Pha composition and method of making the same

Abstract

The present invention relates to a polyhydroxyalkanoate (PHA) composition having improved stability and water resistance and a method for preparing the same. According to the present invention, water-dispersed polyhydroxyalkanoate (PHA) particles can be prevented from aggregation and induced to be re-dispersed, thereby preventing precipitation and improving the dispersion stability and water resistance of PHA. In addition, the composition of the present invention minimizes the use of additives, thereby enabling the recovery of biodegradable PHA, and has excellent compatibility with conventional commercial products and excellent room temperature stability. Furthermore, since the excessive use of a surfactant and an additional step of forming an emulsion are not required in the preparation of PHA, economic feasibility can be improved.

Description

Technical Field

[0001] The present invention relates to a polyhydroxyalkanoate (PHA) composition with improved stability and water resistance and a method for preparing the same.

[0002] This application claims priority to Korean Provisional Patent Application No. 10-2020-0143256, filed on October 30, 2020, which is hereby incorporated by reference in its entirety into this application. Background Art

[0003] Polyhydroxyalkanoate (PHA) is a biodegradable plastic that can be used to make, but is not limited to, films (e.g., packaging films, agricultural films, mulch films), golf tees, hats and lids, agricultural stands and stakes, paper and paperboard coatings (e.g., cups, plates, boxes, etc.), thermoformed products (e.g., trays, containers, yogurt pots, plant pots, noodle bowls, molds, etc.), casings (e.g., for electronic items), bags (e.g., garbage bags, grocery bags, food bags, compost bags, etc.), sanitary products (e.g., diapers, feminine hygiene products, incontinence products, disposable wipes, etc.), and granular products (e.g., granular fertilizers, herbicides, pesticides, seeds, etc.).

[0004] PHA is also used to develop biomedical devices, including sutures, repair devices, repair patches, lanyards, cardiovascular patches, orthopedic staples, adhesion barriers, scaffolds, guided tissue repair / regeneration devices, articular cartilage repair devices, nerve guides, tendon repair devices, bone marrow scaffolds, and wound dressings.

[0005] Polyhydroxyalkanoates (PHAs) can be produced through a fermentation process. Physically dispersed PHA in water aggregates and precipitates due to self-cohesion, and the precipitated particles form agglomerates with strong attractive forces.

[0006] Korean Patent Registration No. 10-0602193 discloses an emulsion polymerization process in which a surfactant is added to disperse a polyester (including PHA) resin after reacting at a temperature of 230° C. or higher for a total of 10 hours or more.

[0007] Typically, to maintain dispersion stability in water, polymerization is performed in an emulsion using a surfactant. This process coats or micellizes each monomer particle. In this case, the polymerization process can take 10 hours or longer, often with a large amount of additives and nitrogen purge. The disadvantage of micellization surfactants is that they require high temperatures of 80°C or higher, making the manufacturing process complex.

[0008] Therefore, in order to meet the purpose of PHA use, it is necessary to study the efficient and economical use of PHA by simplifying the process and improving the physical properties. Summary of the Invention

[0009] Technical issues

[0010] An object of the present invention is to provide a polyhydroxyalkanoate (PHA) composition having improved dispersion stability and water resistance.

[0011] In addition, a method for preparing the PHA composition is provided.

[0012] Solution to the problem

[0013] In order to solve the above problems, the present invention provides a polyhydroxyalkanoate (PHA) composition, which comprises, based on the total weight of the composition:

[0014] 10 to 70 wt% polyhydroxyalkanoate (PHA); and

[0015] 1 to 10% by weight of additives,

[0016] wherein the PHA comprises poly-3-hydroxybutyrate-co-4-hydroxybutyrate (P3HB-4HB),

[0017] The content of 4HB in the PHA copolymer is 0.1 to 20%,

[0018] The additives include rheology modifiers and surfactants or dispersants, and

[0019] The content of the surfactant or dispersant is less than 0.3 wt % based on the total weight of the composition.

[0020] According to one embodiment, the molecular weight Mw of the PHA may be 10,000 to 1,000,000. In addition, the particle size of the PHA may be 10 μm or less.

[0021] According to one embodiment, the surfactant may include one or more of the group consisting of cationic, anionic, nonionic and amphoteric surfactants.

