancing processability and productivity.

Specifically, when the coating compositions prepared in the examples of the present invention were each applied at a coating amount of 8.36 g/m ² to 10.34 g/m ² on a paper substrate having a basis weight of 180 g/m ² and then dried at 170° C., the drying time was 90 seconds or less. When they were each applied at a coating amount of 5.81 g/m ² to 10.61 g/m ² and then dried at 140° C., the drying time was 150 seconds or less.

In addition, a laminate including a coating formed using the coating composition at a high drying rate has excellent water resistance, wherein the water absorption index (WAI) is 30 g/m ² ·10 minutes or less.

In contrast, when the coating compositions of Comparative Examples 1 and 2 each containing no acrylic emulsion were used, the drying time increased and the water absorption index (WAI) increased compared to the coating composition of Example 1, resulting in decreased water resistance.

In addition, when the coating compositions of Comparative Examples 3 to 5 were used, although acrylic emulsion was used, the weight ratio of PHA to acrylic emulsion was outside the range of the present invention, and the water absorption index (WAI) increased significantly, resulting in a significant decrease in water resistance. [Table 4] Coating composition Laminate PHA dispersion: acrylic emulsion (weight ratio) PHA: Acrylic Adhesive (weight ratio) Drying temperature(℃) Drying time(s) Coating amount (g/m ² ) Coating thickness (g/m ² ) Biomass carbon content of coating (%) Example 1 5:5 5:5 170 53 8.91 15 50 Example 2 7:3 7:3 170 75 8.36 15 70 Example 3 3:7 3:7 170 35 10.34 15 30 Example 4 5:5 5:5 170 55 9.69 15 50 Example 5 7:3 7:3 170 90 9.72 15 70 Example 6 3:7 3:7 170 37 8.97 15 30 Example 7 5:5 5:5 140 75 10.61 15 50 Example 8 7:3 7:3 140 150 10.55 15 70 Example 9 3:7 3:7 140 60 8.39 15 30 Example 10 5:5 5:5 140 80 5.81 15 50 Example 11 7:3 7:3 140 120 8.77 15 70 Example 12 3:7 3:7 140 53 9.32 15 30 Example 13 5:5 5:5 120 180 8.75 15 50 Example 14 5:5 5:5 120 180 6.26 15 50 Comparison Example 3 1:9 1:9 170 30 11.68 15 10 Comparison Example 4 1:9 1:9 170 30 8.42 15 10 Comparison Example 5 2:8 2:8 170 30 10.8 15 20

As shown in Table 4, in the composites of Examples 1 to 14, the biochar content of the coating was 30% or greater, with most of them satisfying 50% or greater.

In contrast, in the composites of Comparative Examples 3 to 5, the biogenic carbon content of the coating was only 10% to 20%.

Therefore, the laminates of Examples 1 to 14 are environmentally friendly due to their excellent biodegradability and biocompatibility as well as their increased biocarbon content.

In summary, the coating composition according to one embodiment of the present invention can significantly reduce the drying time after its application, thereby increasing productivity. Specifically, when it is dried at 140° C. to 170° C., the productivity and water resistance of the coating can be optimally enhanced, and it is environmentally friendly due to the increased content of biochar. Therefore, when the coating composition of the present invention is applied to a product requiring water resistance (such as a packaging material or food container for packaging food with a large amount of moisture), it exhibits excellent characteristics and can further enhance the service life characteristics, environmental friendliness and recyclability, so that it can be used for various purposes.

1:Layer 100:Substrate layer 200:Coating layer

FIG. 1 shows a laminate according to an embodiment of the present invention.

FIG. 2 shows another laminate according to another embodiment of the present invention.

1:Laminate

100: substrate layer

200: coating

Claims (18)

