Polyhydroxyalkanoate emulsion preparation method and polyhydroxyalkanoate emulsion prepared using same

Abstract

The present invention relates to a polyhydroxyalkanoate (PHA) emulsion preparation method and a polyhydroxyalkanoate emulsion prepared using same. Specifically, the PHA emulsion preparation method comprises the steps of: preparing a suspension containing PHA; and removing defects in the suspension, wherein the step of removing defects is performed under a pressure of 200-2,000 bar.

Description

Method for producing polyhydroxyalkanoate emulsion and polyhydroxyalkanoate emulsion produced therefrom

[0001] The present invention relates to a method for producing a novel polyhydroxyalkanoate emulsion and a polyhydroxyalkanoate emulsion produced therefrom.

[0002] With growing concerns about environmental issues, research is actively underway on the treatment and recycling of various household waste products. Specifically, inexpensive polymer materials with excellent processability are widely used to manufacture a variety of products, including paper, film, fibers, packaging materials, bottles, and containers. However, incineration of these materials at the end of their lifespan can release hazardous substances, and depending on the type, complete natural decomposition can take hundreds of years.

[0003] Accordingly, research is ongoing on biodegradable polymers that can improve environmental friendliness by decomposing quickly, while also improving mechanical properties, oil resistance, water resistance, and processability, thereby increasing the lifespan of the product itself, thereby reducing the amount of waste or improving recyclability.

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

[0005] In order to apply biodegradable polymers to products, a coating process using an emulsion containing the biodegradable polymer is used. In this case, a process for removing defects caused by agglomeration of fine particles during the emulsion manufacturing process is necessary to improve the coating quality. Conventionally, particles such as grit and grains generated during the emulsion manufacturing process were removed through a filtration process. However, the filtration process takes a long time, and it is difficult to perform the emulsion manufacturing process as a continuous process, resulting in low processability and productivity.

[0006] Accordingly, the present invention aims to provide a method for producing a polyhydroxyalkanoate emulsion that is excellent in biodegradability and biocompatibility, is environmentally friendly, and can efficiently remove defects in an emulsion, thereby providing excellent processability and productivity, and a polyhydroxyalkanoate emulsion produced therefrom.

[0007] A method for producing a polyhydroxyalkanoate emulsion according to one embodiment of the present invention comprises the steps of: producing a suspension containing polyhydroxyalkanoate (PHA); and removing a defect in the suspension; wherein the defect removing step is performed at a pressure of 200 bar to 2,000 bar.

[0008] According to one embodiment of the present invention, the step of preparing the suspension and the step of removing a defect in the suspension may be performed at different pressures.

[0009] According to one embodiment of the present invention, the defect removal step may be performed for a time period of more than 5 minutes and less than or equal to 60 minutes.

[0010] According to one embodiment of the present invention, the defect may include particles including grit or grain.

[0011] According to one embodiment of the present invention, the particles may have an average particle diameter of 6 μm or more, and an average particle size distribution of 10 μm or less.

[0012] According to one embodiment of the present invention, in the step of preparing the suspension, 2.5 to 20 parts by weight of a surfactant may be added based on 100 parts by weight of the PHA.

[0013] According to one embodiment of the present invention, the surfactant may include at least one selected from the group consisting of polyvinyl alcohol, sodium dodecylbenzene sulfonate, polyvinylpyrrolidone, methyl polyethylene alkyl ether, alkylbenzene sulfonate, nonylphenol ether sulfate, sodium lauryl sulfate, lithium dodecyl sulfate, alkyl phosphate, glyceryl ester, and polypropylene glycol ester.

[0014] According to one embodiment of the present invention, the step of preparing the suspension may include a step of performing high-speed dispersion treatment using a homogenizer at room temperature and pressure conditions at a speed of 55% to 85% of the maximum rotational speed per minute (rpm) of the homogenizer for 10 to 60 minutes.

[0015] According to one embodiment of the present invention, the method may further include adding one or more additives selected from the group consisting of a thickener, an antibacterial agent, a stabilizer, and a pH regulator to the suspension from which the defect has been removed.

[0016] According to one embodiment of the present invention, the amount of the additive may be 0.005 parts by weight to 30 parts by weight based on 100 parts by weight of the suspension from which the defect has been removed.

[0017] According to one embodiment of the present invention, the PHA is a polyhydroxyalkanoate copolymer comprising a 4-hydroxybutyrate (4-HB) repeating unit and a 3-hydroxybutyrate (3-HB) repeating unit, and may comprise 0.1 wt% to 60 wt% of the 4-hydroxybutyrate (4-HB) repeating unit.

[0018] According to one embodiment of the present invention, the PHA may have a weight average molecular weight of 30,000 g / mol to 1,200,000 g / mol.

[0019] According to one embodiment of the present invention, the PHA may include a semi-crystalline PHA.

[0020] According to one embodiment of the present invention, the semi-crystalline PHA may contain 0.1 wt% to 30 wt% of 4-hydroxybutyrate (4-HB) repeating units, may have a glass transition temperature (Tg) of -30°C to 80°C, may have a crystallization temperature (Tc) of 30°C to 130°C, and may have a melting temperature (Tm) of 100°C to 175°C.