[0022] According to one embodiment, the additive may further include one or more selected from the group consisting of a thickener and a defoaming agent.

[0023] According to one embodiment, the rheology modifier may include one or more selected from gums, acrylates, polyurethanes, and epoxy resins.

[0024] Additionally, the gum may be non-spherical and may include acidic polysaccharides such as gellan gum, xanthan gum, carrageenan, curdlan gum, karayagum, tragacanth gum, ghatti gum, algin, agargum, furcellaran, and the like.

[0025] According to one embodiment, the dispersant may include one or more dispersants selected from acrylic-based dispersants, polyurethane-based dispersants, epoxy-based dispersants, polyvinyl alcohol, and cellulose-based dispersants.

[0026] According to one embodiment, the content of the rheology modifier is 0.5 wt% or less based on the total weight of the composition.

[0027] Furthermore, the molecular weight Mw of the polyvinyl alcohol may be 10,000 to 200,000, and the degree of hydrolysis may be 80 to 99 mol%.

[0028] According to one embodiment, the coating amount of the composition may be 10 g / m 2 or more up to 30g / m 2 .

[0029] According to one embodiment, the cobb value (water absorption value) of the composition may be 3 g / m 2 or more up to 20g / m 2 .

[0030] According to another embodiment of the present invention, a method for preparing a PHA composition is provided, comprising preparing a PHA aqueous dispersion; and adding an additive to the dispersion under stirring.

[0031] Details of other embodiments of the invention are included in the detailed description below.

[0032] Effects of the Invention

[0033] According to the present invention, precipitation can be prevented by preventing aggregation of polyhydroxyalkanoate (PHA) particles dispersed in a water-based system and inducing redispersion, thereby improving the dispersion stability and water resistance of the PHA.

[0034] Furthermore, the composition of the present invention minimizes the use of additives, thereby enabling the recovery of biodegradable PHA, has excellent compatibility with existing commercially available products, and has excellent stability at room temperature.

[0035] In addition, since the excessive use of surfactants and the additional step of forming an emulsion are not required in the preparation of PHA, economic benefits can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Photographs showing the dispersion stability of the examples are shown.

[0037] Figure 2 A photograph showing the dispersion stability of the comparative example is shown. DETAILED DESCRIPTION

[0038] Best Mode for Implementing the Invention

[0039] The present invention is susceptible to various modifications, and various embodiments and specific implementations will be shown in the drawings and described in detail. However, this does not limit the present invention to the specific implementations, and it should be understood that all modifications, equivalents, and alternatives are included within the spirit and scope of the present invention. When describing the present invention, if it is determined that a detailed description of a related known art may obscure the main points of the present invention, its detailed description will be omitted.

[0040] Unless otherwise specified, the expression "to" used herein in connection with numbers is used as an expression including the corresponding numerical value. Specifically, for example, the expression "1 to 2" means including all numbers between 1 and 2 as well as 1 and 2.

[0041] Unless the context otherwise dictates, a singular expression includes a plural expression.

[0042] As used herein, the term "PHA copolymer" refers to a polymer composed of at least two different hydroxyalkanoic acid monomers.

[0043] Hereinafter, a polyhydroxyalkanoate (PHA) composition and a preparation method thereof according to one embodiment of the present invention will be described in more detail.

[0044] In particular, the present invention provides a polyhydroxyalkanoate (PHA) composition comprising, based on the total weight of the composition:

[0045] 10 to 70 wt% polyhydroxyalkanoate (PHA); and

[0046] 1 to 10% by weight of additives,

[0047] Among them, PHA includes poly-3-hydroxybutyrate-co-4-hydroxybutyrate (P3HB-4HB),

[0048] The content of 4HB in the PHA copolymer is 0.1 to 20%,

[0049] The additives include rheology modifiers and surfactants or dispersants, and

[0050] The content of the surfactant or dispersant is less than 0.3 wt % based on the total weight of the composition.

[0051] According to one embodiment, the composition of the present invention may contain 10 to 70% by weight of a PHA polymer, for example, 20% by weight or more, or 30% by weight or more, and, for example, 60% by weight or less, or 50% by weight or less. The content of the PHA polymer in the composition affects the physical properties of the composition. If the PHA content is too low, the coating film may be unevenly formed, which may reduce physical properties such as water resistance. If the PHA content is too high, the surface coating properties may be impaired for thin film coatings with relatively low thickness.

