Method for producing molded body, method for producing extrusion molded body, and fiber and method for producing same

Abstract

One aspect of the present disclosure provides a method for producing a polyhydroxyalkanoate (PHA) molded body by means of injection molding, the method advantageously utilizing a melt memory effect of a granulated product of a PHA powder. A method for producing a molded body according to one embodiment comprises injection molding of PHA using an injection molding machine. The injection molding includes: melting a granulated product containing a PHA powder at a plasticizing / melting temperature TP (unit: ºC) so as to obtain a molten product; injecting the molten product into a mold; and cooling and solidifying the molten product. The plasticizing / melting temperature TP satisfies formula (A1): TM-20<TP≤TM+20　 (in the formula, TM (unit: ºC) denotes the highest melt peak temperature observed in differential scanning calorimetric measurements in which the temperature of the granulated product of the powder is increased from room temperature at a rate of 10°C / min in a nitrogen atmosphere).

Description

Method for manufacturing a molded article, method for manufacturing an extruded article, and fiber and method for manufacturing the same

[0001] This disclosure relates to a method for manufacturing a molded article. Furthermore, this disclosure relates to a method for manufacturing an extruded article. In addition, this disclosure relates to fibers and methods for manufacturing the same.

[0002] Polyhydroxyalkanoates (PHAs) are biopolyester resins produced by microorganisms within their bodies and are known for their biodegradability in marine environments, making them highly promising for use. However, PHAs are easily decomposed by heat, and thermal decomposition progresses significantly at temperatures exceeding 180°C. Furthermore, although PHAs are crystalline polymers, their crystallization rate is slow, making them difficult to crystallize within the mold during injection molding. For this reason, in PHA injection molding, pellets made by melting and kneading raw PHA powder (hereinafter sometimes referred to as "molten pellets") with added crystallization nucleating agents are sometimes used as the molding material. However, crystallization nucleating agents can adhere to the mold surface, hindering continuous molding. Moreover, the production of PHA molten pellets by the melting and kneading process requires a large amount of electricity.

[0003] Furthermore, because PHA has a slow crystallization solidification rate, problems such as adhesion to cooling rolls, fusion of extruded products, and instability of shape and dimensions due to post-shrinkage occur during extrusion molding. For this reason, even in PHA extrusion molding, molten pellets of PHA with added crystallization nucleating agents or molten pellets made by compounding PHA with other resins are sometimes used as the molding material. However, crystallization nucleating agents can cause the extruded product to stick to the cooling rolls and deposits on the die (called "eye residue"), which can hinder continuous molding. Products manufactured using molten pellets made by compounding PHA with other resins generally tend to have a slow marine disintegration rate.

[0004] Textile products such as monofilaments, multifilaments, and nonwoven fabrics are used in a variety of applications, including marine materials, agricultural materials, civil engineering materials (e.g., fiber sheets for soil reinforcement), medical materials, sanitary materials, automotive interior materials, and industrial materials (e.g., filters, wiping).

[0005] Examples of nonwoven fabric manufacturing methods include the spunbond method and the meltblown method. In the spunbond method, thermoplastic resin raw materials are melt-extruded to form continuous long fibers, which are then stretched with an airflow or the like, deposited on a recovery surface to form a web, and then heat-sealed to produce the nonwoven fabric. The spunbond method achieves high productivity and cost efficiency, and nonwoven fabrics produced by the spunbond method have high strength and are used in a wide range of fields such as civil engineering, construction, medical, and sanitary materials. On the other hand, in the meltblown method, thermoplastic resin raw materials are melted and extruded from a fine nozzle while simultaneously being stretched with a high-temperature airflow to make them finer, and then the fine fibers are deposited on a recovery surface and heat-fused together to form the nonwoven fabric. Nonwoven fabrics produced by the meltblown method have high filter performance and are widely used in medical masks, filter materials, etc.

[0006] Patent Document 1 discloses a powder granule that can be manufactured without melting and kneading. The powder granule is manufactured with less thermal history and less power consumption than molten pellets.

[0007] Patent Document 2 discloses a powder granule that can exhibit excellent crystallization properties due to the "melt memory effect" without the addition of a crystallization nucleating agent.

[0008] Patent Document 3 discloses a method for injection molding PHA using a molding material that does not contain a crystallization nucleating agent.

[0009] Patent No. 7387950, Patent No. 7454097, Patent No. 7525489

[0010] In injection molding of PHA, the crystallization and solidification of PHA can be accelerated by effectively utilizing the melt memory effect of PHA powder granules, even without substantially incorporating a crystallization nucleating agent. Therefore, one aspect of this disclosure provides a method for manufacturing a PHA molded article by injection molding by effectively utilizing the melt memory effect of PHA powder granules.

[0011] Furthermore, one aspect of this disclosure provides a method for manufacturing an extruded article that can stably and continuously produce a PHA extruded article using PHA powder granules.

[0012] Further, from the perspective of environmental compatibility, fiber products using fibers containing PHA are desired. However, since PHA has a slow crystallization rate, it has been difficult to stably produce fibers because the fibers stick to the fiber manufacturing apparatus or the fibers self-fuse to each other. Therefore, one aspect of the present disclosure provides a fiber containing PHA that can be stably produced, and a fiber manufacturing method capable of stably and continuously manufacturing fibers using a PHA powder granule.

[0013] The first aspect of the present disclosure includes the following. [A1] A method for manufacturing a molded body, including injection molding of polyhydroxyalkanoate (PHA) by an injection molding machine, wherein the injection molding includes melting a powder granule 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 (A1) T Ｍ -20 < T Ｐ ≦ T Ｍ + 20 (A1) (wherein T Ｍ (unit: °C) represents the highest melting peak temperature observed in a differential scanning calorimetry measurement in which the powder granule is heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere).) A method that satisfies. [A2] The method according to [A1], wherein the powder granule has a melt memory effect. [A3] The method according to [A1] or [A2], wherein the powder granule is a compression granule. [A4] The method according to [A3], wherein the powder granule has an outer wall portion formed by melting and solidifying at least a part of the PHA powder located on the outer edge of the powder granule, and the PHA powder compressed inside the outer wall portion is contained. [A5] The highest melting peak temperature T Ｍ of the powder granule is 140 °C or higher, and the injection molding satisfies the formula (A2) 10 ≦ S Ｒ × V Ｉ ≦ 5,000 (A2) screw rotation speed S Ｒ (unit: rpm) and injection speed V ＩThe method according to any one of [A1] to [A4], performed in (unit: mm / second). [A6] The method according to any one of [A1] to [A5], wherein the injection molding machine has a single-screw flight screw having a supply zone, a compression zone, and a metering zone. [A7] Screw rotation speed S of 100 rpm or less Ｒ The method according to [A6], wherein the injection molding is performed at an injection speed V of 100 mm / sec or less. [A8] Ｉ The method described in any of [A1] to [A7], which is performed in [A9] the set temperature T of the mold. ＭＯＬＤ (Unit: °C) and the crystallization temperature T of the powder granules. Ｃ However, formula (A3) T Ｃ -60<T ＭＯＬＤ ≦T Ｃ (A3) is satisfied, and the crystallization temperature T of the powder granules is satisfied. Ｃ The method according to any one of [A1] to [A8], wherein the powder granules are 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, and the peak temperature of the crystallization exothermic peak observed during cooling is defined as the peak temperature of the crystallization exothermic peak. [A10] Crystallization temperature T of the powder granules Ｃ The temperature (in °C) is 80°C or higher, and the crystallization temperature T of the powder granules is 80°C or higher. Ｃ The method according to any one of [A1] to [A9], wherein the powder granules are 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, and the peak temperature of the crystallization exothermic peak observed during cooling is defined as the peak temperature of the crystallization exothermic peak. [A11] The set temperature T of the mold ＭＯＬＤ The method according to [A10], wherein the crystallization temperature of the molded article is 60°C to 80°C. [A12] ＣＡ (Unit: °C) and the crystallization temperature T of the powder granules. Ｃ (Unit: °C) is given by equation (A4) 0.8 ≤ T ＣＡ / T Ｃ The following conditions must be met: ≤ 1.2 (A4), and the crystallization temperature T of the powder granules must be met. ＣHowever, in differential scanning calorimetry in which the powder granules are 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 peak temperature of the crystallization exothermic peak observed during cooling is defined as the crystallization temperature T of the molded body. ＣＡ The method according to any one of [A1] to [A11], wherein 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, and the peak temperature of the crystallization exothermic peak observed during cooling is defined as the peak temperature of the crystallization exothermic peak observed during cooling. [A13] The method according to any one of [A1] to [A12], wherein the molded body has a load deflection temperature of 100°C or higher, and the load deflection temperature is measured at a load of 0.45 MPa in accordance with ISO 75. [A14] The melt flow rate MFR of the PHA powder ＯＲＩ (Unit: g / 10 min), Melt flow rate MFR of the powder granules ＧＲＮ (Unit: g / 10 min), and the melt flow rate MFR of the molded body. ＡＲＴ (Unit: g / 10 min) is given by equations (a), (b), and (c) 1 ≤ MFR ＧＲＮ / MFR ＯＲＩ ≦5 (a) 1≦MFR ＡＲＴ / MFR ＧＲＮ ≦5 (b) 1≦MFR ＡＲＴ / MFR ＯＲＩ The following conditions must be met: ≤ 10 (c), and the melt flow rate MFR of the PHA powder ＯＲＩ , the melt flow rate MFR of the powder granules ＧＲＮ , and the melt flow rate MFR of the molded body ＡＲＴ However, the method described in any of [A1] to [A13] is measured at 165°C and a load of 5 kg in accordance with ISO 1133.

[0014] A second aspect of the present disclosure includes: [B1] A method for manufacturing an extruded article, comprising extruding a polyhydroxyalkanoate (PHA) using an extruder, wherein the extrusion process involves plasticizing a powder granule containing PHA powder at a melting temperature T ＰThe process includes melting at a temperature of (°C) to obtain a molten material, extruding the molten material from a die, and cooling the extruded molten material to solidify it, wherein the plasticizing melt temperature T Ｐ However, equation (B1) T Ｍ -10 < T Ｐ ≦T Ｍ +20 (B1) (wherein, T Ｍ A method that satisfies the following conditions: (Unit: °C) represents the highest melting peak temperature observed in differential scanning calorimetry in which the powder granules are heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere. [B2] The method according to [B1], wherein the powder granules have a melt memory effect. [B3] The method according to [B1] or [B2], wherein the powder granules are compression granules. [B4] The method according to [B3], wherein the powder granules have an outer wall portion formed by the melting and solidification of at least a portion of the PHA powder located at the outer edge of the powder granules, and the compressed PHA powder is contained inside the outer wall portion. [B5] The method according to any one of [B1] to [B4], wherein the die is a T-type die, and the molten material extruded from the die is cooled by at least one cooling roll. [B6] The at least one cooling roll includes a first roll and a second roll that sandwich the molten material, the cooled molten material is conveyed along the surface of the second roll, and the surface temperature of the first roll T Ｒ１ (Unit: °C), Surface temperature T of the second roll Ｒ２ (Unit: °C), and the crystallization temperature T of the powder granules. Ｃ However, equations (B2), (B3), and (B4) T Ｃ -80<T Ｒ１ ≦T Ｃ (B2) T Ｃ -60<T Ｒ２ ≦T Ｃ (B3) T Ｒ１ <T Ｒ２ (B4) is satisfied, and the crystallization temperature T of the powder granules is satisfied. ＣThe method according to [B5], wherein the powder granules are 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, and the peak temperature of the crystallization exothermic peak observed during cooling is defined as the peak temperature of the crystallization exothermic peak observed during cooling. [B7] Surface temperature T of the second roll Ｒ２ The method according to [B6], wherein the temperature is 50°C to 80°C. [B8] The method according to any one of [B1] to [B7], wherein the extrusion molding machine has a single-screw flight screw having a supply zone, a compression zone, and a metering zone. [B9] The method according to [B8], wherein the extrusion molding is performed at a screw rotation speed of 100 rpm or less. [B10] The crystallization temperature T of the powder granules. Ｃ The temperature (in °C) is 80°C or higher, and the crystallization temperature T of the powder granules is 80°C or higher. Ｃ The method according to any one of [B1] to [B9], wherein the powder granules are 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, and the crystallization exothermic peak observed during cooling is defined as the peak temperature of the crystallization exothermic peak. [B11] The method according to any one of [B1] to [B4], or [B8] to [B10], relating to [B1] to [B4], wherein the extruded body has a tubular shape. [B12] The crystallization temperature T of the extruded body ＣＡ (Unit: °C) and the crystallization temperature T of the powder granules. Ｃ (Unit: °C) is given by equation (B5) 0.8 ≤ T ＣＡ / T Ｃ The following conditions must be met: ≤ 1.2 (B5), and the crystallization temperature T of the powder granules must be met. Ｃ However, in differential scanning calorimetry in which the powder granules are 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 peak temperature of the crystallization exothermic peak observed during cooling is defined as the crystallization temperature T of the extruded molded body. ＣＡThe method according to any one of [B1] to [B11], wherein the extruded 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, and the peak temperature of the crystallization exothermic peak observed during cooling is defined as the peak temperature of the crystallization exothermic peak. [B13] Melt flow rate MFR of the PHA powder ＯＲＩ (Unit: g / 10 min), Melt flow rate MFR of the powder granules ＧＲＮ (Unit: g / 10 min), and the melt flow rate MFR of the extruded product. ＡＲＴ (Unit: g / 10 min) is given by equations (a), (b), and (c) 1 ≤ MFR ＧＲＮ / MFR ＯＲＩ ≦5 (a) 1≦MFR ＡＲＴ / MFR ＧＲＮ ≦5 (b) 1≦MFR ＡＲＴ / MFR ＯＲＩ The following conditions must be met: ≤ 10 (c), and the melt flow rate MFR of the PHA powder ＯＲＩ , the melt flow rate MFR of the powder granules ＧＲＮ , and the melt flow rate MFR of the extruded product ＡＲＴ However, the method described in any of [B1] to [B12], measured at 165°C and a load of 5 kg in accordance with ISO 1133.

[0015] A third aspect of this disclosure includes: [C1] a fiber comprising a polyhydroxyalkanoate (PHA), wherein the crystallization temperature of the fiber is T ＣＡ (Unit: °C) is given by the following formula (C1): 80°C ≤ T ＣＡ (C1) is satisfied, and the crystallization temperature T of the fiber is satisfied. ＣＡ T is defined as the peak temperature of the crystallization exothermic peak observed during cooling in a differential scanning calorimetry measurement in which the fiber 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, and is the highest melting peak temperature of the fiber. ＭＡ (Unit: °C) is given by the following formula (C2): 140 °C ≤ T ＭＡ (C2) is satisfied, and the highest melting peak temperature T of the fiber is met. ＭＡis defined as the highest melting peak temperature observed in a differential scanning calorimetry measurement in which the fiber is heated from room temperature to 10 °C / min in a nitrogen atmosphere, and the fiber contains substantially no crystallization nucleating agent. [C2] A fiber containing polyhydroxyalkanoate (PHA), where the crystallization temperature T ＣＡ (unit: °C) satisfies the following formula (C1): 80 °C ≤ T ＣＡ (C1), and the crystallization temperature T ＣＡ of the fiber is defined as the peak temperature of the crystallization exothermic peak observed during cooling in a differential scanning calorimetry measurement in which the fiber is heated from room temperature 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 highest melting peak temperature T ＭＡ (unit: °C) of the fiber satisfies the following formula (C2): 140 °C ≤ T ＭＡ (C2), and the highest melting peak temperature T ＭＡ is defined as the highest melting peak temperature observed in a differential scanning calorimetry measurement in which the fiber is heated from room temperature to 10 °C / min in a nitrogen atmosphere, and the fiber has a melt memory effect. [C3] The fiber according to [C1] or [C2], which constitutes a monofilament, multifilament, or non-woven fabric. [C4] The fiber according to any one of [C1] to [C3], having a fiber diameter of 1 μm to 1200 μm. [C5] The fiber has a melt memory effect. In a differential scanning calorimetry measurement in which the fiber is heated from room temperature to 180 °C at a rate of 10 °C / min in a nitrogen atmosphere, held at 180 °C for 2 minutes, cooled to 30 °C at a rate of 10 °C / min, heated from 30 °C to 180 °C at a rate of 10 °C / min, held at 180 °C for 2 minutes, and then cooled to 30 °C at a rate of 10 °C / min, the peak temperature T ＣＡ，１ (unit: °C) of the crystallization exothermic peak observed during the first cooling and the peak temperature T ＣＡ，２ (unit: °C) of the crystallization exothermic peak observed during the second cooling satisfy the following formula (C3): 0.9 ≤ T ＣＡ，２ / T ＣＡ，１The fiber according to any one of [C1] to [C4], satisfying ≦ 1.1 (C3). [C6] A method for producing a fiber containing polyhydroxyalkanoate (PHA), wherein a powder granulate containing PHA powder is melted at a plasticizing melting temperature T Ｐ (unit: °C) by an extruder and extruded in a fibrous form from a die, and the extruded melt is cooled and solidified to obtain a fibrous solidified product, and the plasticizing melting temperature T Ｐ satisfies the following formula (C4): T Ｍ -10 < T Ｐ ≦ T Ｍ +25 (C4) (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. [C7] The method according to [C6], wherein the extruded melt is cooled while being stretched. [C8] The method according to [C6] or [C7], further comprising heating and stretching the fibrous solidified product. [C9] The method according to any one of [C6] to [C8], wherein the extruder has a single-screw flight screw having a feed zone, a compression zone, and a metering zone. [C10] The method according to any one of [C6] to [C9], further comprising winding up the fibrous solidified product. [C11] The method according to any one of [C6] to [C10], wherein the powder granulate is a compression granulate. [C12] The method according to [C11], wherein the powder granulate has an outer wall portion formed by melting and solidifying at least a part of the PHA powder located on the outer edge of the powder granulate, and the PHA powder compressed inside the outer wall portion is contained therein. [C13] The method according to any one of [C6] to [C12], wherein the powder granulate has a melt memory effect. [C14] The crystallization temperature T ＣＡ (unit: °C) of the fiber and the crystallization temperature T Ｃ (unit: °C) of the powder granulate satisfy the following formula (C5) and the following formula (C6): 0.8 ≦ T ＣＡ / T Ｃ ≦ 1.2 (C5) 70 °C ≦ T Ｃ(C6) is satisfied, and the crystallization temperature T of the powder granules is met. Ｃ T is defined as the peak temperature of the crystallization exothermic peak observed during cooling in a differential scanning calorimetry measurement in which the powder granules are 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, and the crystallization temperature T of the fiber is defined as the peak temperature of the crystallization exothermic peak observed during cooling. ＣＡ C15 The method according to any one of [C6] to [C13], wherein the fibers are 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, and the peak temperature of the crystallization exothermic peak observed during cooling is defined as the peak temperature of the crystallization exothermic peak observed during cooling. C15 The method according to any one of [C6] to [C14], wherein the fibers constitute a nonwoven fabric. C16 The method according to [C15], wherein the nonwoven fabric is formed by the spunbond method or the meltblown method.

[0016] A first aspect of this disclosure provides a method for manufacturing a PHA molded article by injection molding, which effectively utilizes the melt memory effect of PHA powder granules.

[0017] A second aspect of this disclosure provides a method for manufacturing an extruded article that can stably and continuously produce a PHA extruded article using PHA powder granules.

[0018] A third aspect of this disclosure provides a fiber containing PHA that can be manufactured stably, and a fiber manufacturing method that enables the stable and continuous production of fiber using PHA powder granules.

[0019] This is the temperature rise DSC curve for the PHA powder and PHA powder granules used in the embodiment of the first embodiment. This is the temperature cooldown DSC curve for the PHA powder and PHA powder granules used in the embodiment of the first embodiment. This is a schematic diagram showing an example of an extrusion molding machine used in the method according to the embodiment of the second embodiment. This is the temperature rise DSC curve for the PHA powder and PHA powder granules used in the embodiment of the second embodiment. This is the temperature cooldown DSC curve for the PHA powder and PHA powder granules used in the embodiment of the second embodiment. This is a schematic diagram showing an example of a fiber manufacturing apparatus used in the method according to the embodiment of the third embodiment. This is a schematic diagram showing an example of a fiber manufacturing apparatus used in the method according to the embodiment of the third embodiment. This is the temperature cooldown DSC curve for the powder granules used in the embodiment of the third embodiment, as well as the first and second temperature cooldown DSC curves for the fibers of Example 9. This is the temperature cooldown DSC curve for the powder granules used in the embodiment of the third embodiment, as well as the first and second temperature cooldown DSC curves for the fibers of Example 10. These are the temperature rise DSC curves of the powder granules used in the third embodiment, and the first temperature rise DSC curve of the fibers in Example 10. These are the temperature fall DSC curves from 180°C to 200°C and the temperature fall DSC curves of the fibers in Example C10. This is an optical microscope image of the fibers in Example C9. This is an optical microscope image of the fibers in Example C10.

[0020] (First Embodiment) A. Powder Granules First, the powder granules used as injection molding materials in the method for manufacturing a molded article according to the embodiment will be described.

[0021] The powder granules contain polyhydroxyalkanoate (PHA) powder, preferably containing PHA powder as the main component, more preferably essentially consisting of PHA powder, and even more preferably consisting of PHA powder. In this specification, "contains" and "includes" mean that additional components or elements may be included unless otherwise specified, and include "essentially consisting of" and "consisting of." "Essentially consisting of" means that additional components or elements may be included that do not substantially adversely affect the product. "Consisting of" means that only the described material or element is included, but does not exclude the inclusion of unavoidable impurities.

