A polyhydroxyalkanoate composition, a polyhydroxyalkanoate shaped body and a method for producing the same

Abstract

The present application relates to a kind of polyhydroxyalkanoate compositions, polyhydroxyalkanoate forming body and its preparation method.The polyhydroxyalkanoate compositions include: polyhydroxyalkanoate resin A, polyhydroxyalkanoate resin B, polyhydroxyalkanoate resin C;And optional additive, the polyhydroxyalkanoate resin A, B and C are respectively 3-hydroxyalkanoate structural unit and one or more other hydroxyalkanoate structural unit with different molar ratio poly (3-hydroxyalkanoate) copolymer.It has the advantages of simple preparation method, excellent processing stability and toughness to prepare polyhydroxyalkanoate forming body using the polyhydroxyalkanoate compositions of the present application.

Description

Technical Field

[0001] This invention belongs to the field of polyhydroxyalkanoate materials technology, and in particular relates to a polyhydroxyalkanoate composition, a polyhydroxyalkanoate molded body and a method for preparing the same. Background Technology

[0002] Polyhydroxyalkanoates (PHAs or PHAs) are intracellular polyhydroxy fatty acid esters synthesized by many microorganisms, and are natural polymeric biomaterials. Most PHA monomers are 3-hydroxy fatty acids with chains of 3-14 carbon atoms, and their side chains are highly variable, consisting of saturated or unsaturated, straight or branched, aliphatic or aromatic groups. This diversity in composition leads to a variety of properties, giving them significant advantages in applications. Furthermore, PHAs are bio-based and biodegradable natural polymers in marine environments, helping to address environmental problems caused by waste plastics. They also possess excellent biocompatibility and mechanical properties, allowing them to be processed into various molded products such as films, straws, tableware, medical stents, and everyday consumer goods.

[0003] Polyhydroxyalkanoates (PHAs) have low thermal decomposition temperatures and poor thermal stability. During processing, PHAs are prone to thermal decomposition at high temperatures, leading to a decline in material properties and problems such as large fluctuations in melt strength and darkening of color, severely impacting product quality. Secondly, PHAs have slow crystallization rates, large crystal sizes, and poor nucleus density, making them susceptible to performance instability during processing. For example, PHA materials such as poly(trihydroxybutyric acid) have high melting points and narrow thermal processing windows; their performance deteriorates significantly after a single processing step, making stable and effective application difficult. Furthermore, the toughness of PHA products still needs improvement in practical applications. For instance, pure PHA straws have poor toughness, easily becoming brittle and prone to cell breakage. While adding toughening agents, adjusting formulations, or optimizing processing techniques can improve performance, existing modification methods still have some shortcomings. For example, adding nucleating agents such as docosuccinic acid and heat stabilizers can improve the heat resistance and toughness of PHA, but these methods still present processing problems and high costs in practical applications.

[0004] In summary, existing PHA straws and other molded materials still have shortcomings in terms of processing stability and toughness. A technical solution is needed that can effectively address the comprehensive performance issues of polyhydroxyalkanoates in terms of toughness, processing efficiency, and processing stability to meet market demands. Summary of the Invention

[0005] One of the objectives of this invention is to provide a polyhydroxyalkanoate composition.

[0006] The second objective of this invention is to provide a molded body prepared from the above-mentioned polyhydroxyalkanoate composition.

[0007] A third objective of this invention is to provide a method for preparing the above-mentioned molded article.

[0008] The fourth objective of this invention is to provide an application of the above composition in the preparation of biodegradable resin molded articles, including resin tubes, resin sheets, injection molded parts, etc.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solutions are proposed.

[0010] In a first aspect, the present invention provides a polyhydroxyalkanoate composition comprising: polyhydroxyalkanoate resin A, polyhydroxyalkanoate resin B, polyhydroxyalkanoate resin C; and optional additives.

[0011] Wherein, the polyhydroxyalkanoate resin A, polyhydroxyalkanoate resin B, and polyhydroxyalkanoate resin C are all poly(3-hydroxyalkanoate) copolymers containing a first structural unit and a second structural unit, wherein the first structural unit is a 3-hydroxyalkanoate structural unit, and the second structural unit is any hydroxyalkanoate structural unit.

[0012] Wherein, in the polyhydroxyalkanoate resin A, the molar ratio of the first structural unit to the second structural unit is 99.9 / 0.1 to 99 / 1; in the polyhydroxyalkanoate resin B, the molar ratio of the first structural unit to the second structural unit is 97 / 3 to 94 / 6; and in the polyhydroxyalkanoate resin C, the molar ratio of the first structural unit to the second structural unit is 80 / 20 to 50 / 50, and

[0013] The polyhydroxyalkanoate composition comprises, based on 100 parts by weight of polyhydroxyalkanoate resin, 1 to 10 parts by weight of polyhydroxyalkanoate resin A, 75 to 90 parts by weight of polyhydroxyalkanoate resin B, and 3 to 15 parts by weight of polyhydroxyalkanoate resin C.

[0014] The manufacturing method of the polyhydroxyalkanoate described in this invention is not particularly limited; it can be a chemical synthesis method or a microbial manufacturing method.

[0015] The polyhydroxyalkanoate of the present invention is particularly preferably a poly(3-hydroxyalkanoate) copolymer produced by microorganisms, wherein all 3-hydroxyalkanoate structural units are contained in the form of (R)3-hydroxyalkanoate structural units.

[0016] The poly(3-hydroxyalkanoate) copolymer is preferably a copolymer of 3-hydroxybutyrate structural units and other hydroxyalkanoate structural units.

[0017] Further, the other hydroxyalkyl ester structural units include one or more of the following: 3-hydroxypropionate, 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyheptanoate, 3-hydroxyoctanoate, 3-hydroxynonanoate, 3-hydroxydecanoate, 3-hydroxyundecanoate, or 4-hydroxybutyrate.