[0052] Furthermore, the molecular weight of the PHA polymer in the composition affects the physical properties of the composition. The weight-average molecular weight (Mw) of the PHA may be from 10,000 to 1,000,000, for example, 100,000 or higher, 200,000 or higher, or 300,000 or higher, and for example, 700,000 or lower, or 600,000 or lower. If the molecular weight of the PHA is too low, flexibility may be reduced during film formation. If the molecular weight is too high, processability may be deteriorated due to high-temperature drying, and the film-forming rate may be reduced.

[0053] According to one embodiment, the 4HB (4-hydroxybutyrate) content in the PHA copolymer affects the physical properties of the PHA. The 4HB content in the PHA copolymer of the present invention may be 0.1 to 20%, for example, 0.1% or more, 1% or more, 2% or more, or 3% or more, and for example, 20% or less, 15% or less, or 10% or less. If the 4HB content in the PHA copolymer is too low, the crystallinity and hardness increase, resulting in cracks after film formation, or shrinkage after coating, making it difficult to adhere to the substrate. If the 4HB content is too high, the physical properties may become that of an amorphous polymer, resulting in a loss of water resistance.

[0054] According to one embodiment, the particle size, ie, the particle diameter of the PHA, may be 10 μm or less, such as 5 μm or less, such as 2 μm or less. Since the PHA of the present invention has a small particle size, it can be applied uniformly and is therefore suitable for use as a coating agent.

[0055] According to one embodiment, the composition of the present invention may contain 1 to 10 wt% of additives, for example, 1 wt% or more, or 2 wt% or more, or 3 wt% or more, and for example 10 wt% or less, or 8 wt% or less, or 7 wt% or less.

[0056] The additive may include, for example, at least one selected from a rheology modifier, a dispersant, a thickener, a defoamer, and a surfactant, for example, the additive includes a rheology modifier, a dispersant, and a thickener. In addition, specifically, the additive may include a rheology modifier and a surfactant or a dispersant.

[0057] Rheology modifier can comprise one or more in the rheology modifier selected from gum, acrylate, polyurethane and epoxy resin.According to one embodiment, the gum rheology modifier used in the present invention can be non-spherical.Non-spherical gum rheology modifier can comprise acidic polysaccharide, particularly gellan gum, xanthan gum, carrageenan, curdlan gum, karaya gum, tragacanth gum, ghatti gum, alginate, agar gum, furcellaran etc.The content of rheology modifier accounts for 0.5 % by weight or lower of total composition, for example 0.3 % by weight or lower, 0.1 % by weight or lower, 0.05 % by weight or lower, and 0.001 % by weight or higher or 0.01 % by weight or higher.

[0058] Aqueous dispersants can be used as dispersants, and for example, they include one or more selected from acrylic acid-based dispersants, urethane-based dispersants, epoxy-based dispersants, pigment dispersants, polyvinyl alcohol and cellulose. Specifically, for example, they can include polyvinyl alcohol (PVA). When composition of the present invention included PVA, the weight-average molecular weight Mw of PVA can be 10,000 to 200,000, for example, Mw is 10,000 to 100,000, for example, Mw is 10,000 to 50,000, and any trade mark can be used.

[0059] In addition, the degree of hydrolysis (DH) of the PVA is 80 to 99 mol%, for example, 80 mol% or more, or 85 mol% or more, and 99 mol% or less, or 98 mol% or less, or 94 mol% or less, or 90 mol% or less.

[0060] The defoaming agent may include alcohol, silicone oil and a water-soluble surfactant, and may include octanol, cyclohexanol, ethylene glycol, sorbitan fatty acid ester and the like.

[0061] The surfactant may include one or more surfactants selected from cationic, anionic, nonionic and amphoteric surfactants.

[0062] The cationic surfactant may include, for example, quaternary ammonium salts, alkylpyridinium salts, alkylimidazolinium salts, aliphatic amine salts, etc. Specifically, it may include dialkyldimethylammonium salts, alkylbenzylmethylammonium salts, benzalkonium chloride, etc.