[0022] The powder granules are produced by granulating PHA powder. Such powder granules have a melt memory effect. The powder granules can preferably be produced by powder compression granulation. Details of the production method will be described later.

[0023] In this specification, a powder granule having a melt memory effect means a powder granule having the following characteristics i) and ii): i) The powder granule is melted in a nitrogen atmosphere at a rate of 10°C / min from room temperature until it reaches a first hold temperature T Ｈ１ The temperature is raised to the first holding temperature T Ｈ１ In a first differential scanning calorimetry (DSC) measurement, where the sample is held for 2 minutes and then cooled at a rate of 10°C / min, the first hold temperature T at which the crystallization exothermic peak of PHA is observed during cooling is... Ｈ１ (Unit: °C) It has a first hold temperature T Ｈ１ The highest melting peak temperature T is Ｍ It is higher than this. Here, the highest melting peak temperature T Ｍ (Unit: °C) is defined as the highest peak temperature of the melting peak observed in differential scanning calorimetry when the powder granules are heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere. ii) When the powder granules are heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere, the second hold temperature T Ｈ２ The temperature is raised to the second holding temperature T. Ｈ２ In a second DSC (Deep Stem Cell) where the mixture is held for 2 minutes and then cooled at a rate of 10°C / min, the second hold temperature T is such that no crystallization exothermic peak of PHA is observed during the cooling process. Ｈ２ (Unit: °C) It has a second hold temperature T Ｈ２ The first hold temperature T Ｈ１ It's higher than that.

[0024] The melt memory effect refers to the phenomenon in which a pseudo-crystalline phase structure order remains in the molten material when a crystalline polymer is heated and melted (thermoplasticized) above its melting point. The melt memory effect is a unique phenomenon that can occur in crystalline polymers, where, even in a temperature range above the melting point, a region remains that does not immediately become disordered and random due to the long relaxation time required for the material to change to a random aggregated state due to thermal disturbance. Hereinafter, the pseudo-crystalline phase structure order produced by the melt memory effect may be referred to as the melt memory structure. Such powder granules are described in Japanese Patent No. 7454097 and can be manufactured by the method described in Japanese Patent No. 7454097.

[0025] The melt memory effect of powder granules can be evaluated by the method described in Japanese Patent No. 7454097. Specifically, the peak temperature of the crystallization exothermic peak (i.e., the crystallization temperature of the powder granules) observed in the cooling DSC curve obtained by differential scanning calorimetry (DSC) after heating the powder granules to a temperature above the melting point of PHA and then cooling them at a rate of 10°C / min is T. Ｃ If the temperature (in °C) is higher than the crystallization temperature of PHA powder measured in the same manner, the powder granules have a high melt memory effect. When powder granules have a high melt memory effect, the crystallization exothermic peak of the powder granules often has a smaller half-width at half maximum than the crystallization exothermic peak of PHA powder measured in the same manner. The above DSC can be performed, for example, by raising the temperature of the sample 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 after, while cooling the sample in a nitrogen atmosphere at a rate of 10 °C / min.

[0026] When a powder granule exhibiting the melt memory effect is heated and melted, the melt memory structure of PHA remaining in the molten material functions as a crystallization nucleus during cooling. Since the melt memory structure is a pseudo-crystalline phase structure of PHA itself, the crystallization temperature T of the powder granule that crystallizes using the melt memory structure as a nucleus is determined. ＣThe crystallization temperature is higher than that of molten pellets to which a crystallization nucleating agent has been added. Furthermore, the melt memory effect of powder granules exhibits excellent persistence with respect to molten residence time. On the other hand, if the melt memory structure in the molten material is lost due to thermal disturbance and leads to a random aggregated state, crystallization will not proceed easily during cooling.

[0027] A method for manufacturing molded articles using powder granules with a melt memory effect as an injection molding material may have the following advantages compared to a conventional method for manufacturing molded articles using molten pellets containing a crystallization nucleating agent as an injection molding material.

[0028] i) As described in Japanese Patent No. 7454097, the powder granules are manufactured under conditions where the temperature of the granules immediately after granulation is below the melting point of PHA. Therefore, thermal decomposition of PHA during the granulation process and the resulting decrease in molecular weight are suppressed. As a result, the PHA contained in the powder granules may have a larger molecular weight than the PHA contained in the molten pellets. Consequently, the PHA in the molded body produced from the powder granules can also have a larger molecular weight, thereby enabling the molded body to have superior physical properties.

[0029] ii) The process for producing powder granules uses significantly less electricity than the melt-mixing granulation process using an extruder for producing molten pellets. Therefore, by producing molded products from powder granules, the total amount of electricity used can be greatly reduced.

[0030] iii) By advantageously utilizing the melt memory effect of powder granules, the range of molding conditions (setting temperature of injection molding machine and mold, injection speed, screw rotation speed, etc.) can be expanded, making it easier to control the appearance and crystallinity of the molded product.

[0031] iv) By using powder granules, molded articles that do not contain crystallization nucleating agents can be manufactured. Since there is no risk of crystallization nucleating agents leaching out of the manufactured molded articles, they can be used for food applications, medical applications, and other uses. Furthermore, the crystallization nucleating agents will not adhere to the molding dies and hinder continuous molding.

[0032] In one embodiment, the powder granules have an outer wall portion formed by the melting and solidification of at least a portion of the PHA powder located at the outer edge of the powder granules, and compressed PHA powder is contained inside the outer wall portion. In this application, melting and solidification means solidification after melting. The outer wall portion is located at the outer edge of the powder granules. In this specification, the outer wall portion is also referred to as the shell portion. The compressed PHA powder inside the outer wall portion may be melted and solidified and welded in place to at least a portion, or it may not be melted and solidified to at least a portion. The compressed PHA powder inside the outer wall portion may be in an unmelted state. That is, at least a portion of the compressed PHA powder inside the outer wall portion may include an unmelted compressed powder form, or it 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 it is not a welded structure strong enough to hold the PHA powder like the outer wall portion. In this specification, the inner part of the outer wall is also referred to as the core. The core inside the outer wall contains compressed PHA powder. In this specification, "compressed" means that the density of the PHA powder located in the core is higher than the bulk density of the PHA powder before granulation. Such powder granules are described in Japanese Patent No. 7387950 and can be manufactured by the method described in Japanese Patent No. 7387950. Furthermore, such powder granules have the melt memory effect described above.

[0033] The outer wall (shell) has a dense structure containing molten and solidified PHA powder. On the other hand, the inner core, although compressed, has a looser structure compared to the dense structure (welded structure) of the outer wall containing the molten and solidified PHA powder. Because the outer wall containing the molten and solidified PHA powder holds the compressed PHA powder present in the core, the powder granules can have a stable structure, minimal powder shedding, and excellent handling and safety, and can also lead to an improved working environment for the manufacture of molded products.

[0034] The outer wall portion (shell portion) has a welded structure in which at least a portion of the thermoplastic resin powder located at the outer edge of the powder granules is melted and solidified. The outer wall portion may be smooth enough to have a glossy appearance. Alternatively, the outer wall portion may be formed by the melting of some of the components of the thermoplastic resin powder and partial welding with adjacent components, even if the melting is not sufficient to form a smooth surface. The outer wall portion can be formed during compression granulation, for example, at the contact surface with the die hole, by the melting of at least a portion of the PHA powder due to frictional heat with the wall surface or heat transfer from the wall surface. The thickness of the outer wall portion can vary depending on the manufacturing conditions of the PHA powder granules.

[0035] The core is the part located inside the outer wall and contains compressed thermoplastic resin powder. The PHA powder in the core may be porous, or it may have a non-welded structure because heat is not transferred to the core during granulation. The core may have a structure in which the PHA powder maintains its powder shape (i.e., a non-welded structure or a powdery structure), or a structure in which it is partially welded but the shape of the PHA powder remains.

[0036] In this specification, for the sake of simplicity of explanation, the terms "outer wall (shell)" and "core" are used. However, as stated above, the outer wall is formed when the PHA powder melts due to the heat during granulation, so in reality, there is no clear boundary between the outer wall (shell) and the core. The outer wall (shell) refers to the part that includes the welded structure of the PHA powder and is located on the outer edge of the powder granules, contributing to maintaining a certain shape of the powder granules. The core refers to the part located inside the outer wall (shell).

[0037] The shape of the powder granules is preferably approximately cylindrical or approximately rectangular prismatic, and it is preferable that the powder granules have an outer wall portion on the side surface. In this disclosure, the powder granules have an approximately cylindrical or approximately rectangular prismatic shape, and it is preferable that an outer wall portion is formed on the side surface of the powder granules having an approximately cylindrical or approximately rectangular prismatic shape.

[0038] Because powder granules with this shape can be directly supplied to injection molding machines for thermoplastic resins, they can be used as injection molding materials.

[0039] Powder granules can take on any suitable shape. Typically, when powder granules are manufactured by compression granulation of powder and granulation is performed by passing the powder through a circular die hole, the basic shape of the powder granules is a cylindrical pellet shape.

[0040] Furthermore, in this specification, "die" refers collectively to a tool equivalent to a mold for compressing and shaping PHA powder granules.

[0041] When the powder granules are approximately cylindrical in shape, the diameter of the powder granules is, for example, 2 mm to 7 mm, preferably 3 mm to 5 mm. The length (height) of the powder granules is, for example, 1 mm to 10 mm, preferably 2 mm to 7 mm. Such a shape results in powder granules that are easy to handle. The diameter of the powder granules can be adjusted, for example, by the diameter of the die holes in the disc plate (die plate) during granulation, and the length can be adjusted by the distance between the disc plate and the cutter. This distance can be any appropriate distance. The distance between the disc plate and the cutter is, for example, 1 mm to 30 mm, preferably 2 mm to 20 mm, preferably 3 mm to 10 mm.

[0042] The fracture strength of the powder granules, based on measurements using a Kiya hardness tester, 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, and preferably 10.0 kg or more. The upper limit may exceed the measurement limit of the Kiya hardness tester (10 kg is the measurement limit for the "WPF1600-B" manufactured by Shiro Sangyo Co., Ltd.). Within this range, powder granules with excellent handling and melt processability can be obtained. Here, fracture strength refers to the average fracture stress (fracture load) measured by crushing powder granules of 20 or more particles (preferably 25 or more particles) in a direction perpendicular to the longitudinal direction (extrusion direction) of the powder granules. In powder granulation, the shell portion is composed of molten resin, making it possible to maintain a stable shape as a granule despite it being a powder granule. The diameter of the pressure surface of the pressure attachment of the Kiya hardness tester is, for example, 5 mm.

[0043] The bulk density of the powder granules can be any appropriate bulk density, but is preferably 0.3 kg / L to 2.0 kg / L, and more preferably 0.5 kg / L to 1.0 kg / L. Increasing the bulk density improves the supply speed and supply stability of the powder granules to the injection molding machine.

[0044] The bulk density of powder granules is calculated by allowing the powder granules to fall naturally into a 1-liter measuring cup until it is level, accurately measuring out 1 liter of powder granules, and then measuring its mass (unit: kg / L).

[0045] B. PHA Powder The PHA powder, which is the raw material for powder granules, is a powdered polyhydroxyalkanoate (PHA) resin. PHA can be a compound produced in the body of microorganisms, for example, by feeding on carbohydrates, oils, etc. Such PHA is primarily extracted from microorganisms as a powdered polymer.

[0046] PHA contains hydroxyalkanoic acid 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-hydroxynanoate, 3-hydroxydecanoate, 3-hydroxytetradecanoate, 3-hydroxyhexadecanoate, 3-hydroxyoctadecanoate, 4-hydroxybutyrate, 4-hydroxyvalerate, 5-hydroxyvalerate, or 6-hydroxyhexanoate. The number of carbon atoms in the 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 in the 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, and particularly 6 or less. The hydroxyalkanoic acid may be used alone or in combination of two or more types.

[0047] Preferred PHAs include poly(3-hydroxyalkanoate) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0048] In 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, and preferably 700,000 or more. The melt memory effect is manifested by a time delay in the process in which polymer molecular chains transition from a crystalline ordered state to a random state in the molten state. Therefore, the larger the molecular weight, the longer the relaxation time (transition time to random chains), which is advantageous in terms of the persistence of the effect. A weight-average molecular weight of PHA of 200,000 or more is preferable because it can effectively delay the decrease or deactivation of the melt memory effect due to thermal disturbance. 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 powder granulation tends to become difficult. For this reason, the weight-average molecular weight of PHA is preferably 3 million or less, preferably 2 million or less, preferably 1.5 million or less, and preferably 1 million or less.

[0049] The weight-average molecular weight (Mw) mentioned above can be determined as the weight-average molecular weight in terms of polystyrene by gel permeation chromatography (GPC). For example, evaluation can be performed using a Showa Denko "Showdex GPC-101" as the GPC apparatus, polystyrene gel (Showa Denko "Showdex K-804") as the column packing material, and an organic solvent mobile phase (e.g., chloroform). The column apparatus, column packing material, and organic solvent mobile phase can be selected as appropriate, but for example, chloroform can be used.

[0050] PHA powder may be a powdery resin obtained through its manufacturing process, i.e., a powdery resin resulting from the manufacturing process, or it may be obtained by pulverizing a non-powdery PHA resin such as pellets, lumps, or molded articles. PHA powder can be obtained, for example, by pulverizing molded articles, pellets, or sprues or runners generated in injection molding at room temperature, or after cooling them with dry ice or liquid nitrogen as needed, using a pulverizer (for example, a Dalton product, trade names "Nearmill," "Sylpheedmill," "Atomizer," or "Impactmill," etc.).

[0051] The particle size of the PHA powder can be any appropriate particle size depending on its form, as long as the effects of this embodiment are obtained. Preferably, the maximum particle size of the PHA powder before granulation is 5 mm or less, and the minimum particle size is 0.0001 mm or more.

[0052] The average particle size of the PHA powder is, for example, 0.001 mm or more and 1.0 mm or less. Preferably, the average particle size of the PHA powder is 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 may be measured by laser diffraction. The average particle size of the PHA powder may be the median diameter (d50) which is the cumulative 50% in the cumulative particle size distribution 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 types.

[0053] The PHA powder before granulation may 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 easily performed.

[0054] The bulk density of PHA powder is calculated by letting the PHA powder fall naturally into a 1-liter measuring cup until it is level, accurately measuring out 1 liter of PHA powder, and then measuring its mass (unit: kg / L).

[0055] C. Other component powder granules contained in the PHA powder granules may include any suitable additives as needed. Additives may be in solid form such as powder, or in liquid form. Examples of additives include binders, dispersants, crystallization nucleating agents, antioxidants, light stabilizers, foaming agents, UV absorbers, antiblocking agents, heat stabilizers, impact modifiers, antibacterial agents, compatibilizers, processing aids, lubricants, coupling agents, hydrolysis inhibitors, oxygen scavengers, or colorants (dyes and pigments). Additives may be used individually or in combination of two or more.

[0056] The additive content in the powder granules 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.

[0057] The powder granules may contain a binder as an additive. Here, "binder" refers collectively to compounds that exist between the PHA powder particles, in addition to the constituent components of the raw material PHA powder, and that bind the powder particles together, thereby increasing the fracture strength of the granules. Various compounds that exhibit a binding effect, preferably water-dispersible or water-soluble polymer compounds, polysaccharides, etc., can be appropriately selected and used as binders as needed.

[0058] In one embodiment, it is preferable to melt and bind a portion of the components of the PHA powder to form a powder granule, and it is preferable not to include a binder.

[0059] The binder content is typically 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), based on the total mass of the PHA powder granules.

[0060] In one embodiment, a dispersant is preferably used as an additive. A surfactant is preferably used as the dispersant. The hydrophilic / hydrophobic balance of the dispersant (surfactant) can be controlled by adjusting the degree of esterification of the compound that becomes the dispersant, the type of fatty acid (e.g., presence or absence of hydroxyl groups, saturated or unsaturated fatty acids, alkyl chain length), the degree of polymerization, etc. The use of a dispersant can bring about effects such as improving the productivity (discharge rate) of powder granules, reducing frictional heat during granulation, and improving the cleanability of the granulation equipment.

[0061] Examples of dispersants include fatty acids, fatty acid metal salts, fatty acid sulfonates, fatty acid amides, acrylamides, polyhydric alcohol fatty acid esters, and polyglycerol fatty acid esters. Dispersants may be used individually or in combination of two or more types.

[0062] In one embodiment, the dispersant is at least one selected from the group consisting of polyhydric alcohol fatty acid esters, fatty acid amides, polyglycerol fatty acid esters, condensed hydroxy fatty acids, and alcohol esters of condensed hydroxy fatty acids.

[0063] Polyhydric alcohol fatty acid esters are ester compounds composed of a polyhydric alcohol and a fatty acid. Examples of polyhydric alcohol fatty acid esters include esters of polyhydric alcohols such as pentaerythritol and glycerin, and fatty acids having eight or more carbon atoms (preferably 8 to 24 carbon atoms, more preferably 10 to 22 carbon atoms).

[0064] Fatty acid amides are compounds that have a structure formed by the dehydration condensation of a fatty acid with 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.

[0065] Polyglycerol fatty acid esters are ester compounds composed of polyglycerol and fatty acids. Examples of polyglycerol fatty acid esters include diglycerol palmitate, diglycerol stearate, diglycerol oleate, decaglycerol palmitate, decaglycerol stearate, and decaglycerol oleate.

[0066] The dispersant content is typically 0% to 10.0% by mass, preferably 0.01% to 9.0% by mass, preferably 0.1% to 7.0% by mass, and more preferably 0.3% to 5.0% by mass, relative to the total mass of the powder granules. Furthermore, the dispersant content is typically 10.0% or less by mass, preferably 5.0% or less by mass, preferably 3.0% or less by mass, preferably 1.0% or less by mass, preferably 0.5% or less by mass, preferably 0.1% or less by mass, and preferably 0% by mass (undetectable), relative to the total mass of the powder granules.

[0067] Crystallization nucleating agents can be added as additives to powder granules. Examples of crystallization nucleating agents that can be added to powder granules include organometallic salt compounds such as phosphate ester metal salts, benzoate metal salts, pimephosphate metal salts, rosin metal salts, oxalate metal salts, and fatty acid metal salts; aliphatic organic esters, triallyl phosphate, polyalkylene glycol or its derivatives, aliphatic polyesters, and organic compounds such as benzylidene sorbitol; dyes and pigments such as pentaerythritol, quinacdrin, cyanine blue, and carbon black; minerals such as talc, mica, kaolin, clay, carbonate minerals, metal oxides, and metal sulfates; ionomers; and polymer compounds such as high-melting-point polyamides.

[0068] In one embodiment, talc, mica, kaolin, or calcium carbonate are used as crystallization nucleating agents. One type of crystallization nucleating agent may be used alone, or two or more types may be used in combination.

[0069] The content of the crystallization nucleating agent in the powder granules 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, and preferably 0.3% by mass or more and 5.0% by mass or less.

[0070] In one embodiment, the powder granules substantially do not contain a crystallization nucleating agent. Because the powder granules can exhibit a melt memory effect, they can achieve excellent crystallization characteristics in molding processes even without the use of a crystallization nucleating agent.

[0071] "Substantially free of crystallization nucleating agents" means, for example, that the content of crystallization nucleating agents in the powder granules is 0.1% by mass or less, preferably less than 0.1% by mass, preferably 0.01% by mass or less, preferably 0.005% by mass or less, preferably 0.001% by mass or less, and preferably 0% by mass (undetectable) of the crystallization nucleating agents in the powder granules.

[0072] Furthermore, those skilled in the art should understand that powder granules may contain a crystallization nucleating agent or that powder granules may be used together with a crystallization nucleating agent. When powder granules contain a crystallization nucleating agent or when powder granules are used together with a crystallization nucleating agent, in addition to the crystallization-promoting effect due to the melt memory effect, a crystallization-promoting effect due to the crystallization nucleating agent can be obtained.

[0073] D. Method for Manufacturing PHA Powder Granules Powder granules can be manufactured using various powder granulators, but preferred granulators include compression granulators such as disc pelletizers, screw extrusion machines, briquetting machines, compaction machines, and tableting machines. Powder granules manufactured by a compression granulator are thought to have an outer wall containing oriented crystals due to the strong shear stress from the wall of the die hole during the granulation process. Therefore, powder granules manufactured by the compression granulation method (i.e., compression granules) can have a particularly high melt memory effect.

[0074] Among the examples given above, the disc pelletizer method is preferred from the viewpoint of granulation productivity and the quality and shape uniformity of the resulting powder granules. In the disc pelletizer method, a semi-wet granulation method can be employed, which involves incorporating an appropriate amount of moisture into the PHA powder. In some cases, granulation can be performed without using water. When granulation is performed without using water, the post-granulation drying treatment described later may become unnecessary. When granulation is performed without using water, the amount of energy required in the drying process can be reduced, and the amount of carbon dioxide emitted during the manufacturing process can be significantly reduced.

[0075] As mentioned above, PHA powder granules can be advantageously obtained by the granulation method described in Japanese Patent No. 7454097 or Japanese Patent No. 7387950.

[0076] When the powder granules are a mixture containing two or more types of PHA powder raw materials, or contain any component other than PHA, it is preferable to mix them uniformly using any suitable mixer. Examples of mixers include Henschel mixers, Nauter mixers, powder kneaders (KDH, KDA, CKD, CPM) (Dalton), Spartan mixers (SPM) (Dalton), and SP granulators (SPG) (Dalton). To obtain a desirable 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, it is preferable to use a combination of upper and lower blades, with the upper blade being a Y1 blade (product name, manufactured by Nippon Coke Industries Co., Ltd.) and the lower blade being an S0 blade (product name, manufactured by Nippon Coke Industries Co., Ltd.). It is also preferable to install a deflector in the stirring tank and mix the mixture. In other words, using a mixing device that can uniformly disperse each component throughout the mixture is advantageous in improving the productivity and quality stability of the final powder granules.