[0018] In short, specific examples of poly(3-hydroxyalkanoate) copolymers include: poly(3-hydroxybutyrate-co-3-hydroxypropionate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (abbreviated as P3HB3HV, hereinafter referred to as PHBV), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (hereinafter referred to as P3HB3HV3HH), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (abbreviated as P3HB3HH, hereinafter referred to as PHBH), poly(3-hydroxybutyrate-co-3-hydroxyheptanoate), and poly(3-hydroxybutyrate-co-3-hydroxyoctanoate). Poly(3-hydroxybutyrate-co-3-hydroxynonanoate), poly(3-hydroxybutyrate-co-3-hydroxydecanoate), poly(3-hydroxybutyrate-co-3-hydroxyundecanoate), poly(3-hydroxybutyrate-co-3-hydroxyundecanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (abbreviated as P3HB4HB, hereinafter referred to as P34HB), etc. Further, the weight-average molecular weight of the poly(3-hydroxybutyrate) resin is 100,000 to 1,000,000; preferably 200,000 to 900,000; more preferably 300,000 to 700,000. When the weight-average molecular weight is less than 100,000, there is a tendency for the mechanical properties of the obtained poly(3-hydroxybutyrate) resin molded article to decrease. On the other hand, when the weight-average molecular weight exceeds 1,000,000, there is a tendency for the mechanical load during melt processing to increase and productivity to decrease.

[0019] Furthermore, the polyhydroxyalkanoate composition of the present invention comprises three or more polyhydroxyalkanoate resins. Specifically, in addition to the aforementioned polyhydroxyalkanoate resin A, polyhydroxyalkanoate resin B, and polyhydroxyalkanoate resin C, the composition further comprises polyhydroxyalkanoate resin D, which is a poly(3-hydroxyalkanoate) copolymer containing a first structural unit and a second structural unit. The first structural unit is a 3-hydroxyalkanoate structural unit, and the second structural unit is any hydroxyalkanoate structural unit. In the polyhydroxyalkanoate resin D, the molar ratio of the first structural unit to the second structural unit is 93 / 7 to 85 / 15.

[0020] In a further embodiment, the polyhydroxyalkanoate composition further comprises a polyhydroxyalkanoate resin D, wherein the molar ratio of the first structural unit to the second structural unit in the polyhydroxyalkanoate resin D is 91 / 9 to 88 / 12.

[0021] In a specific embodiment, based on the total of 100 parts by weight of polyhydroxyalkanoate resins, the polyhydroxyalkanoate composition comprises 1 to 10 parts by weight of polyhydroxyalkanoate resin A, 75 to 90 parts by weight of polyhydroxyalkanoate resin B, 3 to 15 parts by weight of polyhydroxyalkanoate resin C, and 4 to 15 parts by weight of polyhydroxyalkanoate resin D.

[0022] In a further specific embodiment, based on the total of 100 parts by weight of polyhydroxyalkanoate resins, the polyhydroxyalkanoate composition comprises 1 to 10 parts by weight of polyhydroxyalkanoate resin A, 75 to 90 parts by weight of polyhydroxyalkanoate resin B, 3 to 15 parts by weight of polyhydroxyalkanoate resin C, and 5 to 15 parts by weight of polyhydroxyalkanoate resin D.

[0023] Furthermore, the polyhydroxyalkanoate resin D is a poly(3-hydroxyalkanoate) copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units.

[0024] Without inhibiting the effects of the present invention, other additives (or auxiliaries) may be added to the composition according to the production needs of the molded article. These may include, but are not limited to, nucleating agents, plasticizers, toughening agents, reinforcing agents, crosslinking agents, chain extenders, lubricants, dispersants, fillers, and other organic or inorganic materials. They may be used alone or in combination of two or more. Moreover, the amount of additives added can be adjusted according to production needs, and the present invention does not impose any particular limitations on this.

[0025] Preferably, in some embodiments, the polyhydroxyalkanoate composition further includes a nucleating agent. Adding a nucleating agent can reduce the time required for the polyhydroxyalkanoate to become non-sticky, thereby improving processing efficiency.

[0026] More preferably, the nucleating agent is added to the polyhydroxyalkanoate composition in an amount of 0.1-10% by weight, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, or 8%. Excessive addition of the nucleating agent will reduce the mechanical properties of the polyhydroxyalkanoate.

[0027] In some embodiments, the nucleating agent may be one or more selected from calcium carbonate, talc, titanium dioxide, uracil, galactitol, zirconium hydrogen phosphate, L-lactic acid, D-lactic acid, pentaerythritol, amide compounds, and boron nitride; wherein the amide compound is selected from N,N'-hexyl-1,6-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide, tetramethylthiuram disulfide, tetramethylthioperoxydicarbonamide, and N,N'-1,6-hexadiylbis[N- One or more of the following: [2,2,6,6-tetramethyl-4-piperidine]-formamide, N,N'-1,2-ethylenedimethylbisoctadecylamide, (Z,Z)-N,N'-1,2-ethylenediamide bis-9-octadecenamide, behenamide, octadecylamide, erucamide, oleamide, stearylerucamide, N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide, and N,N-di(hydroxyethyl)cocoamide.

[0028] In addition, the nucleating agent in this invention may be one or more selected from fatty acids, fatty alcohols, aliphatic hydroxy acids, and aliphatic carboxylic acid esters.

[0029] Specifically, the fatty acid can be a fatty acid with 5-30 carbon atoms, such as valeric acid and decadecanoic acid (decanoic acid / n-decanoic acid); preferably, it is a higher fatty acid with 10 or more carbon atoms; more preferably, it is a long-chain high-carbon fatty acid with an even number of carbon atoms, specifically, without limitation, such as one or more of lauric acid (dodecanoic acid), myristic acid (tetradecanoic acid), palmitic acid (hexadecanoic acid), stearic acid (octadecanoic acid), arachidic acid (eicosanoic acid), behenic acid (docosahexadecanoic acid), lignotaric acid (tetracosanoic acid), ceric acid (hexadecanoic acid), limonitic acid (octadecanoic acid) or beeswax acid (triadecanoic acid); more preferably, it is behenic acid.

[0030] Specifically, the fatty alcohol can be a fatty alcohol with 5-30 carbon atoms, such as pentanol, octadecyl alcohol, etc.; preferably, higher fatty alcohols with 10 or more carbon atoms; more preferably, long-chain high-carbon fatty alcohols with an even number of carbon atoms, specifically, without limitation, such as one or more of 1,16-hexadecanediol, stearyl alcohol (1,2-octadecanediol), 1,22-docosahexadecanediol, lauryl alcohol (dodecyl alcohol), myristyl alcohol (tetradecanediol), palmitol (hexadecanediol), arachidyl alcohol (eicosyl alcohol), behenyl alcohol (docosahexadecanediol), wax alcohol (hexadecanediol), pril alcohol (octadecanediol), beeswax alcohol (triacontanol), and cercaryl alcohol (tridodecanediol); more preferably, docosahexadecanediol.