[0063] The anionic surfactant may include, for example, fatty acid sodium salts, monoalkyl sulfates, alkylbenzene sulfonates, monoalkyl phosphates, sodium dodecyl sulfate (SDS), and the like.

[0064] Nonionic surfactants may include polyoxyethylene alkyl ethers, fatty acid sorbitan esters, fatty acid diethanolamines, alkyl monoglycerol ethers, and the like, such as Tween 20, Triton X, Pluronic, and the like.

[0065] The amphoteric surfactant may include an imidazoline-based surfactant, a betaine-based surfactant, and the like, specifically, cocamidopropyl betaine, lauryl hydroxysulfobetaine, alkyl sulfobetaine, alkyl carboxybetaine, and the like.

[0066] In the present invention, the emulsion formation process is not necessarily required, and the surfactant may not be an essential component. Therefore, when the surfactant is included in the composition of the present invention, the amount of the surfactant can account for the total composition weight, specifically below 0.3 % by weight of the total composition solids content weight, for example 0.25 % by weight or lower, or 0.2 % by weight or lower, and for example 0.0001 % by weight or higher, or 0.001 % by weight or higher, or 0.01 % by weight or higher. In addition, a dispersant can be used instead of the surfactant.

[0067] When the amount of surfactant used is 0.3 wt% or more, the hydrophobic region of the surfactant increases, making it difficult to achieve uniform dispersion in the aqueous dispersion and to form an interface during coating. In addition, when the particles settle after dispersion, it is difficult to redisperse them, and the PHA particles may aggregate with each other to form clumps.

[0068] According to the present invention, the use of additives (such as surfactants) is greatly reduced, so that the PHA manufacturing process can be carried out economically and efficiently.

[0069] The additives of the present invention are not limited to the above-mentioned additives and are not particularly limited as long as they are commonly used in the art.

[0070] According to another aspect of the present invention, there is provided a method for preparing a PHA composition, comprising:

[0071] preparing an aqueous PHA dispersion; and

[0072] Add additives to the dispersion under stirring,

[0073] The content of 4HB in the PHA copolymer is 0.1 to 20%,

[0074] The additives include rheology modifiers and surfactants or dispersants,

[0075] The content of surfactant or dispersant is less than 0.3% by weight of the total weight of the composition, and

[0076] A method for preparing a PHA composition, wherein the content of PHA in the final composition is 10 to 70 wt%.

[0077] According to one embodiment, preparing the PHA aqueous dispersion may include distilling the PHA aqueous dispersion having a solid content of, for example, 1 to 10%, such as 3 to 8%. Alternatively, it may include dispersing the powder of the PHA dispersion through a dispersing device.

[0078] According to one embodiment, the addition of the additive to the dispersion under stirring can be carried out at room temperature. The present invention is economical because low or high temperature operations alone are not necessarily required to improve dispersibility. Room temperature stirring can be carried out at a temperature of 20 to 30°C, for example, 23 to 26°C.

[0079] Adding additives can include adding 0.1 to 5 wt % of a surfactant or dispersant, for example, 0.1 wt % or more, 0.5 wt % or more, 1 wt % or more, 2 wt % or more, and for example 5 wt % or less, or 4 wt % or less, or 3 wt % or less.

[0080] Furthermore, the method may comprise adding a surfactant or dispersant such that the content of surfactant or dispersant in the composition of the invention is 0.3 wt% or less, such as 0.25 wt% or less, such as 0.2 wt% or less.

[0081] Furthermore, the method can include adding a rheology modifier such that the content of the rheology modifier in the composition of the present invention is from 0.1 to 5 wt %, e.g., 0.1 wt % or more, 0.5 wt % or more, 1 wt % or more, 2 wt % or more, and for example, 5 wt % or less, or 4 wt % or less, or 3 wt % or less.

[0082] According to one embodiment, the coating amount of the composition of the present invention can be 10 g / m 2 or higher up to 30g / m 2 , for example 11g / m 2 or higher, or 12g / m 2 or higher, or 13g / m 2 or higher, and 25g / m 2 or lower, or 20g / m 2 or lower.

[0083] In addition, the composition of the present invention may have a viscosity of 3 g / m 2 or up to 20g / m 2 , for example 4g / m 2 or higher, or 5g / m 2 or higher, and 15g / m 2 or lower, 10g / m2 Within the above range, it can have water resistance characteristics suitable for coating.