[0021] The present invention provides a polyhydroxyalkanoate (PHA) emulsion manufactured by the method for manufacturing the above polyhydroxyalkanoate (PHA) emulsion.

[0022] According to one embodiment of the present invention, the PHA emulsion may have an average particle size of 1.5 ㎛ to 4.5 ㎛, a particle size deviation of ±5 ㎛ or less, a polydispersity index (PDI) of 3 or less, a viscosity of 100 cps to 3,000 cps, and a pH of 6.5 to 11.

[0023] A method for producing a PHA emulsion according to one embodiment of the present invention comprises the steps of: producing a suspension containing polyhydroxyalkanoate (PHA); and removing a defect in the suspension; wherein the defect removing step is performed at a pressure of 200 bar to 2,000 bar, thereby improving processability and productivity.

[0024] Specifically, in the case of the filter process used in the past, it usually took a long process time of more than 90 minutes to sufficiently obtain the effect of removing defects caused by agglomeration of fine particles during the emulsion manufacturing process, and since the filter process was performed during the emulsion manufacturing process, it was difficult to perform the emulsion manufacturing process as a continuous process, so there were problems of low fairness and productivity.

[0025] However, the method for producing a PHA emulsion according to one embodiment of the present invention produces a suspension containing PHA and performs a step of removing defects in the suspension at a pressure of 200 bar to 2,000 bar, thereby sufficiently obtaining the effect of removing defects such as particles containing grit or grains with a simple process of controlling pressure without additional equipment and a short process time, and since the connection with the subsequent process is excellent, a continuous process is possible, and thus the processability and productivity are excellent.

[0026] FIG. 1 is a schematic flowchart (S100) of a method for producing a polyhydroxyalkanoate (PHA) emulsion according to one embodiment of the present invention.

[0027] Hereinafter, the present invention will be described in detail. The present invention is not limited to the contents disclosed below and may be modified in various forms without changing the gist of the invention.

[0028] In this specification, when a part is said to "include" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0029] All numbers and expressions indicating the amounts of components, reaction conditions, etc. described in this specification should be understood to be modified by the term “about” in all cases unless otherwise specified.

[0030] When it is described in this specification that one component is formed on or under another component, it includes both cases where one component is formed directly on or under the other component, or indirectly through the interposition of another component.

[0031] In this specification, the terms "first," "second," "primary," and "secondary" are used to describe various components, and the components are not limited by the terms. The terms are used solely to distinguish one component from another.

[0032]

[0033] Method for producing PHA emulsion

[0034] A method for producing a polyhydroxyalkanoate emulsion according to one embodiment of the present invention comprises the steps of: producing a suspension containing polyhydroxyalkanoate (PHA); and removing a defect in the suspension; wherein the defect removing step is performed at a pressure of 200 bar to 2,000 bar.

[0035] In the process of manufacturing an emulsion using PHA, defects, more specifically, grit or grains in the suspension, may occur due to agglomeration of fine particles depending on the compatibility or dispersibility between the components. In order to improve the quality of the emulsion, such as the coating properties, a process for removing particles containing such grit or grains is necessary.

[0036] Specifically, the particles may include sediment, aggregates, grit, grains, etc., and may include finely ground particles, finely dispersed particles, or foreign substances generated during the high-crystalline PHA manufacturing process. As a specific example, the particles may include grit.

[0037] The particles may have an average particle diameter of 6 μm or more, and an average particle size distribution of 10 μm or less. For example, the average particle diameter of the particles in the suspension may be 7 μm or more, 10 μm or more, or 20 μm or more, and may be 300 μm or less, 250 μm or less, or 200 μm or less. In addition, the average particle size distribution of the particles in the suspension may be 9.5 μm or less, 8 μm or less, 5 μm or less, or 3 μm or less. The average particle diameter of the particles may be measured by a particle size analyzer (trade name: LS 13 320, manufacturer: Beckman Coulter) in the particle size distribution (PSD), and may be a cumulative 50% particle diameter (D50) in the particle size distribution of the particles.

[0038] A method for producing a PHA emulsion according to one embodiment of the present invention comprises producing a suspension containing PHA and performing a step of removing defects in the suspension at a pressure of 200 to 2,000 bar, thereby effectively removing defects such as particles containing grit or grains. Therefore, the method for producing a PHA emulsion according to one embodiment of the present invention can sufficiently obtain the effect of removing defects such as particles containing grit or grains through a simple process of controlling pressure without additional equipment and a short process time, and has excellent connectivity with subsequent processes, enabling a continuous process, thereby providing excellent processability and productivity.

[0039] FIG. 1 is a schematic flowchart (S100) of a method for producing a polyhydroxyalkanoate (PHA) emulsion according to one embodiment of the present invention. Referring to FIG. 1, a detailed description will be given below.

[0040]

[0041] Step of preparing a suspension containing PHA

[0042] A method for producing a PHA emulsion according to one embodiment of the present invention comprises a step of producing a suspension containing PHA.

[0043] According to one embodiment of the present invention, the suspension comprises PHA. As a specific example, the suspension may be a powdered form of PHA dispersed in distilled water.