[0031] Specifically, the aliphatic hydroxy acid can be an aliphatic hydroxy acid with 5-30 carbon atoms, preferably an aliphatic hydroxy acid with 10 or more carbon atoms, specifically and without limitation, such as one or more of 3-hydroxytridecanoic acid, 3-hydroxytetradecanoic acid, 8-hydroxytetradecanoic acid, 15-hydroxypentadecanoic acid, 2-hydroxyhexadecanoic acid, 3-hydroxyhexadecanoic acid, 16-hydroxyhexadecanoic acid, 9,10,16-trihydroxyhexadecanoic acid, 3-hydroxyheptadecanoic acid, 17-hydroxyheptadecanoic acid, 2-hydroxyoctadecanoic acid, 3-hydroxyoctadecanoic acid, 12-hydroxyoctadecanoic acid, 20-hydroxyeicosanoic acid, 2-hydroxydienoic acid, and 22-hydroxydienoic acid.

[0032] Specifically, the aliphatic carboxylic acid ester can be an aliphatic carboxylic acid ester with 5-30 carbon atoms, preferably an aliphatic carboxylic acid ester with 10 or more carbon atoms, specifically and without limitation, such as one or more of ethyl hexadecanoate, 2-ethylhexyl hexadecanoate, hexadecanoate, methyl nonadecanoate, methyl eicosanoate, ethyl eicosanoate, methyl docosahexadecanoate, ethyl docosahexadecanoate, methyl docosahexadecanoate, and methyl triacontadecanoate.

[0033] Preferably, in some embodiments, the polyhydroxyalkanoate composition further includes a plasticizer. The addition of a plasticizer further enhances the flexibility of the polyhydroxyalkanoate and can synergistically regulate its molecular weight and melt flow index within a suitable range.

[0034] More preferably, the amount of plasticizer added to the polyhydroxyalkanoate composition is 0.1%-15% by weight, preferably 1%-10%, more preferably 1%-5%.

[0035] In some embodiments, the plasticizer may be one or more selected from polyethylene glycol and its derivatives, glyceryl esters, citrates, sebacic acid esters, isosorbides, and diesters. Preferably, polyethylene glycol and its derivatives, such as polyethylene glycol monoglycidyl ether and polyethylene glycol diglycidyl ether, are used.

[0036] Preferably, in some embodiments, the polyhydroxyalkanoate composition further includes inorganic fillers, which can synergistically promote crystallization nucleation during the thermoplastic processing of polyhydroxyalkanoates, control nucleation size, reduce crystal points in the molded body, and improve strength.

[0037] Specifically, the inorganic filler includes calcium carbonate, talc, kaolin, montmorillonite, wollastonite, silicon dioxide, titanium dioxide, aluminum oxide, barium sulfate, and mica powder.

[0038] The average particle size of the inorganic filler is preferably 0.1–50 μm, more preferably 0.5–30 μm, and even more preferably 1–10 μm.

[0039] Polyhydroxyalkanoates are sensitive to moisture and are prone to hydrolysis during thermal processing, leading to a decrease in performance. The moisture content of the inorganic filler is <1%, preferably <0.5%, and more preferably <0.1%.

[0040] The inorganic filler is added to the polyhydroxyalkanoate composition at a weight percentage of 0.5%-20%, preferably 1%-15%, and more preferably 1%-10%.

[0041] Furthermore, without suppressing the effect of the present invention, other bio-based or biodegradable materials may be added to the polyhydroxyalkanoate composition of this application according to the production needs of the molded body. These materials may include, but are not limited to, one or more of the following: polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene adipate succinate (PBSA), polycaprolactone (PCL), polyglycolic acid (PGA), and polypropylene carbonate (PPC).

[0042] Furthermore, the melt mass flow rate of the polyhydroxyalkanoate composition is 5-15 g / 10 min, more preferably 5-10 g / 10 min.

[0043] The polyhydroxyalkanoate compositions of the present invention can be prepared using conventional techniques and equipment known in the art, and can be added to processing equipment using granules, powders, or liquid feeders, and blended at room temperature.

[0044] In a second aspect, the present invention also provides a molded article prepared from a polyhydroxyalkanoate composition according to the present invention.

[0045] The molded body obtained by this invention has the advantages of good processing stability, high processing efficiency, good mechanical properties (such as toughness), and a smooth and uniform surface with good heat resistance. Furthermore, the prepared molded body possesses biodegradable characteristics in marine environments, completely decomposing into harmless substances in the natural environment without releasing microplastic particles during degradation, and is non-toxic and harmless to the human body during use.

[0046] Thirdly, the present invention also provides a method for preparing the above-mentioned molded article.

[0047] When the above-mentioned polyhydroxyalkanoate molded body is prepared using thermoplastic molding equipment, the lower the temperature in the first stage, the shorter the time required for the molded body to not stick together and to cure in the second stage; however, if the temperature in the first stage is too low, it will affect the melt plasticization of polyhydroxyalkanoate and the blending and dispersion effect of various types of polyhydroxyalkanoate resins.

[0048] The present invention has found that when polyhydroxyalkanoate compositions with different types of additives are melt-plasticized at the first stage temperature and cooled and molded at the second stage temperature, they are less prone to sticking. Therefore, a higher first stage temperature can be used.

[0049] However, the higher the temperature in the first stage, the greater the degree of thermal degradation of polyhydroxyalkanoates. Taking all factors into consideration, in the first stage, the system temperature should be controlled to be 10°C to 60°C above the melting point (Tm) of polyhydroxyalkanoates, preferably 10°C to 40°C above the melting point (Tm), and more preferably 10°C to 20°C above the melting point (Tm).

[0050] Specifically, for example, the melting and plasticizing temperature is generally 10-15°C higher than the melting point, such as 130-165°C.