[0077] When producing powder granules using the semi-wet granulation method described above, the amount of water added can be any appropriate amount depending on the properties of the powder (e.g., water absorption). In this case, the amount of water added is 3 to 30 parts by mass, preferably 5 to 25 parts by mass, and more preferably 5 to 20 parts by mass, per 100 parts by mass of crystalline polymer powder. The semi-wet method can be used to improve the stability of granulation.

[0078] In the granulation process of powder granules, localized heat generation can lead to die clogging. Therefore, incorporating an appropriate amount of moisture into the PHA powder during granulation and using the heat of vaporization of water to suppress excessive temperature rise during granulation can be advantageous for continuous granulation.

[0079] The powder granules can be dried after granulation, but the final moisture content of the powder granules 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 final moisture content of the powder granules can be appropriately selected depending on the intended use.

[0080] It is preferable that the powder granules are granulated without the addition of water. If the moisture content of the powder granules is low, post-granulation drying may not be necessary. If granulation can be performed without using water, drying is unnecessary, which can significantly reduce the amount of carbon dioxide emitted during the powder granulation process.

[0081] The moisture content of the granulated powder without the addition of 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.

[0082] When producing powder granules using a screw extrusion compression granulator, it is easy to install a temperature control device on the compression granulator, and compression granulation can be performed at low screw rotation speeds, thus reducing localized heat generation due to rapid shear heat generation during granulation. When producing powder granules using a bricketing, compaction, or tableting compression granulator, the shear stress on the powder from the die hole walls is smaller compared to the disc pelletizer method, thus reducing localized heat generation during granulation. Therefore, with the screw extrusion, bricketing, compaction, and tableting methods, powder granules can be produced continuously and stably without causing die clogging due to localized heat generation, even without the addition of water. When granulation is performed without the addition of water, post-granulation drying is unnecessary, thus simplifying the manufacturing process and reducing energy consumption for drying.

[0083] The moisture content of powder granules is measured using an infrared moisture meter.

[0084] A disc pelletizer type granulator has, as a basic structure, one (flat die) or two discs (indicating cylindrical dies) with numerous holes ranging from 2 mm to 30 mm in size, and rollers for pressurizing the raw material into the holes of the discs. PHA powder (which may contain moisture) supplied between the disc and the roller, or between two discs, is pressed into the holes of the discs as the roller rotates, forming a cylindrical extruded product. The extruded product is cut on the back surface of the disc with a cutter or the like to obtain pelletized powder granules. The length of the granules can be adjusted by the distance between the back surface of the disc and the cutter, the rotation speed of the roller, etc. The distance between the disc plate and the cutter can be any appropriate distance. For example, the distance between the disc plate and the cutter is 1 mm to 30 mm, more preferably 2 mm to 20 mm, and even more preferably 3 mm to 10 mm.

[0085] More specifically, disc pelletizer systems include roller-disc die systems, roller-ring die systems, double die systems, and flat die systems. A commercially available disc pelletizer granulator is, for example, the Dalton F-series disc pelletizer.

[0086] The powder granules may be thoroughly dried immediately before use as an injection molding material. This effectively suppresses the decrease in molecular weight of PHA and / or defects in the appearance of the molded product that occur during injection molding. The moisture content of the powder granules immediately before use 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 carried out at 70°C to 110°C, 75°C to 100°C, or 80°C to 90°C until the predetermined moisture content is reached. The moisture content of the powder granules is measured using an infrared moisture meter.

[0087] E. Method for manufacturing a molded article by injection molding The method for manufacturing a molded article according to the embodiment includes using powder granules containing PHA as a molding material and injecting the PHA using an injection molding machine. Injection molding includes melting the powder granules put into the injection molding machine to obtain a molten material, injecting the molten material into a mold, and cooling the molten material to solidify it. More specifically, the powder granules are heated and melted in the cylinder of the injection molding machine, the molten material is injected into a mold through a nozzle attached to the tip of the cylinder, and the molten material is cooled and solidified in the mold to obtain a molded article.

[0088] Injection molding machine plasticizes powder granules at melting temperature T Ｐ It is melted at the plasticizing melt temperature T. Ｐ (Unit: °C) is given by formula (A1) T Ｍ -20<T Ｐ ≦T Ｍ +20 (A1) (where T Ｍ (Unit: °C) represents the highest melting peak temperature observed in differential scanning calorimetry (DSC) where powder granules are heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere.

[0089] Note that the highest melting peak temperature T Ｍ If multiple melting peaks are observed by DSC, this refers to the highest peak temperature among those melting peaks. If only one melting peak is observed by DSC, this refers to the peak temperature of that melting peak.

[0090] In this specification, the plasticizing melt temperature T Ｐ This is defined as the set temperature of the cylinder. If the set temperature differs depending on the part (zone) of the cylinder, generally the temperature is set higher in the downstream part in the flow direction of the powder granules and their molten material, so the plasticizing melt temperature T Ｐ This is defined as the set temperature at the point closest to the nozzle (i.e., the downstream point of the cylinder). Note that the nozzle's set temperature is generally the same as or lower than the downstream set temperature of the cylinder. Plasticization melting temperature T Ｐ This is generally approximately equal to the temperature of the molten material immediately before it is poured into the mold. The temperature of the molten material immediately before it is poured into the mold can be measured with a contact thermometer (e.g., a thermocouple).

[0091] Plasticizing melt temperature T that satisfies equation (A1) Ｐ By melting the powder granules, the loss of the melt memory effect of the powder granules due to thermal disturbances, mechanical mixing, etc., can be suppressed, thereby enabling injection molding that effectively utilizes the melt memory effect.

[0092] Plasticization melting temperature T Ｐ Preferably, T Ｍ -15<T Ｐ ≦T Ｍ Satisfying +15, more preferably T Ｍ -10 < T Ｐ ≦T Ｍ Satisfying +10, and more preferably T Ｍ -5 < T Ｐ ≦T Ｍ Satisfy +5.

[0093] In conventional injection molding using molten PHA pellets as a molding material, the plasticizing melt temperature T Ｐ If the temperature is set below the melting peak temperature of the molten pellet, it not only places an excessive load on the molding machine, but also results in insufficient plasticization, making the injection-molded product prone to surface defects such as sink marks or flow marks due to insufficient flow.

[0094] In contrast, in the method according to this embodiment, which uses powdered granules of PHA as a molding material, the load on the molding machine is reduced due to the large porosity of the powdered granules, so the plasticization melting temperature T Ｐ ga T Ｍ -20<T Ｐ <T Ｍ Even when these conditions are met, the powder granules can be sufficiently plasticized and injection molded without placing an excessive load on the molding machine.

[0095] Inside the injection molding machine, a flow field is formed by the rotation of the screw for plasticization metering and the piston movement of the screw for injection. The maximum temperature at which the melt memory effect is maintained in the flow field may be lower than the maximum temperature at which the melt memory effect is maintained in the stationary field. Plasticization melt temperature T Ｐ However, T Ｐ >TＭ If the condition +20 is met, the melt memory effect decreases or disappears due to the action of the flow field, slowing down crystal solidification within the mold. This can lead to problems such as poor mold release, resulting deformation of the molded product, and longer molding cycles, potentially reducing productivity.

[0096] In one embodiment, the highest melting peak temperature T of the powder granules Ｍ The temperature is 140°C or higher, and the screw rotation speed S of the injection molding machine is also 140°C or higher. Ｒ (Unit: rpm) and injection speed V Ｉ (Unit: mm / second) is given by the following formula (A2): 10 ≤ S Ｒ ×V Ｉ The condition ≤ 5,000 (A2) is satisfied.

[0097] S Ｒ ×V Ｉ The value of is preferably 4,000 or less, more preferably 3,000 or less, even more preferably 2,500 or less, and most preferably 2,000 or less. Also, S Ｒ ×V Ｉ The value is preferably 50 or more, more preferably 100 or more, even more preferably 200 or more, and even more preferably 300 or more.

[0098] S Ｒ ×V Ｉ By setting the value of to between 10 and 5,000, PHA injection molded articles with excellent quality and appearance can be manufactured with high productivity.

[0099] In one embodiment, injection speed V Ｉ Preferably, the speed is 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.

[0100] In one embodiment, the screw of the injection molding machine is a single-screw flight screw. The single-screw flight screw has a supply zone, a compression zone, and a metering zone in the flow direction of the powder granules and their molten material, from upstream to downstream. Such a single-screw flight screw can suppress the reduction or disappearance of the melt memory effect due to the flow field caused by thermal disturbance and / or mechanical mixing. When the screw of the injection molding machine is a single-screw flight screw, the screw rotation speed S Ｒ The rotational speed of the screw is preferably 100 rpm or less, 80 rpm or less, 60 rpm or less, 50 rpm or less, or 30 rpm or less. Ｒ By reducing this, the reduction or disappearance of the melt memory effect caused by the flow field generated by mechanical mixing can be suppressed. Screw rotation speed S Ｒ The speed may be 10 rpm or higher.

[0101] In one embodiment, the set temperature of the mold T ＭＯＬＤ (Unit: °C) and crystallization temperature T of powder granules Ｃ (Unit: °C) is given by formula (A3) T Ｃ -60<T ＭＯＬＤ ≦T Ｃ (A3) is satisfied. Note that the crystallization temperature T Ｃ This is defined as the peak temperature of the crystallization exothermic peak observed during cooling in differential scanning calorimetry (DSC) where powder granules are 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] Mold setting temperature T ＭＯＬＤ and the crystallization temperature T of the powder granules Ｃ Preferably, T Ｃ -50<T ＭＯＬＤ ≦T Ｃ More favorably, T Ｃ -45<T ＭＯＬＤ ≦T Ｃ More preferably, T Ｃ -40<T ＭＯＬＤ ≦T Ｃ Particularly preferred, T Ｃ -30<T ＭＯＬＤ ≦TＣ It satisfies the condition.

[0103] Mold setting temperature T ＭＯＬＤ The crystallization temperature of powder granules is T Ｃ By keeping the temperature below (°C), the crystallization and solidification of PHA within the mold can be accelerated, enabling the production of molded products with superior quality and appearance with high productivity. The melt memory effect of powder granules originates from the pseudo-crystalline phase structure of PHA itself, therefore the crystallization temperature of powder granules T Ｃ This can be higher than the crystallization temperature of molten pellets to which a crystallization nucleating agent has been added. Therefore, when performing injection molding using powder granules with a melt memory effect as a molding material, the mold set temperature T can be higher compared to conventional injection molding using molten pellets. ＭＯＬＤ The set temperature of the mold can be increased. ＭＯＬＤ A high is advantageous for improving the crystallinity of the molded article, making it possible to manufacture molded articles with high dimensional accuracy that have a high temperature of deflection under load (DTUL), flexural modulus (rigidity), and flexural strength, while also having fewer surface defects such as sink marks, flow marks, and orange peel texture.

[0104] For example, T Ｃ If the temperature is between 95°C and 100°C, the mold setting temperature T ＭＯＬＤ The temperature is preferably 50°C to 95°C, more preferably 55°C to 90°C, even more preferably 60°C to 85°C, and most preferably 65°C to 80°C.

[0105] For example, T Ｃ If the temperature is between 80°C and 95°C, the mold setting temperature T ＭＯＬＤ The temperature is preferably 35°C to 80°C, more preferably 40°C to 75°C, even more preferably 45°C to 73°C, and most preferably 50°C to 70°C.

[0106] Thus, the crystallization temperature T of the powder granules Ｃ Depending on the setting temperature of the mold, ＭＯＬＤBy appropriately selecting the elements, the melt memory effect can be effectively utilized to improve the crystallinity of the molded article, making it possible to manufacture molded articles with high dimensional accuracy that have a high load deflection temperature, flexural modulus, and flexural strength, as well as fewer surface defects such as sink marks, flow marks, and orange peel texture.

[0107] Mold setting temperature T ＭＯＬＤ However, T ＭＯＬＤ ≦T Ｃ If the temperature is -60°C, the molded article produced may not have sufficient crystallinity, which can lead to a decrease in the load deflection temperature and / or bending strength of the molded article, and / or an increase in appearance defects.

[0108] The highest melting peak temperature T of powder granules Ｍ If the temperature is 140°C or higher, the powder granules will have a high crystallization temperature of 80°C or higher due to the melt memory effect. Ｃ (Unit: °C) may have. For example, the powder granules used in the first embodiment described later have a maximum melting peak temperature T Ｍ The temperature is 147°C, and the crystallization temperature is T Ｃ The temperature is 95°C. When performing injection molding using this powder granule, the mold setting temperature T ＭＯＬＤ By maintaining a high temperature of around 70°C (for example, 60°C to 80°C), the molten powder granules can be crystallized and solidified within the mold, enabling the production of molded articles with superior quality and appearance with high productivity.

[0109] In the method according to the embodiment, powder granules that do not contain crystallization nucleating agents can be used as the molding material. Crystallization nucleating agents can cause problems such as adhering to the mold and hindering continuous molding, reducing the bending strength and / or load deflection temperature of the molded body, and causing stickiness in the molded body, making it difficult to remove the molded body from the mold. By using powder granules that do not contain crystallization nucleating agents as the molding material, these problems can be avoided.

[0110] In one embodiment, the crystallization temperature T of the molded body ＣＡ (Unit: °C) and crystallization temperature T of powder granules Ｃ (Unit: °C) is given by formula (A4) 0.8 ≤ T ＣＡ / T ＣThe condition ≤ 1.2 (A4) is satisfied. Note that the crystallization temperature T of the powder granules is also satisfied. Ｃ T is defined as the peak temperature of the crystallization exothermic peak observed during cooling in a DSC (Deep Scaling Control) procedure where powder granules are 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. ＣＡ This is defined as the peak temperature of the crystallization exothermic peak observed during cooling in a DSC (Deep Steady Compression) procedure in which a molded body (specifically, a measurement piece cut 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.

[0111] The above formula (A4) represents the crystallization temperature T of the molded body. ＣＡ The crystallization temperature of powder granules T Ｃ This indicates that the change in crystallization temperature due to injection molding is small, and that the melt memory effect of the powder granules was effectively utilized in injection molding. Molded articles manufactured by effectively utilizing the melt memory effect have a high degree of crystallinity, as described above. Therefore, molded articles that satisfy formula (A4) can have a high load deflection temperature, bending strength, bending modulus, dimensional accuracy, and excellent appearance.

[0112] In one embodiment, the powder granules are manufactured under conditions that the temperature of the granules immediately after granulation is below the melting point of PHA, and in this case, the melt flow rate MFR of the PHA powder ＯＲＩ (Unit: g / 10 min), Melt flow rate MFR of powder granules ＧＲＮ (Unit: g / 10 min), and the melt flow rate MFR of the molded product. 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 The following can satisfy ≤10 (c). Melt flow rate MFR of PHA powder ＯＲＩ Melt flow rate MFR of powder granules ＧＲＮ, and the melt flow rate MFR of the molded product ＡＲＴ It is measured at 165°C and under a load of 5 kg in accordance with ISO 1133.

[0113] Formulas (a), (b), and (c) above indicate that the decrease in molecular weight of PHA during the process of manufacturing a molded article of PHA from PHA powder was sufficiently suppressed. By suppressing the decrease in molecular weight of PHA, it becomes possible to manufacture a molded article with superior mechanical properties.

[0114] In one embodiment, the molded article produced has a load deflection temperature of 100°C or higher. The load deflection temperature is measured at a load of 0.45 MPa in accordance with ISO 75.

[0115] The applications of the molded articles produced by the method according to this embodiment are not particularly limited. The molded articles can be used in a variety of applications, such as medical supplies, tableware supplies, agricultural supplies, fishing supplies, forestry supplies, office automation parts, home appliance parts, automotive parts, daily necessities, stationery, and bottle molding preforms. The powder granules used in the method according to this embodiment can be manufactured with less energy compared to molten pellets used in conventional injection molding. Furthermore, the molded articles produced by the method according to this embodiment have excellent physical properties and appearance, as well as being biodegradable in seawater. Therefore, the method according to this embodiment can contribute to reducing greenhouse gas emissions and improving environmental problems caused by the dumping of plastics into the ocean.

[0116] (Second Embodiment) A. Powder Granules First, the powder granules used as the extrusion molding material in the method for manufacturing an extruded molded article according to the embodiment will be described.

[0117] The powder granules contain polyhydroxyalkanoate (PHA) powder, preferably containing PHA powder as the main component, more preferably essentially consisting of PHA powder, and even more preferably consisting of PHA powder. In this specification, "contains" and "includes" mean that additional components or elements may be included unless otherwise specified, and include "essentially consisting of" and "consisting of." "Essentially consisting of" means that additional components or elements may be included that do not substantially adversely affect the product. "Consisting of" means that only the described material or element is included, but does not exclude the inclusion of unavoidable impurities.

[0118] Powder granules are produced by granulating PHA powder. Such powder granules have a melt memory effect. Powder granules can preferably be produced by powder compression granulation (hereinafter also referred to as compression granulation). Details of the method for producing powder granules will be described later.

[0119] In this specification, a powder granule having a melt memory effect means a powder granule having the following characteristics i) and ii): i) The powder granule is melted in a nitrogen atmosphere at a rate of 10°C / min from room temperature until it reaches a first hold temperature T Ｈ１ The temperature is raised to the first holding temperature T Ｈ１ In a first differential scanning calorimetry (DSC) measurement, where the sample is held for 2 minutes and then cooled at a rate of 10°C / min, the first hold temperature T at which the crystallization exothermic peak of PHA is observed during cooling is... Ｈ１ (Unit: °C) It has a first hold temperature T Ｈ１ The highest melting peak temperature T is Ｍ It is higher than this. Here, the highest melting peak temperature T Ｍ (Unit: °C) is defined as the highest peak temperature of the melting peak observed in differential scanning calorimetry when the powder granules are heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere. ii) When the powder granules are heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere, the second hold temperature T Ｈ２ The temperature is raised to the second holding temperature T. Ｈ２In a second DSC (Deep Stem Cell) where the mixture is held for 2 minutes and then cooled at a rate of 10°C / min, the second hold temperature T is such that no crystallization exothermic peak of PHA is observed during the cooling process. Ｈ２ (Unit: °C) It has a second hold temperature T Ｈ２ The first hold temperature T Ｈ１ It's higher than that.

[0120] The melt memory effect refers to the phenomenon in which a pseudo-crystalline phase structure order remains in the molten material when a crystalline polymer is heated and melted (thermoplasticized) above its melting point. The melt memory effect is a unique phenomenon that can occur in crystalline polymers, where, even in a temperature range above the melting point, a region remains that does not immediately become disordered and random due to the long relaxation time required for the material to change to a random aggregated state due to thermal disturbance. Hereinafter, the pseudo-crystalline phase structure order produced by the melt memory effect may be referred to as the melt memory structure. Such powder granules are described in Japanese Patent No. 7454097 and can be manufactured by the method described in Japanese Patent No. 7454097.

[0121] The melt memory effect of powder granules can be evaluated by the method described in Japanese Patent No. 7454097. Specifically, the peak temperature of the crystallization exothermic peak (i.e., the crystallization temperature of the powder granules) observed in the cooling DSC curve obtained by differential scanning calorimetry (DSC) after heating the powder granules to a temperature above the melting point of PHA and then cooling them at a rate of 10°C / min is T. Ｃ If the temperature (in °C) is higher than the crystallization temperature of PHA powder measured in the same manner, the powder granules have a high melt memory effect. When powder granules have a high melt memory effect, the crystallization exothermic peak of the powder granules often has a smaller half-width at half maximum than the crystallization exothermic peak of PHA powder measured in the same manner. The above DSC can be performed, for example, by raising the temperature of the sample 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 after, while cooling the sample in a nitrogen atmosphere at a rate of 10 °C / min.

[0122] When a powder granule exhibiting the melt memory effect is heated and melted, the melt memory structure of PHA remaining in the molten material functions as a crystallization nucleus during cooling. Since the melt memory structure is a pseudo-crystalline phase structure of PHA itself, the crystallization temperature T of the powder granule that crystallizes using the melt memory structure as a nucleus is determined. Ｃ The crystallization temperature is higher than that of molten pellets to which a crystallization nucleating agent has been added. Furthermore, the melt memory effect of powder granules exhibits excellent persistence with respect to molten residence time. On the other hand, if the melt memory structure in the molten material is lost due to thermal disturbance and leads to a random aggregated state, crystallization will not proceed easily during cooling.

[0123] A method for manufacturing an extruded article using powder granules with a melt memory effect as the extrusion molding material may have the following advantages compared to a conventional method for manufacturing an extruded article using molten pellets containing a crystallization nucleating agent as the extrusion molding material.

[0124] i) As described in Japanese Patent No. 7454097, the powder granules are manufactured under conditions where the temperature of the granules immediately after granulation is below the melting point of PHA. Therefore, thermal decomposition of PHA during the granulation process and the resulting decrease in molecular weight are suppressed. As a result, the PHA contained in the powder granules may have a larger molecular weight than the PHA contained in the molten pellets. Consequently, the PHA in the extruded molded article produced from the powder granules can also have a larger molecular weight, thereby enabling the extruded molded article to have superior physical properties.

[0125] ii) The process for producing powder granules uses significantly less electricity than the melt-mixing granulation process using an extruder for producing molten pellets. Therefore, by producing extruded molded products from powder granules, the total amount of electricity used can be greatly reduced.

[0126] iii) By advantageously utilizing the melt memory effect of powder granules, the range of molding conditions (set temperatures of the extrusion molding machine and cooling rolls, screw rotation speed, etc.) can be expanded, making it easier to control the appearance and crystallinity of the extruded product, and also increasing the degree of freedom in the shape of the extruded product (thickness of the extruded product, etc.).