[0044] The above PHA is a thermoplastic natural polyester polymer that accumulates within microbial cells. Since it is a biodegradable material, it can be composted, does not produce toxic waste, and can ultimately be decomposed into carbon dioxide, water, and organic waste.

[0045] Specifically, the PHA is formed when certain bacteria accumulate PHA within microbial cells to store carbon sources and energy when nutrients (nitrogen sources, phosphorus sources, etc.) are supplied unbalanced.

[0046] In addition, the PHA has properties similar to synthetic polymers such as polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate terephthalate (PBST), and polybutylene succinate adipate (PBSA) derived from conventional petroleum, and exhibits complete biodegradability and excellent biocompatibility.

[0047] In particular, unlike other eco-friendly plastic materials such as PBS, PLA, and PTT, the PHA can be synthesized from over 150 different monomers. Therefore, hundreds of different PHAs can be manufactured depending on the type of monomer. These hundreds of different PHAs, each with completely different structures and properties, differ significantly from one another. Therefore, ongoing research is being conducted on the structure and properties of different monomers that make up PHA, as well as their compatibility with other components.

[0048] The above PHA may comprise a single monomer repeating unit present in a living cell, and may be formed by polymerizing one or more monomer repeating units. Specifically, the PHA may be a single polyhydroxyalkanoate (hereinafter referred to as HOMO PHA) or a polyhydroxyalkanoate copolymer (hereinafter referred to as PHA copolymer), i.e., a copolymer in which different repeating units are regularly or randomly distributed in the polymer chain.

[0049] Examples of repeating units that may be included in the above PHA include 2-hydroxybutyrate, lactic acid, glycolic acid, 3-hydroxybutyrate (hereinafter referred to as 3-HB), 3-hydroxypropionate (hereinafter referred to as 3-HP), 3-hydroxyvalerate (hereinafter referred to as 3-HV), 3-hydroxyhexanoate (hereinafter referred to as 3-HH), 3-hydroxyheptanoate (hereinafter referred to as 3-HHep), 3-hydroxyoctanoate (hereinafter referred to as 3-HO), 3-hydroxynonanoate (hereinafter referred to as 3-HN), 3-hydroxydecanoate (hereinafter referred to as 3-HD), 3-hydroxydodecanoate (hereinafter referred to as 3-HDd), There may be 4-hydroxybutyrate (hereinafter referred to as 4-HB), 4-hydroxyvalerate (hereinafter referred to as 4-HV), 5-hydroxyvalerate (hereinafter referred to as 5-HV), and 6-hydroxyhexanoate (hereinafter referred to as 6-HH), and the PHA may contain one or more repeating units selected from these.

[0050] Specifically, the PHA may comprise one or more repeating units selected from the group consisting of 3-HB, 4-HB, 3-HP, 3-HH, 3-HV, 4-HV, 5-HV, and 6-HH.

[0051] More specifically, the PHA may contain 0.1 wt% to 60 wt% of the 4-HB repeating unit. For example, the PHA may contain 0.2 wt% to 50 wt%, 0.5 wt% to 40 wt%, 1 wt% to 25 wt%, 2 wt% to 15 wt%, or 3 wt% to 10 wt% of the 4-HB repeating unit. By satisfying the content of the 4-HB repeating unit within the above range, sufficient biodegradability that can be decomposed in soil and the ocean can be secured, while improving coatability and processability.

[0052] In addition, the PHA may be a PHA copolymer that includes the 4-HB repeating unit, and additionally includes one repeating unit different from the 4-HB repeating unit, or additionally includes two, three, four, five, six or more repeating units that are different from each other.

[0053] Additionally, the PHA may include isomers. For example, the PHA may include structural isomers, enantiomers, or geometric isomers. Specifically, the PHA may include structural isomers.

[0054] Additionally, the PHA may be a PHA copolymer with controlled crystallinity. For example, the PHA may include at least one 4-HB repeating unit, and the crystallinity of the PHA may be controlled by controlling the content of the 4-HB repeating unit.

[0055] For example, the PHA may be a PHA copolymer comprising one or more repeating units selected from the group consisting of 3-HB, 4-HB, 3-HP, 3-HH, 3-HV, 4-HV, 5-HV, and 6-HH.

[0056] Specifically, the PHA copolymer may further include at least one repeating unit selected from the group consisting of a 3-HB repeating unit, a 3-HP repeating unit, a 3-HH repeating unit, a 3-HV repeating unit, a 4-HV repeating unit, a 5-HV repeating unit, and a 6-HH repeating unit, while including a 4-HB repeating unit. More specifically, the PHA copolymer may include a 4-HB repeating unit and a 3-HB repeating unit. For example, the PHA may be poly 3-hydroxybutyrate-co-4-hydroxybutyrate (hereinafter referred to as P3HB-co-4HB).