[0051] Meanwhile, the temperature in the second stage affects the time required for the polyhydroxyalkanoate molded body to reach a non-adhesive state. Extensive testing has verified that the temperature in the second stage system is preferably between the glass transition temperature and melting point of the resulting molded body, ideally between 30°C above the glass transition temperature and 20°C below the melting point. More preferably, it is between 40°C above the glass transition temperature and 60°C below the melting point.

[0052] Specifically, for example, the water bath temperature for particles / straws is generally 40-65℃, preferably 50-65℃, the mold temperature for injection molding, and the cold roller temperature for extruded sheets and coating processes.

[0053] Preferably, polyhydroxyalkanoates with different molar ratios of 3-hydroxybutyrate units / other hydroxyalkanoate units are blended with nucleating agents, plasticizers, and other additives using commonly used extrusion granulation equipment in the art, such as parallel co-rotating twin-screw extruders, parallel counter-rotating twin-screw extruders, conical twin-screw extruders, and single-screw extruders, to prepare particle molded articles. Then, the particle molded articles are used to prepare other molded articles through thermoplastic processing methods such as extrusion molding, injection molding, calendering, casting molding, blow molding, and biaxial stretching molding.

[0054] Fourthly, the present invention also provides the application of the polyhydroxyalkanoate composition according to the present invention in the preparation of resin tubes. Specifically, a resin tube and a method for preparing the same are provided.

[0055] After the above-mentioned polyhydroxyalkanoate composition is mixed (it can be a well-mixed composition particle (granulated particle) or a raw material powder mixture), a straw is prepared by a straw extruder; the melt mass flow rate of the mixed polyhydroxyalkanoate composition is 5-15 g / 10 min, more preferably 5-10 g / 10 min.

[0056] The resin tube obtained by this invention has the following advantages: good processing stability, good mechanical properties, good toughness, smooth and uniform surface, and good heat resistance.

[0057] The wall thickness of the resin tube of the present invention is 0.01 mm or more and 10 mm or less, more preferably 0.1 mm to 5 mm, and more preferably 0.1 mm to 2 mm.

[0058] The application includes a method for preparing straws comprising the following steps: feeding the material obtained from the above composition into a resin tube extruder, and after extrusion, water cooling in a water bath for tube crystallization and shaping. The extruder barrel and die heating sections are heated to 130-165℃ (first stage temperature); the water bath is heated to 50-65℃ (second stage temperature) for tube crystallization and shaping. The material obtained from the above composition can be obtained by mixing and granulating the components using a granulator, or a mixed granulated product can be used; the melt flow rate of the mixed granulated product is 5-15 g / 10 min, more preferably 5-10 g / 10 min.

[0059] The equipment involved in the molding process includes, but is not limited to:

[0060] Mixing equipment: High-speed mixers are used for mixing at room temperature.

[0061] Particle molding equipment: Commonly used extrusion granulation equipment in this field, such as parallel co-rotating twin-screw extruders, parallel counter-rotating twin-screw extruders, conical twin-screw extruders, and single-screw extruders, can be used. In addition to the main feeding device, the extrusion granulation equipment should have at least one set of side feeding devices, and these side feeding devices should be able to handle liquid feeding. The length-to-diameter ratio of the extrusion granulation equipment is preferably L / D ≥ 20:1 and ≤ 44:1. Subsequently, pelletizing equipment such as air-cooled strip pelletizing, water bath strip pelletizing, die-face hot cutting, water ring cutting, and underwater pelletizing can be used. Commonly used equipment such as water baths, oil baths, hot air blowers, and high-temperature drying tunnels are preferred during the production process for the crystallization and solidification of the strips or particles. The prepared particles are dried using a forced-air drying oven or other drying equipment to eliminate the influence of moisture on particle properties and to ensure complete particle crystallization.

[0062] Resin tube molding equipment: Single-color straw extruders and multi-color straw extruders can be used, including commonly used extrusion tube manufacturing equipment in this field for round tubes, square tubes, and porous tubes. The length-to-diameter ratio of the extrusion equipment is preferably L / D ≥ 20:1 and ≤ 28:1. Commonly used equipment such as water baths, oil baths, hot air blowers, and high-temperature drying tunnels are used for tube cooling tanks, with water baths and oil baths being preferred for crystallization and solidification of the straws.

[0063] Sheet forming equipment: Common sheet manufacturing equipment in this field can be used, such as parallel co-rotating twin-screw extruders, parallel counter-rotating twin-screw extruders, conical twin-screw extruders, and single-screw extruders. Common designs in this field, such as T-die, straight die, coat hanger die, or branch die, can be employed. The extruder length-to-diameter ratio (L / D) is preferably 28:1 to 36:1. The cooling and shaping system uses a three-roll calender unit (inline, triangular, etc. arrangement). Common equipment such as water baths, oil baths, hot air blowers, and high-temperature drying tunnels can be used to further accelerate the crystallization and solidification of the sheet.

[0064] Injection molding equipment: Horizontal injection molding machines, vertical injection molding machines, angle injection molding machines, and other commonly used injection molding equipment in this field can be used; there is no restriction on the length-to-diameter ratio of the injection molding equipment, such as choosing a length-to-diameter ratio L / D=18-24; and the injection molding equipment needs to be equipped with a mold temperature controller, the type of mold temperature controller is not particularly restricted, and commonly used equipment in this field can be used.

[0065] Beneficial effects

[0066] 1. The method of preparing polyhydroxyalkanoate molded articles using the composition of the present invention is simpler. The articles can be prepared by blending and extrusion. Compared with the existing technology for improving processing stability or toughness, it can be thermoplastically molded to obtain high-quality thermoplastic molded articles without the need for compounding with reaction catalysts, chain extenders and other additives, thereby reducing production costs. Moreover, the raw materials in this composition are inexpensive and readily available.

[0067] 2. Using the composition described in this invention to prepare polyhydroxyalkanoate molded articles results in faster crystallization during processing, leading to higher processing efficiency and improved production efficiency. Furthermore, the prepared molded articles exhibit very few crystal point problems, thus improving the product qualification rate.

[0068] 3. This invention provides an application of polyhydroxyalkanoate composition in improving the processing stability and toughness of molded articles, solving the problem that the application of materials in this field is difficult to expand due to poor processing stability and toughness, and providing an application direction for the innovation of injection molding and straw preparation technologies.