[0127] iv) By using powder granules, extruded articles that do not contain crystallization nucleating agents can be manufactured. Since there is no risk of crystallization nucleating agents leaching out of the manufactured extruded articles, they can be used for food applications, medical applications, and other uses. Furthermore, crystallization nucleating agents can cause problems such as adhesion to cooling rolls, the formation of eye discharge, and increased tackiness of the extruded material and / or extruded articles, leading to the extruded material sticking to the cooling rolls and the extruded articles fusing together, thus hindering continuous extrusion molding. By performing extrusion molding using powder granules that do not contain crystallization nucleating agents, these problems can be avoided, making continuous extrusion molding easier.

[0128] In one embodiment, the powder granules have an outer wall portion formed by the melting and solidification of at least a portion of the PHA powder located at the outer edge of the powder granules, and compressed PHA powder is contained inside the outer wall portion. In this application, melting and solidification means solidification after melting. The outer wall portion is located at the outer edge of the powder granules. In this specification, the outer wall portion is also referred to as the shell portion. The compressed PHA powder inside the outer wall portion may be melted and solidified and welded in place to at least a portion, or it may not be melted and solidified to at least a portion. The compressed PHA powder inside the outer wall portion may be in an unmelted state. That is, at least a portion of the compressed PHA powder inside the outer wall portion may include an unmelted compressed powder form, or it 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 it is not a welded structure strong enough to hold the PHA powder like the outer wall portion. In this specification, the inner part of the outer wall is also referred to as the core. The core inside the outer wall contains compressed PHA powder. In this specification, "compressed" means that the density of the PHA powder located in the core is higher than the bulk density of the PHA powder before granulation. Such powder granules are described in Japanese Patent No. 7387950 and can be manufactured by the method described in Japanese Patent No. 7387950. Furthermore, such powder granules have the melt memory effect described above.

[0129] The outer wall (shell) has a dense structure containing molten and solidified PHA powder. On the other hand, the inner core, although compressed, has a looser structure compared to the dense structure (welded structure) of the outer wall containing the molten and solidified PHA powder. Because the outer wall containing the molten and solidified PHA powder holds the compressed PHA powder present in the core, the powder granules can have a stable structure, less powder shedding, and excellent handling and safety, and can also lead to an improved working environment for the manufacture of extruded molded products.

[0130] The outer wall portion (shell portion) has a welded structure in which at least a portion of the thermoplastic resin powder located at the outer edge of the powder granules is melted and solidified. The outer wall portion may be smooth enough to have a glossy appearance. Alternatively, the outer wall portion may be formed by the melting of some of the components of the thermoplastic resin powder and partial welding with adjacent components, even if the melting is not sufficient to form a smooth surface. The outer wall portion can be formed during compression granulation, for example, at the contact surface with the die hole, by the melting of at least a portion of the PHA powder due to frictional heat with the wall surface or heat transfer from the wall surface. The thickness of the outer wall portion can vary depending on the manufacturing conditions of the PHA powder granules.

[0131] The core is the part located inside the outer wall and contains compressed thermoplastic resin powder. The PHA powder in the core may be porous, or it may have a non-welded structure because heat is not transferred to the core during granulation. The core may have a structure in which the PHA powder maintains its powder shape (i.e., a non-welded structure or a powdery structure), or a structure in which it is partially welded but the shape of the PHA powder remains.

[0132] In this specification, for the sake of simplicity of explanation, the terms "outer wall (shell)" and "core" are used. However, as stated above, the outer wall is formed when the PHA powder melts due to the heat during granulation, so in reality, there is no clear boundary between the outer wall (shell) and the core. The outer wall (shell) refers to the part that includes the welded structure of the PHA powder and is located on the outer edge of the powder granules, contributing to maintaining a certain shape of the powder granules. The core refers to the part located inside the outer wall (shell).

[0133] The shape of the powder granules is preferably approximately cylindrical or approximately rectangular prismatic, and it is preferable that the powder granules have an outer wall portion on the side surface. In this disclosure, the powder granules have an approximately cylindrical or approximately rectangular prismatic shape, and it is preferable that an outer wall portion is formed on the side surface of the powder granules having an approximately cylindrical or approximately rectangular prismatic shape.

[0134] Because powder granules with this shape can be directly supplied to extrusion molding machines for thermoplastic resins, they can be used as extrusion molding materials.

[0135] Powder granules can take on any suitable shape. Typically, when powder granules are manufactured by compression granulation of powder and granulation is performed by passing the powder through a circular die hole, the basic shape of the powder granules is a cylindrical pellet shape.

[0136] In this specification, the term "die" used in the manufacture of powder granules refers collectively to tools equivalent to molds used to compress and shape PHA powder granules.

[0137] When the powder granules are approximately cylindrical in shape, the diameter of the powder granules is, for example, 2 mm to 7 mm, preferably 3 mm to 5 mm. The length (height) of the powder granules is, for example, 1 mm to 10 mm, preferably 2 mm to 7 mm. Such a shape results in powder granules that are easy to handle. The diameter of the powder granules can be adjusted, for example, by the diameter of the die holes in the disc plate (die plate) during granulation, and the length can be adjusted by the distance between the disc plate and the cutter. This distance can be any appropriate distance. The distance between the disc plate and the cutter is, for example, 1 mm to 30 mm, preferably 2 mm to 20 mm, preferably 3 mm to 10 mm.

[0138] The fracture strength of the powder granules, based on measurements using a Kiya hardness tester, 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, and preferably 10.0 kg or more. The upper limit may exceed the measurement limit of the Kiya hardness tester (10 kg is the measurement limit for the "WPF1600-B" manufactured by Shiro Sangyo Co., Ltd.). Within this range, powder granules with excellent handling and melt processability can be obtained. Here, fracture strength refers to the average fracture stress (fracture load) measured by crushing powder granules of 20 or more particles (preferably 25 or more particles) in a direction perpendicular to the longitudinal direction (extrusion direction) of the powder granules. In powder granulation, the shell portion is composed of molten resin, making it possible to maintain a stable shape as a granule despite it being a powder granule. The diameter of the pressure surface of the pressure attachment of the Kiya hardness tester is, for example, 5 mm.

[0139] The bulk density of the powder granules can be any appropriate bulk density, but is preferably 0.3 kg / L to 2.0 kg / L, and more preferably 0.5 kg / L to 1.0 kg / L. Increasing the bulk density improves the supply speed and supply stability of the powder granules to the extrusion molding machine.

[0140] The bulk density of powder granules is calculated by allowing the powder granules to fall naturally into a 1-liter measuring cup until it is level, accurately measuring out 1 liter of powder granules, and then measuring its mass (unit: kg / L).

[0141] B. PHA Powder The PHA powder, which is the raw material for powder granules, is a powdered polyhydroxyalkanoate (PHA) resin. PHA can be a compound produced in the body of microorganisms, for example, by feeding on carbohydrates, oils, etc. Such PHA is primarily extracted from microorganisms as a powdered polymer.

[0142] PHA contains hydroxyalkanoic acid 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-hydroxynanoate, 3-hydroxydecanoate, 3-hydroxytetradecanoate, 3-hydroxyhexadecanoate, 3-hydroxyoctadecanoate, 4-hydroxybutyrate, 4-hydroxyvalerate, 5-hydroxyvalerate, or 6-hydroxyhexanoate. The number of carbon atoms in the 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 in the 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, and particularly 6 or less. The hydroxyalkanoic acid may be used alone or in combination of two or more types.

[0143] Preferred PHAs include poly(3-hydroxyalkanoate) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0144] In 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, and preferably 700,000 or more. The melt memory effect is manifested by a time delay in the process in which polymer molecular chains transition from a crystalline ordered state to a random state in the molten state. Therefore, the larger the molecular weight, the longer the relaxation time (transition time to random chains), which is advantageous in terms of the persistence of the effect. A weight-average molecular weight of PHA of 200,000 or more is preferable because it can effectively delay the decrease or deactivation of the melt memory effect due to thermal disturbance. 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 powder granulation tends to become difficult. For this reason, the weight-average molecular weight of PHA is preferably 3 million or less, preferably 2 million or less, preferably 1.5 million or less, and preferably 1 million or less.

[0145] The weight-average molecular weight (Mw) mentioned above can be determined as the weight-average molecular weight in terms of polystyrene by gel permeation chromatography (GPC). For example, evaluation can be performed using a Showa Denko "Showdex GPC-101" as the GPC apparatus, polystyrene gel (Showa Denko "Showdex K-804") as the column packing material, and an organic solvent mobile phase (e.g., chloroform). The column apparatus, column packing material, and organic solvent mobile phase can be selected as appropriate, but for example, chloroform can be used.

[0146] PHA powder may be a powdery resin obtained through its manufacturing process, i.e., a powdery resin resulting from the manufacturing process, or it may be obtained by pulverizing a non-powdery PHA resin such as pellets, lumps, or molded articles. PHA powder can be obtained, for example, by pulverizing molded articles, pellets, trimming scraps generated in extrusion molding, or sprues or runners generated in injection molding at room temperature, or after cooling them with dry ice or liquid nitrogen as needed, using a pulverizer (for example, Dalton products, trade names "Nearmill," "Sylpheedmill," "Atomizer," or "Impactmill," etc.).

[0147] The particle size of the PHA powder can be any appropriate particle size depending on its form, as long as the effects of this embodiment are obtained. Preferably, the maximum particle size of the PHA powder before granulation is 5 mm or less, and the minimum particle size is 0.0001 mm or more.

[0148] The average particle size of the PHA powder is, for example, 0.001 mm or more and 1.0 mm or less. Preferably, the average particle size of the PHA powder is 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 may be measured by laser diffraction. The average particle size of the PHA powder may be the median diameter (d50) which is the cumulative 50% in the cumulative particle size distribution 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 types.

[0149] The PHA powder before granulation may 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 easily performed.

[0150] The bulk density of PHA powder is calculated by letting the PHA powder fall naturally into a 1-liter measuring cup until it is level, accurately measuring out 1 liter of PHA powder, and then measuring its mass (unit: kg / L).

[0151] C. Other component powder granules contained in the PHA powder granules may include any suitable additives as needed. Additives may be in solid form such as powder, or in liquid form. Examples of additives include binders, dispersants, crystallization nucleating agents, antioxidants, light stabilizers, foaming agents, UV absorbers, antiblocking agents, heat stabilizers, impact modifiers, antibacterial agents, compatibilizers, processing aids, lubricants, coupling agents, hydrolysis inhibitors, oxygen scavengers, or colorants (dyes and pigments). Additives may be used individually or in combination of two or more.

[0152] 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.

[0153] The powder granulate may contain a binder as an additive. Here, the "binder" generally refers to a compound that exists between PHA powder particles in addition to the components of the raw material PHA powder, binds the powder particles together, and can exhibit the effect of increasing 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.

[0154] 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.

[0155] 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, and preferably 0% by mass (undetectable) with respect to the total mass of the PHA powder granulate.

[0156] In one embodiment, a dispersant is preferably used as the 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, etc. The use of the dispersant can bring effects such as improving the productivity (discharge rate) of the powder granulate, reducing the frictional heat during granulation, and enhancing the cleaning property of the granulation device.

[0157] Examples of the dispersant include fatty acids, fatty acid metal salts, fatty acid sulfonates, fatty acid amides, acrylamides, polyhydric alcohol fatty acid esters, and polyglycerol fatty acid esters. The dispersant may be used alone or in combination of two or more.

[0158] In one embodiment, the dispersant is at least one selected from the group consisting of polyhydric alcohol fatty acid esters, fatty acid amides, polyglycerol fatty acid esters, condensed hydroxy fatty acids, and alcohol esters of condensed hydroxy fatty acids.

[0159] 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.

[0160] The 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 the fatty acid amide include saturated fatty acid monoamides such as lauric acid amide, palmitic acid amide, stearic acid amide, and behenic acid amide.

[0161] The polyglycerol fatty acid ester is an ester compound composed of polyglycerol and a fatty acid. Examples of the polyglycerol fatty acid ester include diglycerol palmitate, diglycerol stearate, diglycerol oleate, decaglycerol palmitate, decaglycerol stearate, decaglycerol oleate, and the like.

[0162] The content of the dispersant is usually 0% to 10.0% by mass, preferably 0.01% to 9.0% by mass, preferably 0.1% to 7.0% by mass, and more preferably 0.3% to 5.0% by mass based on the total mass of the powder granulate. 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 (not detectable) based on the total mass of the powder granulate.

[0163] Crystallization nucleating agents can be added as additives to powder granules. Examples of crystallization nucleating agents that can be added to powder granules include organometallic salt compounds such as phosphate ester metal salts, benzoate metal salts, pimephosphate metal salts, rosin metal salts, oxalate metal salts, and fatty acid metal salts; aliphatic organic esters, triallyl phosphate, polyalkylene glycol or its derivatives, aliphatic polyesters, and organic compounds such as benzylidene sorbitol; dyes and pigments such as pentaerythritol, quinacdrin, cyanine blue, and carbon black; minerals such as talc, mica, kaolin, clay, carbonate minerals, metal oxides, and metal sulfates; ionomers; and polymer compounds such as high-melting-point polyamides.

[0164] In one embodiment, talc, mica, kaolin, or calcium carbonate are used as crystallization nucleating agents. One type of crystallization nucleating agent may be used alone, or two or more types may be used in combination.

[0165] The content of the crystallization nucleating agent in the powder granules 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, and preferably 0.3% by mass or more and 5.0% by mass or less.

[0166] In one embodiment, the powder granules substantially do not contain a crystallization nucleating agent. Because the powder granules can exhibit a melt memory effect, they can achieve excellent crystallization characteristics in molding processes even without the use of a crystallization nucleating agent.

[0167] "Substantially free of crystallization nucleating agents" means, for example, that the content of crystallization nucleating agents in the powder granules is 0.1% by mass or less, preferably less than 0.1% by mass, preferably 0.01% by mass or less, preferably 0.005% by mass or less, preferably 0.001% by mass or less, and preferably 0% by mass (undetectable) of the crystallization nucleating agents in the powder granules.

[0168] Furthermore, those skilled in the art should understand that powder granules may contain a crystallization nucleating agent or that powder granules may be used together with a crystallization nucleating agent. When powder granules contain a crystallization nucleating agent or when powder granules are used together with a crystallization nucleating agent, in addition to the crystallization-promoting effect due to the melt memory effect, a crystallization-promoting effect due to the crystallization nucleating agent can be obtained.

[0169] D. Method for Manufacturing PHA Powder Granules Powder granules can be manufactured using various powder granulators, but preferred granulators include compression granulators such as disc pelletizers, screw extrusion machines, briquetting machines, compaction machines, and tableting machines. Powder granules manufactured by a compression granulator are thought to have an outer wall containing oriented crystals due to the strong shear stress from the wall of the die hole during the granulation process. Therefore, powder granules manufactured by the compression granulation method (i.e., compression granules) can have a particularly high melt memory effect.

[0170] Among the examples given above, the disc pelletizer method is preferred from the viewpoint of granulation productivity and the quality and shape uniformity of the resulting powder granules. In the disc pelletizer method, a semi-wet granulation method can be employed, which involves incorporating an appropriate amount of moisture into the PHA powder. In some cases, granulation can be performed without using water. When granulation is performed without using water, the post-granulation drying treatment described later may become unnecessary. When granulation is performed without using water, the amount of energy required in the drying process can be reduced, and the amount of carbon dioxide emitted during the manufacturing process can be significantly reduced.

[0171] As mentioned above, PHA powder granules can be advantageously obtained by the granulation method described in Japanese Patent No. 7454097 or Japanese Patent No. 7387950.

[0172] When the powder granules are a mixture containing two or more types of PHA powder raw materials, or contain any component other than PHA, it is preferable to mix them uniformly using any suitable mixer. Examples of mixers include Henschel mixers, Nauter mixers, powder kneaders (KDH, KDA, CKD, CPM) (Dalton), Spartan mixers (SPM) (Dalton), and SP granulators (SPG) (Dalton). To obtain a desirable 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, it is preferable to use a combination of upper and lower blades, with the upper blade being a Y1 blade (product name, manufactured by Nippon Coke Industries Co., Ltd.) and the lower blade being an S0 blade (product name, manufactured by Nippon Coke Industries Co., Ltd.). It is also preferable to install a deflector in the stirring tank and mix the mixture. In other words, using a mixing device that can uniformly disperse each component throughout the mixture is advantageous in improving the productivity and quality stability of the final powder granules.

[0173] When producing powder granules using the semi-wet granulation method described above, the amount of water added can be any appropriate amount depending on the properties of the powder (e.g., water absorption). In this case, the amount of water added is 3 to 30 parts by mass, preferably 5 to 25 parts by mass, and more preferably 5 to 20 parts by mass, per 100 parts by mass of crystalline polymer powder. The semi-wet method can be used to improve the stability of granulation.

[0174] In the granulation process of powder granules, localized heat generation can lead to die clogging. Therefore, incorporating an appropriate amount of moisture into the PHA powder during granulation and using the heat of vaporization of water to suppress excessive temperature rise during granulation can be advantageous for continuous granulation.

[0175] The powder granules can be dried after granulation, but the final moisture content of the powder granules 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 final moisture content of the powder granules can be appropriately selected depending on the intended use.

[0176] It is preferable that the powder granules are granulated without the addition of water. If the moisture content of the powder granules is low, post-granulation drying may not be necessary. If granulation can be performed without using water, drying is unnecessary, which can significantly reduce the amount of carbon dioxide emitted during the powder granulation process.

[0177] The moisture content of the granulated powder without the addition of 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.

[0178] When producing powder granules using a screw extrusion compression granulator, it is easy to install a temperature control device on the compression granulator, and compression granulation can be performed at low screw rotation speeds, thus reducing localized heat generation due to rapid shear heat generation during granulation. When producing powder granules using a bricketing, compaction, or tableting compression granulator, the shear stress on the powder from the die hole walls is smaller compared to the disc pelletizer method, thus reducing localized heat generation during granulation. Therefore, with the screw extrusion, bricketing, compaction, and tableting methods, powder granules can be produced continuously and stably without causing die clogging due to localized heat generation, even without the addition of water. When granulation is performed without the addition of water, post-granulation drying is unnecessary, thus simplifying the manufacturing process and reducing energy consumption for drying.

[0179] The moisture content of powder granules is measured using an infrared moisture meter.

[0180] A disc pelletizer type granulator has, as a basic structure, one (flat die) or two discs (indicating cylindrical dies) with numerous holes ranging from 2 mm to 30 mm in size, and rollers for pressurizing the raw material into the holes of the discs. PHA powder (which may contain moisture) supplied between the disc and the roller, or between two discs, is pressed into the holes of the discs as the roller rotates, forming a cylindrical extruded product. The extruded product is cut on the back surface of the disc with a cutter or the like to obtain pelletized powder granules. The length of the granules can be adjusted by the distance between the back surface of the disc and the cutter, the rotation speed of the roller, etc. The distance between the disc plate and the cutter can be any appropriate distance. For example, the distance between the disc plate and the cutter is 1 mm to 30 mm, more preferably 2 mm to 20 mm, and even more preferably 3 mm to 10 mm.

[0181] More specifically, disc pelletizer systems include roller-disc die systems, roller-ring die systems, double die systems, and flat die systems. A commercially available disc pelletizer granulator is, for example, the Dalton F-series disc pelletizer.

[0182] The powder granules may be thoroughly dried immediately before use as an extrusion molding material. This effectively suppresses the decrease in molecular weight of PHA and / or defects in the appearance of the extruded product that occur during extrusion molding. The moisture content of the powder granules immediately before use as an extrusion 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 carried out at 70°C to 110°C, 75°C to 100°C, or 80°C to 90°C until the predetermined moisture content is reached. The moisture content of the powder granules is measured using an infrared moisture meter.

[0183] E. Method for manufacturing an extruded article by extrusion molding The method for manufacturing an extruded article according to the embodiment includes using powder granules containing PHA as a molding material and extruding the PHA using an extrusion molding machine. Extrusion molding includes melting the powder granules fed into the extrusion molding machine to obtain a molten material, extruding the molten material from a die, and cooling the extruded molten material to solidify it. The extruded article may have a sheet-like or tubular shape, but is not limited to these.

[0184] In this specification, the term "die" used in extrusion molding refers to a general term for a tool that corresponds to a mold for extruding molten PHA into a desired shape.

[0185] E-1. Method for Manufacturing Sheet-Shaped Extruded Moldings When manufacturing sheet-shaped extruded moldings, for example, the extruded moldings can be manufactured using the extruder 1 shown in Figure 3. The extruder 1 comprises an extruder 10, at least one cooling roll 30, at least one conveying roll 50, and a winding roll 70. The extruder 10 comprises a cylinder 12, a screw 14 housed in the cylinder 12, a hopper 16 for supplying powder granules 92 to the cylinder 12, a die head 17, an adapter 19, and a T-type die 18. The hopper 16 is located at the uppermost part of the extruder 10. The die head 17, adapter 19, and T-type die 18 are connected in this order downstream of the cylinder 12. The T-type die 18 is located at the lowermost part of the extruder 10. The cooling roll 30 is located below the T-type die 18 in the direction of gravity. In the extrusion molding machine 1 shown in Figure 3, at least one cooling roll 30 consists of a first roll 32 and a second roll 34, and at least one conveying roll 50 consists of a third roll 52 located downstream of the second roll 34, and a pair of pinch rolls 54 located downstream of the third roll 52. The temperature of each part of the extrusion molding machine 1 can be controlled by heating heaters (not shown) and / or cooling units (not shown) provided in each part.