A coating composition comprises a polyhydroxyalkanoate (PHA) and an acrylic adhesive, wherein the weight ratio of the polyhydroxyalkanoate (PHA) to the acrylic adhesive is 3:7 to 7:3. A coating composition as claimed in claim 1, wherein when the coating composition is applied to a paper substrate having a basis weight of 20 to 400 g/m ² at a coating amount of 1 g/m ² to 100 g/m ² and then dried at 170° C. or less, the drying time is less than 200 seconds. The coating composition of claim 1, wherein the content of biochar is 25% or more based on the total weight of the coating composition. The coating composition of claim 1, wherein the polyhydroxyalkanoate (PHA) has a weight average molecular weight (Mw) of 200,000 g/mol to 900,000 g/mol, an average particle size of 5 μm or less, and a polydispersity index (PDI) of 3 or less. The coating composition of claim 1, wherein the polyhydroxyalkanoate (PHA) has a glass transition temperature (Tg) of -10°C to 10°C, a crystallization temperature (Tc) of 70°C to 120°C, and a melting temperature (Tm) of 100°C to 170°C. The coating composition of claim 1, wherein the polyhydroxyalkanoate (PHA) comprises a repeating unit derived from at least one monomer selected from the group consisting of 4-hydroxybutyrate (4-HB), 3-hydroxybutyrate (3-HB), 3-hydroxypropionate (3-HP), 3-hydroxyvalerate (3-HV), 3-hydroxyhexanoate (3-HH), 4-hydroxyvalerate (4-HV), 5-hydroxyvalerate (5-HV) and 6-hydroxyhexanoate (6-HH). The coating composition of claim 6, wherein the polyhydroxyalkanoate (PHA) is a PHA copolymer comprising a repeating unit derived from a 3-hydroxybutyrate (3-HB) monomer and a repeating unit derived from a 4-hydroxybutyrate (4-HB) monomer, and wherein the repeating unit derived from the 4-hydroxybutyrate (4-HB) monomer is 0.1 mol% to 60 mol% based on the total molar number of the repeating unit derived from the 3-hydroxybutyrate (3-HB) monomer and the repeating unit derived from the 4-hydroxybutyrate (4-HB) monomer. A coating composition as claimed in claim 1, wherein the acrylic binder comprises an acrylic monomer, or a copolymer comprising the acrylic monomer and at least one monomer selected from the group consisting of a polysilicone monomer and a styrene monomer, or a combination thereof, and has an average particle size of 1 μm or less and a polydispersity index (PDI) of 2 or less. A coating composition as claimed in claim 1, wherein the coating composition further comprises at least one additive selected from the group consisting of: a dispersant, a thickener, a preservative, a defoaming agent and a pH adjuster, and wherein the additive is used in an amount of 0.1 wt % to 30 wt % based on the total weight of the solid content of the coating composition. A method for preparing a coating composition, comprising: Preparing a polyhydroxyalkanoate (PHA) dispersion containing a polyhydroxyalkanoate (PHA); and Mixing the polyhydroxyalkanoate (PHA) dispersion with an acrylic emulsion containing an acrylic adhesive, wherein the weight ratio of the polyhydroxyalkanoate (PHA) to the acrylic adhesive is 3:7 to 7:3. A method for preparing a coating composition as claimed in claim 10, wherein the polyhydroxyalkanoate (PHA) dispersion comprises a polyhydroxyalkanoate (PHA), a dispersant and a solvent, and the polyhydroxyalkanoate (PHA) is used in an amount of 10 wt % to 60 wt % based on the total weight of the polyhydroxyalkanoate (PHA) dispersion. A method for preparing a coating composition as claimed in claim 10, wherein the polyhydroxyalkanoate (PHA) dispersion has a pH value of 5 to 8 and a viscosity of 50 to 1,000 cPs measured at 25°C. A method for preparing a coating composition as claimed in claim 10, wherein the acrylic emulsion has a pH of 8 or less and a viscosity of 1,000 cPs or less measured at 25°C. A laminate comprises a substrate layer and a coating layer, wherein the coating layer comprises a polyhydroxyalkanoate (PHA) and an acrylic adhesive, and the weight ratio of the polyhydroxyalkanoate (PHA) to the acrylic adhesive is 3:7 to 7:3. The laminate of claim 14, wherein the coating has a thickness of 5 to 30 g/m ² and a water absorption index (WAI) of 30 g/m ² ·10 minutes or less when measured using the Cobb water absorption test according to TAPPI T441 standard. A method for preparing a layer, comprising: (1) preparing a coating composition as claimed in claim 1, and (2) coating the coating composition on a substrate and drying it to form a coating. A method for preparing a layer as claimed in claim 16, wherein the drying is performed at 100°C to 250°C for less than 200 seconds. A method for preparing a layer as claimed in claim 16, wherein the coating composition is applied to the substrate in an amount of 1 to 100 g/ ^m2 .