[0057] In addition, the PHA is a PHA copolymer comprising a 4-HB repeating unit and a 3-HB repeating unit, and may contain 20 wt% or more of the 3-HB repeating unit. For example, the PHA may contain 35 wt% or more, 40 wt% or more, 50 wt% or more, 60 wt% or more, 70 wt% or more, or 75 wt% or more of the 3-HB repeating unit, and may contain 99 wt% or less, 98 wt% or less, 97 wt% or less, 96 wt% or less, 95 wt% or less, 93 wt% or less, 91 wt% or less, 90 wt% or less, 80 wt% or less, 70 wt% or less, 60 wt% or less, or 55 wt% or less of the 3-HB repeating unit.

[0058] Additionally, the weight average molecular weight of the PHA may be 30,000 g / mol to 1,200,000 g / mol. For example, the weight average molecular weight of the PHA may be 50,000 g / mol to 1,000,000 g / mol, 100,000 g / mol to 850,000 g / mol, 200,000 g / mol to 600,000 g / mol, 250,000 g / mol to 500,000 g / mol, or 300,000 g / mol to 450,000 g / mol.

[0059] The above PHA with controlled crystallinity may have controlled crystallinity and amorphousness by increasing irregularity in the molecular structure, and specifically, may have controlled the type or ratio of monomers or the type or content of isomers.

[0060] According to one embodiment of the present invention, the PHA may include a semi-crystalline PHA. Specifically, the PHA may include a semi-crystalline PHA with controlled crystallinity. More specifically, the PHA may be composed of a semi-crystalline PHA with controlled crystallinity. Furthermore, the PHA used in one embodiment of the present invention may be a mixture of a semi-crystalline PHA with controlled crystallinity and an amorphous PHA.

[0061] The semi-crystalline PHA may comprise 0.1 wt% to 30 wt% of the 4-hydroxybutyrate (4-HB) repeating unit. For example, the semi-crystalline PHA may comprise 0.2 wt% to 30 wt%, 0.5 wt% to 20 wt%, 1 wt% to 15 wt%, 2 wt% to 10 wt%, or 3 wt% to 10 wt% of the 4-HB repeating unit.

[0062] The glass transition temperature (Tg) of the semi-crystalline PHA may be -30°C to 80°C, -30°C to 10°C, -25°C to 5°C, -25°C to 0°C, -20°C to 0°C, or -15°C to 0°C. The crystallization temperature (Tc) of the semi-crystalline PHA may be 30°C to 130°C, 45°C to 125°C, 50°C to 120°C, 65°C to 115°C, or 70°C to 110°C, and the melting temperature (Tm) may be 100°C to 175°C, 105°C to 170°C, 105°C to 165°C, 110°C to 160°C, or 115°C to 150°C.

[0063] According to one embodiment of the present invention, the suspension may contain 5 wt% to 95 wt% of the PHA. For example, the content of PHA may be 5 wt% to 85 wt%, 10 wt% to 75 wt%, 15 wt% to 60 wt%, 25 wt% to 55 wt%, or 30 wt% to 50 wt% based on the total weight of the suspension. By satisfying the content of PHA within the above range, sufficient biodegradability that can be decomposed in soil and the ocean can be secured, while improving coatability and processability.

[0064] Additionally, in the step of preparing a suspension containing PHA, 2.5 to 20 parts by weight of a surfactant can be added based on 100 parts by weight of the PHA.

[0065] Specifically, the surfactant may include at least one selected from the group consisting of polyvinyl alcohol, sodium dodecylbenzene sulfonate, polyvinylpyrrolidone, methyl polyethylene alkyl ether, alkylbenzene sulfonate, nonylphenol ether sulfate, sodium lauryl sulfate, lithium dodecyl sulfate, alkyl phosphate, glyceryl ester, polypropylene glycol ester, polyacrylate-based compound, fatty acid-based compound, acrylic acid-based compound, and acrylic-based ammonia salt.

[0066] For example, the amount of the surfactant may be 2.5 parts by weight to 15 parts by weight, 3 parts by weight to 12 parts by weight, 3.5 parts by weight to 10 parts by weight, or 3.5 parts by weight to 7 parts by weight based on 100 parts by weight of the PHA.

[0067] According to one embodiment of the present invention, the step of preparing a suspension including the PHA may be performed under room temperature and pressure conditions. More specifically, the step of preparing the suspension may include a step of performing high-speed dispersion treatment using a homogenizer at room temperature and pressure conditions at a speed of 55% to 85% of the maximum rotational speed per minute (rpm) of the homogenizer for 10 to 60 minutes.

[0068] As a specific example, the step of preparing the suspension may be performed by high-speed dispersion treatment using a homogenizer at room temperature and pressure conditions at a speed of 58% to 83%, 60% to 80%, 65% to 80%, or 65% to 75% of the maximum rotational speed per minute (rpm) of the homogenizer for 15 to 50 minutes, 20 to 45 minutes, or 25 to 40 minutes.

[0069]

[0070] Step to remove defects in suspension

[0071] A method for producing a PHA emulsion according to one embodiment of the present invention includes a step of removing a defect in the suspension.

[0072] According to one embodiment of the present invention, the pressures at which the step of preparing the suspension and the step of removing defects within the suspension are performed may be different. Specifically, the pressure at which the step of removing defects is performed may be higher than the pressure at which the step of preparing the suspension is performed.