[0069] The present invention has been described in detail above; however, the above embodiments are merely illustrative in nature and are not intended to limit the invention. Furthermore, this document is not limited to the foregoing prior art or the invention itself, or to any theory described in the following embodiments.

[0070] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. Attached Figure Description

[0071] Figure 1 A photograph is shown of an injection-molded article prepared from the composition of Experimental Example 20 of this application.

[0072] Figure 2 A photograph is shown of a resin tube molded body prepared from the composition of Experimental Example 20 of this application.

[0073] Figure 3 A photograph is shown of a sheet molded article prepared from the composition of Experimental Example 20 of this application. Detailed Implementation

[0074] The present invention will be further described below with reference to the embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0075] Unless otherwise specified, the raw materials, reagents, and methods used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0076] Unless otherwise specified, all raw materials used in the following embodiments and comparative examples were commercially available.

[0077] raw material

[0078] The poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) in the following experimental examples / comparative examples were manufactured according to the methods described in CN114381415A and Example 3 therein, and according to the methods described in CN114480318A and Examples 2-4 therein. Different raw material monomers were distinguished by the content ratio of 3-hydroxyhexanoate (HHX), namely, PHBH with 3-hydroxyhexanoate (HHX) contents of 0.6 mol%, 1 mol%, 2 mol%, 3 mol%, 4 mol%, 6 mol%, 7 mol%, 9 mol%, 10 mol%, 12 mol%, 15 mol%, 20 mol%, 24 mol%, and 39 mol%; their weight-average molecular weights were all between 600,000 and 700,000 g / mol.

[0079] The poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) in the following experimental examples / comparative examples was manufactured according to the methods described in CN102816729A and Example 1 therein, and CN102120973A and Example 2 therein. Different raw material monomers were distinguished by their 3HV content ratio, resulting in PHBV with 3HV contents of 0.6 mol%, 3 mol%, 4 mol%, 10 mol%, 12 mol%, 20 mol%, 24 mol%, and 39 mol%; their weight-average molecular weights were all between 600,000 and 700,000 g / mol.

[0080] The poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) in the following experimental examples / comparative examples was manufactured according to the method described in CN110079489A and Examples 1 to 6 therein. Different raw material monomers were distinguished by the 4HB content ratio, namely P34HB with 4HB contents of 0.6 mol%, 1 mol%, 6 mol%, and 24 mol%; their weight-average molecular weights were all between 600,000 and 700,000 g / mol.

[0081] Polyethylene glycol diglycidyl ether, molecular weight 1000, commercially available.

[0082] L-lactic acid, net content 80%, commercially available.

[0083] Hexagonal boron nitride, average particle size ≤3μm, commercially available.

[0084] equipment:

[0085] The mixing equipment used in this embodiment is the SHR-50L high-speed mixer from Zhangjiagang Zhengde Machinery Factory.

[0086] The extrusion granulation equipment used in the examples is the HK36 twin-screw extruder unit from Nanjing Keya.

[0087] The straw extrusion equipment used in the embodiment is the Guangzhou Sanhuiying SJ-φ25 straw extruder unit.

[0088] The sheet extrusion equipment used in the embodiment is a Changzhou Kingway CJWH35-40D twin-screw sheet extruder.

[0089] The injection molding equipment used in this embodiment is the Guangdong Yizumi UN120A5S precision mechanical hinge servo pump horizontal injection molding machine.

[0090] <Performance Evaluation>

[0091] Weight-average molecular weight of polyhydroxyalkanoates: determined using a gel permeation chromatography system (Shimadzu Corporation HPLC GPC system) with chloroform solution and by conversion to polystyrene. A column suitable for determining weight-average molecular weight was used as the column in this gel permeation chromatography system.

[0092] Melt mass flow rate (MFR) was tested using particle molded bodies, while other properties were tested using injection molded bodies further prepared from the particle molded bodies described below.

[0093] Melt index:

[0094] The testing standard is ISO1133-1:2011, and the testing equipment is a melt flow rate tester. The following polyhydroxyalkanoate particle molded body is used to determine the melt flow index at 165°C and 2.16 kg. The unit of melt flow index is g / 10min.

[0095] Tensile strength and elongation at break:

[0096] The testing standard is ISO 527-2:2012, and the testing equipment is a universal testing machine. The tensile property test specimens of the following polyhydroxyalkanoate injection molded parts are used to determine the tensile strength and elongation at break at a test speed of 50 mm / min. The unit of tensile strength is MPa, and the unit of elongation at break is _____.

[0097] Notched impact strength:

[0098] The testing standard is ISO 179-1:2010, and the testing equipment is a pendulum impact testing machine. Notched impact test specimens from the following polyhydroxyalkanoate injection molded parts are used to determine the notched impact strength of a simply supported beam; the unit is kJ / m. 2 .

[0099] Heat distortion temperature under load:

[0100] The testing standard is ISO 75-1:2020, and the testing equipment is a heat distortion temperature tester. The following test specimens of polyhydroxyalkanoate injection molded parts are used, with a bending stress of 0.45 MPa and general test conditions. The heat distortion temperature under load is determined, and the unit is ℃.

[0101] <Effect Evaluation>

[0102] Resin tube molding body

[0103] For each evaluation item, the ranking from best to worst is indicated by ●. , ○, × represent.

[0104] toughness

[0105] Ten straws were prepared using the method described below. Each straw was horizontally fixed to the bottom of a vertical cylinder, ensuring it was in flat contact with the bottom. A calibrated 200g standard weight was suspended along the central axis of the cylinder, with the initial height of the weight's bottom set at 500mm. A free-fall release device was used to vertically impact the center of the straw, and the impact area was observed for cracks (crack depth ≥ 0.5mm was considered a failure). All ten samples had to pass the highest test height without cracking. If any straw cracked during the test, the batch was deemed unqualified, and the height was adjusted by 50mm each time. The testing environment was controlled at a temperature of 23±2℃ and humidity of 50±5%. Data records included the critical height for each sample and the final judgment result. The test data were used for evaluation.

[0106] Excellent: ≥800mm, indicated by ●

[0107] Good: <800mm, but ≥500mm. express

[0108] Difference: <500mm, indicated by ×.

