Method for manufacturing a shaped body

Abstract

Provided is a method for manufacturing a PHA molded article by injection molding, effectively utilizing the melt memory effect of a polyhydroxyalkanoate (PHA) powder granulate. 【Solution means】The method for manufacturing a molded article includes injection molding PHA by an injection molding machine. The injection molding includes melting a powder granulate containing PHA powder at a plasticizing melting temperature T P (unit: °C) to obtain a melt, injecting the melt into a mold, and cooling and solidifying the melt. The plasticizing melting temperature T P is represented by formula (1) T M -20 < T P ≦ T M +20 (1) (In the formula, T M (unit: °C) represents the highest melting peak temperature observed in differential scanning calorimetry in which the powder granulate is heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere.) is satisfied.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a molded article.

Background Art

[0002] Polyhydroxyalkanoate (PHA) is a biodegradable polyester resin produced by microorganisms in their bodies and is known for its biodegradability by microorganisms. On the other hand, PHA is easily decomposed by heat. For example, thermal decomposition significantly progresses in a temperature range exceeding 180°C. Further, although PHA is a crystalline polymer, its crystallization rate is slow, and it is difficult to crystallize in a mold during injection molding. Therefore, in the injection molding of PHA, in some cases, a pellet (hereinafter, may also be referred to as a "melt pellet") produced by melt-kneading raw material PHA powder and added with a crystallization nucleating agent is used as a molding material. However, the crystallization nucleating agent may adhere to the mold surface and become a factor that hinders continuous molding. Furthermore, the production of PHA melt pellets by a melt-kneading process requires a large amount of electric power.

[0003] Patent Document 1 discloses a powder granulated product that can be produced without undergoing melt-kneading. The powder granulated product is produced with less heat history and lower power consumption than melt pellets.

[0004] Patent Document 2 discloses a powder granulated product that can exhibit excellent crystallization characteristics due to the "melt memory effect" without blending a crystallization nucleating agent.

[0005] Patent Document 3 discloses a method for injection molding PHA using a molding material that does not contain a crystallization nucleating agent.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the injection molding of PHA, by effectively utilizing the melt memory effect of the PHA powder granulate, the crystallization and solidification of PHA can be accelerated without substantially blending a crystallization nucleating agent. Therefore, the present disclosure provides a method for manufacturing a PHA molded article by injection molding, effectively utilizing the melt memory effect of the PHA powder granulate.

Means for Solving the Problems

[0008] Aspects of the present disclosure include the following. [Aspect 1] A method for manufacturing a molded article, including injection molding polyhydroxyalkanoate (PHA) with an injection molding machine, wherein the injection molding includes melting a powder granulate containing PHA powder at a plasticizing melting temperature T P (unit: °C) to obtain a melt, injecting the melt into a mold, and cooling and solidifying the melt, wherein the plasticizing melting temperature T P satisfies the formula (1) T M -20 < T P ≦ T M +20 (1) (wherein T M (unit: °C) represents the highest melting peak temperature observed in a differential scanning calorimetry measurement in which the powder granulate is heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere.) A method satisfying the above. [Aspect 2] The method according to Aspect 1, wherein the powder granulate has a melt memory effect. [Aspect 3] The method according to Aspect 1 or 2, wherein the powder granulate is a compression granulate. [Aspect 4] The method according to aspect 3, wherein the powder granule has an outer wall portion formed by melting and solidifying at least a part of the PHA powder located at the outer edge of the powder granule, and the PHA powder compressed inside the outer wall portion is contained therein. [Aspect 5] The highest melting peak temperature T of the powder granule M is 140 °C or higher, The injection molding is performed according to formula (2) 10 ≦ S R ×V I ≦ 5,000 (2) The screw rotation speed S R (unit: rpm) and the injection speed V I (unit: mm / sec) are as defined in any one of aspects 1 to 4. [Aspect 6] The method according to any one of aspects 1 to 5, wherein the injection molding machine has a single-screw flight screw having a supply zone, a compression zone, and a metering zone. [Aspect 7] The injection molding is performed at a screw rotation speed S of 100 rpm or less R as defined in aspect 6. [Aspect 8] The injection molding is performed at an injection speed V of 100 mm / sec or less I as defined in any one of aspects 1 to 7. [Aspect 9] The set temperature T of the mold MOLD (unit: °C) and the crystallization temperature T of the powder granule C satisfy the formula (3) T C -60 < T MOLD ≦ T C (3) and The crystallization temperature T of the powder granule C is defined as the peak temperature of the crystallization exothermic peak observed during cooling in a differential scanning calorimetry measurement in which the powder granule is heated to 180 °C at a rate of 10 °C / min in a nitrogen atmosphere, held at 180 °C for 2 minutes, and then cooled at a rate of 10 °C / min, as defined in any one of aspects 1 to 8. [Aspect 10] The crystallization temperature T of the powder granulate C (unit: °C) is 80°C or higher, The crystallization temperature T of the powder granulate C is defined as the peak temperature of the crystallization exothermic peak observed during the temperature decrease in differential scanning calorimetry in which the powder granulate is heated to 180°C at a rate of 10°C / min in a nitrogen atmosphere, held at 180°C for 2 minutes, and then cooled at a rate of 10°C / min, according to the method described in any one of Aspects 1 to 9. [Aspect 11] The set temperature T of the mold MOLD is 60°C to 80°C, according to the method described in Aspect 10. [Aspect 12] The crystallization temperature T of the molded body CA (unit: °C) and the crystallization temperature T of the powder granulate C (unit: °C) satisfy the formula (4) 0.8 ≦ T CA / T C ≦ 1.2 (4) and The crystallization temperature T of the powder granulate C is defined as the peak temperature of the crystallization exothermic peak observed during the temperature decrease in differential scanning calorimetry in which the powder granulate is heated to 180°C at a rate of 10°C / min in a nitrogen atmosphere, held at 180°C for 2 minutes, and then cooled at a rate of 10°C / min, The crystallization temperature T of the molded body CA is defined as the peak temperature of the crystallization exothermic peak observed during the temperature decrease in differential scanning calorimetry in which the molded body is heated to 180°C at a rate of 10°C / min in a nitrogen atmosphere, held at 180°C for 2 minutes, and then cooled at a rate of 10°C / min, according to the method described in any one of Aspects 1 to 11. [Aspect 13] The molded body has a heat deflection temperature of 100°C or higher, and the heat deflection temperature is measured at a load of 0.45 MPa in accordance with ISO 75, according to the method described in any one of Aspects 1 to 12. [Aspect 14] The melt flow rate MFR of the PHA powder ORI (unit: g / 10 min), the melt flow rate MFR of the powder granulate GRN(Unit: g / 10 min), and the melt flow rate MFR of the molded article ART (Unit: g / 10 min) is given by formulas (a), (b), and (c) 1 ≦ MFR GRN / MFR ORI ≦ 5 (a) 1 ≦ MFR ART / MFR GRN ≦ 5 (b) 1 ≦ MFR ART / MFR ORI ≦ 10 (c) is satisfied, and the melt flow rate MFR of the PHA powder ORI , the melt flow rate MFR of the powder granulate GRN , and the melt flow rate MFR of the molded article ART is measured at 165 °C under a load of 5 kg in accordance with ISO 1133, and is the method according to any one of Aspects 1 to 13 [Advantages of the Invention]

[0009] According to the present disclosure, there is provided a method for producing a PHA molded article by injection molding, effectively utilizing the melt memory effect of the PHA powder granulate [Brief Description of the Drawings]

[0010]

Figure 1

Figure 2

[0011] A. Powder Granulate First, the powder granulate used as an injection molding material in the method for producing a molded article according to the embodiment will be described

[0012] The powder granulate contains polyhydroxyalkanoate (PHA) powder, preferably contains PHA powder as the main component, more preferably consists essentially of PHA powder, and even more preferably consists of PHA powder. In this specification, "including" and "containing" mean that additional components or elements may be included unless otherwise specified, and include "consisting essentially of" and "consisting of". "Consisting essentially of" means that additional components or elements that do not substantially have an adverse effect may be included. "Consisting of" means including only the described materials or elements, but does not exclude further containing inevitable impurities.

[0013] The powder granulate is produced by granulating PHA powder. Such a powder granulate has a melt memory effect. The powder granulate can preferably be produced by a powder compression granulation method. Details of the production method will be described later.

[0014] In this specification, a powder granulate having a melt memory effect means a powder granulate having the following characteristics i) and ii). i) In the first differential scanning calorimetry (DSC) in which the powder granulate is heated from room temperature to the first hold temperature T H1 at a rate of 10 °C / min in a nitrogen atmosphere, held at the first hold temperature T H1 for 2 minutes, and then cooled at a rate of 10 °C / min, a crystallization exothermic peak of PHA is observed during the cooling process, and the first hold temperature T H1 (unit: °C) is present. The first hold temperature T H1 is higher than the highest melting peak temperature T M . Here, the highest melting peak temperature T M (unit: °C) is defined as the highest temperature among the peak temperatures of the melting peaks observed in the differential scanning calorimetry in which the powder granulate is heated from room temperature to 10 °C / min in a nitrogen atmosphere. ii) In the second differential scanning calorimetry in which the powder granulate is heated from room temperature to the second hold temperature T H2 at a rate of 10 °C / min in a nitrogen atmosphere, held at the second hold temperature T H2In a second DSC where it is held for 2 minutes and cooled at a rate of 10 °C / min, the second hold temperature T H2 (unit: °C) is present. The second hold temperature T H2 is higher than the first hold temperature T H1 .