[0073] A method for producing a PHA emulsion according to one embodiment of the present invention does not uniformly control the pressure of the entire steps of producing a PHA emulsion, but rather sets the pressures of the defacing step and the step of producing a suspension differently, more specifically, by setting only the pressure of the defacing step high, thereby removing defacs more effectively and improving processability and productivity.

[0074] As a specific example, the step of preparing the suspension may be performed at atmospheric pressure, and the step of removing the defecation may be performed at a pressure of 200 bar to 2,000 bar.

[0075] For example, the defecation step may be performed at a pressure of 200 bar to 1,800 bar, 200 bar to 1,500 bar, or 200 bar to 1,000 bar. In addition, the defecation step may be performed for a time period of more than 5 minutes to less than 60 minutes. For example, the defecation step may be performed for 6 minutes to 45 minutes, 7 minutes to 35 minutes, or 7 minutes to 30 minutes. As a specific example, the defecation step may be a solid-liquid dispersion step.

[0076] By performing the above-described defect removal step at a pressure that satisfies the above range, defects such as particles containing grit or grains can be effectively removed in a short period of time, while improving the dispersibility and coatability of the final PHA emulsion produced.

[0077]

[0078] Meanwhile, a method for producing a PHA emulsion according to one embodiment of the present invention may further include a step of adding one or more additives selected from the group consisting of a thickener, an antimicrobial agent, a stabilizer, and a pH regulator to the suspension from which the defects have been removed. As a specific example, the additives may be added after the solid-liquid dispersion step.

[0079] The amount of the additive may be 0.005 parts by weight to 30 parts by weight based on 100 parts by weight of the suspension from which the defect has been removed. For example, the amount of the additive may be 0.005 parts by weight to 25 parts by weight, 0.01 parts by weight to 30 parts by weight, 0.01 parts by weight to 25 parts by weight, 0.05 parts by weight to 20 parts by weight, 0.1 parts by weight to 20 parts by weight, 0.2 parts by weight to 20 parts by weight, 0.5 parts by weight to 20 parts by weight, 1 part by weight to 18 parts by weight, 3 parts by weight to 16 parts by weight, or 4 parts by weight to 15 parts by weight based on 100 parts by weight of the suspension from which the defect has been removed.

[0080] The above thickener may include at least one selected from the group consisting of gum, cellulose-based compounds, and inorganic particles. For example, the thickener may be at least one selected from the group consisting of carrageenan, alginin, alginic acid, sodium alginate, guar gum, xanthan gum, carboxylmethyl cellulose, clay, montmorillonite (MMT), silica, collagen, alginate, gelatin, furcellaran, agar, carrageenan, casein, locust bean gum, pectin, polyethylene oxide, polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone, but is not limited thereto.

[0081] The thickener may be added in an amount of 0.005 to 5 parts by weight based on 100 parts by weight of the suspension from which the defecation has been removed. For example, the content of the thickener may be 0.01 to 5 parts by weight, 0.05 to 4.5 parts by weight, 0.1 to 4 parts by weight, or 0.15 to 3 parts by weight based on 100 parts by weight of the suspension from which the defecation has been removed.

[0082] The antibacterial agent may be at least one natural antibacterial agent selected from the group consisting of organic acids, bacteriocins, and calcium preparations, or a compound containing an element such as colloid or silver. For example, the antibacterial agent may be at least one selected from the group consisting of polylysine, benzisothiazolinone, vinegar powder, chitooligosaccharide, hydrogen peroxide, ethylenediaminetetraacetic acid, potassium sorbate, sorbic acid, propionic acid, potassium propionate, sodium benzoate, 1,2-hexanediol, and 1,2-octanediol, but is not limited thereto.

[0083] The antibacterial agent may be added in an amount of 0.005 to 5 parts by weight based on 100 parts by weight of the suspension from which the defecation has been removed. For example, the content of the antibacterial agent may be 0.01 to 5 parts by weight, 0.05 to 4 parts by weight, 0.1 to 3 parts by weight, or 0.2 to 2 parts by weight based on 100 parts by weight of the suspension from which the defecation has been removed.

[0084] The above stabilizer is an additive that protects against oxidation and heat and prevents color change. Any commonly used stabilizer can be used as long as it does not impede the effectiveness of the present invention.

[0085] The stabilizer may be added in an amount of 0.005 to 10 parts by weight based on 100 parts by weight of the suspension from which the defecation has been removed. For example, the content of the stabilizer may be 0.01 to 10 parts by weight, 0.02 to 10 parts by weight, 0.05 to 9 parts by weight, or 0.1 to 8 parts by weight based on 100 parts by weight of the suspension from which the defecation has been removed.

[0086] The above pH adjusting agent refers to a substance that is added to a solution to adjust the pH, and may include both a pH reducing agent that reduces the pH and a pH increasing agent that increases the pH. Specifically, the pH reducing agent may be a strongly acidic substance such as sulfuric acid, hydrochloric acid, etc., or an ammonium salt aqueous solution, and the pH increasing agent may be a basic substance such as ammonia water, sodium hydroxide, lithium hydroxide, potassium hydroxide, etc., or an acetate salt aqueous solution.