[0109] Crystal point

[0110] Thirty straws prepared using the method described below were taken and their crystal spots were examined. The crystal spots were visually counted using transmitted light, and the results were evaluated based on the number of crystal spots.

[0111] Excellent: ≤3 pieces / 30 pieces, indicated by ●

[0112] Good: >3 / 30, but ≤5 / 20. express

[0113] Generally: >5 / 30 pieces, but ≤10 / 20 pieces, indicated by ○.

[0114] Difference: >10 / 30 pieces, indicated by ×.

[0115] Processing stability

[0116] The following resin tube molded body has an outer diameter of 6 mm, a wall thickness of 0.25 mm, and a length of 210 mm. During the manufacturing process of the straw (resin tube molded body), the straw diameter may fluctuate. The fluctuation of the straw diameter is monitored by a non-contact laser velocimetry and diameter measuring instrument at the traction device, and the data is evaluated as a percentage.

[0117] Excellent: ≤3%, indicated by ●

[0118] Good: >3%, but ≤6%, with express

[0119] Generally: >6% but ≤10%, indicated by ○.

[0120] Difference: >10%, indicated by ×.

[0121] Processing efficiency

[0122] In the process of preparing straws (resin tube molded bodies), the crystallization and solidification speed of the tube body in the water bath is directly related to its processing efficiency. Using the above-mentioned extrusion straw processing equipment, the straw processing linear speed is monitored by a non-contact laser velocimeter and diameter gauge at the traction device, measured in m / min, and the data is evaluated.

[0123] Excellent: ≥55m / min, indicated by ●

[0124] Good: <55m / min, but ≥35m / min. express

[0125] Difference: <35m / min, indicated by ×.

[0126] Sheet Molded Body

[0127] toughness

[0128] Ten sheet samples were randomly selected from the production batch, cut to a length of 150mm and a width of 50mm. The samples must be intact, free of scratches, and have no burrs on the edges. Each sample was horizontally fixed to the bottom of a vertical cylinder (the clamping edge was ≥10mm from the sample edge to prevent stress concentration). A calibrated dart system (initially configured with a 1000g standard weight, bottom height 500mm) was suspended through the central axis of the cylinder. A free-fall release device was used to allow the weight to impact the geometric center area of ​​the sheet vertically. Cracks were observed at the impact point (crack depth ≥0.5mm or area >5mm² was considered a failure). All ten samples had to pass the highest test height (initially 500mm) without cracking. If any sample failed, the batch was deemed unqualified. The test height was adjusted in increments of 50mm. The critical height for each sample (accurate to ±1mm) and the final judgment result were recorded. The data were used to generate a trend chart using SPC software. The testing environment must be controlled at a temperature of 23±2℃ and a humidity of 50±5%. Data recordings must include the critical height of each sample and the final judgment result. Evaluation will be based on the test data.

[0129] Excellent: ≥800mm, indicated by ●

[0130] Good: <800mm, but ≥500mm. express

[0131] Difference: <500mm, indicated by ×.

[0132] Processing efficiency

[0133] In the sheet molding process described below, the crystallization and solidification rate of the sheet in the water bath is directly related to its processing efficiency. Using the extrusion sheet processing equipment described above, the sheet processing linear speed is monitored by a non-contact laser velocimeter and diameter gauge at the traction device, measured in m / min, and the data is evaluated.

[0134] Excellent: ≥20m / min, indicated by ●

[0135] Good: <20m / min, but ≥10m / min. express

[0136] Difference: <10m / min, indicated by ×.

[0137] Experimental Examples 1–20 and Comparative Examples 1–8: Preparation of Particle Moldings

[0138] In Experimental Examples 1-20 and Comparative Examples 1-8, particle-shaped bodies were prepared. Nucleating agents were added to the compositions. The nucleating agents consisted of 0.5% L-lactic acid and 0.5% hexagonal boron nitride by weight of the total composition.

[0139] In Experimental Examples 1-20 and Comparative Examples 1-8, particle-shaped bodies were prepared. A plasticizer was added to the composition, and the plasticizer was 2% polyethylene glycol diglycidyl ether by weight of the total composition.

[0140] Particle-shaped bodies were prepared using the compositions provided in Experimental Examples 1-20 and Comparative Examples 1-8 in Tables 1-3 below, respectively. The specific steps are as follows:

[0141] Step 1, Mixing: Place the polyhydroxyalkanoate powder and various additives in a high-speed mixer and mix at room temperature. The mixing speed is 200-600 (r / min) and the mixing time is 3-10 min. Take out the mixed composition for later use.

[0142] Step 2, Extrusion: Set the temperature of the extrusion granulation equipment to the range of 50-180℃, then put the mixture prepared in Step 1 into the loss-in-weight weigher and feed it into the extruder from the main feeder. Add the yellowness regulator into the liquid feeder and feed it into the extruder from the side feeder. Use a screw speed of 100-500 (r / min) and perform melt extrusion according to the set ratio.

[0143] Step 3, Granulation: Granulation is carried out by water bath strip cutting. The water bath heating temperature is 40-65℃ to make the strip crystallize and solidify. Then, the strip is cut into particles of uniform size by a pelletizer.

[0144] Step 4, Drying: Place the particles prepared in Step 3 in a vacuum oven to dry at a temperature of 60-80℃ for 4-8 hours to complete the preparation of polyhydroxyalkanoate particle molded bodies.

[0145] The melt flow index of the prepared particles was measured according to the method described above. The test results are shown in Table 1 below.

[0146] Example 1: Preparation of Injection Molded Body

[0147] The particle molded body prepared in the above experimental example was used to prepare the injection molded body using a horizontal injection molding machine. The heating temperature of each section of the injection molding machine barrel was 120-160℃ (first-stage temperature). The injection mold was selected from those used for tensile performance testing, notched impact performance testing, and load heat deflection temperature testing. The mold temperature was adjusted to 40-60℃ (second-stage temperature) using a mold temperature controller to allow the injection molded part to crystallize and solidify, thus completing the preparation of the polyhydroxyalkanoate injection molded body. The result was obtained from the particle molded body preparation in Experimental Example 20. Figure 1 The injection-molded body shown.