[0084] According to one embodiment, the composition of the present invention can be made into a coating agent. Specifically, for example, it can be made into a latex composition. The latex composition can be used as a coating agent for paper materials (e.g., paper cups, books, printed materials, shopping bags), or as a coating agent for ester-based films (e.g., PET) or polymer film materials (e.g., EVOH). For example, it can also be made into food packaging materials such as oil-proof paper, pizza boxes, and bread bags.

[0085] In addition, the physical properties of PHAs can be optimized to improve their dispersibility and water resistance, making them suitable for coating applications.

[0086] According to the present invention, the use of additives is minimized and no additional process for forming an emulsion is required. In particular, the PHA composition can be prepared economically and efficiently by minimizing the content of surfactants.

[0087] The embodiments of the present invention will be described in detail below so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in several different forms and is not limited to the embodiments described herein.

[0088] Example 1

[0089] A PHA aqueous dispersion having a solid content of 5% (manufactured by CJ CheilJedang, Mw 600,000, PDI 1.9, particle size <2 μm, 4HB 10%) was vacuum distilled to a solid content of 41%.

[0090] In a stirring apparatus equipped with a paddle or turbine impeller, while stirring 98 parts of the prepared 41% PHA aqueous dispersion at 1500 rpm at room temperature, 1 part of 10% dissolved polyvinyl alcohol (PVA, Kuraray, Mw 14200, degree of hydrolysis (DH) 88 mol%) was added, followed by stirring for 1 hour.

[0091] Then, 1 part of a 5% xanthan gum dispersion (manufactured by Dynesoze) was added and stirred for another 10 minutes to prepare a 40% PHA aqueous coating solution.

[0092] Thus, a composition comprising 10% PVA at 0.24 wt% and 5% xanthan gum at 0.12 wt% of the PHA solids content was prepared.

[0093] Example 2

[0094] 39 parts of completely dried PHA powder (manufactured by CJ CheilJedang, Mw 600000, PDI 1.9, 4HB 10 wt%) having a particle size of 2 μm or less and 56 parts of deionized water were added and dispersed in a high-pressure disperser for 2 hours to prepare a PHA aqueous dispersion having a solid content of 41%.

[0095] In a stirring apparatus equipped with a paddle or turbine impeller, while stirring 98 parts of the prepared 41% PHA aqueous dispersion at 1500 rpm at room temperature, 1 part of 10% dissolved polyvinyl alcohol (PVA, Kuraray, Mw 14200, degree of hydrolysis (DH) 88 mol%) was added, followed by stirring for 1 hour.

[0096] Then, 1 part of a 5% xanthan gum dispersion (manufactured by Dynesoze) was added and stirred for another 10 minutes to prepare a 40% PHA aqueous coating solution.

[0097] Thus, a composition comprising 10% PVA at 0.24 wt% and 5% xanthan gum at 0.12 wt% of the PHA solids content was prepared.

[0098] Example 3

[0099] A PHA aqueous dispersion having a solid content of 5% (manufactured by CJ CheilJedang, Mw 600,000, PDI 1.9, particle size <2 μm, 4HB 10%) was vacuum distilled to a solid content of 41%.

[0100] While stirring 99 parts of the prepared 41% PHA aqueous dispersion at 1500 rpm in a stirring device equipped with a paddle or turbine impeller at room temperature, 0.1 parts of SDS (sodium dodecyl sulfate, Sigma-Aldrich) was added, followed by stirring for 1 hour.

[0101] Then, 1 part of a 5% xanthan gum dispersion (manufactured by Dynesoze) was added and stirred for another 10 minutes to prepare a 40% PHA aqueous coating solution.

[0102] Thus, a composition comprising 0.24 wt% of SDS and 0.12 wt% of 5% xanthan gum based on the solid content of PHA was prepared.

[0103] Example 4

[0104] A PHA aqueous dispersion having a solid content of 5% (manufactured by CJ CheilJedang, Mw 600,000, PDI 1.9, particle size <2 μm, 4HB 10%) was vacuum distilled to a solid content of 41%.