[0015] The melt memory effect refers to the phenomenon where a pseudo-crystalline phase structure order remains in the melt when a crystalline polymer is heated and melted (thermoplastically) above its melting point. The melt memory effect is a unique phenomenon that can occur in crystalline polymers. In the temperature region above the melting point, due to the long relaxation time for changing to a random aggregation state due to thermal disturbance, there remains a region that does not reach a disordered random state in a short time. Hereinafter, the pseudo-crystalline phase structure order caused by the melt memory effect may be referred to as a melt memory structure. Such a powder granulate is described in Patent No. 7454097 and can be manufactured by the method described in Patent No. 7454097.

[0016] The melt memory effect of the powder granulate can be evaluated by the method described in Patent No. 7454097. That is, in the cooling DSC curve obtained by differential scanning calorimetry (DSC) where the powder granulate is heated to a temperature above the melting point of PHA and then cooled at a rate of 10 °C / min, the peak temperature of the crystallization exothermic peak observed (i.e., the crystallization temperature of the powder granulate) T C (unit: °C) is higher than the crystallization temperature of the PHA powder measured in the same manner, then the powder granulate has a high melt memory effect. When the powder granulate has a high melt memory effect, the crystallization exothermic peak of the powder granulate often has a half-width smaller than the half-width of the crystallization exothermic peak of the PHA powder measured in the same manner. The above DSC can be performed, for example, by heating the measurement piece from room temperature to 180 °C at a rate of 10 °C / min in a nitrogen atmosphere, then holding it at 180 °C for 2 minutes, and immediately cooling the measurement piece at a rate of 10 °C / min in a nitrogen atmosphere.

[0017] When the powder granulate having a melt memory effect is heated and melted, the melt memory structure of PHA remaining in the melt functions as nuclei for crystallization during cooling. Since the melt memory structure is a pseudo-crystalline phase structure of PHA itself, the crystallization temperature T C of the powder granulate that crystallizes with the melt memory structure as nuclei is higher than the crystallization temperature of the molten pellet to which a crystallization nucleating agent is added. Also, the melt memory effect of the powder granulate is excellent in terms of persistence with respect to the melt residence time. On the other hand, when the melt memory structure in the melt is lost due to thermal disturbance and reaches a random agglomerated state, crystallization does not easily proceed during cooling.

[0018] A method for manufacturing a molded article using a powder granulate having a melt memory effect as an injection molding material can be advantageous in the following respects compared to a method for manufacturing a molded article using a conventional molten pellet containing a crystallization nucleating agent as an injection molding material.

[0019] i) Since the powder granulate is manufactured under the condition that the temperature of the granulate immediately after granulation is equal to or lower than the melting point of PHA as described in Patent No. 7454097, thermal decomposition of PHA during the granulation process and the resulting decrease in molecular weight are suppressed. Therefore, the PHA contained in the powder granulate can have a larger molecular weight than the PHA contained in the molten pellet. Accordingly, the PHA in the molded article manufactured from the powder granulate can also have a large molecular weight, whereby the molded article can have excellent physical properties.

[0020] ii) The process for manufacturing the powder granulate consumes significantly less electric power than the melt kneading granulation process using an extruder for manufacturing the molten pellet. Therefore, by manufacturing a molded article from the powder granulate, the total electric power consumption can be significantly reduced.

[0021] iii) By advantageously utilizing the melt memory effect of the powder granulate, the range of molding processing conditions (set temperatures of the injection molding machine and the mold, injection speed, screw rotation speed, etc.) can be expanded, so that it is easy to control the appearance and degree of crystallinity of the molded article.

[0022] iv) By using the powder granulate, a molded article not containing a crystallization nucleating agent can be produced. Since there is no risk of the crystallization nucleating agent eluting from the produced molded article, it can also be used for applications such as food use and medical use. Also, the crystallization nucleating agent does not adhere to the mold for molding and does not hinder continuous molding.

[0023] In one embodiment, the powder granulate has an outer wall portion formed by at least a part of the PHA powder located at the outer edge of the powder granulate being melted and solidified. Inside the outer wall portion, the compressed PHA powder is contained. In the present application, "melted and solidified" means solidifying after melting. The outer wall portion is located at the outer edge of the powder granulate. In the present specification, the outer wall portion is also referred to as a shell portion. At least a part of the compressed PHA powder inside the outer wall portion may be melted and solidified and welded, or at least a part may not be melted and solidified. The compressed PHA powder inside the outer wall portion may be in an unmelted state. That is, at least a part of the compressed PHA powder inside the outer wall portion may include an unmelted compressed powder form, or may include a partially melted and solidified form. The partially melted and solidified form is intended to be a form in which the constituent components of the PHA powder are partially melted and solidified, but do not form a strong welding structure capable of holding the PHA powder like the outer wall portion. In the present specification, the inside of the outer wall portion is also referred to as a core portion. The compressed PHA powder is contained in the core portion inside the outer wall portion. In the present specification, "compressed" means that the density of the PHA powder located in the core portion is higher than the bulk density of the PHA powder before granulation. Such a powder granulate is described in Japanese Patent No. 7387950 and can be produced by the method described in Japanese Patent No. 7387950. Also, such a powder granulate has the melt memory effect described above.

[0024] The outer wall part (shell part) has a dense structure containing a melt-solidified product of the PHA powder. On the other hand, although the core part inside it is compressed, it has a looser structure compared to the dense structure (welded structure) of the outer wall part containing the melt-solidified product. Since the outer wall containing the melt-solidified product of the PHA powder holds the compressed PHA powder present in the core part, the powder granule can have a stable structure, less powder loss, excellent handleability and safety, and can also bring about an improvement in the working environment for manufacturing the molded body.

[0025] The outer wall part (shell part) has a welded structure in which at least a part of the thermoplastic resin powder located at the outer edge of the powder granule is melt-solidified. The outer wall part may be a smooth surface to the extent that it has a glossy surface appearance. Also, even though it has not melted to the extent of becoming a smooth surface, the outer wall part may be constituted by a part of the constituent components of the thermoplastic resin powder melting and partially welding to adjacent components. The outer wall part can be formed by at least a part of the PHA powder melting due to frictional heat with the wall surface or heat transfer from the wall surface, for example, at the contact surface with the die hole in compression granulation. The thickness of the outer wall part can take various thicknesses depending on the manufacturing conditions of the PHA powder granule.

[0026] The core part is a part located inside the outer wall part and is a part where the compressed thermoplastic resin powder is contained. The PHA powder located in the core part may be porous, or may have a non-welded structure because heat does not reach the core part during granulation. The core part can have a structure in which the PHA powder maintains its powder shape (that is, a non-welded structure or a powder-like structure), or a structure in which a part is welded but the shape of the PHA powder remains.

[0027] In this specification, for the sake of simplicity of explanation, terms such as "outer wall part (shell part)" and "core part" are used. However, as described above, since the outer wall part is formed by melting the PHA powder due to heat during granulation, actually, the boundary between the outer wall part (shell part) and the core part does not clearly exist. The outer wall part (shell part) includes the welded structure of the PHA powder and refers to the part located at the outer edge of the powder granule and contributing to maintaining a certain shape of the powder granule. The core part refers to the part located inside the outer wall part (shell part).

[0028] The shape of the powder granule is preferably substantially cylindrical or substantially prismatic, and the powder granule preferably has an outer wall part on the side surface of the powder granule. In the present disclosure, the powder granule has a substantially cylindrical or substantially prismatic shape, and it is preferable that an outer wall part is formed on the side surface of the powder granule having a substantially cylindrical or substantially prismatic shape.

[0029] The powder granule having such a shape can be directly supplied to an injection molding machine for thermoplastic resins and thus can be used as a material for injection molding.

[0030] The powder granule can have any appropriate shape. Typically, when the powder granule is produced by compression granulation of the powder and granulation is carried out by passing through a circular die hole, the basic shape of the powder granule is a cylindrical pellet shape.

[0031] In addition, the "die" in this specification is a general term for tools corresponding to the mold for compressing and shaping the PHA powder granule.

[0032] When the powder granule is substantially cylindrical, the diameter of the powder granule is, for example, 2 mm to 7 mm, preferably 3 mm to 5 mm. The length (height) of the powder granule is, for example, 1 mm to 10 mm, preferably 2 mm to 7 mm. With such a shape, the powder granule is easy to handle. The diameter of the powder granule can be adjusted, for example, by the diameter of the die hole of the disk plate (die plate) during granulation, and the length can be adjusted by the distance between the disk plate and the cutter. The said distance can be any appropriate distance. The distance between the disk plate and the cutter is, for example, 1 mm to 30 mm, preferably 2 mm to 20 mm, preferably 3 mm to 10 mm.

[0033] The breaking strength based on the measurement of the wooden hardness tester of the powder granule is preferably 1.0 kg or more, preferably 2.0 kg or more, preferably 3.0 kg or more, preferably 4.0 kg or more, preferably 5.0 kg or more, preferably 6.0 kg or more, preferably 7.0 kg or more, preferably 8.0 kg or more, preferably 9.0 kg or more, preferably 10.0 kg or more. The upper limit may exceed the measurement limit of the wooden hardness tester (the measurement limit is 10 kg for "WPF1600 - B" manufactured by Shiro Sangyo Co., Ltd.). Within such a range, a powder granule excellent in handleability and melt processability can be obtained. Here, the breaking strength means the average breaking stress (breaking load) measured by pressing and crushing 20 or more (preferably 25 or more) powder granules in a direction perpendicular to the longitudinal direction (extrusion direction) of the powder granule. In the powder granule, since the shell part is composed of a molten resin, it is possible to maintain a stable shape as a granule despite being a powder granule. The diameter of the pressure surface of the pressure attachment of the wooden hardness tester is, for example, 5 mm.

[0034] The bulk density of the powder granule can be any appropriate bulk density, but is preferably 0.3 kg / L to 2.0 kg / L, preferably 0.5 kg / L to 1.0 kg / L. By increasing the bulk density, the supply speed and supply stability of the powder granule to the injection molding machine are increased.