[0148] In the above-mentioned polyhydroxyalkanoate injection molded parts, the tensile test specimens meet the ISO 527-2:2012, Type 1A test standard; the notched impact test specimens meet the ISO 179-1:2010, Type 1A notched test standard; and the load heat distortion temperature test specimens meet the ISO 75-1:2020 test standard. Specific test results are shown in Table 1 below.

[0149] Table 1

[0150]

[0151] In the table above, HHX represents 3-hydroxyhexanoate, 3HV represents 3-hydroxyvalerate, and 4HB represents 4-hydroxybutyrate. The percentages in parentheses represent the molar percentages of the aforementioned monomer units.

[0152] As shown in Table 1 above, the toughness and molding cycle of Examples 1-20 are generally better than those of Comparative Examples 1-8. This indicates that the injection-molded articles prepared by the compositions of the present invention have better overall toughness, shorter injection molding time, and higher production efficiency.

[0153] Example 2: Preparation of resin tube molded body

[0154] The particle molded bodies prepared in the above experimental examples and comparative examples were used to prepare straws (central control tube molded bodies) using a single-color straw extruder. The straws had an outer diameter of 6 mm, a wall thickness of 0.25 mm, and a length of 210 mm. The heating temperature of each section of the extruder barrel and die head was 130-165℃ (first stage temperature); the water bath temperature was 50-65℃ for tube crystallization and shaping. The shaped tubes were led out by a crawler-type traction device at a constant linear speed and cut to a preset length by a rotary flying knife cutter. A non-contact laser velocimeter and diameter gauge was installed at the outlet of the traction device to collect the linear velocity signal of the tubes in real time. The particle molded body prepared in Experimental Example 20 was used to obtain the tubes as shown in the figure. Figure 2 The resin tube molded body shown.

[0155] Example 3: Preparation of sheet-molded body

[0156] The particle-shaped bodies prepared in the above experimental examples and comparative examples were used to prepare sheets using a twin-screw sheet extruder. The sheets were 400 mm wide and 0.8 mm thick. The extruder barrel and die heating sections were heated to 130-165℃ (first-stage temperature); the cold roll, stationary roll, and pressure roll were heated to 50-65℃ for sheet crystallization and shaping. The shaped sheets were then fed into the winding area by a traction machine, positioned using guide rollers to ensure centering, and drawn out at a constant linear speed. They were then wound by a winding machine. A non-contact laser velocimetry and thickness gauge was installed at the traction device outlet to collect real-time signals of sheet linear speed and thickness fluctuations. The particle-shaped bodies prepared in Experimental Example 20 were used to obtain the sheet as shown in the image. Figure 3 The sheet material shown.

[0157] The straws and sheets prepared above were evaluated for performance according to the aforementioned method, and the results are shown in Tables 2 to 4 below.

[0158] Table 2

[0159]

[0160] As shown in Table 2, Examples 1-8 used different types of polyhydroxyalkanoates, each containing three types of poly(3-hydroxyalkanoate) resins. The ratios of the first structural unit (3-hydroxybutyrate) and the second structural unit (other hydroxyalkanoates) of the three types of poly(3-hydroxyalkanoate) resins were as follows: 3-hydroxybutyrate unit / other hydroxyalkanoate unit = 99.9 / 0.1 to 99 / 1 (mol% / mol%), 3-hydroxybutyrate unit / other hydroxyalkanoate unit = 97 / 3 to 94 / 6 (mol% / mol%), and 3-hydroxybutyrate unit / other hydroxyalkanoate unit = 80 / 20 to 50 / 50 (mol% / mol%). Comparative Examples 1-4 used two types of poly(3-hydroxyalkanoate) resins. Compared with Comparative Examples 1-4, Examples 1-8 showed the following results: the molded articles prepared from the compositions of the three types of poly(3-hydroxyalkanoate) resins exhibited relatively strong toughness, high processing efficiency, fewer crystal points, and better processing stability.

[0161] Table 3

[0162]

[0163] As shown in Table 3, Experimental Examples 9-12 and Comparative Examples 5-8 used different types of polyhydroxyalkanoates, each containing three types of poly(3-hydroxyalkanoate) resins. In Experimental Examples 9-12, the ratios of the first structural unit (3-hydroxybutyrate) to the second structural unit (other hydroxyalkanoates) in the three types of poly(3-hydroxyalkanoate) resins met the following ratios: 3-hydroxybutyrate unit / other hydroxyalkanoate unit = 99.9 / 0.1 to 99 / 1 (mol% / mol%), 3-hydroxybutyrate unit / other hydroxyalkanoate unit = 97 / 3 to 94 / 6 (mol% / mol%), and 3-hydroxybutyrate unit / other hydroxyalkanoate unit = 80 / 20 to 50 / 50 (mol% / mol%). Comparative Examples 5-8 show three types of poly(3-hydroxyalkanoate) resins, where the ratio of the second structural units of one or two PHAs does not completely conform to the ratios described above. The following results can be observed: the molded articles prepared from the compositions of the three types of PHAs, where the ratio of the first structural unit (3-hydroxybutyrate) and the second structural unit (other hydroxyalkanoates) of PHAs respectively conforms to the ratios described above, exhibit relatively strong toughness, high processing efficiency, fewer crystal points, and better processing stability.

[0164] Table 4

[0165]