[0087] For example, the pH adjusting agent may be at least one selected from the group consisting of acetic acid, lactic acid, hydrochloric acid, phosphoric acid, sodium hydroxide, citric acid, malic acid, fumaric acid, potassium phosphate, sodium bicarbonate, and sodium phosphate, but is not limited thereto.

[0088] The pH regulator may be added in an amount of 0.005 to 10 parts by weight based on 100 parts by weight of the suspension from which the defecation has been removed. For example, the content of the pH regulator may be 0.01 to 10 parts by weight, 0.02 to 10 parts by weight, 0.05 to 9 parts by weight, or 0.1 to 8 parts by weight based on 100 parts by weight of the suspension from which the defecation has been removed.

[0089]

[0090] PHA emulsion

[0091] The present invention provides a polyhydroxyalkanoate (PHA) emulsion manufactured by the method for manufacturing the above polyhydroxyalkanoate (PHA) emulsion.

[0092] The above PHA emulsion may have an average particle size of 1.5 μm to 4.5 μm. For example, the average particle size of the PHA emulsion may be 4 μm or less, 3.5 μm or less, or 3.1 μm or less. Specifically, the average particle size of the PHA emulsion may be 1.6 μm to 4 μm, 1.8 μm to 3.5 μm, 2 μm to 3.2 μm, or 2.3 μm to 3.1 μm.

[0093] The particle size deviation of the above PHA emulsion may be ±5 ㎛ or less. For example, the average particle size of the above PHA emulsion may be ±3.5 ㎛ or less, ±3 ㎛ or less, or ±2 ㎛ or less.

[0094] The polydispersity index (PDI) of the above PHA emulsion may be 3 or less. For example, the polydispersity index of the above PHA emulsion may be 2.5 or less or 2 or less.

[0095] The viscosity of the PHA emulsion may be from 100 cps to 3,000 cps. For example, the viscosity of the PHA emulsion may be from 150 cps to 3,000 cps, from 200 cps to 2,500 cps, from 300 cps to 2,000 cps, or from 450 cps to 1,800 cps.

[0096] The pH of the PHA emulsion may be 6.5 to 11. For example, the pH of the PHA emulsion may be 7 to 10.5 or 7.5 to 10.

[0097] Additionally, the solids content of the PHA emulsion may be from 5 wt% to 70 wt%. For example, the solids content of the PHA emulsion may be from 5 wt% to 65 wt%, from 5 wt% to 60 wt%, from 10 wt% to 60 wt%, from 10 wt% to 50 wt%, from 15 wt% to 50 wt%, from 20 wt% to 50 wt%, or from 25 wt% to 45 wt%.

[0098] The above contents are explained in more detail with the following examples. However, the following examples are only intended to illustrate the present invention, and the scope of the examples is not limited to these examples.

[0099]

[0100] [Example]

[0101] Preparation of PHA emulsion

[0102] Example 1

[0103] (1) Step of preparing a suspension containing PHA

[0104] 40 parts by weight of polyhydroxyalkanoate (PHA) powder (4-hydroxybutyrate (4-HB) content: 8.5 wt%, weight average molecular weight (Mw): 350,000 g / mol, manufacturer: CJ CheilJedang), 20 parts by weight of 10% concentration polyvinyl alcohol (PVA, manufacturer: Kuraray), and 40 parts by weight of distilled water (DI water) were placed in a 1 L glass beaker, and a suspension was prepared by high-speed dispersion treatment at 60% to 80% of the maximum rotational speed per minute (rpm) for 30 minutes using a homogenizer (maximum rotational speed per minute: 12,000 rpm) under room temperature and pressure conditions.

[0105] (2) Step for removing defects in suspension

[0106] The above suspension was put into a high pressure homogenizer (product name: Atomo 3.0, manufacturer: Bertori) and ground once at a pressure of 500 bar for 10 minutes.

[0107] (3) Step for preparing PHA emulsion

[0108] Under atmospheric pressure conditions, 0.5 parts by weight of carrageenan (manufacturer: Dain Materials) as a thickener and 0.1 parts by weight of K10N (manufacturer: Wonjin Chemical) as an antibacterial agent were added to 100 parts by weight of the suspension from which the defecation was removed, and stirred to prepare a PHA emulsion.

[0109]

[0110] Example 2

[0111] (1) Step of preparing a suspension containing PHA

[0112] It was prepared in the same manner as the step of preparing the suspension of Example 1.

[0113] (2) Step for removing defects in suspension

[0114] The above suspension was put into a high pressure homogenizer (product name: Atomo 3.0, manufacturer: Bertori) and ground once at a pressure of 1,500 bar for 20 minutes.

[0115] (3) Step for preparing PHA emulsion

[0116] It was prepared in the same manner as the steps for preparing the PHA emulsion of Example 1.

[0117]

[0118] Example 3

[0119] (1) Step of preparing a suspension containing PHA

[0120] It was prepared in the same manner as the step of preparing the suspension of Example 1.

[0121] (2) Step for removing defects in suspension

[0122] The above suspension was put into a high pressure homogenizer (product name: Atomo 3.0, manufacturer: Bertori) and ground once for 7 minutes at a pressure of 200 bar.