[0035] The bulk density of the powder granulate is calculated by allowing the powder granulate to naturally fall into a 1-liter measuring cylinder until it is full, weighing out exactly 1 liter of the powder granulate in volume, and measuring its mass (unit: kg / L).

[0036] B.PHA powder The PHA powder, which is the raw material of the powder granulate, is a powdery polyhydroxyalkanoate (PHA) resin. PHA can be, for example, a compound produced in vivo by microorganisms using carbohydrates, oils and fats, etc. as food. Such PHA is primarily taken out from microorganisms as a powdery polymer.

[0037] PHA contains hydroxyalkanoic acid as a raw material component as a polymerization component and has at least repeating units derived from hydroxyalkanoic acid. PHA may be artificially synthesized or biosynthesized by microorganisms. Examples of hydroxyalkanoic acid include glycolic acid, 3-hydroxybutyrate, 3-hydroxypropionate, 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyheptanoate, 3-hydroxyoctanoate, 3-hydroxynonanoate, 3-hydroxydecanoate, 3-hydroxytetradecanoate, 3-hydroxyhexadecanoate, 3-hydroxyoctadecanoate, 4-hydroxybutyrate, 4-hydroxyvalerate, 5-hydroxyvalerate, or 6-hydroxyhexanoate, etc. The number of carbon atoms of hydroxyalkanoic acid may be 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, or 8 or more, preferably 3 or more. The number of carbon atoms of hydroxyalkanoic acid may be 15 or less, 12 or less, 10 or less, 8 or less, 6 or less, or 4 or less, preferably 10 or less, particularly 6 or less. Hydroxyalkanoic acid may be used alone or in combination of two or more.

[0038] Preferred examples of PHA include poly(3-hydroxyalkanoate) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0039] In the PHA powder, the weight-average molecular weight (Mw) of PHA is 200,000 or more, preferably 300,000 or more, preferably 500,000 or more, preferably 700,000 or more. Since the melt memory effect is manifested by the time delay in the process of the polymer molecular chain shifting from the crystalline ordered state to the random state in the molten state, the larger the molecular weight, the longer the relaxation time (the transition time to the random chain), which is advantageous in terms of the sustainability of the effect. When the weight-average molecular weight of PHA is 200,000 or more, it is preferable because the decrease or deactivation of the melt memory effect due to thermal disturbance can be effectively delayed. On the other hand, if the molecular weight of PHA becomes too large, the viscosity becomes too high, which is disadvantageous for causing solid-phase deformation, and the powder granulation tends to be difficult. Therefore, the weight-average molecular weight of PHA is preferably 3,000,000 or less, preferably 2,000,000 or less, preferably 1,500,000 or less, preferably 1,000,000 or less.

[0040] The above-mentioned weight-average molecular weight (Mw) can be determined as the weight-average molecular weight in terms of polystyrene by gel permeation chromatography (GPC). For example, as a GPC device, "Shodex GPC-101" manufactured by Showa Denko KK can be used, and as a column packing agent, polystyrene gel ("Shodex K-804" manufactured by Showa Denko KK) can be used, and it can be evaluated by GPC using an organic solvent mobile phase (for example, chloroform). Note that the column device, column packing agent, and organic solvent mobile phase can be appropriately selected, and for example, chloroform can be used.

[0041] The PHA powder may be a powdery resin obtained through its manufacturing process, i.e., it may be powdery due to the manufacturing process, or it may be obtained by pulverizing a non-powdery PHA resin such as pellets, lumps, or molded articles. The PHA powder can be obtained, for example, by cooling a molded article, pellet, or sprue or runner generated in injection molding at room temperature or using dry ice or liquid nitrogen as needed, and then pulverizing it using a pulverizer (e.g., manufactured by Dalton, trade names "Near Mill", "Silphy Feed Mill", "Atomizer", or "Impact Mill", etc.).

[0042] As long as the effects of the present embodiment can be obtained, the particle size of the PHA powder can be any appropriate particle size according to its form. The maximum diameter of the particles of the PHA powder before granulation is preferably 5 mm or less, and the minimum diameter is preferably 0.0001 mm or more.

[0043] The average particle size of the PHA powder is, for example, 0.001 mm or more and 1.0 mm or less. The average particle size of the PHA powder is preferably 1.0 mm or less, preferably 0.01 mm or more and 0.8 mm or less, and preferably 0.1 mm or more and 0.5 mm or less. In this specification, the average particle size can be measured by the laser diffraction method. The average particle size of the PHA powder can be the median diameter (d50) at which the cumulative particle size distribution is 50% on a volume basis. The median diameter (d50) may be a mixture of primary particles and aggregated particles. The PHA powder may be used alone or in combination of two or more kinds.

[0044] The PHA powder before granulation can have any bulk density, but the bulk density of the PHA powder is preferably 0.05 kg / L to 1.0 kg / L, more preferably 0.1 kg / L to 0.8 kg / L, and even more preferably 0.2 kg / L to 0.6 kg / L. When the bulk density of the PHA powder is within this range, compression granulation is easy to perform.

[0045] The bulk density of the PHA powder is calculated by allowing the PHA powder to fall naturally into a 1-liter measuring cylinder until it is full, accurately weighing out 1 liter of the PHA powder by volume, and measuring its mass (unit: kg / L).

[0046] Other components contained in the C.PHA powder granulate The powder granulate may contain any suitable additive as required. The additive may be in solid form such as powder or in liquid form. Examples of the additive include a binder, a dispersant, a crystallization nucleating agent, an antioxidant, a light stabilizer, a foaming agent, an ultraviolet absorber, an anti-blocking agent, a heat stabilizer, an impact modifier, an antibacterial agent, a compatibilizer, a processing aid, a lubricant, a coupling agent, a hydrolysis inhibitor, a deoxidizer, or a colorant (dye or pigment), etc. The additive may be used alone or in combination of two or more kinds.

[0047] The content of the additive in the powder granulate is, for example, 10.0% by mass or less, preferably 5.0% by mass or less, preferably 3.0% by mass or less, and more preferably 1.0% by mass or less.

[0048] The powder granulate may contain a binder as an additive. Here, the "binder" generally refers to a compound that exists between the PHA powders in addition to the components of the raw material PHA powder and can bind the powders together and exert the effect of enhancing the breaking strength of the granulate. However, if necessary, various compounds having a binding effect, preferably water-dispersible or water-soluble polymer compounds, polysaccharides, etc. can be appropriately selected and used as the binder.

[0049] In one embodiment, it is preferable to melt and bind a part of the components of the PHA powder to form a powder granulate, and it is preferable not to blend a binder.

[0050] The content of the binder is usually 10.0% by mass or less, preferably 5.0% by mass or less, preferably 3.0% by mass or less, preferably 1.0% by mass or less, preferably 0.5% by mass or less, preferably 0.1% by mass or less, preferably 0% by mass (undetectable) with respect to the total mass of the PHA powder granulated product.

[0051] In one embodiment, a dispersant is preferably used as an additive. As the dispersant, a surfactant is preferably used. The hydrophilic / hydrophobic balance in the dispersant (surfactant) can be controlled by adjusting the degree of esterification of the compound serving as the dispersant, the type of fatty acid (for example, the presence or absence of a hydroxyl group, saturated or unsaturated fatty acid, alkyl chain length), the degree of polymerization, and the like. The use of the dispersant can bring about effects such as improving the productivity (discharge rate) of the powder granulated product, reducing the frictional heat during granulation, and enhancing the cleanability of the granulation apparatus.

[0052] Examples of the dispersant include fatty acids, fatty acid metal salts, fatty acid sulfonates, fatty acid amides, acrylamides, polyhydric alcohol fatty acid esters, and polyglycerin fatty acid esters. The dispersant may be used alone or in combination of two or more.

[0053] In one embodiment, the dispersant is at least one selected from the group consisting of polyhydric alcohol fatty acid esters, fatty acid amides, polyglycerin fatty acid esters, condensed hydroxy fatty acids, and alcohol esters of condensed hydroxy fatty acids.

[0054] The polyhydric alcohol fatty acid ester is an ester compound composed of a polyhydric alcohol and a fatty acid. As the polyhydric alcohol fatty acid ester, for example, esters of polyhydric alcohols such as pentaerythritol and glycerin and fatty acids having 8 or more carbon atoms (preferably 8 to 24 carbon atoms, more preferably 10 to 22 carbon atoms) are used.

[0055] A fatty acid amide is a compound having a structure formed by dehydration condensation of a fatty acid and ammonia or a primary or secondary amine. Examples of fatty acid amides include saturated fatty acid monoamides such as lauric acid amide, palmitic acid amide, stearic acid amide, and behenic acid amide.

[0056] A polyglycerol fatty acid ester is an ester compound composed of polyglycerol and a fatty acid. Examples of polyglycerol fatty acid esters include diglycerol palmitate, diglycerol stearate, diglycerol oleate, decaglycerol palmitate, decaglycerol stearate, decaglycerol oleate, and the like.

[0057] The content of the dispersant is usually 0% by mass to 10.0% by mass, preferably 0.01% by mass to 9.0% by mass, preferably 0.1% by mass to 7.0% by mass, and more preferably 0.3% by mass to 5.0% by mass with respect to the total mass of the powder granulated product. Also, the content of the dispersant is usually 10.0% by mass or less, preferably 5.0% by mass or less, preferably 3.0% by mass or less, preferably 1.0% by mass or less, preferably 0.5% by mass or less, preferably 0.1% by mass or less, and preferably 0% by mass (undetectable) with respect to the total mass of the powder granulated product.

[0058] A crystallization nucleating agent can be blended as an additive in the powder granulated product. Examples of crystallization nucleating agents that can be blended in the powder granulated product include organometallic salt compounds such as metal phosphates, metal benzoates, metal pimelates, metal rosins, metal oxalates, and metal fatty acid salts; aliphatic organic esters; triallyl phosphate; polyalkylene glycols or their derivatives; aliphatic polyesters; organic compounds such as benzylidene sorbitol; dyes and pigments such as pentaerythritol, quinacridone, cyanine blue, and carbon black; minerals such as talc, mica, kaolin, clay, carbonate minerals, metal oxides, and metal sulfates; ionomers; or high melting point polyamides and other polymer compounds.