[0166] As shown in Table 4, Experimental Examples 13-14 and 15-20 used different types of polyhydroxyalkanoates, each containing four types of poly(3-hydroxyalkanoate) resins. In Experimental Examples 13-14, three of the four types of poly(3-hydroxyalkanoate) resins had the following ratios: 3-hydroxybutyrate unit / other hydroxyalkanoate unit = 99.9 / 0.1–99 / 1 (mol% / mol%), 3-hydroxybutyrate unit / other hydroxyalkanoate unit = 97 / 3–94 / 6 (mol% / mol%), and 3-hydroxybutyrate unit / other hydroxyalkanoate unit = 80 / 20–50 / 50 (mol% / mol%). The other type of poly(3-hydroxyalkanoate) resin did not meet the ratio requirement of 3-hydroxybutyrate unit / other hydroxyalkanoate unit = 91 / 9–88 / 12 (mol% / mol%). Experimental Examples 15-20 each contain four types of poly(3-hydroxyalkanoate) resins, wherein the ratio of the first structural unit (3-hydroxybutyrate) to the second structural unit (other hydroxyalkanoates) conforms to the following: 3-hydroxybutyrate unit / other hydroxyalkanoate unit = 99.9 / 0.1 to 99 / 1 (mol% / mol%), 3-hydroxybutyrate unit / other hydroxyalkanoate unit = 97 / 3 to 94 / 6 (mol% / mol%), 3-hydroxybutyrate unit / other hydroxyalkanoate unit = 91 / 9 to 88 / 12 (mol% / mol%), and 3-hydroxybutyrate unit / other hydroxyalkanoate unit = 80 / 20 to 50 / 50 (mol% / mol%). The toughness and processing efficiency of Experimental Examples 13-14 were good, and the crystal point condition and processing stability were excellent. Compared with Experimental Examples 1-12, the following results can be observed: the overall performance of the molded articles prepared from the composition of poly(3-hydroxyalkanoate) resins of four types of PHA, wherein the ratio of the first structural unit (3-hydroxybutyrate) and the second structural unit (other hydroxyalkanoates) in three of the PHAs respectively conforms to the above description.

[0167] The molded articles prepared in Examples 15-20 all exhibited excellent toughness, processing efficiency, crystal point characteristics, and processing stability. Compared with Examples 13-14, the following results can be observed: the molded articles prepared from compositions of four types of PHA resins, with the first structural unit (3-hydroxybutyrate) and the second structural unit (other hydroxyalkanoates) in proportions conforming to the above descriptions, possess relatively strong toughness, high processing efficiency, fewer crystal points, and better processing stability.

[0168] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and substance defined by the present invention; and such modifications or substitutions are still within the scope defined by the present invention.

Claims

1. A polyhydroxyalkanoate composition, characterized in that, The polyhydroxyalkanoate composition comprises: a polyhydroxyalkanoate-based resin A, a polyhydroxyalkanoate-based resin B, a polyhydroxyalkanoate-based resin C; and an optional additive, wherein the polyhydroxyalkanoate-based resin A, the polyhydroxyalkanoate-based resin B, and the polyhydroxyalkanoate-based resin C are each a poly(3-hydroxyalkanoate) copolymer containing a first structural unit and a second structural unit, the first structural unit being a 3-hydroxyalkanoate structural unit, and the second structural unit being an arbitrary hydroxyalkanoate structural unit, wherein in the polyhydroxyalkanoate-based resin A, the molar ratio of the first structural unit / the second structural unit is 99.9 / 0.1 to 99 / 1; in the polyhydroxyalkanoate-based resin B, the molar ratio of the first structural unit / the second structural unit is 97 / 3 to 94 / 6; and in the polyhydroxyalkanoate-based resin C, the molar ratio of the first structural unit / the second structural unit is 80 / 20 to 50 / 50, and wherein based on 100 parts by weight of the total of the polyhydroxyalkanoate-based resins, the polyhydroxyalkanoate composition comprises 1 to 10 parts by weight of the polyhydroxyalkanoate-based resin A, 75 to 90 parts by weight of the polyhydroxyalkanoate-based resin B, and 3 to 15 parts by weight of the polyhydroxyalkanoate-based resin C, wherein the polyhydroxyalkanoate composition further comprises a polyhydroxyalkanoate-based resin D, the polyhydroxyalkanoate-based resin D being a poly(3-hydroxyalkanoate) copolymer containing a first structural unit and a second structural unit, the first structural unit being a 3-hydroxyalkanoate structural unit, and the second structural unit being an arbitrary hydroxyalkanoate structural unit, wherein in the polyhydroxyalkanoate-based resin D, the molar ratio of the first structural unit / the second structural unit is 93 / 7 to 85 / 15, and The poly(3-hydroxyalkanoate) copolymer is a copolymer containing a 3-hydroxybutyrate unit as the first structural unit and another hydroxyalkanoate unit different from the first structural unit as the second structural unit.

2. The polyhydroxyalkanoate composition according to claim 1, characterized in that, Based on 100 parts by weight of the total of the polyhydroxyalkanoate-based resins, the polyhydroxyalkanoate composition comprises 1 to 10 parts by weight of the polyhydroxyalkanoate-based resin A, 75 to 90 parts by weight of the polyhydroxyalkanoate-based resin B, 3 to 15 parts by weight of the polyhydroxyalkanoate-based resin C, and 4 to 15 parts by weight of the polyhydroxyalkanoate-based resin D.

3. The polyhydroxyalkanoate composition of claim 1, wherein, In the polyhydroxyalkanoate-based resin D, the molar ratio of the first structural unit / the second structural unit is 91 / 9 to 88 / 12, and Based on 100 parts by weight of the total of the polyhydroxyalkanoate-based resins, the polyhydroxyalkanoate composition comprises 1 to 10 parts by weight of the polyhydroxyalkanoate-based resin A, 75 to 90 parts by weight of the polyhydroxyalkanoate-based resin B, 3 to 15 parts by weight of the polyhydroxyalkanoate-based resin C, and 5 to 15 parts by weight of the polyhydroxyalkanoate-based resin D.

4. The polyhydroxyalkanoate composition of claim 1, wherein The additive is selected from one or more of a nucleating agent, a plasticizer, a toughening agent, a reinforcing agent, a crosslinking agent, a chain extender, a lubricant, a dispersant, an organic filler, and an inorganic filler; and Optionally, the polyhydroxyalkanoate composition further comprises other bio-based or biodegradable materials.

5. A molded body prepared from the polyhydroxyalkanoate composition according to any one of claims 1 to 4.

6. The molded body according to claim 5, which comprises a molded body formed by extrusion molding, injection molding, calender molding, flow casting, blow molding, biaxial stretching; and / or the molded body comprises a tubular, sheet-like or film-like molded body.

7. A method for preparing a molded body using the polyhydroxyalkanoate composition according to any one of claims 1 to 4, the method comprising the steps of: 1) heating and melting the polyhydroxyalkanoate composition at a first temperature of 130 to 165°C; and 2) cooling the molten material in step 1) at a second temperature of 40 to 65°C to form a molded body. In step 2), the second temperature is 50 to 65°C.

8. The method of claim 7, wherein, ​

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