[0123] (3) Step for preparing PHA emulsion

[0124] It was prepared in the same manner as the steps for preparing the PHA emulsion of Example 1.

[0125]

[0126] Example 4

[0127] (1) Step of preparing a suspension containing PHA

[0128] It was prepared in the same manner as the step of preparing the suspension of Example 1.

[0129] (2) Step for removing defects in suspension

[0130] The above suspension was put into a high pressure homogenizer (product name: Atomo 3.0, manufacturer: Bertori) and ground once at a pressure of 2,000 bar for 30 minutes.

[0131] (3) Step for preparing PHA emulsion

[0132] It was prepared in the same manner as the steps for preparing the PHA emulsion of Example 1.

[0133]

[0134] Comparative Example 1

[0135] (1) Step of preparing a suspension containing PHA

[0136] It was prepared in the same manner as the step of preparing the suspension of Example 1.

[0137] (2) Step for removing defects in suspension

[0138] The suspension was filtered once over 40 minutes using a filter net having a pore size of 110 μm under room temperature and pressure conditions.

[0139] (3) Step for preparing PHA emulsion

[0140] It was prepared in the same manner as the steps for preparing the PHA emulsion of Example 1.

[0141]

[0142] Comparative Example 2

[0143] (1) Step of preparing a suspension containing PHA

[0144] It was prepared in the same manner as the step of preparing the suspension of Example 1.

[0145] (2) Step for removing defects in suspension

[0146] Under room temperature and pressure conditions, the suspension was subjected to high-speed dispersion treatment using a homogenizer (maximum rotation speed per minute: 12,000 rpm) at a speed of 60% to 80% of the maximum rotation speed per minute (rpm) for 30 minutes.

[0147] (3) Step for preparing PHA emulsion

[0148] It was prepared in the same manner as the steps for preparing the PHA emulsion of Example 1.

[0149]

[0150] Comparative Example 3

[0151] (1) Step of preparing a suspension containing PHA

[0152] It was prepared in the same manner as the step of preparing the suspension of Example 1.

[0153] (2) Step for removing defects in suspension

[0154] Under room temperature and pressure conditions, the suspension was subjected to high-speed dispersion treatment using a homogenizer (maximum rotation speed per minute: 12,000 rpm) at a speed of 60% to 80% of the maximum rotation speed per minute (rpm) for 60 minutes.

[0155] (3) Step for preparing PHA emulsion

[0156] It was prepared in the same manner as the steps for preparing the PHA emulsion of Example 1.

[0157]

[0158] Comparative Example 4

[0159] (1) Step of preparing a suspension containing PHA

[0160] It was prepared in the same manner as the step of preparing the suspension of Example 1.

[0161] (2) Step for removing defects in suspension

[0162] The above suspension was put into a high pressure homogenizer (product name: Atomo 3.0, manufacturer: Bertori) and ground once for 5 minutes at a pressure of 100 bar.

[0163] (3) Step for preparing PHA emulsion

[0164] It was prepared in the same manner as the steps for preparing the PHA emulsion of Example 1.

[0165]

[0166] Comparative Example 5

[0167] (1) Step of preparing a suspension containing PHA

[0168] It was prepared in the same manner as the step of preparing the suspension of Example 1.

[0169] (2) Step for removing defects in suspension

[0170] The above suspension was put into a high pressure homogenizer (product name: Atomo 3.0, manufacturer: Bertori) and an attempt was made to grind it at a pressure of 2,500 bar, but the agglomerated and surface-crystallized particles exploded or erupted due to the pressurization, making solid-liquid dispersion treatment impossible.

[0171] (3) Step for preparing PHA emulsion

[0172] It was prepared in the same manner as the steps for preparing the PHA emulsion of Example 1.

[0173]

[0174] Experimental Example 1: Average particle size

[0175] For the PHA emulsions of Examples 1 to 4 and Comparative Examples 1 to 5, the average particle size was measured using a particle size analyzer (particle size analysis, product name: LS I3 220, manufacturer: BECKMAN COULTER).

[0176]

[0177] Experimental Example 2: Grit Removal Evaluation

[0178] The degree of grit removal was evaluated for the PHA emulsions of Examples 1 to 4 and Comparative Examples 1 to 5. Specifically, after coating one side of a paper substrate measuring 210 mm in width and 297 mm in length with the PHA emulsion, the number of grits (average particle size of 6 ㎛ or more) visually observed over the entire area was counted to evaluate the degree of grit removal.

[0179] ◎: Less than 3

[0180] ○: 3 to 5

[0181] △: More than 5 to 20

[0182] ×: More than 20

[0183]

[0184] Experimental Example 3: Loss percentage (%)

[0185] For the manufacturing process of the PHA emulsion of Examples 1 to 4 and Comparative Examples 1 to 5, the yield was evaluated by calculating the loss rate (%) according to the following formula A.

[0186] [Formula A]

[0187] Loss rate (%) = ((Wa - Wc) / Wa) × 100

[0188] In equation A,

[0189] Wa is the volume (ml) of the suspension containing PHA (solids content 40 wt%) before the step of removing the defecation,

[0190] Wc is the volume (ml) of the suspension from which the defecation has been removed.