[0059] In one embodiment, talc, mica, kaolin, calcium carbonate, or the like is used as the crystallization nucleating agent. The crystallization nucleating agent may be used alone or in combination of two or more.

[0060] The content of the crystallization nucleating agent in the powder granulate is, for example, 0.1% by mass or more and 10.0% by mass or less, preferably more than 0.1% by mass and less than 10.0% by mass, preferably 0.2% by mass or more and 7.0% by mass or less, preferably 0.3% by mass or more and 5.0% by mass or less.

[0061] In one embodiment, the powder granulate substantially does not contain a crystallization nucleating agent. Since the powder granulate can exhibit a melt memory effect, excellent crystallization characteristics can be exhibited in the molding process without using a crystallization nucleating agent.

[0062] "Substantially does not contain a crystallization nucleating agent" means, for example, that the content of the crystallization nucleating agent in the powder granulate is 0.1% by mass or less, preferably that the content of the crystallization nucleating agent in the powder granulate is less than 0.1% by mass, preferably that the content of the crystallization nucleating agent in the powder granulate is 0.01% by mass or less, preferably that the content of the crystallization nucleating agent in the powder granulate is 0.005% by mass or less, preferably that the content of the crystallization nucleating agent in the powder granulate is 0.001% by mass or less, preferably that the content of the crystallization nucleating agent in the powder granulate is 0% by mass (undetectable).

[0063] Those skilled in the art should understand that the powder granulate may contain a crystallization nucleating agent or the powder granulate may be used together with a crystallization nucleating agent. When the powder granulate contains a crystallization nucleating agent or the powder granulate is used together with a crystallization nucleating agent, in addition to the crystallization promoting action by the melt memory effect, the crystallization promoting action by the crystallization nucleating agent can be obtained.

[0064] Method for manufacturing D.PHA powder granulate The powder granulated product can be manufactured by various powder granulators. For example, compression granulators such as the disk pelletizer method, screw extrusion method, briquetting method, compaction method, and tabletting method are mentioned as preferable granulators. The powder granulated product manufactured by the compression granulator is considered to have an outer wall portion containing oriented crystals due to the strong shear stress from the wall surface of the die holes in the granulation process. Therefore, the powder granulated product (i.e., compression granulated product) manufactured by the compression granulation method can particularly have a high melt memory effect.

[0065] Among the above examples, from the viewpoints of granulation productivity and the quality and shape uniformity of the obtained powder granulated product, the disk pelletizer method is preferably adopted. In the disk pelletizer method, a semi-wet granulation method in which appropriate moisture is contained in the PHA powder can be adopted. There may also be cases where granulation can be performed without using water. When granulation is performed without using water, the subsequent drying treatment after granulation may not be required. When granulation is performed without using water, the amount of energy required in the drying process can be reduced, and the emission amount of carbon dioxide generated in the manufacturing process can be greatly reduced.

[0066] As described above, the PHA powder granulated product can be advantageously obtained by the granulation method described in Patent No. 7454097 or Patent No. 7387950.

[0067] When the powder granulate is a mixture containing two or more types of PHA powder raw materials, or when it contains any component other than PHA, it is preferably uniformly mixed using any appropriate mixer. Examples of mixers include Henschel mixers, Nauta mixers, kneaders for powders (KDH, KDA, CKD, CPM) (Dalton Co.), Spartan mixers (SPM) (Dalton Co.), and SP granulators (SPG) (Dalton Co.). In order to obtain a preferable mixture with excellent granulation properties, it is preferable to use a mixing and stirring device equipped with appropriate stirring blades. For example, when using a Henschel mixer type mixer, the mixer blades are a combination of upper blades and lower blades. The upper blades are preferably Y1 blades (trade name, manufactured by Nippon Coke Industry Co., Ltd.), and the lower blades are preferably S0 blades (trade name, manufactured by Nippon Coke Industry Co., Ltd.). Also, it is preferable to install a deflector in the stirring tank and mix. That is, by using a mixing device capable of uniformly dispersing each component throughout the mixture, it is advantageous for enhancing the productivity and quality stability of the finally obtained powder granulate.

[0068] When manufacturing a powder granulate by the semi-wet granulation method described above, the blending amount of water can be any appropriate amount depending on the properties of the powder (e.g., water absorption). In this case, the blending amount of water is 3 to 30 parts by mass, preferably 5 to 25 parts by mass, and more preferably 5 to 20 parts by mass with respect to 100 parts by mass of the crystalline polymer powder. The semi-wet method can be adopted to improve the stability of granulation properties.

[0069] In the granulation process of the powder granulate, since local heat generation leads to die clogging, it may be advantageous for continuous granulation to include an appropriate amount of moisture in the PHA powder to suppress excessive temperature rise during granulation by the heat of vaporization of water.

[0070] The powder granulate can be dried after granulation, but the water content of the final powder granulate is preferably 10% by mass or less, preferably 5.0% by mass or less, preferably 3.0% by mass or less, preferably 1.0% by mass or less, and preferably 0.5% by mass or less. The water content of the final powder granulate can be appropriately selected according to the intended use.

[0071] The powder granulate is preferably granulated without adding water. When the water content of the powder granulate is low, the drying process after granulation may not be required. If granulation can be carried out without using water, the drying process is not required, so the carbon dioxide emissions generated in the powder granulation process can be greatly reduced.

[0072] The water content of the powder granulate granulated without adding water is, for example, 1.0% by mass or less, preferably 0.5% by mass or less, preferably 0.3% by mass or less, and preferably 0.2% by mass or less.

[0073] When manufacturing the powder granulate with a screw extrusion type compression granulator, since it is easy to install a temperature control device on the compression granulator and compression granulation can be performed at a low screw rotation speed, local heat generation due to rapid shear heating during granulation can be reduced. When manufacturing the powder granulate with a briquetting type, compaction type, or tableting type compression granulator, since the shear stress received by the powder from the wall surface of the die hole is smaller compared to the disk pelleter type, local heat generation during granulation can be reduced. Therefore, with the screw extrusion type, briquetting type, compaction type, and tableting type, the powder granulate can be continuously and stably manufactured without causing die clogging due to local heat generation even without adding water. When granulation is carried out without adding water, the drying process after granulation is not required, so the manufacturing process can be simplified and the energy consumption for the drying process can be reduced.

[0074] The water content of the powder granulate is measured using an infrared moisture meter.

[0075] The disk pelletizer granulator, as its basic structure, has one (flat die) or two disks (indicating cylindrical dies) with many holes of 2 mm to 30 mm, and a roller for pumping raw materials into the holes of the disks. The PHA powder (which may contain moisture) supplied between the disk and the roller or between two disks is pressed into the holes of the disk as the roller rotates, and a cylindrical extrudate is formed. By cutting the extrudate with a cutter or the like on the back surface of the disk, a pellet-shaped powder granulate can be obtained. The length of the granulate can be adjusted by the distance between the back surface of the disk and the cutter, the rotation speed of the roller, etc. The distance between the disk plate and the cutter can be any appropriate distance. The distance between the disk plate and the cutter is, for example, 1 mm to 30 mm, more preferably 2 mm to 20 mm, and even more preferably 3 mm to 10 mm.

[0076] More specifically, examples of the disk pelletizer method include the roller-disk die method, the roller-ring die method, the double-die method, the flat-die method, etc. Examples of commercially available disk pelletizer granulators include the disk pelletizer F series manufactured by Dalton.

[0077] The powder granulate may be sufficiently dried immediately before being used as an injection molding material. Thereby, the decrease in the molecular weight of PHA and / or the appearance defect of the molded body accompanying injection molding can be effectively suppressed. The moisture content of the powder granulate immediately before being used as an injection molding material is preferably 0.3% by mass or less, 0.1% by mass or less, 0.05% by mass or less, 0.03% by mass or less, or 0.02% by mass or less. Drying is usually preferably carried out at 70°C to 110°C, 75°C to 100°C, or 80°C to 90°C until a predetermined moisture content is reached. The moisture content of the powder granulate is measured using an infrared moisture meter.

[0078] E. Method for manufacturing a molded body by injection molding The manufacturing method of the molded article according to the embodiment includes using a powder granulate containing PHA as a molding material and injection-molding the PHA with an injection molding machine. The injection molding includes melting the powder granulate charged into the injection molding machine to obtain a melt, injecting the melt into a mold, and cooling and solidifying the melt. More specifically, after heating and melting the powder granulate in the cylinder of the injection molding machine, the melt is injected into the mold through a nozzle attached to the tip of the cylinder, and the melt is cooled and solidified in the mold to obtain a molded article.

[0079] The powder granulate is plastically melted at the plasticizing melting temperature T P in the injection molding machine. The plasticizing melting temperature T P (unit: °C) is given by formula (1) T M -20 < T P ≤ T M + 20 (1) (wherein T M (unit: °C) represents the highest melting peak temperature observed in a differential scanning calorimetry (DSC) in which the powder granulate is heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere).) is satisfied.

[0080] Note that the highest melting peak temperature T M means the highest temperature among the peak temperatures of those melting peaks when a plurality of melting peaks are observed by DSC, and means the peak temperature of that melting peak when one melting peak is observed by DSC.

[0081] In this specification, the plasticizing melting temperature T P is defined as the set temperature of the cylinder. When the set temperature varies depending on the part (zone) of the cylinder, generally, since the temperature of the part downstream in the flow direction of the powder granulate and its melt is set higher, the plasticizing melting temperature T P is defined as the set temperature of the part closest to the nozzle (i.e., the most downstream part of the cylinder). Note that the set temperature of the nozzle is generally the same as or lower than the set temperature of the most downstream part of the cylinder. The plasticizing melting temperature T Pis generally approximately equal to the temperature of the melt immediately before injection into the mold. The temperature of the melt immediately before injection into the mold can be measured with a contact thermometer (e.g., a thermocouple).