[0105] In a stirring apparatus equipped with a paddle or turbine impeller, while stirring 98 parts of the prepared 41% PHA aqueous dispersion at 1500 rpm at room temperature, 1 part of 10% dissolved polyvinyl alcohol (PVA, Kuraray, Mw 14200, degree of hydrolysis (DH) 88 mol%) was added, followed by stirring for 1 hour.

[0106] Then, 1 part of a 5% gellan gum dispersion (manufactured by Dynesoze) was added and stirred for another 10 minutes to prepare a 40% PHA aqueous coating solution.

[0107] Thus, a composition comprising 10% PVA at 0.24 wt% and 5% gellan gum at 0.12 wt% based on the PHA solid content was prepared.

[0108] Example 5

[0109] A PHA aqueous dispersion having a solid content of 5% (manufactured by CJ CheilJedang, Mw 600,000, PDI 1.9, particle size <2 μm, 4HB 10%) was vacuum distilled to a solid content of 41%.

[0110] In a stirring apparatus equipped with a paddle or turbine impeller, while stirring 98 parts of the prepared 41% PHA aqueous dispersion at 1500 rpm at room temperature, 1 part of 10% dissolved polyvinyl alcohol (PVA, Kuraray, Mw 14200, degree of hydrolysis (DH) 88 mol%) was added, followed by stirring for 1 hour.

[0111] Then, 1 part of a 5% carrageenan dispersion (manufactured by ES Food Co.) was added and stirred for another 10 minutes to prepare a 40% PHA aqueous coating solution.

[0112] Thus, a composition comprising 10% PVA at 0.24 wt% and 5% carrageenan at 0.12 wt% of the PHA solids content was prepared.

[0113] Comparative Example 1

[0114] A PHA aqueous dispersion with a solid content of 5% (manufactured by CJ CheilJedang, Mw 600,000, PDI 1.9, particle size <2 μm, 4HB 10%) was vacuum distilled to a solid content of 40%.

[0115] Comparative Example 2

[0116] A PHA aqueous dispersion having a solid content of 5% (manufactured by CJ CheilJedang, Mw 600,000, PDI 1.9, particle size <2 μm, 4HB 10%) was vacuum distilled to a solid content of 41%.

[0117] In a stirring apparatus equipped with a paddle or turbine impeller, while stirring 99 parts of the prepared 41% PHA aqueous dispersion at 1500 rpm at room temperature, 1 part of 10% dissolved polyvinyl alcohol (PVA, Kuraray, Mw 14200, degree of hydrolysis (DH) 88 mol%) was added, followed by stirring for 1 hour.

[0118] Thus, a composition comprising 10% PVA at 0.24 wt% PHA solids was prepared.

[0119] Comparative Example 3

[0120] A PHA aqueous dispersion having a solid content of 5% (manufactured by CJ CheilJedang, Mw 600,000, PDI 1.9, particle size <2 μm, 4HB 10 wt %) was vacuum distilled to a solid content of 41%.

[0121] In a stirring apparatus equipped with a paddle or turbine impeller, while stirring 95 parts of the prepared 41% PHA aqueous dispersion at 1500 rpm at room temperature, 5 parts of 10% dissolved polyvinyl alcohol (PVA, Kuraray, Mw 14200, degree of hydrolysis (DH) 88 mol%) were added, followed by stirring for 1 hour.

[0122] Thus, a composition comprising 10% PVA at 1.2 wt% PHA solids was prepared.

[0123] Comparative Example 4

[0124] A PHA aqueous dispersion having a solid content of 5% (manufactured by CJ CheilJedang, Mw 600,000, PDI 1.9, particle size <2 μm, 4HB 10%) was vacuum distilled to a solid content of 41%.

[0125] In a stirring apparatus equipped with a paddle or turbine impeller, while stirring 98 parts of the prepared 41% PHA aqueous dispersion at 1500 rpm at room temperature, 1 part of 10% dissolved polyvinyl alcohol (PVA, Kuraray, Mw 14200, degree of hydrolysis (DH) 88 mol%) was added, followed by stirring for 1 hour.

[0126] Then, 1 part of a 5% gum arabic dispersion (manufactured by ES Food Co.) was added and stirred for another 10 minutes to prepare a 40% PHA aqueous coating solution.

[0127] Thus, a composition comprising 10% PVA at 0.24 wt% and 5% gum arabic at 0.12 wt% of the PHA solids content was prepared.