[0186] The powder granulated product 92 charged into the hopper 16 is supplied into the cylinder 12. The powder granulated product 92 is heated and melted in the cylinder 12. The melt is sent by the rotating screw 14 to the T-die 18 via the die head 17 and the adapter 19, and the sheet-like melt 94 is continuously extruded from the T-die 18.

[0187] The plasticizing melt temperature T of the powder granulated product 92 in the extruder 10 Ｐ (unit: °C) satisfies the formula (B1): T Ｍ -10 < T Ｐ ≤ T Ｍ +20 (B1) (where T Ｍ (unit: °C) represents the highest melting peak temperature observed in a differential scanning calorimetry (DSC) in which the powder granulated product is heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere.)

[0188] Incidentally, the highest melting peak temperature T Ｍ means the highest temperature among the peak temperatures of those melting peaks when multiple melting peaks are observed by DSC, and means the peak temperature of that melting peak when one melting peak is observed by DSC.

[0189] In this specification, the plasticizing melt temperature T Ｐ is defined as the temperature of the melt in the die head 17. The temperature of the melt in the die head 17 is measured by a thermocouple attached to the die head 17.

[0190] The plasticizing melt temperature T Ｐ By satisfying the formula (B1), disappearance of the melt memory effect of the powder granulated product 92 due to heat disturbance, mechanical mixing, etc. can be suppressed, and thereby extrusion molding utilizing the melt memory effect effectively can be performed.

[0191] The plasticizing melt temperature T Ｐ is preferably: T Ｍ -8 < T Ｐ ≤ T Ｍ +15, and more preferably: T Ｍ -5 < T Ｐ ≤ T ＭSatisfying +10, and more preferably T Ｍ -5 < T Ｐ ≦T Ｍ Satisfy +5.

[0192] In conventional extrusion molding using molten PHA pellets as a molding material, the plasticizing melt temperature T Ｐ If the temperature is set below the melting peak temperature of the molten pellets, it not only places an excessive load on the extruder, but also results in insufficient plasticization, which can lead to residual unmelted material being mixed into the extruded molded product, and insufficient flow causing defects in the extruded molded product such as shrinkage, poor transfer, uneven flow, uneven thickness, and orange peel texture.

[0193] In contrast, in the method according to this embodiment, which uses PHA powder granules 92 as a molding material, the load on the extruder 10 is reduced due to the large porosity of the powder granules 92, so the plasticization melting temperature T Ｐ ga T Ｍ -10 < T Ｐ <T Ｍ Even when this condition is met, the powder granules 92 can be sufficiently plasticized and extruded without placing an excessive load on the molding machine.

[0194] Inside the extruder 10, a flow field is formed as the screw 14 for plasticization metering rotates. The maximum temperature at which the melt memory effect is maintained in the flow field may be lower than the maximum temperature at which the melt memory effect is maintained in the stationary field. Plasticization melt temperature T Ｐ However, T Ｐ >T Ｍ If the value of +20 is met, the melt memory effect decreases or disappears due to the action of the flow field, slowing down the crystallization and solidification of the molten material 94 extruded from the T-type die 18. This can lead to various problems such as poor release from the cooling roll 30, sticking of extruded molded bodies to each other, deformation of the extruded molded bodies, difficulty in thinning the extruded molded bodies, reduction of effective sheet width, and post-shrinkage, potentially reducing productivity. The effective sheet width refers to the width of the region within the sheet-shaped extruded molded body that has a thickness within a set range.

[0195] In one embodiment, the screw 14 is a single-screw flight screw. The single-screw flight screw has a supply zone, a compression zone, and a metering zone in the flow direction of the powder granules and their molten material, from upstream to downstream. Such a single-screw flight screw can suppress the reduction or disappearance of the melt memory effect due to the flow field generated by thermal disturbances and / or mechanical mixing. When the screw of the extrusion molding machine is a single-screw flight screw, the rotational speed S of the screw 14 Ｒ The rotational speed S of the screw 14 is preferably 100 rpm or less, 80 rpm or less, 60 rpm or less, 50 rpm or less, or 30 rpm or less. Ｒ By reducing this, the reduction or disappearance of the melt memory effect caused by the flow field generated by mechanical mixing can be suppressed. The rotational speed S of the screw 14. Ｒ The speed may be 10 rpm or higher.

[0196] The sheet-like molten material 94 extruded from the T-type die 18 is drawn down between the first roll 32 and the second roll 34, which constitute the cooling roll 30. The molten material 94 is sandwiched between the first roll 32 and the second roll 34 and then conveyed along the surface of the second roll 34. During this time, the molten material 94 is cooled by the cooling roll 30 and crystallizes and solidifies. This forms a sheet-like extruded molded body 96. The extruded molded body 96 is conveyed to the winding roll 70 via the conveying roll 50 and wound up by the winding roll 70. The winding speed of the extruded molded body 96 can be controlled by the rotational speed of the second roll 34.

[0197] The first roll 32 may have an outermost layer made of elastomer. When the outermost layer of the first roll 32 is made of elastomer, the first roll 32 can deform and press the entire molten material 94 against the second roll 34, allowing for efficient control of the thickness of the extruded product 96. The surfaces of the first roll 32 and / or the second roll 34 may be mirror-like or may have irregularities of a predetermined shape. The surface shape of the first roll 32 and / or the second roll 34 can be transferred to the surface of the extruded product 96.

[0198] The surface temperatures of the cooling roll 30 (i.e., the first roll 32 and the second roll 34) and the conveying roll 50 can be set as appropriate. Surface temperature T of the first roll 32 Ｒ１ The surface temperature T of the second roll 34 Ｒ２ Preferably, each is controlled independently. Surface temperature T of the first roll 32 Ｒ１ The surface temperature T of the second roll 34 Ｒ２ These may be controlled integrally. Surface temperature T of the second roll 34 Ｒ２ The surface temperature T of the third roll 52 is Ｒ３ The surface temperature of each roll may be controlled integrally. The surface temperature of each roll can be controlled by a temperature control device (e.g., water cooling device, oil cooling device, heater) provided on each roll. Multiple rolls may share a single temperature control device, thereby controlling the surface temperatures of the multiple rolls integrally. The surface temperature of each roll is measured by a contact thermometer (e.g., thermocouple) provided on the surface of each roll.

[0199] In one embodiment, the surface temperature T of the first roll 32 Ｒ１ (Unit: °C), surface temperature T of the second roll 34 Ｒ２ (Unit: °C), and crystallization temperature T of the powder granules 92 Ｃ (Unit: °C) is given by formulas (B2), (B3), and (B4) T Ｃ -80<T Ｒ１ ≦T Ｃ (B2) T Ｃ -60<T Ｒ２ ≦T Ｃ (B3) T Ｒ１ <T Ｒ２ (B4) may be satisfied. Note that the crystallization temperature T Ｃ This is defined as the peak temperature of the crystallization exothermic peak observed during cooling in differential scanning calorimetry (DSC) in which powder granules 92 are 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.

[0200] Surface temperature T of the first roll 32 Ｒ１ The surface temperature T of the second roll 34 Ｒ２By being lower than the surface temperature T of the second roll 34, the molten material 94 is prevented from sticking to the first roll 32, and the molten material 94 is conveyed along the surface of the second roll 34 with high reliability. Ｒ２ and the surface temperature T of the first roll 32 Ｒ１ The difference (T Ｒ２ -T Ｒ１ The temperature range may be 5°C to 60°C, 10°C to 50°C, or 20°C to 40°C.

[0201] Surface temperature T of the first roll 32 Ｒ１ , the surface temperature T of the second roll 34 Ｒ２ , and the crystallization temperature T of the powder granules 92 Ｃ Preferably, T Ｃ -75<T Ｒ１ ≦T Ｃ , and T Ｃ -60<T Ｒ２ ≦T Ｃ More favorably, T Ｃ -70<T Ｒ１ ≦T Ｃ , and T Ｃ -55<T Ｒ２ ≦T Ｃ More preferably, T Ｃ -70<T Ｒ１ ≦T Ｃ , and T Ｃ -50<T Ｒ２ ≦T Ｃ Particularly preferred, T Ｃ -70<T Ｒ１ ≦T Ｃ , and T Ｃ -45<T Ｒ２ ≦T Ｃ It satisfies the condition.

[0202] Surface temperature T of the second roll 34 Ｒ２ The crystallization temperature T of the powder granule 92 Ｃ By doing the following, the crystallization solidification of the molten material 94 extruded from the T-type die 18 can be rapidly advanced, and an extruded molded body 96 with excellent quality and appearance can be manufactured with high productivity. The crystallization temperature T of the powder granules 92 having the melt memory effect as described above. ＣSince the crystallization temperature of the molten pellet with the crystallization nucleating agent added is higher than that of the molten pellet, when extrusion molding is performed using powder granules 92 having a melt memory effect as the molding material, the surface temperature T of the second roll 34 is higher compared to conventional extrusion molding using molten pellets. Ｒ２ The surface temperature T of the second roll 34 can be increased. Ｒ２ A high crystallinity is advantageous for improving the crystallinity of the extruded article 96 produced. Improved crystallinity leads to the production of an extruded article 96 with high heat resistance, high elastic modulus (rigidity), and high shape and dimensional stability, as well as fewer appearance defects. High heat resistance means a high thermal shrinkage onset temperature. High shape and dimensional stability means that the extruded article 96 shrinks little or no after production, does not warp, and if shrinkage occurs, its anisotropy is small.

[0203] In one embodiment, the highest melting peak temperature T of the powder granules 92 Ｍ The temperature is above 140°C, and the powder granules 92 have a high crystallization temperature of 80°C or higher due to the melt memory effect. Ｃ It may have the following. In this case, the surface temperature T of the second roll 34 Ｒ２ By maintaining a high temperature of 50°C to 80°C, the molten material 94 in contact with the second roll 34 can be rapidly crystallized and solidified. As a result, the extruded product 96 does not adhere to the second roll 34, and an extruded product 96 with excellent quality and appearance can be manufactured with high productivity.

[0204] For example, the powder granules used in the second embodiment described later have a maximum melting peak temperature T Ｍ The temperature is 147°C, and the crystallization temperature is T Ｃ The temperature is 95°C. When extrusion molding is performed using this powder granule, the surface temperature T of the second roll 34 Ｒ２ By maintaining a temperature of 63°C, the molten material 94 in contact with the second roll 34 can be rapidly crystallized and solidified. As a result, the extruded product 96 does not adhere to the second roll 34, and an extruded product 96 with excellent quality and appearance can be manufactured with high productivity.

[0205] The surface temperature of each roll in the extrusion molding machine 1 is the crystallization temperature T of the powder granules 92. ＣThe crystallization temperature T of the powder granules 92 may be set as appropriate. For example, the crystallization temperature T of the powder granules 92 Ｃ If the temperature is between 95°C and 100°C, the surface temperature T of the first roll 32 Ｒ１ The temperature is preferably 20°C to 60°C, more preferably 30°C to 50°C, and the surface temperature T of the second roll 34 is Ｒ２ The temperature is preferably 50°C to 95°C, more preferably 55°C to 90°C, even more preferably 58°C to 85°C, and most preferably 60°C to 80°C.

[0206] For example, the crystallization temperature T of the powder granule 92 Ｃ If the temperature is between 80°C and 95°C, the surface temperature T of the first roll 32 Ｒ１ The temperature is preferably 10°C to 50°C, more preferably 20°C to 45°C, and the surface temperature T of the second roll 34 is Ｒ２ The temperature is preferably 50°C to 85°C, more preferably 40°C to 80°C, even more preferably 40°C to 80°C, and most preferably 40°C to 70°C.

[0207] Thus, the crystallization temperature T of the powder granules Ｃ Accordingly, the surface temperature T of the first roll 32 Ｒ１ The surface temperature T of the second roll 34 Ｒ２ By appropriately selecting the elements, the melt memory effect can be effectively utilized to rapidly crystallize the molten material 94. This results in various advantages, such as improved release properties from the cooling roll 30, prevention of sticking between extruded bodies 96, prevention or reduction of deformation of the extruded bodies 96, improved ease of thinning the extruded bodies 96, increased effective sheet width, and reduced shrinkage after extrusion molding, enabling efficient extrusion molding. Furthermore, the manufactured extruded bodies 96 can have a high degree of crystallinity, thus possessing high heat resistance, elastic modulus, and stability of shape and dimensions, and exhibiting fewer appearance defects.

[0208] Surface temperature T of the second roll 34 Ｒ２ However, the crystallization temperature T of the powder granules 92 ＣIf the temperature is 60°C or more lower than the specified temperature, the extruded article 96 produced may not have sufficient crystallinity, and shrinkage after extrusion may reduce the dimensional and shape stability of the extruded article 96, as well as increase the appearance defects such as sheet warping, transfer defects, and uneven thickness.

[0209] In the method according to this embodiment, a powder granule 92 that does not contain a crystallization nucleating agent can be used as the molding material. Crystallization nucleating agents can cause problems such as adhering to the cooling roll, generating eye discharge, and increasing the stickiness of the extruded product and / or extruded molded product, leading to the extruded product sticking to the cooling roll and the extruded molded product fusing together, which can hinder continuous extrusion molding. Furthermore, crystallization nucleating agents can also be a factor in reducing the heat resistance of the manufactured extruded molded product. These problems can be avoided by performing extrusion molding using a powder granule that does not contain a crystallization nucleating agent.

[0210] In one embodiment, the crystallization temperature T of the extruded body 96 ＣＡ (Unit: °C) and crystallization temperature T of powder granule 92 Ｃ (Unit: °C) is given by formula (B5) 0.8 ≤ T ＣＡ / T Ｃ The condition ≤ 1.2 (B5) is satisfied. Note that the crystallization temperature T of the powder granules 92 Ｃ T is defined as the peak temperature of the crystallization exothermic peak observed during cooling in a DSC (Deep Scaling Control) where powder granules 92 are 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. ＣＡ This is defined as the peak temperature of the crystallization exothermic peak observed during cooling in a DSC (Deep Steady Compression) in which an extruded body 96 (specifically, a measurement piece cut from the extruded body 96) 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.

[0211] The above formula (B5) represents the crystallization temperature T of the extruded body 96. ＣＡ The crystallization temperature T of the powder granule 92 ＣThis indicates that the temperature is almost equivalent to that of the previous model, meaning that the change in crystallization temperature due to extrusion molding is small, and that the melt memory effect of the powder granules 92 was effectively utilized in the extrusion molding process. As mentioned above, effectively utilizing the melt memory effect is advantageous for improving the degree of crystallization of the extruded body 96, and as a result, the extruded body 96 can have a large effective sheet width, reduced shrinkage after extrusion molding, and high heat resistance.

[0212] Crystallization temperature T of the extruded body 96 ＣＡ The crystallization temperature T of the powder granule 92 Ｃ It may be higher than that. In that case, the extruded product 96 is thought to have a higher melt memory effect than the powder granules 92, which may be advantageous when further molding the extruded product 96.

[0213] In one embodiment, the powder granules 92 are manufactured under conditions that the temperature of the granules immediately after granulation is below the melting point of PHA, and in this case, the melt flow rate MFR of the PHA powder ＯＲＩ (Unit: g / 10 min), Melt flow rate MFR of powder granule 92 ＧＲＮ (Unit: g / 10 min), and the melt flow rate MFR of the extruded product 96 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 The following can satisfy ≤10 (c). Melt flow rate MFR of PHA powder ＯＲＩ , Melt flow rate MFR of powder granule 92 ＧＲＮ , and the melt flow rate MFR of the extruded body 96 ＡＲＴ It is measured at 165°C and under a load of 5 kg in accordance with ISO 1133.

[0214] Formulas (a), (b), and (c) above indicate that the decrease in molecular weight of PHA during the process of producing the PHA extruded article 96 from PHA powder was sufficiently suppressed. By suppressing the decrease in molecular weight of PHA, it becomes possible to produce an extruded article 96 with superior mechanical properties.

[0215] E-2. Method for manufacturing tubular extruded articles Examples of tubular extruded articles include elongated cylindrical molded products with a hollow interior, such as straws and pipes. Extruded articles have a roughly circular cross-sectional shape.

[0216] A tubular extruded body can be manufactured using an extruder equipped with a cylinder, a screw housed within the cylinder, a hopper for supplying powdered granules to the cylinder, and an annular die. The extruder has the same configuration as the extruder 10 described above shown in Figure 3, except that it is equipped with an annular die instead of a T-shaped die. The plasticization melt temperature in this extruder is the plasticization melt temperature T in the extruder shown in Figure 3. Ｐ The settings are the same as above. A tubular extruded body can be manufactured by melting powder granules in a cylinder, extruding the tubular molten material from an annular die into water, and cooling the molten material in water to solidify it into crystals.

[0217] When an extruded body is used as a drinking straw, from the viewpoint of ease of drinking, the extruded body preferably has an outer diameter of 2 mm to 10 mm, more preferably 4 mm to 8 mm, even more preferably 5 mm to 7 mm, and preferably an average thickness of 0.005 mm to 0.5 mm, more preferably 0.01 mm to 0.3 mm, even more preferably 0.02 mm to 0.2 mm, even more preferably 0.03 mm to 0.15 mm, and particularly preferably 0.04 mm to 0.10 mm. In the method according to the embodiment, by effectively utilizing the melt memory effect of the powder granules, the molten material can be rapidly crystallized and solidified even without a crystallization nucleating agent, so that an extruded body having such a small average thickness (for example, an average thickness of 0.1 mm or less) and sufficient thickness accuracy, rigidity, and heat resistance can be manufactured. When an extruded body is used as a drinking straw, it is preferable that the cross-section of the extruded body is as close to a perfect circle as possible.

[0218] When an extruded product is used as a drinking straw, the extruded product may be subjected to secondary processing to form a stopper portion and / or a bellows portion, etc.

[0219] E-3. Extruded articles usable as bottles or containers can also be manufactured by the method of the embodiment of other shapes of extruded articles. Specifically, an extruder is used which is equipped with a cylinder, a screw housed in the cylinder, a hopper for supplying powdered granules to the cylinder, and an annular die. The powdered granules are melted in the cylinder, and the tubular molten material is extruded from the annular die and sent into an open mold. The mold is closed to seal one end of the tubular molten material, air is blown into the molten material to make it adhere to the mold, and the molten material is cooled and crystallized. This makes it possible to manufacture extruded articles usable as bottles or containers.

[0220] The applications of the extruded articles produced by the method according to this embodiment are not particularly limited. The extruded articles can be used in a variety of applications, such as medical supplies, tableware supplies, agricultural supplies, fishery supplies, forestry supplies, office automation parts, home appliance parts, automotive parts, daily necessities, stationery, and bottle molding preforms. The powder granules used in the method according to this embodiment can be manufactured with less energy than molten pellets used in conventional extrusion molding. Furthermore, the extruded articles produced by the method according to this embodiment have excellent physical properties and appearance, as well as being biodegradable in seawater. Therefore, the method according to this embodiment can contribute to reducing greenhouse gas emissions and improving environmental problems caused by the dumping of plastics into the ocean.

[0221] (Third aspect) A. Powder granules First, the powder granules used as processing raw materials in the fiber manufacturing method according to the embodiment will be described.

[0222] The powder granules contain polyhydroxyalkanoate (PHA) powder, preferably containing PHA powder as the main component, more preferably essentially consisting of PHA powder, and even more preferably consisting of PHA powder. In this specification, "contains" and "includes" mean that additional components or elements may be included unless otherwise specified, and include "essentially consisting of" and "consisting of." "Essentially consisting of" means that additional components or elements may be included that do not substantially adversely affect the product. "Consisting of" means that only the described material or element is included, but does not exclude the inclusion of unavoidable impurities.

[0223] Powder granules are produced by granulating PHA powder. Such powder granules have a melt memory effect and can preferably be produced by powder compression granulation (hereinafter also referred to as compression granulation). Details of the method for producing powder granules will be described later.

[0224] In this specification, a powder granule having a melt memory effect means a powder granule having the following characteristics i) and ii): i) The powder granule is melted in a nitrogen atmosphere at a rate of 10°C / min from room temperature until it reaches a first hold temperature T Ｈ１ The temperature is raised to the first holding temperature T Ｈ１ In a first differential scanning calorimetry (DSC) measurement, where the sample is held for 2 minutes and then cooled at a rate of 10°C / min, the first hold temperature T at which the crystallization exothermic peak of PHA is observed during cooling is... Ｈ１ (Unit: °C) It has a first hold temperature T Ｈ１ The highest melting peak temperature T is Ｍ It is higher than this. Here, the highest melting peak temperature T Ｍ (Unit: °C) is defined as the highest peak temperature of the melting peak observed in differential scanning calorimetry when a powder granule is heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere. In one embodiment, the first hold temperature T Ｈ１ The temperature can be 180°C. ii) The powder granules are processed in a nitrogen atmosphere at a rate of 10°C / min from room temperature until the second holding temperature T Ｈ２ The temperature is raised to the second holding temperature T. Ｈ２In a second DSC (Deep Stem Cell) where the mixture is held for 2 minutes and then cooled at a rate of 10°C / min, the second hold temperature T is such that no crystallization exothermic peak of PHA is observed during the cooling process. Ｈ２ (Unit: °C) It has a second hold temperature T Ｈ２ The first hold temperature T Ｈ１ Higher than. In one embodiment, the second hold temperature T Ｈ２ It can reach 200°C.

[0225] The melt memory effect refers to the phenomenon in which a pseudo-crystalline phase structure order remains in the molten material when a crystalline polymer is heated and melted (thermoplasticized). The melt memory effect is a unique phenomenon that can occur in crystalline polymers, where, even in a temperature range above the melting point, a region remains that does not become disordered and random in a short time because the relaxation time for changing to a random aggregated state due to thermal disturbance is long. Hereinafter, the pseudo-crystalline phase structure order produced by the melt memory effect may be referred to as the melt memory structure. Such powder granules are described in Japanese Patent No. 7454097 and can be manufactured by the method described in Japanese Patent No. 7454097.