[0082] The plasticizing melt temperature T that satisfies formula (1) P By melting the powder granulate, it is possible to suppress the disappearance of the melt memory effect of the powder granulate due to thermal disturbance, mechanical mixing, etc., and thereby perform injection molding effectively utilizing the melt memory effect.

[0083] The plasticizing melt temperature T P is preferably T M -15 < T P ≦ T M +15 satisfies, and more preferably T M -10 < T P ≦ T M +10 satisfies, and even more preferably T M -5 < T P ≦ T M +5 satisfies.

[0084] In conventional injection molding using a melt pellet of PHA as a molding material, if the plasticizing melt temperature T P is less than the melting peak temperature of the melt pellet, not only will an excessive load be applied to the molding machine, but also plasticization will be insufficient, and surface defects such as sink marks or flow marks are likely to occur in the injection molded article due to insufficient flow.

[0085] On the other hand, in the method according to this embodiment using a powder granulate of PHA as a molding material, since the load on the molding machine is alleviated due to the large porosity of the powder granulate, even when the plasticizing melt temperature T P is T M -20 < T P < T M < T

[0086] Inside the injection molding machine, a flow field is formed along with the rotation of the screw for plasticization and metering and the piston movement of the screw for injection. The maximum temperature at which the melt memory effect in the flow field is maintained can be lower than the maximum temperature at which the melt memory effect in the stationary field is maintained. The plasticizing melt temperature T P is such that T P >T M + 20. When this condition is satisfied, the melt memory effect is reduced or disappears due to the action of the flow field, and the crystal solidification in the mold becomes slow. As a result, problems such as poor mold release from the mold, deformation of the molded body associated therewith, and lengthening of the molding cycle occur, and productivity may decrease.

[0087] In one embodiment, the maximum melting peak temperature T M of the powder granulated product is 140 °C or higher, and the screw rotation speed S R (unit: rpm) and injection speed V I (unit: mm / sec) of the injection molding machine satisfy the following formula (2) 10 ≦ S R × V I ≦ 5,000 (2) is satisfied.

[0088] S R × V I The value of is preferably 4,000 or less, more preferably 3,000 or less, still more preferably 2,500 or less, and most preferably 2,000 or less. Also, the value of S R × V I is preferably 50 or more, more preferably 100 or more, still more preferably 200 or more, and still more preferably 300 or more.

[0089] S R × V I By setting the value of to be 10 or more and 5,000 or less, an injection molded body of PHA with excellent quality and appearance can be manufactured with high productivity.

[0090] In one embodiment, the injection speed V Iis preferably 100 mm / second or less, 80 mm / second or less, 60 mm / second or less, 50 mm / second or less, or 30 mm / second or less.

[0091] In one embodiment, the screw of the injection molding machine is a single-screw flighted screw. The single-screw flighted screw has a feed zone, a compression zone, and a metering zone from upstream to downstream in the flow direction of the powder granulate and its melt. Such a single-screw flighted screw can suppress a decrease or disappearance of the melt memory effect due to a flow field caused by thermal disturbance and / or mechanical mixing. When the screw of the injection molding machine is a single-screw flighted screw, the rotational speed S of the screw R is preferably 100 revolutions per minute (rpm) or less, 80 rpm or less, 60 rpm or less, 50 rpm or less, or 30 rpm or less. The rotational speed S of the screw R can be suppressed from decreasing or disappearing due to a flow field caused by mechanical mixing by reducing it. The rotational speed S of the screw R can be 10 rpm or more.

[0092] In one embodiment, the set temperature T of the mold MOLD (unit: °C) and the crystallization temperature T of the powder granulate C (unit: °C) satisfy Equation (3) T C -60 < T MOLD ≤ T C (3) Note that the crystallization temperature T C is defined as the peak temperature of the crystallization exothermic peak observed during cooling in a differential scanning calorimetry (DSC) in which the powder granulate is heated to 180 °C at a rate of 10 °C / min in a nitrogen atmosphere, held at 180 °C for 2 minutes, and then cooled at a rate of 10 °C / min.

[0093] The set temperature T of the mold MOLD and the crystallization temperature T of the powder granulate C are preferably T C -50 < T MOLD ≤ T C More preferably, T C -45 < T MOLD ≤ T C More preferably, T C -40 < T MOLD ≤ T C Particularly preferably, T C -30 < T MOLD ≤ T C is satisfied.

[0094] The set temperature T of the mold MOLD is set to be equal to or lower than the crystallization temperature T C (°C) of the powder granulate, so that the crystallization and solidification of PHA in the mold can proceed rapidly, and a molded article with excellent quality and appearance can be produced with high productivity. Since the melt memory effect of the powder granulate is derived from the pseudo-crystalline phase structure of PHA itself, the crystallization temperature T C of the powder granulate can be higher than the crystallization temperature of the molten pellet to which a crystallization nucleating agent is added. Therefore, when injection molding is performed using a powder granulate having a melt memory effect as a molding material, compared with the conventional injection molding using a molten pellet, the set temperature T MOLD of the mold can be made higher. A higher set temperature T MOLD of the mold is advantageous for improving the crystallinity of the molded article, and it is possible to produce a molded article having a high heat deflection temperature under load (DTUL), flexural modulus (rigidity), and flexural strength, and having few appearance defects such as sink marks, flow marks, and orange peel, with high dimensional accuracy.

[0095] For example, when T C is 95°C to 100°C, the set temperature T MOLD of the mold is preferably 50°C to 95°C, more preferably 55°C to 90°C, still more preferably 60°C to 85°C, and most preferably 65°C to 80°C.

[0096] For example, when T C is 80°C to 95°C, the set temperature T MOLDis preferably 35°C to 80°C, more preferably 40°C to 75°C, still more preferably 45°C to 73°C, and most preferably 50°C to 70°C.

[0097] Thus, according to the crystallization temperature T C of the powder granulate, by appropriately selecting the set temperature T MOLD of the mold, the crystallization degree of the molded body can be effectively improved by making good use of the melt memory effect, and a molded body having a high load deflection temperature, flexural modulus, and flexural strength, and few appearance defects such as sink marks, flow marks, and orange peel can be manufactured with high dimensional accuracy.

[0098] When the set temperature T MOLD of the mold satisfies T MOLD ≤ T C - 60°C, the produced molded body cannot have sufficient crystallinity, which may lead to a decrease in the load deflection temperature and / or flexural strength of the molded body, and / or an increase in appearance defects.

[0099] When the highest melting peak temperature T M of the powder granulate is 140°C or higher, due to the melt memory effect, the powder granulate can have a high crystallization temperature T C (unit: °C). For example, the powder granulate used in the examples described later has a highest melting peak temperature T M of 147°C and a crystallization temperature T C of 95°C. When injection molding is performed using this powder granulate, while setting the set temperature T MOLD of the mold to a high temperature around 70°C (for example, 60°C to 80°C), the melt of the powder granulate is crystallized and solidified in the mold, and a molded body with excellent quality and appearance can be manufactured with high productivity.

[0100] In the method according to the embodiment, a powder granulate containing no crystallization nucleating agent can be used as a molding material. The crystallization nucleating agent may cause problems such as adhering to the mold and hindering continuous molding, lowering the flexural strength and / or the heat distortion temperature of the molded body, or causing adhesiveness in the molded body and making it difficult to remove the molded body from the mold. By using a powder granulate containing no crystallization nucleating agent as a molding material, these problems can be avoided.

[0101] In one embodiment, the crystallization temperature T CA (unit: °C) of the molded body and the crystallization temperature T C (unit: °C) of the powder granulate satisfy the formula (4) 0.8 ≤ T CA / T C ≤ 1.2 (4) Here, the crystallization temperature T C of the powder granulate is defined as the peak temperature of the crystallization exothermic peak observed during the temperature decrease in a DSC in which the powder granulate is heated to 180 °C at a rate of 10 °C / min in a nitrogen atmosphere, held at 180 °C for 2 minutes, and then cooled at a rate of 10 °C / min. The crystallization temperature T CA of the molded body is defined as the peak temperature of the crystallization exothermic peak observed during the temperature decrease in a DSC in which the molded body (specifically, a measurement piece cut out from the molded body) is heated to 180 °C at a rate of 10 °C / min in a nitrogen atmosphere, held at 180 °C for 2 minutes, and then cooled at a rate of 10 °C / min.

[0102] The above formula (4) indicates that the crystallization temperature T CA of the molded body is approximately equal to the crystallization temperature T C of the powder granulate, that is, the change in the crystallization temperature due to injection molding is small, indicating that the melt memory effect of the powder granulate is effectively exhibited in injection molding. A molded body manufactured by effectively exhibiting the melt memory effect has a high degree of crystallinity as described above. Therefore, a molded body satisfying the formula (4) can have a high heat distortion temperature, flexural strength, flexural modulus, dimensional accuracy, and excellent appearance.

[0103] In one embodiment, the powder granulate is produced under conditions such that the temperature of the granulate immediately after granulation is equal to or lower than the melting point of the PHA. In this case, the melt flow rate MFR ORI (unit: g / 10 min) of the PHA powder, the melt flow rate MFR GRN (unit: g / 10 min) of the powder granulate, and the melt flow rate MFR ART (unit: g / 10 min) of the molded article satisfy equations (a), (b), and (c) 1 ≤ MFR GRN / MFR ORI ≤ 5 (a) 1 ≤ MFR ART / MFR GRN ≤ 5 (b) 1 ≤ MFR ART / MFR ORI ≤ 10 (c) . The melt flow rate MFR ORI of the PHA powder, the melt flow rate MFR GRN of the powder granulate, and the melt flow rate MFR ART of the molded article are measured at 165°C and a load of 5 kg in accordance with ISO 1133.