[0128] Test Example 1

[0129] The dispersion stability of the compositions of the examples and comparative examples was evaluated under strict evaluation conditions (50°C, 2 weeks). 2 Coated on a basis weight of 180g / m 2 The samples were coated onto uncoated kraft paper and dried at 170° C. for 10 minutes. Thus, samples after the coating operation were prepared.

[0130] The coating was performed using an RDS Mayer bar coater, and water resistance was measured using the TAPPI T 441 standard KE value, with the test conditions being 10 x 10 cm, 100 mL, and 2 min.

[0131] The evaluation results of dispersion stability are as follows Figure 1 (Example) and Figure 2 The results of the water resistance evaluation are shown in Table 1.

[0132] [Table 1]

[0133]

[0134]

[0135] As shown in Table 1, it can be seen that the compositions described in the examples exhibit excellent physical properties as paper coating solutions.

[0136] On the other hand, it was confirmed that the physical properties were not suitable for the paper coatings of Comparative Example 1 without additives, Comparative Example 2 without rheology modifier, Comparative Example 3 using excess additives, and Comparative Example 4 using gum arabic rheology modifier having spherical particle shape.

[0137] As described above, the composition and method according to the present invention can simplify the manufacturing process of the PHA composition and improve the physical properties of the composition to make it suitable for use while minimizing the content of additives.

[0138] The above description is merely an illustration of the technical concept of the present invention, and those skilled in the art may make various modifications and changes without departing from the basic features of the present invention.

[0139] Furthermore, the embodiments disclosed herein are not intended to limit the technical concepts of the present invention, but rather to illustrate the technical concepts. The scope of the technical concepts of the present invention is not limited by these embodiments. The scope of protection of the present invention shall be interpreted by the following claims, and all technical concepts within the scope of the equivalents of the claims shall be interpreted as being included within the scope of the present invention.

Claims

1. Use of a polyhydroxyalkanoate (PHA) aqueous dispersion composition as a coating agent for a paper material or a polymer film material, wherein the composition comprises, based on the total weight of the composition: 10 to 70 wt% polyhydroxyalkanoate (PHA); and 1 to 10% by weight of additives, wherein the PHA comprises poly-3-hydroxybutyrate-co-4-hydroxybutyrate (P3HB-4HB), The content of 4HB in the PHA copolymer is 0.1 to 20%, The additives include rheology modifiers, surfactants or dispersants, thickeners and defoamers, and The content of the surfactant or dispersant is less than 0.3% by weight of the total weight of the composition; wherein the rheology modifier comprises one or more selected from the group consisting of gum, acrylate, urethane and epoxy resin, and wherein the gum is non-spherical; The composition has a viscosity of 3 g / m 2 or more up to 20g / m 2 .

2. The method according to claim 1, wherein the molecular weight Mw of the PHA is from 10,000 to 1,000,000.

3. The use according to claim 1, wherein the particle size of PHA is 10 μm or less.

4. The method according to claim 1, wherein the surfactant comprises one or more of the group consisting of cationic, anionic, nonionic and amphoteric surfactants.

5. The method according to claim 1, wherein the gum comprises one or more selected from the group consisting of gellan gum, xanthan gum, carrageenan, curdlan gum, karaya gum, tragacanth gum, ghatti gum, alginate, agar gum, and furcellaran.

6. The use according to claim 1, wherein the dispersant comprises one or more dispersants selected from the group consisting of acrylic acid-based dispersants, urethane-based dispersants, epoxy-based dispersants, polyvinyl alcohol and cellulose.

7. The method according to claim 6, wherein the polyvinyl alcohol has a molecular weight Mw of 10,000 to 200,000 and a degree of hydrolysis of 80 to 99 mol%.

8. The use according to claim 1, wherein the content of the rheology modifier is 0.5 wt% or less based on the total weight of the composition.

9. The use according to claim 1, wherein the coating amount of the composition is 10 g / m 2 or more up to 30g / m 2 .

10. The use according to claim 1, wherein the composition is used for coating paper materials or polymer films.

11. A method for preparing the PHA composition of claim 1, comprising: preparing an aqueous PHA dispersion; and adding additives to the dispersion under stirring.

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