[0226] The degree of the melt memory effect of powder granules can be evaluated by the method described in Japanese Patent No. 7454097. Specifically, the peak temperature of the crystallization exothermic peak observed in the cooling DSC curve obtained by differential scanning calorimetry (DSC) after heating the powder granules to a temperature above the melting point of PHA and then cooling them at a rate of 10°C / min (i.e., the crystallization temperature of the powder granules) T Ｃ If the temperature (in °C) is higher than the crystallization temperature of PHA powder measured in the same manner, the powder granules have a high melt memory effect. When powder granules have a high melt memory effect, the crystallization exothermic peak of the powder granules often has a smaller half-width at half maximum than the crystallization exothermic peak of PHA powder measured in the same manner. The above DSC can be performed, for example, by raising the temperature of the sample 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 after, while cooling the sample in a nitrogen atmosphere at a rate of 10 °C / min.

[0227] When a powder granule exhibiting the melt memory effect is heated and melted, the melt memory structure of PHA remaining in the molten material functions as a crystallization nucleus during cooling. Since the melt memory structure is a pseudo-crystalline phase structure of PHA itself, the crystallization temperature T of the powder granule that crystallizes using the melt memory structure as a nucleus is determined. Ｃ The crystallization temperature is higher than that of molten pellets to which a crystallization nucleating agent has been added. Furthermore, the melt memory effect of powder granules exhibits excellent persistence with respect to molten residence time. On the other hand, if the melt memory structure in the molten material is lost due to thermal disturbance and leads to a random aggregated state, crystallization will not proceed easily during cooling.

[0228] A method for manufacturing fibers using powder granules with a melt memory effect as a processing material may have the following advantages compared to conventional methods for manufacturing fibers using molten pellets containing a crystallization nucleating agent as a processing material.

[0229] i) As described in Japanese Patent No. 7454097, the powder granules are manufactured under conditions where the temperature of the granules immediately after granulation is below the melting point of PHA. Therefore, thermal decomposition of PHA during the granulation process and the resulting decrease in molecular weight are suppressed. As a result, the PHA contained in the powder granules may have a larger molecular weight than the PHA contained in the molten pellets. Consequently, the PHA in the fibers produced from the powder granules can also have a larger molecular weight, thereby enabling the fibers to have superior physical properties.

[0230] ii) The process for producing powder granules uses significantly less electricity than the melt-mixing granulation process using an extruder for producing molten pellets. Therefore, by producing fibers from powder granules, the total amount of electricity used can be greatly reduced.

[0231] iii) By advantageously utilizing the melt memory effect of powder granules, the range of selectable fiber manufacturing conditions (extruder setting temperature, screw rotation speed, cooling temperature, etc.) can be expanded, making it easier to control the appearance and crystallinity of the fibers, and also increasing the degree of freedom in the shape of the fibers and fiber products (fiber diameter, nonwoven fabric thickness, etc.).

[0232] iv) By using powder granules, it is possible to manufacture fibrous materials that do not contain crystallization nucleating agents. Since there is no risk of crystallization nucleating agents leaching out of the manufactured fibers, they can be used in applications such as food and medical use. Furthermore, crystallization nucleating agents can cause problems such as adhering to cooling mechanisms such as cooling rolls and cooling belts, causing deposits to form on the dies (mouthpieces) of extruders, and increasing the stickiness of extruded materials and / or fibers, leading to sticking of extruded materials to cooling mechanisms and / or fusion of fibers, thus hindering continuous fiber manufacturing. By manufacturing fibers using powder granules that do not contain crystallization nucleating agents, these problems can be avoided, making continuous fiber manufacturing easier.

[0233] In one embodiment, the powder granules have an outer wall portion formed by the melting and solidification of at least a portion of the PHA powder located at the outer edge of the powder granules, and compressed PHA powder is contained inside the outer wall portion. In this application, melting and solidification means solidification after melting. The outer wall portion is located at the outer edge of the powder granules. In this specification, the outer wall portion is also referred to as the shell portion. The compressed PHA powder inside the outer wall portion may be melted and solidified and welded in place to at least a portion, or it may not be melted and solidified to at least a portion. The compressed PHA powder inside the outer wall portion may be in an unmelted state. That is, at least a portion of the compressed PHA powder inside the outer wall portion may include an unmelted compressed powder form, or it 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 it is not a welded structure strong enough to hold the PHA powder like the outer wall portion. In this specification, the inner part of the outer wall is also referred to as the core. The core inside the outer wall contains compressed PHA powder. In this specification, "compressed" means that the density of the PHA powder located in the core is higher than the bulk density of the PHA powder before granulation. Such powder granules are described in Japanese Patent No. 7387950 and can be manufactured by the method described in Japanese Patent No. 7387950. Furthermore, such powder granules have the melt memory effect described above.

[0234] The outer wall (shell) has a dense structure containing molten and solidified PHA powder. On the other hand, the inner core, although compressed, has a looser structure compared to the dense structure (welded structure) of the outer wall containing the molten and solidified PHA powder. Because the outer wall containing the molten and solidified PHA powder holds the compressed PHA powder present in the core, the powder granules can have a stable structure, minimal powder shedding, and excellent handling and safety, and can also lead to an improved working environment for fiber manufacturing.

[0235] The outer wall portion (shell portion) has a welded structure in which at least a portion of the thermoplastic resin powder located at the outer edge of the powder granules is melted and solidified. The outer wall portion may be smooth enough to have a glossy appearance. Alternatively, the outer wall portion may be formed by the melting of some of the components of the thermoplastic resin powder and partial welding with adjacent components, even if the melting is not sufficient to form a smooth surface. The outer wall portion can be formed during compression granulation, for example, at the contact surface with the die hole, by the melting of at least a portion of the PHA powder due to frictional heat with the wall surface or heat transfer from the wall surface. The thickness of the outer wall portion can vary depending on the manufacturing conditions of the PHA powder granules.

[0236] The core is the part located inside the outer wall and contains compressed thermoplastic resin powder. The PHA powder in the core may be porous, or it may have a non-welded structure because heat is not transferred to the core during granulation. The core may have a structure in which the PHA powder maintains its powder shape (i.e., a non-welded structure or a powdery structure), or a structure in which it is partially welded but the shape of the PHA powder remains.

[0237] In this specification, for the sake of simplicity of explanation, the terms "outer wall (shell)" and "core" are used. However, as stated above, the outer wall is formed when the PHA powder melts due to the heat during granulation, so in reality, there is no clear boundary between the outer wall (shell) and the core. The outer wall (shell) refers to the part that includes the welded structure of the PHA powder and is located on the outer edge of the powder granules, contributing to maintaining a certain shape of the powder granules. The core refers to the part located inside the outer wall (shell).

[0238] The shape of the powder granules is preferably approximately cylindrical or approximately rectangular prismatic, and it is preferable that the powder granules have an outer wall portion on the side surface. In this disclosure, the powder granules have an approximately cylindrical or approximately rectangular prismatic shape, and it is preferable that an outer wall portion is formed on the side surface of the powder granules having an approximately cylindrical or approximately rectangular prismatic shape.

[0239] Because powder granules with this shape can be directly supplied to extruders for thermoplastic resins, they can be used as processing raw materials for fiber manufacturing.

[0240] Powder granules can take on any suitable shape. Typically, when powder granules are manufactured by compression granulation of powder and granulation is performed by passing the powder through a circular die hole, the basic shape of the powder granules is a cylindrical pellet shape.

[0241] In this specification, the term "die" used in the manufacture of powder granules refers collectively to tools that correspond to molds (nozzles) for compressing and shaping PHA powder granules.

[0242] When the powder granules are approximately cylindrical in shape, the diameter of the powder granules is, for example, 2 mm to 7 mm, preferably 3 mm to 5 mm. The length (height) of the powder granules is, for example, 1 mm to 10 mm, preferably 2 mm to 7 mm. Such a shape results in powder granules that are easy to handle. The diameter of the powder granules can be adjusted, for example, by the diameter of the die holes in the disc plate (die plate) during granulation, and the length can be adjusted by the distance between the disc plate and the cutter. This distance can be any appropriate distance. The distance between the disc plate and the cutter is, for example, 1 mm to 30 mm, preferably 2 mm to 20 mm, preferably 3 mm to 10 mm.

[0243] The fracture strength of the powder granules, based on measurements using a Kiya hardness tester, 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, and preferably 10.0 kg or more. The upper limit may exceed the measurement limit of the Kiya hardness tester (for example, the measurement limit for "WPF1600-B" manufactured by Shiro Sangyo Co., Ltd. is 10 kg). Within this range, powder granules with excellent handling properties and melt processability can be obtained. Here, fracture strength refers to the average fracture stress (fracture load) measured by crushing powder granules with 20 or more particles (preferably 25 or more particles) in a direction perpendicular to the longitudinal direction (extrusion direction) of the powder granules. In powder granulation, the shell portion is composed of molten resin, making it possible to maintain a stable shape as a granule despite it being a powder granule. The diameter of the pressure surface of the pressure attachment of the Kiya hardness tester is, for example, 5 mm.

[0244] The bulk density of the powder granules can be any appropriate bulk density, but is preferably 0.3 kg / L to 2.0 kg / L, and more preferably 0.5 kg / L to 1.0 kg / L. Increasing the bulk density improves the supply speed and supply stability of the powder granules to the extrusion molding machine.

[0245] The bulk density of powder granules is calculated by allowing the powder granules to fall naturally into a 1-liter measuring cup until it is level, accurately measuring out 1 liter of powder granules, and then measuring its mass (unit: kg / L).

[0246] In one embodiment, the crystallization temperature T of the powder granules Ｃ (Unit: °C) is given by the following formula (C6): 70°C ≤ T Ｃ (C6) is satisfied. Here, the crystallization temperature T of the powder granules is met. Ｃ This is defined as the peak temperature of the crystallization exothermic peak observed during cooling in a DSC (Deep Scaling Control) procedure in which powder granules are 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.

[0247] In the fiber manufacturing method according to the embodiment, the temperature of the molten material during cooling is preferably 70°C to 80°C, as will be described later. Considering this, the crystallization temperature T of the powder granules is expressed by the above formula (C6). Ｃ The temperature is preferably 70°C or higher. Ｃ The difference between the temperature of the molten material (for example, if the temperature of the molten material is 70°C, T Ｃ This is because -70) becomes the driving force for crystallization. Also, the crystallization temperature T Ｃ The greater the temperature difference between the molten material and the granulated material, the faster crystallization can occur, thereby further improving the stability of fiber manufacturing and the quality of the manufactured fibers. Therefore, the crystallization temperature T of the powder granules is important. Ｃ More preferably, the temperature is 75°C or higher, 80°C or higher, 85°C or higher, 90°C or higher, or 95°C or higher.

[0248] B. PHA Powder The PHA powder, which is the raw material for powder granules, is a powdered polyhydroxyalkanoate (PHA) resin. PHA can be a compound produced in the body of microorganisms, for example, by feeding on carbohydrates, oils, etc. Such PHA is primarily extracted from microorganisms as a powdered polymer.

[0249] PHA contains hydroxyalkanoic acid 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-hydroxynanoate, 3-hydroxydecanoate, 3-hydroxytetradecanoate, 3-hydroxyhexadecanoate, 3-hydroxyoctadecanoate, 4-hydroxybutyrate, 4-hydroxyvalerate, 5-hydroxyvalerate, or 6-hydroxyhexanoate. The number of carbon atoms in the 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 in the 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, and particularly 6 or less. The hydroxyalkanoic acid may be used alone or in combination of two or more types.

[0250] Preferred PHAs include poly(3-hydroxyalkanoate) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0251] In 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, and preferably 700,000 or more. The melt memory effect is manifested by a time delay in the process in which polymer molecular chains transition from a crystalline ordered state to a random state in the molten state. Therefore, the larger the molecular weight, the longer the relaxation time (transition time to random chains), which is advantageous in terms of the persistence of the effect. A weight-average molecular weight of PHA of 200,000 or more is preferable because it can effectively delay the decrease or deactivation of the melt memory effect due to thermal disturbance. 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 powder granulation tends to become difficult. For this reason, the weight-average molecular weight of PHA is preferably 3 million or less, preferably 2 million or less, preferably 1.5 million or less, and preferably 1 million or less.

[0252] The weight-average molecular weight (Mw) mentioned above can be determined as the weight-average molecular weight in terms of polystyrene by gel permeation chromatography (GPC). For example, evaluation can be performed using a GPC apparatus such as "Showdex GPC-101" manufactured by Resonaq Corporation, with polystyrene gel ("Showdex K-804" manufactured by Resonaq Corporation) as the column packing material, and an organic solvent mobile phase (e.g., chloroform). The column apparatus, column packing material, and organic solvent mobile phase can be selected as appropriate, but for example, chloroform can be used.

[0253] PHA powder may be a powdery resin obtained through its manufacturing process, i.e., a powdery resin resulting from the manufacturing process, or it may be obtained by pulverizing a non-powdery PHA resin such as pellets, lumps, or molded articles. PHA powder can be obtained, for example, by pulverizing molded articles, pellets, trimming scraps generated in extrusion molding, or sprues or runners generated in injection molding at room temperature, or after cooling them with dry ice or liquid nitrogen as needed, using a pulverizer (for example, Dalton Co., Ltd.'s "Nearmill," "Sylpheedmill," "Atomizer," or "Impactmill," etc.).

[0254] The particle size of the PHA powder can be any appropriate particle size depending on its form, as long as the effects of this embodiment are obtained. Preferably, the maximum particle size of the PHA powder before granulation is 5 mm or less, and the minimum particle size is 0.0001 mm or more.

[0255] The average particle size of the PHA powder is, for example, 0.001 mm or more and 1.0 mm or less. When the average particle size of the PHA powder is 1.0 mm or less, the fracture strength of the tare granules tends to improve. When the average particle size of the PHA powder is 0.001 mm or more, the production efficiency of the powder granules is high. 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 laser diffraction. The average particle size of the PHA powder may be the median diameter (d50) which is the cumulative 50% in the cumulative particle size distribution 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 types.

[0256] The PHA powder before granulation may 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 easily performed.

[0257] The bulk density of PHA powder is calculated by letting the PHA powder fall naturally into a 1-liter measuring cup until it is level, accurately measuring out 1 liter of PHA powder, and then measuring its mass (unit: kg / L).

[0258] C. Other component powder granules contained in the PHA powder granules may include any suitable additives as needed. Additives may be in solid form such as powder, or in liquid form. Examples of additives include binders, dispersants, crystallization nucleating agents, antioxidants, light stabilizers, foaming agents, UV absorbers, antiblocking agents, heat stabilizers, impact modifiers, antibacterial agents, compatibilizers, processing aids, lubricants, coupling agents, hydrolysis inhibitors, oxygen scavengers, or colorants (dyes and pigments). Additives may be used individually or in combination of two or more.

[0259] The additive content in the powder granules 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.

[0260] The powder granules may contain a binder as an additive. Here, "binder" refers collectively to compounds that exist between the PHA powder particles, in addition to the constituent components of the raw material PHA powder, and that bind the powder particles together, thereby increasing the fracture strength of the granules. Various compounds that exhibit a binding effect, preferably water-dispersible or water-soluble polymer compounds, polysaccharides, etc., can be appropriately selected and used as binders as needed.

[0261] In one embodiment, it is preferable to melt and bind a portion of the components of the PHA powder to form a powder granule, and it is preferable not to include a binder.

[0262] The binder content is typically 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), based on the total mass of the PHA powder granules.

[0263] In one embodiment, a dispersant is preferably used as an additive. A surfactant is preferably used as the dispersant. The hydrophilic / hydrophobic balance of the dispersant (surfactant) can be controlled by adjusting the degree of esterification of the compound that becomes the dispersant, the type of fatty acid (e.g., presence or absence of hydroxyl groups, saturated or unsaturated fatty acids, alkyl chain length), the degree of polymerization, etc. The use of a dispersant can bring about effects such as improving the productivity (discharge rate) of powder granules, reducing frictional heat during granulation, and improving the cleanability of the granulation equipment.

[0264] Examples of dispersants include fatty acids, fatty acid metal salts, fatty acid sulfonates, fatty acid amides, acrylamides, polyhydric alcohol fatty acid esters, and polyglycerol fatty acid esters. Dispersants may be used individually or in combination of two or more types.

[0265] In one embodiment, the dispersant is at least one selected from the group consisting of polyhydric alcohol fatty acid esters, fatty acid amides, polyglycerol fatty acid esters, condensed hydroxy fatty acids, and alcohol esters of condensed hydroxy fatty acids.

[0266] Polyhydric alcohol fatty acid esters are ester compounds composed of a polyhydric alcohol and a fatty acid. Examples of polyhydric alcohol fatty acid esters include esters of polyhydric alcohols such as pentaerythritol and glycerin, and fatty acids having eight or more carbon atoms (preferably 8 to 24 carbon atoms, more preferably 10 to 22 carbon atoms).

[0267] Fatty acid amides are compounds that have a structure formed by the dehydration condensation of a fatty acid with 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.

[0268] Polyglycerol fatty acid esters are ester compounds composed of polyglycerol and fatty acids. Examples of polyglycerol fatty acid esters include diglycerol palmitate, diglycerol stearate, diglycerol oleate, decaglycerol palmitate, decaglycerol stearate, and decaglycerol oleate.

[0269] The dispersant content is typically 0% to 10.0% by mass, preferably 0.01% to 9.0% by mass, preferably 0.1% to 7.0% by mass, and more preferably 0.3% to 5.0% by mass, relative to the total mass of the powder granules. Furthermore, the dispersant content is typically 10.0% or less by mass, preferably 5.0% or less by mass, preferably 3.0% or less by mass, preferably 1.0% or less by mass, preferably 0.5% or less by mass, preferably 0.1% or less by mass, and preferably 0% by mass (undetectable), relative to the total mass of the powder granules.

[0270] Crystallization nucleating agents can be added as additives to powder granules. Examples of crystallization nucleating agents that can be added to powder granules include organometallic salt compounds such as phosphate ester metal salts, benzoate metal salts, pimephosphate metal salts, rosin metal salts, oxalate metal salts, and fatty acid metal salts; aliphatic organic esters, triallyl phosphate, polyalkylene glycol or its derivatives, aliphatic polyesters, and organic compounds such as benzylidene sorbitol; dyes and pigments such as pentaerythritol, quinacdrin, cyanine blue, and carbon black; minerals such as talc, mica, kaolin, clay, carbonate minerals, metal oxides, and metal sulfates; ionomers; and polymer compounds such as high-melting-point polyamides.

[0271] In one embodiment, talc, mica, kaolin, or calcium carbonate are used as crystallization nucleating agents. One type of crystallization nucleating agent may be used alone, or two or more types may be used in combination.

[0272] The content of the crystallization nucleating agent in the powder granules 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, and preferably 0.3% by mass or more and 5.0% by mass or less.

[0273] In one embodiment, the powder granules substantially do not contain a crystallization nucleating agent. Because the powder granules can exhibit a melt memory effect, they can achieve excellent crystallization characteristics in molding processes even without the use of a crystallization nucleating agent.

[0274] "The powder granules are substantially free of crystallization nucleating agents" means that the content of crystallization nucleating agents in the powder granules is 0.1% by mass or less. Preferably, the content of crystallization nucleating agents in the powder granules is less than 0.1% by mass, 0.01% by mass or less, 0.005% by mass or less, 0.001% by mass or less, or 0% by mass (undetectable).

[0275] Furthermore, those skilled in the art should understand that powder granules may contain a crystallization nucleating agent or that powder granules may be used together with a crystallization nucleating agent. When powder granules contain a crystallization nucleating agent or when powder granules are used together with a crystallization nucleating agent, in addition to the crystallization-promoting effect due to the melt memory effect, a crystallization-promoting effect due to the crystallization nucleating agent can be obtained.

[0276] D. Method for Manufacturing PHA Powder Granules Powder granules can be manufactured using various powder granulators, but preferred granulators include compression granulators such as disc pelletizers, screw extrusion machines, briquetting machines, compaction machines, and tableting machines. Powder granules manufactured by a compression granulator are thought to have an outer wall containing oriented crystals due to the strong shear stress from the wall of the die hole during the granulation process. Therefore, powder granules manufactured by the compression granulation method (i.e., compression granules) can have a particularly high melt memory effect.

[0277] Among the examples given above, the disc pelletizer method is preferred from the viewpoint of granulation productivity and the quality and shape uniformity of the resulting powder granules. In the disc pelletizer method, a semi-wet granulation method can be employed, which involves incorporating an appropriate amount of moisture into the PHA powder. In some cases, granulation can be performed without using water. When granulation is performed without using water, the post-granulation drying treatment described later may become unnecessary. When granulation is performed without using water, the amount of energy required in the drying process can be reduced, and the amount of carbon dioxide emitted during the manufacturing process can be significantly reduced.

[0278] As mentioned above, PHA powder granules can be advantageously obtained by the granulation method described in Japanese Patent No. 7454097 or Japanese Patent No. 7387950.

[0279] When the powder granules are a mixture containing two or more types of PHA powder raw materials, or contain any component other than PHA, it is preferable to mix them uniformly using any suitable mixer. Examples of mixers include Henschel mixers, Nauter mixers, powder kneaders (KDH, KDA, CKD, CPM) (Dalton Co., Ltd.), Spartan mixers (SPM) (Dalton Co., Ltd.), and SP granulators (SPG) (Dalton Co., Ltd.). To obtain a desirable 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, it is preferable to use a combination of upper and lower blades, with the upper blade being a "Y1 blade" manufactured by Nippon Coke Industries Co., Ltd. and the lower blade being an "S0 blade" manufactured by Nippon Coke Industries Co., Ltd. It is also preferable to install a deflector in the stirring tank and mix the materials. In other words, using a mixing device that can uniformly disperse each component throughout the mixture is advantageous in improving the productivity and quality stability of the final powder granules.