[0104] The above equations (a), (b), and (c) indicate that the decrease in the molecular weight of the PHA during the process of producing a molded article from the PHA powder is sufficiently suppressed. By suppressing the decrease in the molecular weight of the PHA, it becomes possible to produce a molded article having more excellent mechanical properties.

[0105] In one embodiment, the produced molded article has a heat distortion temperature of 100°C or higher. The heat distortion temperature is measured at a load of 0.45 MPa in accordance with ISO 75.

[0106] The use of the molded article produced by the method according to the embodiment is not particularly limited. The molded article can be used for various purposes such as medical materials, tableware materials, agricultural materials, fishing materials, forestry materials, OA parts, home appliance parts, automobile members, daily sundries, stationery, preforms for bottle molding, etc. The powder granulate used in the method according to the embodiment can be manufactured with lower energy compared to the molten pellets used in conventional injection molding. Further, the molded article produced by the method according to the embodiment has excellent physical properties and appearance, and also has seawater degradability. Therefore, the method according to the embodiment can contribute to the reduction of the amount of greenhouse gas generation and the improvement of environmental problems caused by the marine disposal of plastics.

Examples

[0107] Hereinafter, the present embodiment will be specifically described with reference to examples, but the present embodiment is not limited to these examples at all. In addition, parts and % are based on mass standards unless otherwise specified.

[0108] Example 1 (1) Preparation of raw material powder Powder of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), which is a commercially available copolymer polyester of 3-hydroxybutyric acid and 3-hydroxyhexanoic acid (PHA powder), was prepared. The hydroxyhexanoate content of the PHA powder was 6 mol%, the bulk density was 0.30 kg / L, the highest melting peak temperature was 145 °C, the crystallization temperature was 85 °C, and the melt flow rate MFR ORI was 3.0 g / 10 min.

[0109] The bulk density of the PHA powder was measured in the same manner as the bulk density of the powder granulate described later.

[0110] The highest melting peak temperature and crystallization temperature of the PHA powder were measured in the same manner as the highest melting peak temperature T M and crystallization temperature T C of the powder granulate described later using 5 mg by weight of the PHA powder (see FIGS. 1 and 2).

[0111] Melt flow rate MFR of the PHA powder ORI was measured in accordance with ISO 1133 using a melt indexer (“No. 120 - FWP” manufactured by Yasuda Seiki Seisakusho Co., Ltd.) at a cylinder set temperature of 165°C, a load of 5 kg, and preheating for 4 minutes.

[0112] (2) Production of the powder granulated product 100 parts by mass of the PHA powder was charged into an FM mixer (manufactured by Nippon Coke & Engineering Co., Ltd., trade name “5FM5C / I”; processing volume: 5 L), and while rotating the stirring blades at a rotational speed of 2,000 rpm, 15 parts by mass of tap water was continuously spray - injected for 5 minutes to obtain a water - containing powder.

[0113] The water - containing powder was charged into a disk pelletizer (manufactured by Dalton Co., Ltd., trade name “Disk Pelletizer F - 5 / 11 - 175”), and a substantially cylindrical granulated product precursor was produced under the condition of a roller rotational speed of 108 rpm. The thickness of the die plate of the disk pelletizer was 15 mm, and the hole diameter was 3 mmφ. The length of the water - containing powder receiving compressive stress from the die hole wall surface inside the die plate (referred to as the effective length) was 12 mm. The granulation speed was 70 kg / h.

[0114] The obtained granulated product precursor was dried at 100°C for 9 hours using a hot - air circulation dryer (manufactured by Espec Co., Ltd., trade name “PH - 402”) to obtain a powder granulated product.

[0115] (3) Evaluation of the powder granulated product i) Structure observation The obtained powder granulated product was cut perpendicularly to the extrusion direction from the die hole with a razor blade to obtain an observation piece with a thickness of 0.5 mm, and the cut surface was observed with an optical microscope. An outer wall structure (shell structure) in which a part of the PHA powder was melted was observed at the outer edge of the cut surface, and the original form of the PHA powder that was not melted was recognized inside the outer wall structure (core part). From this observation result, it was confirmed that a powder granulated product having the same core - shell structure as the powder granulated product described in Patent No. 7387950 was produced.

[0116] ii) Bulk density The bulk density of the powder granulate was calculated by measuring the mass of 1 liter of the powder granulate obtained by allowing the dried powder granulate to fall naturally into a 1-liter graduated cylinder. The bulk density of the powder granulate was 0.45 kg / L.

[0117] iii) Moisture content The moisture content remaining in the powder granulate was measured using an infrared moisture meter (FD-660 manufactured by Kett Scientific Co., Ltd.). The moisture content of the powder granulate was 0.05% by mass.

[0118] iv) Fracture stress The fracture stress (unit: kg) of 25 powder granulates was measured using a wooden hardness tester (manufactured by Shiro Sangyo Co., Ltd., trade name "WPF1600-B"), and the average of the measured values was calculated. The fracture stress was measured by setting the powder granulate on the hardness tester with the side of the powder granulate facing down and pressing and crushing the powder granulate from the side using a 5 mmφ cylindrical pressing tool. In other words, the fracture stress was measured by pressing and crushing the powder granulate in a direction perpendicular to the longitudinal direction (extrusion direction). The average fracture stress of the powder granulate was 7 kg, and the powder granulate had excellent handleability.

[0119] v) Maximum melting peak temperature T M and crystallization temperature T C The powder granulate was cut perpendicular to the longitudinal direction (extrusion direction) with a razor blade to obtain a measurement piece weighing 5 mg. Differential scanning calorimetry (DSC) of the measurement piece was performed using "DSC6220" manufactured by SII NanoTechnology Inc. Specifically, in a nitrogen atmosphere, the measurement piece was heated from room temperature to 180°C at a rate of 10°C / min, held at 180°C for 2 minutes, and then cooled at a rate of 10°C / min while performing DSC to obtain the DSC curves shown in FIGS. 1 and 2. In the DSC curve during heating shown in FIG. 1, an endothermic melting peak was observed, and the highest peak temperature (i.e., the maximum melting peak temperature) T M was 147°C. In the DSC curve during cooling shown in FIG. 2, a distinct exothermic crystallization peak was observed, and the peak temperature (i.e., the crystallization temperature) T C was 95°C. The crystallization temperature T of the powder granulate CIt was higher than the crystallization temperature (85 °C) of the raw material PHA powder. Also, in a nitrogen atmosphere, the temperature of the measurement piece was raised from room temperature to 200 °C at a rate of 10 °C / min, held at 200 °C for 2 minutes, and then cooled at a rate of 10 °C / min while performing DSC. As a result, no crystallization exothermic peak was observed. From these facts, it was shown that a high melt memory effect was exhibited in the powder granulate. The half-value width of the crystallization exothermic peak of the powder granulate was smaller than that of the PHA powder.

[0120] vi) Melt flow rate MFR GRN Melt flow rate MFR of the powder granulate GRN was measured in accordance with ISO 1133 using a melt indexer (“No. 120 - FWP” manufactured by Yasuda Seiki Seisakusho Co., Ltd.) at a cylinder set temperature of 165 °C, a load of 5 kg, and preheating for 4 minutes. The melt flow rate MFR of the powder granulate GRN was 3.0 g / 10 min.

[0121] (4) Injection molding Using a dryer (manufactured by Espec, product name “PH - 402”), the powder granulate was dried at 100 °C for 8 hours to make the moisture content of the powder granulate 0.02 mass% or less. After drying, the powder granulate was put into an injection molding machine (“SI - 80IV - D150B” manufactured by Toyo Machine Metal Co., Ltd., clamping force 80 tons), and a dumbbell - shaped molded body for ISO test (thickness 4 mm) was produced.

[0122] The screw of the injection molding machine was a single - flight screw having a feed zone, a compression zone, and a metering zone from upstream to downstream in the flow direction of the powder granulate and its melt. The cylinder of the injection molding machine was divided into a region under the hopper for charging the powder granulate (zone 1), a region corresponding to the feed zone of the screw (zone 2), a region corresponding to the compression zone of the screw (zone 3), a region corresponding to the metering zone of the screw (zone 4), and a region corresponding to the tip of the screw (zone 5) from upstream to downstream in the flow direction of the powder granulate and its melt, and the temperatures of zones 1 - 5 and the nozzle attached to the tip of the cylinder were controlled independently. The set temperature of zone 1 was 40°C, and the set temperatures of zones 2 - 5 and the nozzle were all 160°C. In this case, the plasticizing melt temperature T P was 160°C. Also, when the temperature of the melt immediately before being injected into the mold ejected from the nozzle was measured with a contact thermocouple, it was 160°C.

[0123] The screw rotation speed S R was 30 rpm, the injection speed V I was 40 mm / s, the mold set temperature T MOLD was 70°C, and the cooling time was 60 seconds.

[0124] (5) Evaluation of the molded body i) Ease of removal from the mold Multiple injection moldings were performed, and the ease of removal of the molded body from the mold was evaluated according to the following criteria. The results are shown in Table 1.

[0125] A: Crystallization was sufficient, and it could be easily pushed out from the mold by the ejector pins. B: Crystallization had progressed, but there were cases where it could not be pushed out from the mold by the ejector pins. C: Crystallization was insufficient, and it could not be pushed out from the mold by the ejector pins.

[0126] ii) Crystallization temperature T CA Using a razor blade, a measurement piece weighing 5 mg was cut out from the central part of the molded body. In the same manner as the melt memory effect of the above-described powder granulate, the crystallization temperature T CA of the molded body was measured. The results are shown in Table 1. The crystallization temperature T CA of the molded body was 98°C, which was 3°C higher than the crystallization temperature T C (95°C) of the powder granulate.