[0191]

[0192] ClassificationAverage particle size(㎛)Grit removal evaluationLoss rate(%)Example 12.9◎7.1Example 22.5◎7.4Example 33.0◎6.4Example 42.3◎7.6Comparative example 13.3○7.4Comparative example 23.2×6.1Comparative example 33.2×6.5Comparative example 43.2△6.4Comparative example 5---

[0193] As shown in Table 1 above, the PHA emulsions of Examples 1 to 5 were able to secure a low average particle size even with a short process time, and had an excellent grit removal effect.

[0194] Specifically, Examples 1 to 5 performed a grit removal step at a pressure of 200 bar to 2,000 bar, and thus were superior in terms of average particle size and grit removal even with a short process time compared to Comparative Example 1 performed with a conventional filtration step or Comparative Examples 2 and 3 performed with a conventional dispersion treatment. In addition, Comparative Example 4, which did not satisfy the process conditions according to the present invention, was worse than Examples 1 to 5 in terms of average particle size and grit removal, and Comparative Example 5 made solid-liquid dispersion treatment impossible because the aggregated and surface-crystallized particles exploded or erupted due to pressurization.

Claims

1. A step of preparing a suspension containing polyhydroxyalkanoate (PHA); and A step of removing a defect in the above suspension; A method for producing a polyhydroxyalkanoate emulsion, wherein the above-mentioned defecation step is performed at a pressure of 200 bar to 2,000 bar.

2. In paragraph 1, A method for producing a polyhydroxyalkanoate emulsion, wherein the pressures at which the step of producing the suspension and the step of removing a defect in the suspension are performed are different from each other.

3. In paragraph 1, A method for producing a polyhydroxyalkanoate emulsion, wherein the above-mentioned defecation step is performed for a time of more than 5 minutes and less than 60 minutes.

4. In paragraph 1, The above defect comprises particles including grit or grain, A method for producing a polyhydroxyalkanoate emulsion, wherein the particles have an average particle diameter of 6 ㎛ or more and an average particle size distribution of 10 ㎛ or less.

5. In paragraph 1, A method for producing a polyhydroxyalkanoate emulsion, wherein 2.5 to 20 parts by weight of a surfactant is added based on 100 parts by weight of the PHA in the step of producing the suspension.

6. In paragraph 5, A method for producing a polyhydroxyalkanoate emulsion, wherein the surfactant comprises at least one selected from the group consisting of polyvinyl alcohol, sodium dodecylbenzene sulfonate, polyvinylpyrrolidone, methyl polyethylene alkyl ether, alkylbenzene sulfonate, nonylphenol ether sulfate, sodium lauryl sulfate, lithium dodecyl sulfate, alkyl phosphate, glyceryl ester, and polypropylene glycol ester.

7. In paragraph 1, A method for producing a polyhydroxyalkanoate emulsion, wherein the step of producing the suspension comprises a step of performing high-speed dispersion treatment using a homogenizer at a speed of 55% to 85% of the maximum rotational speed per minute (rpm) of the homogenizer for 10 to 60 minutes under room temperature and pressure conditions.

8. In paragraph 1, A method for producing a polyhydroxyalkanoate emulsion, further comprising a step of adding at least one additive selected from the group consisting of a thickener, an antibacterial agent, a stabilizer, and a pH regulator to the suspension from which the defect has been removed.

9. In paragraph 8, A method for producing a polyhydroxyalkanoate emulsion, wherein the amount of the additive is 0.005 to 30 parts by weight based on 100 parts by weight of the suspension from which the defect has been removed.

10. In paragraph 1, A method for producing a polyhydroxyalkanoate emulsion, wherein the PHA is a polyhydroxyalkanoate copolymer comprising a 4-hydroxybutyrate (4-HB) repeating unit and a 3-hydroxybutyrate (3-HB) repeating unit, and the polyhydroxyalkanoate emulsion comprises 0.1 to 60 wt% of the 4-hydroxybutyrate (4-HB) repeating unit.

11. In paragraph 1, A method for producing a polyhydroxyalkanoate emulsion, wherein the above PHA has a weight average molecular weight of 30,000 g / mol to 1,200,000 g / mol.

12. In paragraph 1, The above PHA comprises a semi-crystalline PHA, A method for producing a polyhydroxyalkanoate emulsion, wherein the semi-crystalline PHA contains 0.1 to 30 wt% of a 4-hydroxybutyrate (4-HB) repeating unit, has a glass transition temperature (Tg) of -30°C to 80°C, a crystallization temperature (Tc) of 30°C to 130°C, and a melting temperature (Tm) of 100°C to 175°C.

13. A polyhydroxyalkanoate emulsion manufactured by the method for manufacturing a polyhydroxyalkanoate emulsion of claim 1.

14. In paragraph 13, The above polyhydroxyalkanoate emulsion is a polyhydroxyalkanoate emulsion having an average particle size of 1.5 ㎛ to 4.5 ㎛, a particle size deviation of ±5 ㎛ or less, a polydispersity index (PDI) of 3 or less, a viscosity of 100 cps to 3,000 cps, and a pH of 6.5 to 11.

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