[0280] When producing powder granules using the semi-wet granulation method described above, the amount of water added can be any appropriate amount depending on the properties of the powder (e.g., water absorption). In this case, the amount of water added is 3 to 30 parts by mass, preferably 5 to 25 parts by mass, and more preferably 5 to 20 parts by mass, per 100 parts by mass of crystalline polymer powder. The semi-wet method can be used to improve the stability of granulation.

[0281] In the granulation process of powder granules, localized heat generation can lead to die clogging. Therefore, incorporating an appropriate amount of moisture into the PHA powder during granulation and using the heat of vaporization of water to suppress excessive temperature rise during granulation can be advantageous for continuous granulation.

[0282] The powder granules can be dried after granulation, but the final moisture content of the powder granules 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 final moisture content of the powder granules can be appropriately selected depending on the intended use.

[0283] It is preferable that the powder granules are granulated without the addition of water or with the addition of only a very small amount of water. If the moisture content of the powder granules is low, the drying process after granulation can be simplified or omitted. If granulation can be performed without using water, the drying process becomes unnecessary, which can significantly reduce the amount of carbon dioxide emitted during the powder granulation process.

[0284] The moisture content of the granulated powder without the addition of 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.

[0285] When producing powder granules using a screw extrusion compression granulator, it is easy to install a temperature control device on the compression granulator, and compression granulation can be performed at low screw rotation speeds, thus reducing localized heat generation due to rapid shear heat generation during granulation. When producing powder granules using a bricketing, compaction, or tableting compression granulator, the shear stress on the powder from the die hole walls is smaller compared to the disc pelletizer method, thus reducing localized heat generation during granulation. Therefore, with the screw extrusion, bricketing, compaction, and tableting methods, powder granules can be produced continuously and stably without causing die clogging due to localized heat generation, even without the addition of water. When granulation is performed without the addition of water, post-granulation drying is unnecessary, thus simplifying the manufacturing process and reducing energy consumption for drying.

[0286] The moisture content of powder granules is measured using an infrared moisture meter.

[0287] A disc pelletizer type granulator has, as a basic structure, one (flat die) or two discs (indicating cylindrical dies) with numerous holes ranging from 2 mm to 30 mm in size, and rollers for pressurizing the raw material into the holes of the discs. PHA powder (which may contain moisture) supplied between the disc and the roller, or between two discs, is pressed into the holes of the discs as the roller rotates, forming a cylindrical extruded product. The extruded product is cut on the back surface of the disc with a cutter or the like to obtain pelletized powder granules. The length of the granules can be adjusted by the distance between the back surface of the disc and the cutter, the rotation speed of the roller, etc. The distance between the disc plate and the cutter can be any appropriate distance. For example, the distance between the disc plate and the cutter is 1 mm to 30 mm, more preferably 2 mm to 20 mm, and even more preferably 3 mm to 10 mm.

[0288] More specifically, disc pelletizer systems include roller-disc die systems, roller-ring die systems, double die systems, and flat die systems. A commercially available disc pelletizer granulator is, for example, the F-series disc pelletizer manufactured by Dalton Co., Ltd.

[0289] The powder granules may be thoroughly dried immediately before use as a processing raw material. This effectively suppresses the decrease in molecular weight of PHA and / or defects in the appearance of the fibers during fiber production. The moisture content of the powder granules immediately before use as a processing raw 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 carried out at 70°C to 110°C, 75°C to 100°C, or 80°C to 90°C until the predetermined moisture content is reached. The moisture content of the powder granules is measured using an infrared moisture meter.

[0290] E. Method for manufacturing fibers The method for manufacturing fibers according to the embodiment involves using a powder granule containing PHA as a processing material and plasticizing the powder granule by extruding it to a melting temperature T Ｐ The method for producing fibers according to the embodiment includes melting the material at a temperature of °C and extruding the molten material from a die in a fibrous form, and cooling the extruded molten material to solidify it and obtain a fibrous solid. The method for producing fibers according to the embodiment may further include heating and stretching the fibrous solid. The method for producing fibers according to the embodiment may further include winding the fibrous solid.

[0291] In this specification, the term "die" used in fiber manufacturing is a general term for tools that correspond to molds (nozzles) that extrude molten PHA in a desired shape.

[0292] The fibers produced by the method according to the embodiment may constitute monofilaments, multifilaments, or nonwoven fabrics. A monofilament refers to a thread or linear body composed of a single continuous fiber (filament). A multifilament refers to a thread or linear body composed of multiple continuous fibers. A nonwoven fabric refers to a sheet-like structure formed by bonding long or short fibers together by mechanical, chemical, or thermal means, without crossing or knitting the fibers as in woven or knitted fabrics.

[0293] Examples of apparatus used in the fiber manufacturing method according to the embodiment are shown in Figures 6 and 7. Figure 6 shows an example of an apparatus for manufacturing fibers constituting a nonwoven fabric (i.e., an apparatus for manufacturing a nonwoven fabric). Figure 7 shows an example of an apparatus for manufacturing fibers constituting a monofilament or multifilament (i.e., an apparatus for manufacturing a filament or multifilament).

[0294] The manufacturing apparatus 101 shown in Figure 6 comprises an extruder 110, a collector 130, and a winding roll 170. The extruder 110 is a screw-type extruder and comprises a cylinder 112, a screw 114 housed within the cylinder 112, a hopper 116 for supplying powder granules 192 to the cylinder 112, a die head 117, an adapter 119, and a die 118. The hopper 116 is located at the uppermost part of the extruder 110. The die head 117, adapter 119, and die 118 are connected in this order downstream of the cylinder 112. The die 118 is located at the lowermost part of the extruder 110. The die 118 is provided with at least one, preferably more, die holes (orifices). The powder granules 192 fed into the hopper 116 are supplied into the cylinder 112. The powder granules 192 are heated and melted within the cylinder 112. The molten material is fed to the die 118 via the die head 117 and adapter 119 by a rotating screw 114, and is continuously extruded in a fibrous manner from the die holes of the die 118. The collector 130 is located below the die 118 in the direction of gravity and collects the molten material 194 or its solidified material extruded in a fibrous manner from the die 118 to form a nonwoven fabric 196. The collector 130 is equipped with a conveyor belt 132 and a conveyor roll 134 that drives the conveyor belt 132. The winding roll 170 is located at the downstream end of the manufacturing apparatus 101 and winds up the formed nonwoven fabric 196. A stretching mechanism (not shown) may be provided to stretch the molten material 194 or its solidified material extruded in a fibrous manner from the die 118 by an airflow at room temperature or high temperature before it is collected in the collector 130. Examples of stretching mechanisms include stretching rolls and air nozzles that eject airflow. The stretching mechanism may be provided between the die 118 and the collector 130. The conveyor belt 132 may be permeable, and a suction device (not shown) may be provided to suck up the fibrous molten material 194 or its solidified material via the conveyor belt 132 and accumulate the molten material 194 on the conveyor belt 132. A calender roll (not shown) may also be provided to pressurize the nonwoven fabric 196 and fuse the fibers together.The manufacturing apparatus 101 may be an apparatus for manufacturing nonwoven fabric by the melt-blown method or the spun-bond method. That is, in this embodiment, nonwoven fabric can be manufactured by the spun-bond method or the melt-blown method.

[0295] The manufacturing apparatus 102 shown in Figure 7 comprises an extruder 120, a pulley 136, and a take-up roll 150. The extruder 120 is a piston-type extruder and comprises a cylinder 122, a piston 124 housed within the cylinder 122, and a die 128. The die 128 is located at the downstream end of the extruder 120. The die 128 is provided with at least one die hole (orifice). The powder granules are heated and melted in the cylinder 112, and the piston 124 continuously extrudes the molten material in a fibrous manner from the die hole of the die 118. The molten material 194 extruded in a fibrous manner from the die 128 is cooled to form a monofilament or multifilament 198, which is then taken up by the take-up roll 150 via the pulley 136. Downstream of the take-up roll 150, the manufactured monofilament or multifilament 198 may be wound up by a winding roll (not shown).

[0296] The extruder 110 in the manufacturing apparatus 101 in Figure 6 is a screw-type extruder (kneading extruder) 110, but a piston-type extruder 120 as shown in Figure 7 can be used instead. Similarly, the extruder 120 in the manufacturing apparatus 102 in Figure 7 is a piston-type extruder 120, but a screw-type extruder 110 as shown in Figure 6 can be used instead. The screw-type extruder 110 may be a single-screw extruder or a twin-screw extruder. In the piston-type extruder 120, plasticization is performed in a gentler flow field compared to the screw-type extruder 110, which involves the rotation of a screw 114, making it preferable for utilizing the melt memory effect.

[0297] In the manufacturing method according to the embodiment, first, the powder granules are plasticized and melted to a temperature T using extruders 110 and 120. Ｐ The material is melted at (unit: °C) and the molten material 194 is extruded in a fibrous manner from dies 118 and 128.

[0298] The flow rate of the extruded molten material 194 may be adjusted by a control device such as a gear pump. The temperature of the dies 118 and 128 may be set appropriately within a range in which the melt memory structure of the powder granules does not disappear, for example, 140°C to 180°C, 150°C to 175°C, or 155°C to 170°C. The number of die holes provided in the dies 118 and 128 may be appropriately selected according to the number of monofilaments to be manufactured, the number of fibers constituting the multifilaments, the diameter of the multifilaments, the diameter of the fibers constituting the nonwoven fabric, the thickness of the nonwoven fabric, etc. The shape of the die holes may also be appropriately selected, for example, circular, elliptical, Y-shaped, X-shaped, H-shaped, and multi-lobed shapes. The size of the die holes may also be appropriately selected, for example, if the die holes are circular, the diameter of the die holes is preferably 0.1 mm to 20 mm, 0.3 mm to 10 mm, 0.5 mm to 5 mm, or 1 mm to 3 mm. Furthermore, when the die hole is circular, the ratio of the length of the die hole (L / D) to the diameter (D) of the die hole is preferably 1 to 10, and more preferably 2 to 5. The flow rate of the molten material extruded from one die hole is preferably 0.1 to 3 kg / h, 0.2 to 3 kg / h, 0.25 to 2 kg / h, or 0.3 to 1.5 kg / h.

[0299] Plasticization and melting temperature T of the powder granules in extruders 110 and 120 Ｐ (Unit: °C) is given by formula (C4) T Ｍ -10 < T Ｐ ≦T Ｍ +25 (C4) (wherein, T Ｍ (Unit: °C) represents the highest melting peak temperature observed in differential scanning calorimetry (DSC) where powder granules are heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere.

[0300] Note that the highest melting peak temperature T Ｍ If multiple melting peaks are observed by DSC, this refers to the highest peak temperature among those melting peaks. If only one melting peak is observed by DSC, this refers to the peak temperature of that melting peak.

[0301] When using a screw-type extruder 110, the plasticizing melt temperature T ＰThis is defined as the temperature of the molten material inside the die head 117. The temperature of the molten material inside the die head 117 is measured by a thermocouple attached to the die head 117. When using a piston-type extruder 120, the plasticizing melt temperature T Ｐ This is defined as the temperature of die 128.

[0302] Plasticization melting temperature T Ｐ By satisfying equation (C4), the loss of the melt memory effect of powder granules due to thermal disturbances, mechanical mixing, etc., can be suppressed, thereby enabling fiber manufacturing that effectively utilizes the melt memory effect.

[0303] Plasticization melting temperature T Ｐ Preferably, T Ｍ -10 < T Ｐ ≦T Ｍ Satisfying +20, more comfortably, T Ｍ -8 < T Ｐ ≦T Ｍ Satisfying +15, and more preferably, T Ｍ -5 < T Ｐ ≦T Ｍ Satisfying +10, and particularly preferably, T Ｍ -5 < T Ｐ ≦T Ｍ Satisfy +5.

[0304] In conventional fiber manufacturing, which uses molten PHA pellets as a processing raw material, the plasticizing melt temperature T Ｐ If the temperature is set below the melting peak temperature of the molten pellet, it not only places an excessive load on the extruder, but also results in insufficient plasticization, which can easily lead to problems such as residual unmelted material mixing with the manufactured fibers, discontinuity in the extruded fibrous molten material 194, and clogging of the die holes.

[0305] In contrast, in the method according to this embodiment, which uses PHA powder granules as a processing raw material, the load on the extruders 110 and 120 is reduced due to the large porosity of the powder granules, so T Ｍ -10 < T Ｐ <T ＭEven in such cases, it may be possible to sufficiently plasticize and extrude the powder granules without placing an excessive load on the extruders 110 and 120.

[0306] In a screw-type extruder 110, a flow field is formed as the screw 114 rotates for plasticization and metering. Similarly, in a piston-type extruder 120, a flow field is formed as the piston 124 performs linear extrusion. Factors influencing the melt memory effect include temperature and the flow field; the maximum temperature at which the melt memory effect is maintained in a flow field may be lower than the maximum temperature at which the melt memory effect is maintained in a stationary field. Ｐ >T Ｍ In the case of +25, the melt memory effect decreases or disappears due to the action of the flow field, slowing down the crystallization and solidification of the molten material 194 extruded from the die 118. This can lead to various problems such as the molten material 194 sticking to components such as the pulley 136, take-up roll 150, and conveyor belt 132, fusion of fibers (self-fusion), resulting in instability of the fiber shape, difficulty in miniaturization, reduction of the effective width of the nonwoven fabric, and post-shrinkage, which can reduce productivity. The effective width of the nonwoven fabric refers to the width of the region of the nonwoven fabric that has a thickness within a set range.

[0307] The screw-type extruder 110 may be a single-screw extruder or a twin-screw extruder as described above, but is preferably a single-screw extruder, and the screw 114 used in the single-screw extruder is preferably a single-screw flight screw. The single-screw flight screw has a supply zone, a compression zone, and a metering zone in the flow direction of the powder granules and their molten material, from upstream to downstream. Such a single-screw flight screw can suppress the reduction or disappearance of the melt memory effect due to the flow field generated by thermal disturbance and / or mechanical mixing. When the screw 114 of the extruder 110 is a single-screw flight screw, the rotation speed of the screw 114 is preferably 100 rpm or less, 80 rpm or less, 60 rpm or less, 50 rpm or less, or 30 rpm or less. By reducing the rotation speed of the screw 14, the reduction or disappearance of the melt memory effect due to the flow field generated by mechanical mixing can be suppressed. The rotation speed of the screw 114 may be 10 rpm or more.

[0308] In the nonwoven fabric manufacturing apparatus 101 shown in Figure 6, the extruded molten material 194 may be stretched with a high-temperature airflow or the like.

[0309] Next, the extruded molten material 194 is cooled and solidified to obtain a fibrous solid. The cooling method may be selected as appropriate, and cooling may be performed by air cooling or water cooling. Cooling of the molten material 194 may be performed in air or water, or on a conveyor belt 132 or cooling roll (not shown) provided in the transport path of the molten material 194. From the viewpoint of simplifying the manufacturing process, cooling of the molten material 194 is preferably performed in air or on a conveyor belt 132 or cooling roll.

[0310] The temperature of the molten material 194 during cooling may be 70°C to 80°C. In one embodiment, the fibers produced have a maximum melting peak temperature T of 140°C or higher, as described later. ＭＡ It may have such a maximum melting peak temperature T ＭＡ This is because the crystallization rate of the PHA molten material, which is the raw material for fibers containing [the specified fiber type], tends to be maximum at 70°C to 80°C. When the molten material 194 is rapidly cooled to below 70°C, the viscosity of the molten material 194 increases rapidly, suppressing molecular movement, delaying crystallization, and resulting in a so-called supercooled state. In this state, crystallization does not proceed sufficiently, and many amorphous regions remain in the solidified fibers. As a result, self-fusing of the fibers is more likely to occur, hindering transport and winding, and tending to reduce the stability of fiber manufacturing. Furthermore, if there are many amorphous regions, crystallization may progress due to external heat, causing deformation of the fibers, so thermal stability is also likely to be insufficient. On the other hand, when the temperature of the molten material 194 exceeds 80°C, molecular motion becomes excessively active, suppressing crystal nucleation and tending to decrease the crystallization rate. In this case as well, crystallization is insufficient, making self-fusing of the fibers more likely, and tending to reduce the stability of fiber manufacturing. Therefore, from the viewpoint of efficiently promoting crystallization, it is preferable to set the temperature of the molten material 194 during cooling to 70°C to 80°C. This allows the crystallization of the molten material 194 to proceed rapidly, as described above.

[0311] The molten material 194 may be cooled while being stretched. The stretching may be uniaxial stretching. For example, in the nonwoven fabric manufacturing apparatus 101 of Figure 6, stretching can be performed by airflow. In the filament or multifilament manufacturing apparatus 102 of Figure 7, stretching can be performed by a stretching roll (not shown), or by appropriately adjusting the extrusion speed of the molten material 194 from the die 128 and the take-up speed by the take-up roll 150. The formed fibrous solid may also be heated and stretched again, and this stretching can be performed, for example, by a stretching roll (not shown).

[0312] By performing stretching, the orientation of PHA can be increased, thereby increasing the strength of the manufactured fibers. Increasing fiber strength is particularly important in the manufacture of monofilaments. The temperature of the molten material 194 or fibrous solidified material during stretching may be set to a temperature suitable for improving the orientation of PHA. If the temperature of the molten material 194 or fibrous solidified material during stretching is too high, the orientation of PHA may not be effectively increased. If the temperature of the molten material 194 or fibrous solidified material during stretching is too low, the molten material 194 or fibrous solidified material may break, and continuous fibers may not be manufactured. Furthermore, by increasing the orientation of PHA in the fibers through stretching, the melt memory effect of the manufactured fibers can be improved.

[0313] As described above, the fibrous solidified material (i.e., fibers) stretched as needed forms a nonwoven fabric 196 on the conveyor belt 132 in the manufacturing apparatus 101 of Figure 6. The nonwoven fabric 196 may be subjected to calendering, embossing, etc., as needed, and then conveyed to the winding roll 170 and wound up. In the manufacturing apparatus 102 of Figure 7, the fibrous solidified material (i.e., fibers) stretched as needed forms a monofilament, or is bundled as needed to form a multifilament. The monofilament or multifilament 198 may be conveyed to the winding roll (not shown) and wound up.

[0314] F. Fibers Fibers that can be manufactured by the method according to the above embodiment will be described.

[0315] The fibers according to the embodiment contain PHA, preferably as a main component, more preferably essentially composed of PHA, and even more preferably composed of PHA. In one embodiment, the fibers constitute a monofilament, a multifilament, or a nonwoven fabric.

[0316] Crystallization temperature T of the fiber according to the embodiment ＣＡ (Unit: °C) is given by the following formula (C1): 80°C ≤ T ＣＡ (C1) is satisfied. Crystallization temperature T of the fiber ＣＡ This is defined as the peak temperature of the crystallization exothermic peak observed during cooling in differential scanning calorimetry, where a fiber 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.

[0317] Crystallization temperature T that satisfies equation (C1) ＣＡ Fibers possessing this property are less prone to fusion between fibers and can be manufactured stably. The crystallization temperature of the fiber is T. ＣＡ The temperature may preferably be 82°C or higher, 84°C or higher, 86°C or higher, 88°C or higher, or 90°C or higher.

[0318] The highest melting peak temperature T of the fiber according to the embodiment ＭＡ (Unit: °C) is given by the following formula (C2): 140 °C ≤ T ＭＡ (C2) is satisfied. The highest melting peak temperature T of the fiber. ＭＡ It is defined as the highest peak temperature of the melting peak observed in differential scanning calorimetry, where the fiber is heated from room temperature at a rate of 10°C / min in a nitrogen atmosphere.

[0319] Generally, the crystallization temperature T of PHA fibers ＣＡ T is the highest melting peak temperature of the fiber. ＭＡ It is correlated with the highest melting peak temperature T of the fiber. ＭＡ The lower the value, the higher the crystallization temperature T. ＣＡ The highest melting peak temperature T that satisfies the above formula (C2) (i.e., 140°C or higher) ＭＡ Fibers having the crystallization temperature T satisfy formula (C1) ＣＡIt is easy to maintain this property, and therefore, fusion between fibers is less likely to occur, making stable production possible. The maximum melting peak temperature of the fiber is T ＭＡ The temperature may preferably be 142°C or higher, 145°C or higher, or 147°C or higher. On the other hand, the maximum melting peak temperature T of the fiber. ＭＡ If the temperature is below 140°C, the crystallization temperature of the fiber T ＣＡ Consequently, the temperature also decreases, and crystallization tends to slow down at molten material temperatures of 70-80°C as described above. In this case, the temperature range in which crystallization proceeds easily is expected to shift to even lower temperatures, and the time required for crystallization will also increase.

[0320] Generally, when manufacturing fibers from processed raw materials, the crystallization temperature T of the manufactured fibers is... ＣＡ The crystallization temperature T of the raw material is Ｃ It depends on the crystallization temperature T of the fiber. In the production of PHA fibers using conventional melt pellet-type processed raw materials, unless a crystallization nucleating agent is added to the processed raw material, the crystallization temperature T of the fiber will not be determined. ＣＡ It is practically difficult to satisfy formula (C1), which states that the temperature is 80°C or higher. On the other hand, in the manufacturing method according to the embodiment that uses the powder granules having the melt memory effect described above as a processing raw material, it is possible to stably produce fibers that satisfy formula (C1). Therefore, it is possible to suppress the self-fusing of fibers or their adhesion to the components of the manufacturing equipment, and to improve the manufacturing stability of the fibers.