[0127] iii) Melt Flow Rate MFR ART A measurement piece was cut out from the molded body, and the melt flow rate MFR ART of the molded body was measured using this measurement piece. The measurement was carried out in accordance with ISO1133, using a melt indexer ("No. 120 - FWP" manufactured by Yasuda Seiki Seisakusho Co., Ltd.), at a cylinder setting temperature of 165°C, a load of 5 kg, and a preheating time of 4 minutes. The results are shown in Table 1.

[0128] iv) Appearance The appearance of the molded body was evaluated according to the following criteria. The results are shown in Table 1.

[0129] AA: There were almost no appearance defects such as sink marks, flow marks, and orange peel. A+: Appearance defects such as sink marks, flow marks, and orange peel were occasionally seen (the appearance defects were mild). A: Appearance defects such as sink marks, flow marks, and orange peel were easily confirmed (the appearance defects were moderate). B: Appearance defects such as sink marks, flow marks, and orange peel were severe (the appearance defects were severe).

[0130] Since sink marks are depressions due to the shrinkage of the molded body, a molded body with sink marks is judged to have poor dimensional accuracy.

[0131] v) Bending test In accordance with ISO178, using an autograph ("AG-X" manufactured by Shimadzu Corporation), in a constant temperature chamber at 23°C, at a speed of 2 mm / min, the flexural strength (unit: MPa) and flexural modulus (unit: MPa) of the molded body were measured. For the measurement, strip-shaped test pieces with a length of 80 mm prepared by cutting from dumbbell-shaped molded bodies were used. The results are shown in Table 1.

[0132] vi) Heat deflection temperature In accordance with ISO75, using an HDT ("3M-2" manufactured by Toyo Seiki Seisakusho), in a constant temperature chamber at 23°C, with a load of 0.45 MPa and a heating rate of 120°C / h, the heat deflection temperature was measured. For the measurement, strip-shaped test pieces with a length of 80 mm prepared by cutting from dumbbell-shaped molded bodies were used. The results are shown in Table 1.

[0133] As shown in Table 1, the molded body could be easily taken out from the mold and had excellent appearance, high flexural strength, high flexural modulus, and high heat deflection temperature. These indicate that the molded body has sufficient crystallinity.

[0134] Example 2 A dumbbell-shaped molded body was produced in the same manner as in Example 1, except that the injection speed in injection molding was 10 mm / sec. The ease of removal of the molded body, crystallization temperature T CA , melt flow rate MFR ART , appearance, flexural strength, flexural modulus, and heat deflection temperature were evaluated in the same manner as in Example 1. The results are shown in Table 1. The molded body could be easily taken out from the mold and had excellent appearance, high flexural strength, high flexural modulus, and high heat deflection temperature.

[0135] Example 3 In injection molding, except that the set temperatures of zones 2 to 5 and the nozzle were all 150°C to make the plasticizing and melting temperature T P 150°C and the screw rotation speed S R 100 rpm, a dumbbell-shaped molded body was produced in the same manner as in Example 1. The ease of removal of the molded body, crystallization temperature T CA , melt flow rate MFRART The appearance, flexural strength, flexural modulus, and heat distortion temperature were evaluated in the same manner as in Example 1. The results are shown in Table 1. The molded article could be easily taken out of the mold and had excellent appearance, high flexural strength, high flexural modulus, and high heat distortion temperature.

[0136] Example 4 In injection molding, except that the set temperatures of zones 2 to 5 and the nozzle were all 140°C and the plasticizing and melting temperature T P was 140°C and the screw rotation speed S R was 100 rpm, a dumbbell-shaped molded article was produced in the same manner as in Example 1, and the ease of removal of the molded article, crystallization temperature T CA , melt flow rate MFR ART , appearance, flexural strength, flexural modulus, and heat distortion temperature were evaluated in the same manner as in Example 1. The results are shown in Table 1. The molded article could be easily taken out of the mold and had excellent appearance, high flexural strength, high flexural modulus, and high heat distortion temperature.

[0137] Example 5 In injection molding, except that the injection speed V I was 80 mm / s, a dumbbell-shaped molded article was produced in the same manner as in Example 1, and the ease of removal of the molded article, crystallization temperature T CA , melt flow rate MFR ART , appearance, flexural strength, flexural modulus, and heat distortion temperature were evaluated in the same manner as in Example 1. The results are shown in Table 1. The molded article sometimes could not be taken out with the ejector pins. Appearance defects were found in the molded article.

[0138] Example 6 In injection molding, except that the mold set temperature T MOLD was 40°C, a dumbbell-shaped molded article was produced in the same manner as in Example 1, and the ease of removal of the molded article, crystallization temperature T CA , melt flow rate MFR ART, Appearance, flexural strength, flexural modulus, and heat distortion temperature were evaluated in the same manner as in Example 1. The results are shown in Table 1. The molded article had sufficient appearance, flexural strength, flexural modulus, and heat distortion temperature, but had more sink marks and a lower heat distortion temperature than the molded article of Example 1. In Example 6, the mold set temperature T MOLD was 40 °C, which was lower than the mold set temperature T MOLD of Example 1. Therefore, compared with Example 1, the crystallization and solidification of PHA inside the mold were slower, resulting in inferior appearance and heat distortion temperature compared to Example 1.

[0139] Example 7 A dumbbell-shaped molded article was produced in the same manner as in Example 1, except that the screw rotation speed S R in injection molding was 100 rpm. The ease of removing the molded article from the mold, crystallization temperature T CA , melt flow rate MFR ART , appearance, flexural strength, flexural modulus, and heat distortion temperature were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0140] The molded article sometimes could not be removed from the mold with the ejection pins. The molded article removed from the mold by hand had sufficient appearance, high flexural strength, high flexural modulus, and high heat distortion temperature, but had more orange peel and sink marks and inferior appearance compared to the molded article of Example 1, and had a lower heat distortion temperature. In Example 7, since the screw rotation speed S R was larger than that of Example 1, the melt memory effect decreased due to the flow field, resulting in inferior ease of removing the molded article, appearance, and heat distortion temperature compared to Example 1. A broad exothermic peak was observed in the cooling DSC curve of the molded article, and the peak temperature was about 73 °C. This is significantly different from the crystallization temperature T C (95 °C) of the powder granulate, indicating that the crystallization temperature was not maintained during the injection molding process. This result also suggests that the melt memory effect decreased due to the influence of the flow field caused by a large screw rotation speed S R .

[0141] Comparative Example 1 In injection molding, except that the set temperatures of zones 2 to 5 and the nozzle were both 170°C and the plasticizing and melting temperature T P was 170°C, a dumbbell-shaped molded article was produced in the same manner as in Example 1. The molded article had insufficient crystal solidification and could not be taken out from the mold with a push pin. Therefore, the molded article was taken out from the mold manually, and the crystallization temperature T CA and appearance of the molded article were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0142] The molded article had severe orange peel and sink marks. In addition, a broad exothermic peak was observed in the cooling DSC curve of the molded article, and the peak temperature was about 73°C. This is significantly different from the crystallization temperature T C (95°C) of the powder granulate, and it is understood that the crystallization temperature was not maintained during the injection molding process.

[0143] [Table 1]

[0144] In this specification, a numerical range represented by the symbol "~" includes the numerical values described before and after the symbol "~" as the lower limit and the upper limit, respectively, unless otherwise specified. Also, the upper limit value and / or the lower limit value of the numerical range described in this specification can define a preferred range by any combination. For example, a preferred range can be defined by any combination of the upper limit value and the lower limit value of the numerical range, a preferred range can be defined by any combination of the upper limit values of the numerical range, and a preferred range can be defined by any combination of the lower limit values of the numerical range.

[0145] In this application, the term "and / or" represents at least one of the listed items and all possible combinations.

[0146] Although the above embodiment has been described in detail, the specific configuration is not limited to this embodiment, and even if there are design changes within the scope not departing from the gist of the present disclosure, they are included in the present disclosure.

Claims

1. A method for producing a molded body, comprising the steps of: Injecting polyhydroxyalkanoate (PHA) with an injection molding machine; The injection molding is performed by subjecting the powder granules containing the PHA powder to a plasticization melting temperature T Ｐ (unit: ° C.) to obtain a melt, pouring the melt into a mold, and cooling the melt to solidify; The plasticizing melting temperature T Ｐ But, formula (1) T Ｍ -20<T Ｐ ≦T Ｍ +20 (1) (In the formula, T Ｍ (unit: ° C.) represents the highest melting peak temperature observed in differential scanning calorimetry in which the powder granule is heated from room temperature at a rate of 10° C. / min in a nitrogen atmosphere.) The method, wherein the powder granulation has a melt memory effect.

2. A method for producing a molded body, comprising the steps of: Injecting polyhydroxyalkanoate (PHA) with an injection molding machine; The injection molding includes melting a powder granulation material containing a PHA powder at a plasticizing melting temperature T P (unit: ° C.) to obtain a melt, injecting the melt into a mold, and cooling the melt to solidify it; The plasticization melting temperature T P is expressed by the formula (1) T M -20<T P ≦T M +20 (1) (wherein T M (unit: ° C.) represents the highest melting peak temperature observed in differential scanning calorimetry in which the powder granule is heated from room temperature at a rate of 10° C. / min in a nitrogen atmosphere), The powder granule is a compressed granule, The powder granulation product has an outer wall portion formed by melting and solidifying at least a portion of the PHA powder located at the outer edge of the powder granulation product, and the compressed PHA powder is contained inside the outer wall portion.

3. A method for producing a molded body, comprising: Injecting polyhydroxyalkanoate (PHA) with an injection molding machine; The injection molding includes melting a powder granulation material containing a PHA powder at a plasticizing melting temperature T P (unit: ° C.) to obtain a melt, injecting the melt into a mold, and cooling the melt to solidify it; The plasticization melting temperature T P is expressed by the formula (1) T M -20<T P ≦T M +20 (1) (wherein T M (unit: ° C.) represents the highest melting peak temperature observed in differential scanning calorimetry in which the powder granule is heated from room temperature at a rate of 10° C. / min in a nitrogen atmosphere), The set temperature T MOLD (unit: ° C.) of the mold and the crystallization temperature T C of the powder granulated product are expressed by the following formula (3). T C -60<T MOLD ≦T C (3) Fulfilling The crystallization temperature T C of the powder granule is defined as a peak temperature of a crystallization exothermic peak observed during temperature decrease in a differential scanning calorimetry measurement in which the powder granule is heated to 180° C. at a rate of 10° C. / min in a nitrogen atmosphere, held at 180° C. for 2 minutes, and then cooled at a rate of 10° C. / min.

4. A method for producing a molded body, comprising the steps of: Injecting polyhydroxyalkanoate (PHA) with an injection molding machine; The injection molding includes melting a powder granulation material containing a PHA powder at a plasticizing melting temperature T P (unit: ° C.) to obtain a melt, injecting the melt into a mold, and cooling the melt to solidify it; The plasticization melting temperature T P is expressed by the formula (1) T M -20<T P ≦T M +20 (1) (wherein T M (unit: ° C.) represents the highest melting peak temperature observed in differential scanning calorimetry in which the powder granule is heated from room temperature at a rate of 10° C. / min in a nitrogen atmosphere), The crystallization temperature T C (unit: ° C.) of the powder granule is 80° C. or higher; The crystallization temperature T C of the powder granule is defined as a peak temperature of a crystallization exothermic peak observed during temperature decrease in a differential scanning calorimetry measurement in which the powder granule is heated to 180° C. at a rate of 10° C. / min in a nitrogen atmosphere, held at 180° C. for 2 minutes, and then cooled at a rate of 10° C. / min.

5. A method for producing a molded body, comprising the steps of: Injecting polyhydroxyalkanoate (PHA) with an injection molding machine; The injection molding includes melting a powder granulation material containing a PHA powder at a plasticizing melting temperature T P (unit: ° C.) to obtain a melt, injecting the melt into a mold, and cooling the melt to solidify it; The plasticization melting temperature T P is expressed by the formula (1) T M -20<T P ≦T M +20 (1) (wherein T M (unit: ° C.) represents the highest melting peak temperature observed in differential scanning calorimetry in which the powder granule is heated from room temperature at a rate of 10° C. / min in a nitrogen atmosphere), The crystallization temperature T CA (unit: ° C.) of the molded body and the crystallization temperature T C (unit: ° C.) of the powder granulated product are expressed by the following formula (4): 0.8≦T CA / TC ≦1.2 (4) Fulfilling The crystallization temperature T C of the powder granulated product is defined as the peak temperature of a crystallization exothermic peak observed during temperature drop in a differential scanning calorimetry in which the powder granulated product is heated to 180° C. at a rate of 10° C. / min in a nitrogen atmosphere, held at 180° C. for 2 minutes, and then cooled at a rate of 10° C. / min; The crystallization temperature T CA of the molded body is defined as the peak temperature of a crystallization exothermic peak observed during cooling in a differential scanning calorimetry measurement in which the molded body is heated to 180° C. at a rate of 10° C. / min in a nitrogen atmosphere, held at 180° C. for 2 minutes, and cooled at a rate of 10° C. / min.

6. A method for producing a molded body, comprising the steps of: Injecting polyhydroxyalkanoate (PHA) with an injection molding machine; The injection molding includes melting a powder granulation material containing a PHA powder at a plasticizing melting temperature T P (unit: ° C.) to obtain a melt, injecting the melt into a mold, and cooling the melt to solidify it; The plasticization melting temperature T P is expressed by the formula (1) T M -20<T P ≦T M +20 (1) (wherein T M (unit: ° C.) represents the highest melting peak temperature observed in differential scanning calorimetry in which the powder granule is heated from room temperature at a rate of 10° C. / min in a nitrogen atmosphere), The molded article has a deflection temperature under load of 100° C. or more, the deflection temperature being measured at a load of 0.45 MPa in accordance with ISO 75.

7. A method for producing a molded body, comprising the steps of: Injecting polyhydroxyalkanoate (PHA) with an injection molding machine; The injection molding includes melting a powder granulation material containing a PHA powder at a plasticizing melting temperature T P (unit: ° C.) to obtain a melt, injecting the melt into a mold, and cooling the melt to solidify it; The plasticization melting temperature T P is expressed by the formula (1) T M -20<T P ≦T M +20 (1) (wherein T M (unit: ° C.) represents the highest melting peak temperature observed in differential scanning calorimetry in which the powder granule is heated from room temperature at a rate of 10° C. / min in a nitrogen atmosphere), The melt flow rate MFR ORI (unit: g / 10 min) of the PHA powder, the melt flow rate MFR GRN (unit: g / 10 min) of the powder granule, and the melt flow rate MFR ART (unit: g / 10 min) of the molded body are expressed by the formulas (a), (b), and (c). 1≦MFR GRN / MFR ORI ≦5 (a) 1≦MFR ART / MFR GRN ≦5 (b) 1≦MFR ART / MFR ORI ≦10 (c) and a melt flow rate MFR ORI of the PHA powder, a melt flow rate MFR GRN of the powder granule, and a melt flow rate MFR ART of the molded body are measured at 165° C. and a load of 5 kg in accordance with ISO 1133.

8. The method according to any one of claims 2 to 7, wherein the powder granule has a melt memory effect.

9. The method according to any one of claims 1, 3 to 7, wherein the powder granules are compressed granules.

10. The method according to claim 9, wherein the powder granulation product has an outer wall portion formed by melting and solidifying at least a portion of the PHA powder located at the outer edge of the powder granulation product, and the compressed PHA powder is contained inside the outer wall portion.

11. The maximum melting peak temperature T Ｍ is 140° C. or more, The injection molding is carried out by reacting a mixture of the above-mentioned components represented by the formula (2) 10≦S Ｒ ×V Ｉ ≦5,000 (2) The screw rotation speed S that satisfies Ｒ (unit: rpm) and injection speed V Ｉ The method according to any one of claims 1 to 7, wherein the method is carried out in mm / sec.

12. The method of any one of claims 1 to 7, wherein the injection molding machine has a single flight screw having a feed zone, a compression zone, and a metering zone.

13. Screw rotation speed S below 100 rpm Ｒ The method of claim 12 , wherein the injection molding is performed at

14. The injection molding is performed at an injection speed V of 100 mm / sec or less. Ｉ The method according to any one of claims 1 to 7, wherein

15. The set temperature T ＭＯＬＤ (unit: ° C.) and the crystallization temperature T Ｃ But, equation (3) T Ｃ -60<T ＭＯＬＤ ≦T Ｃ (3) Fulfilling The crystallization temperature T Ｃ is defined as the peak temperature of a crystallization exothermic peak observed during temperature reduction in a differential scanning calorimetry measurement in which the powder granule is heated to 180°C at a rate of 10°C / min in a nitrogen atmosphere, held at 180°C for 2 minutes, and cooled at a rate of 10°C / min.

16. The crystallization temperature T Ｃ (unit: ° C.) is 80° C. or more, The crystallization temperature T Ｃ is defined as the peak temperature of a crystallization exothermic peak observed during temperature reduction in a differential scanning calorimetry measurement in which the powder granule is heated to 180°C at a rate of 10°C / min in a nitrogen atmosphere, held at 180°C for 2 minutes, and cooled at a rate of 10°C / min.

17. The set temperature T ＭＯＬＤ The method according to claim 4, wherein the temperature is from 60°C to 80°C.

18. The method according to claim 16, wherein the set temperature T MOLD of the mold is 60°C to 80°C.

19. The crystallization temperature T ＣＡ (unit: ° C.) and the crystallization temperature T Ｃ (unit: ° C.) is expressed by the formula (4) 0.8≦T ＣＡ / T Ｃ ≦1.2 (4) Fulfilling The crystallization temperature T Ｃ is defined as the peak temperature of the crystallization exothermic peak observed during temperature drop in a differential scanning calorimetry measurement in which the powder granule is heated to 180° C. at a rate of 10° C. / min in a nitrogen atmosphere, held at 180° C. for 2 minutes, and then cooled at a rate of 10° C. / min, The crystallization temperature T ＣＡ is defined as the peak temperature of a crystallization exothermic peak observed during cooling in a differential scanning calorimetry measurement in which the molded body is heated to 180°C at a rate of 10°C / min in a nitrogen atmosphere, held at 180°C for 2 minutes, and cooled at a rate of 10°C / min.

20. The method according to any one of claims 1 to 5 and 7, wherein the molded body has a deflection temperature under load of 100 ° C. or more, and the deflection temperature under load is measured at a load of 0.45 MPa in accordance with ISO 75.

21. Melt flow rate (MFR) of the PHA powder ＯＲＩ (Unit: g / 10 min), the melt flow rate MFR of the powder granule ＧＲＮ (unit: g / 10 min), and the melt flow rate MFR of the molded product ＡＲＴ (Unit: g / 10 min) is represented by the formulas (a), (b), and (c) 1≦MFR ＧＲＮ / MFR ＯＲＩ ≦5 (a) 1≦MFR ＡＲＴ / MFR ＧＲＮ ≦5 (b) 1≦MFR ＡＲＴ / MFR ＯＲＩ ≦10 (c) and the melt flow rate MFR of the PHA powder is ＯＲＩ The melt flow rate MFR of the powder granule ＧＲＮ and the melt flow rate MFR of the molded body ＡＲＴ The method according to any one of claims 1 to 6, wherein the thermal expansion coefficient is measured at 165 ° C and a load of 5 kg in accordance with ISO 1133.

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