[0321] In one embodiment, the fibers are substantially free of crystallization nucleating agents. "Substantially free of crystallization nucleating agents" means that the content of crystallization nucleating agents in the fibers is 0.1% by mass or less. Preferably, the content of crystallization nucleating agents in the fibers is less than 0.1% by mass, 0.01% by mass or less, 0.005% by mass or less, 0.001% by mass or less, or 0% by mass (undetectable).

[0322] In one embodiment, the fiber has a melt memory effect. A fiber having a melt memory effect means a fiber having the following characteristics i) and ii): i) The fiber is melted in a nitrogen atmosphere at a rate of 10°C / min from room temperature to a first hold temperature T Ｈ１ The temperature is raised to the first holding temperature T ＨＡ１In a first differential scanning calorimetry (DSC) measurement, where the sample is held for 2 minutes and then cooled at a rate of 10°C / min, the first hold temperature T at which the crystallization exothermic peak of PHA is observed during cooling is... ＨＡ１ (Unit: °C) It has a first hold temperature T ＨＡ１ T is the highest melting peak temperature of the fiber. ＭＡ Higher than. Maximum melting peak temperature T Ｍ The definition is as described above. In one embodiment, the first hold temperature T ＨＡ１ The temperature can be 180°C. ii) The fibers are subjected to a second holding temperature T in a nitrogen atmosphere at a rate of 10°C / min from room temperature. ＨＡ２ The temperature is raised to the second holding temperature T. ＨＡ２ In a second DSC (Deep Stem Cell) where the mixture is held for 2 minutes and then cooled at a rate of 10°C / min, the second hold temperature T is such that no crystallization exothermic peak of PHA is observed during the cooling process. ＨＡ２ (Unit: °C) It has a second hold temperature T ＨＡ２ The first hold temperature T ＨＡ１ Higher than. In one embodiment, the second hold temperature T ＨＡ２ It can reach 200°C.

[0323] In one embodiment, the fibers have a fiber diameter of 1 μm to 1200 μm. Preferably, the fiber diameter is 2 μm to 1000 μm, 5 μm to 800 μm, 10 μm to 700 μm, or 20 μm to 500 μm.

[0324] In one embodiment, in differential scanning calorimetry, a fiber is heated to 180°C at a rate of 10°C / min in a nitrogen atmosphere, held at 180°C for 2 minutes, cooled to 30°C at a rate of 10°C / min, heated from 30°C to 180°C at a rate of 10°C / min, held at 180°C for 2 minutes, and cooled to 30°C at a rate of 10°C / min, and the peak temperature of the crystallization exothermic peak observed during the first cooling (also referred to as the first crystallization temperature) T ＣＡ，１ (Unit: °C) and the peak temperature of the crystallization exothermic peak observed during the second cooling (also referred to as the second crystallization temperature) T ＣＡ，２ (Unit: °C) is given by the following formula (C3): 0.9 ≤ T ＣＡ，２ / T ＣＡ，１The equation ≤ 1.1 (C3) is satisfied. Equation (C3) indicates that the melt memory effect of the fiber is substantially maintained even when the fiber is heated to a temperature of 180°C or lower. Fibers in which the melt memory effect is substantially maintained in this way are expected to undergo more favorable orientation crystallization when subjected to heat stretching as a secondary processing, and the range of selectable heating temperatures is also widened.

[0325] In one embodiment, the crystallization temperature of the fiber T ＣＡ (Unit: °C) and the crystallization temperature T of the powder granules used as processing raw materials. Ｃ (Unit: °C) is given by the following formulas (C5) and (C6): 0.8 ≤ T ＣＡ / T Ｃ ≦1.2 (C5) 70℃≦T Ｃ (C6) is satisfied. Note that the crystallization temperature T of the powder granules is Ｃ This is as defined above. The crystallization temperature T of the fiber ＣＡ T is defined as the peak temperature of the crystallization exothermic peak observed during cooling in a DSC (Deep Steady Compression) where a fiber 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. Note that the crystallization temperature of the fiber is T. ＣＡ The first crystallization temperature T of the aforementioned fiber is ＣＡ，１ It is equal to.

[0326] The above formula (C5) represents the crystallization temperature T of the fiber. ＣＡ The crystallization temperature of powder granules T Ｃ This indicates that the crystallization temperature change in the fiber manufacturing process is small, meaning that the melt memory effect of the powder granules was effectively utilized in the fiber manufacturing process. As mentioned above, effectively utilizing the melt memory effect is advantageous for improving the crystallinity of the manufactured fibers. Such fibers can be manufactured stably and have excellent quality. In particular, T ＣＡ / T Ｃ The value may be greater than 1, which indicates that the melt memory effect was further enhanced by fibrosis. ＣＡ / T ＣIf the value is 1.2 or less, the fiber production stability is high. ＣＡ / T Ｃ However, if the value exceeds 1.2, the cooling of the fibers may be insufficient, making them prone to self-fusing.

[0327] As described above, by performing uniaxial stretching in the fiber manufacturing process, the melt memory effect of the fiber can be further improved, thereby increasing the fiber's crystallization temperature T ＣＡ This can further enhance it.

[0328] The uses of the fibers according to the embodiment are not particularly limited. Monofilaments and multifilaments composed of the fibers according to the embodiment can be used in a variety of applications such as braids, tapes, agricultural lure nets, fishing lines, fishing nets, aquaculture nets, seaweed seedling threads, artificial turf materials, toothbrush bristles, beverage extraction filters (tea bag fabrics), insect nets, animal nets, sutures, surgical nets, stents, prosthetic materials, 3D printing filaments, tennis strings, hook-and-loop fasteners (e.g., Velcro®), tire cords, printing screens, wigs, hose reinforcements, weft knitted fabrics for clothing, grass cutting cords (wires), screen door nets, woven fabrics, tarpaulin, core filaments of filament core spun yarns, ribbons, and more. The nonwoven fabric composed of the fibers according to the embodiment can be used in a variety of industries such as sanitary materials, medical materials, automotive interior materials, industrial materials (filters, wiping, etc.), civil engineering materials, agricultural materials, geotextiles (soil reinforcement fiber sheets), and environmental applications. It can be used for various purposes such as filter materials, nonwoven fabrics for masks, nonwoven fabrics for heat bonding, filters for extracting food and beverages (e.g., coffee drip filters, tea bags, filters for broth powder), blood filters for collecting blood cells, and cell separation filters.

[0329] The above embodiments will be described in detail below with reference to examples, but the above embodiments are not limited in any way by these examples. Unless otherwise specified, parts and percentages are based on mass.

[0330] (Example of the first embodiment) Example A1 (1) Preparation of raw material powder A commercially available copolymer polyester of 3-hydroxybutyrate and 3-hydroxyhexanoate, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), was prepared as powder (PHA powder). The hydroxyhexanoate content of the PHA powder was 6 mol%, the bulk density was 0.30 kg / L, the maximum melting peak temperature was 145°C, the crystallization temperature was 85°C, and the melt flow rate was MFR ＯＲＩ The value was 3.0 g / 10 min.

[0331] The bulk density of the PHA powder was measured using the same method as that used for the bulk density of the powder granules described later.

[0332] The maximum melting peak temperature and crystallization temperature of PHA powder are determined using 5 mg of PHA powder, and the maximum melting peak temperature T of the powder granules described later is used. Ｍ and crystallization temperature T Ｃ The same procedure was used for measurement (see Figures 1 and 2).

[0333] Melt flow rate MFR of PHA powder ＯＲＩ The measurement was performed in accordance with ISO 1133, using a melt indexer (Yasuda Seiki Seisakusho Co., Ltd. "No. 120-FWP"), with a cylinder set temperature of 165°C, a load of 5 kg, and preheating for 4 minutes.

[0334] (2) Production of powder granules 100 parts by mass of PHA powder was put into an FM mixer (manufactured by Nippon Coke Industries Co., Ltd., product name "5FM5C / I"; processing volume: 5L), and 15 parts by mass of tap water was continuously sprayed in for 5 minutes while the stirring blades were rotated at a speed of 2,000 rpm to obtain a water-containing powder.

[0335] A water-containing powder was fed into a disc pelletizer (Dalton Co., Ltd., product name "Disc Pelletizer F-5 / 11-175"), and a roughly cylindrical granular precursor was produced under conditions of a roller rotation speed of 108 rpm. The thickness of the die plate of the disc pelletizer was 15 mm, and the hole diameter was 3 mmφ. The length of the water-containing powder that receives compressive stress from the die hole wall inside the die plate (referred to as the effective length) was 12 mm. The granulation rate was 70 kg / h.

[0336] The obtained granule precursor was dried at 100°C for 9 hours using a hot air circulating dryer (manufactured by ESPEC, product name "PH-402") to obtain powder granules.

[0337] (3) Evaluation of the powder granules i) Structural observation The obtained powder granules were cut perpendicular 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 the PHA powder was partially melted was observed at the outer edge of the cut surface, and the original form of the unmelted PHA powder was observed inside the outer wall structure (core part). From these observation results, it was confirmed that a powder granule with a core-shell structure similar to the powder granules described in Patent No. 7387950 was manufactured.

[0338] ii) Bulk density: The bulk density of the powder granules was calculated by measuring the mass of 1 liter of powder granules obtained by letting the dried powder granules fall naturally into a 1-liter measuring cup. The bulk density of the powder granules was 0.45 kg / L.

[0339] iii) Moisture content: The amount of moisture remaining in the powder granules was measured using an infrared moisture meter (FD-660, manufactured by Kett Scientific Laboratories). The moisture content of the powder granules was 0.05% by mass.

[0340] iv) Fracture stress: The fracture stress (unit: kg) of 25 powder granules was measured using a Kiya-type hardness tester (manufactured by Shiro Sangyo Co., Ltd., product name "WPF1600-B"), and the average of the measured values ​​was calculated. The fracture stress was measured by setting the powder granule with the side facing downwards in the hardness tester and crushing the powder granule from the side using a 5 mm diameter cylindrical press. In other words, the fracture stress was measured by crushing the powder granule perpendicular to the longitudinal direction (extrusion direction). The average fracture stress of the powder granules was 7 kg, indicating that the powder granules had excellent handling properties.

[0341] v) Maximum melting peak temperature T Ｍ and crystallization temperature T ＣA 5 mg sample was obtained by cutting the powder granules perpendicular to the longitudinal direction (extrusion direction) with a razor blade. Differential scanning calorimetry (DSC) was performed on the sample using a DSC6220 manufactured by SII Nanotechnology, Inc. Specifically, the sample was heated from room temperature 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 while performing DSC to obtain the DSC curves shown in Figures 1 and 2. In the DSC curve during heating shown in Figure 1, a melting endothermic peak was observed, and its highest peak temperature (i.e., the highest melting peak temperature) T Ｍ The temperature was 147°C. In the DSC curve during cooling shown in Figure 2, a clear crystallization exothermic peak was observed, and its peak temperature (i.e., crystallization temperature) T Ｃ The temperature was 95°C. Crystallization temperature T of powder granules Ｃ The temperature was higher than the crystallization temperature of the raw material PHA powder (85°C). Furthermore, when the measurement sample was heated from room temperature to 200°C at a rate of 10°C / min in a nitrogen atmosphere, held at 200°C for 2 minutes, and then cooled at a rate of 10°C / min while DSC was performed, no crystallization exothermic peak was observed. These results indicate that a high melt memory effect is present in the powder granules. The full width at half maximum (FMAX) of the crystallization exothermic peak of the powder granules was smaller than that of the crystallization exothermic peak of the PHA powder.

[0342] vi) Melt Flow Rate (MFR) ＧＲＮ Melt flow rate (MFR) of powder granules ＧＲＮ The melt flow rate (MFR) of the powder granules was measured in accordance with ISO 1133, using a melt indexer (Yasuda Seiki Seisakusho Co., Ltd. "No. 120-FWP"), with a cylinder set temperature of 165°C, a load of 5 kg, and preheating for 4 minutes. ＧＲＮ The value was 3.0 g / 10 min.

[0343] (4) Using an injection molding dryer (ESPEC, product name "PH-402"), the powder granules were dried at 100°C for 8 hours to reduce the moisture content of the powder granules to 0.02% by mass or less. After drying, the powder granules were fed into an injection molding machine (Toyo Machinery & Metals, "SI-80IV-D150B", clamping force 80 tons) to produce dumbbell-shaped molded bodies (4 mm thick) for ISO testing.

[0344] The injection molding machine's screw was a single-screw flight screw having a supply zone, a compression zone, and a metering zone, arranged from upstream to downstream in the flow direction of the powder granules and their molten material. The injection molding machine's cylinder was divided into four zones, from upstream to downstream in the flow direction of the powder granules and their molten material: a region below the hopper where the powder granules are fed (zone 1), a region corresponding to the screw's supply zone (zone 2), a region corresponding to the screw's compression zone (zone 3), a region corresponding to the screw's metering zone (zone 4), and a region corresponding to the tip of the screw (zone 5). The temperatures of zones 1 to 5 and the nozzle attached to the tip of the cylinder were controlled independently. The set temperature for zone 1 was 40°C, and the set temperatures for zones 2 to 5 and the nozzle were all 160°C. In this case, the plasticizing melt temperature T Ｐ The temperature was 160°C. Furthermore, the temperature of the molten material immediately before it was injected into the mold after being ejected from the nozzle was measured with a contact thermocouple and was also 160°C.

[0345] Screw rotation speed S Ｒ The injection speed is 30 rpm, and the injection speed is V. Ｉ The speed is 40 mm / s, and the mold setting temperature is T. ＭＯＬＤ The temperature was set to 70°C and the cooling time was 60 seconds.

[0346] (5) Evaluation of molded products i) Ease of removal from the mold Multiple injection moldings were performed, and the ease of removal of the molded products from the mold was evaluated according to the following criteria. The results are shown in Table 1.

[0347] A: Crystallization was sufficient, and the material could be easily ejected from the mold using an ejector pin. B: Crystallization was progressing, but it was sometimes not possible to eject the material from the mold using an ejector pin. C: Crystallization was insufficient, and the material could not be ejected from the mold using an ejector pin.

[0348] ii) Crystallization temperature T ＣＡ A 5 mg sample was cut from the center of the molded body using a razor blade. The crystallization temperature T of the molded body was determined using the same method as described above for the melt memory effect of powder granules. ＣＡ The crystallization temperature T of the molded body was measured. The results are shown in Table 1. ＣＡ The temperature is 98°C, and the crystallization temperature of powder granules is T Ｃ It was 3 degrees Celsius higher than (95 degrees Celsius).

[0349] iii) Melt Flow Rate MFR ＡＲＴ A measurement piece is cut from the molded body, and the melt flow rate (MFR) of the molded body is measured using this measurement piece. ＡＲＴ The following measurements were taken. The measurements were performed in accordance with ISO 1133, using a melt indexer (Yasuda Seiki Seisakusho Co., Ltd. "No. 120-FWP"), with a cylinder set temperature of 165°C, a load of 5 kg, and preheating for 4 minutes. The results are shown in Table 1.

[0350] iv) Appearance The appearance of the molded articles was evaluated according to the following criteria. The results are shown in Table 1.

[0351] AA: Almost no surface defects such as shrinkage, flow marks, or orange peel texture. A+: Some surface defects such as shrinkage, flow marks, or orange peel texture were observed (the surface defects were mild). A: Surface defects such as shrinkage, flow marks, or orange peel texture were easily observed (the surface defects were moderate). B: Severe surface defects such as shrinkage, flow marks, or orange peel texture were observed (the surface defects were severe).

[0352] Furthermore, since sink marks are indentations caused by the shrinkage of the molded product, molded products with sink marks are considered to have inferior dimensional accuracy.

[0353] v) Bending Test In accordance with ISO 178, the bending strength (unit: MPa) and bending modulus (unit: MPa) of the molded body were measured in a constant temperature room at 23°C at a speed of 2 mm / min using an Autograph (Shimadzu Corporation "AG-X"). For the measurement, a strip-shaped test piece with a length of 80 mm, cut from a dumbbell-shaped molded body, was used. The results are shown in Table 1.

[0354] vi) Load deflection temperature In accordance with ISO 75, the load deflection temperature was measured in a constant temperature room at 23°C using an HDT (3M-2, manufactured by Toyo Seiki Seisakusho Co., Ltd.) with a load of 0.45 MPa and a heating rate of 120°C / h. For the measurement, a strip-shaped test piece with a length of 80 mm, cut from a dumbbell-shaped molded body, was used. The results are shown in Table 1.

[0355] As shown in Table 1, the molded articles could be easily removed from the mold and possessed excellent appearance, high flexural strength, high flexural modulus, and high load deflection temperature. These characteristics indicate that the molded articles had a sufficient degree of crystallinity.

[0356] Example A2 A dumbbell-shaped molded body was produced in the same manner as in Example A1, except that the injection speed was set to 10 mm / second during injection molding. The ease of removal of the molded body and the crystallization temperature T were evaluated. ＣＡ Melt flow rate MFR ＡＲＴ Appearance, bending strength, bending modulus, and temperature of deflection under load were evaluated in the same manner as in Example A1. The results are shown in Table 1. The molded articles could be easily removed from the mold and had excellent appearance, high bending strength, high bending modulus, and high temperature of deflection under load.

[0357] Example A3: In injection molding, the set temperatures for zones 2-5 and the nozzle are all set to 150°C, and the plasticizing melt temperature T Ｐ Set the temperature to 150°C and the screw rotation speed S Ｒ Except for setting the rotation speed to 100 rpm, a dumbbell-shaped molded body was produced in the same manner as in Example A1. Ease of removal of the molded body, crystallization temperature T ＣＡ Melt flow rate MFR ＡＲＴ Appearance, bending strength, bending modulus, and temperature of deflection under load were evaluated in the same manner as in Example A1. The results are shown in Table 1. The molded articles could be easily removed from the mold and had excellent appearance, high bending strength, high bending modulus, and high temperature of deflection under load.

[0358] Example A4: In injection molding, the set temperatures for zones 2-5 and the nozzle are all 140°C, and the plasticization melt temperature T Ｐ Set the temperature to 140°C and the screw rotation speed S ＲExcept for setting the rotation speed to 100 rpm, a dumbbell-shaped molded body was produced in the same manner as in Example A1, and the ease of removing the molded body and the crystallization temperature T were examined. ＣＡ Melt flow rate MFR ＡＲＴ Appearance, bending strength, bending modulus, and temperature of deflection under load were evaluated in the same manner as in Example A1. The results are shown in Table 1. The molded articles could be easily removed from the mold and had excellent appearance, high bending strength, high bending modulus, and high temperature of deflection under load.

[0359] Example A5: Injection molding with injection speed V Ｉ Except for setting the temperature to 80 mm / s, a dumbbell-shaped molded body was produced in the same manner as in Example A1, and the ease of removing the molded body and the crystallization temperature T were examined. ＣＡ Melt flow rate MFR ＡＲＴ Appearance, bending strength, bending modulus, and temperature of deflection under load were evaluated in the same manner as in Example A1. The results are shown in Table 1. In some cases, the molded articles could not be removed from the mold with ejector pins. Appearance defects were observed in the molded articles.

[0360] Example A6: Injection molding, mold setting temperature T ＭＯＬＤ Except for setting the temperature to 40°C, a dumbbell-shaped molded body was prepared in the same manner as in Example A1, and the ease of removing the molded body and the crystallization temperature T were examined. ＣＡ Melt flow rate MFR ＡＲＴ Appearance, bending strength, bending modulus, and load deflection temperature were evaluated in the same manner as in Example A1. The results are shown in Table 1. The molded article had sufficient appearance, bending strength, bending modulus, and load deflection temperature, but compared to the molded article of Example A1, it showed more sink marks and a lower load deflection temperature. In Example A6, the mold setting temperature T ＭＯＬＤ The temperature is 40°C, and the mold setting temperature T of Example A1 ＭＯＬＤ Because the temperature was lower than that of Example A1, the crystallization and solidification of PHA inside the mold was slower, resulting in inferior appearance and load deflection temperature compared to Example A1.

[0361] Example A7 Screw rotation speed S in injection molding ＲExcept for setting the rotation speed to 100 rpm, a dumbbell-shaped molded body was produced in the same manner as in Example A1, and the ease of removing the molded body and the crystallization temperature T were examined. ＣＡ Melt flow rate MFR ＡＲＴ Appearance, bending strength, bending modulus, and temperature at which deflection under load were evaluated in the same manner as in Example A1. The results are shown in Table 1.

[0362] The molded body could not be removed from the mold with an ejector pin. The molded body removed from the mold manually had a good appearance, high bending strength, high bending modulus, and high load deflection temperature, but compared to the molded body of Example A1, it had a worse appearance with more orange peel texture and sink marks, and a lower load deflection temperature. In Example A7, the screw rotation speed S Ｒ Because the value was greater than in Example A1, the melt memory effect was reduced by the flow field, resulting in inferior ease of removal, appearance, and load deflection temperature of the molded product compared to Example A1. A broad exothermic peak was observed in the cooling DSC curve of the molded product, and its peak temperature was approximately 73°C. This is because the crystallization temperature T of the powder granules was greater than in Example A1. Ｃ This is significantly different from (95°C), indicating that the crystallization temperature was not maintained during the injection molding process. This result also suggests that a large screw rotation speed S is not suitable. Ｒ This suggests that the melt memory effect was reduced due to the influence of the fluid field.

[0363] Comparative Example A1: In injection molding, the set temperatures for zones 2-5 and the nozzle are all 170°C, and the plasticizing melt temperature T Ｐ A dumbbell-shaped molded body was prepared in the same manner as in Example A1, except that the temperature was set to 170°C. The molded body was not sufficiently crystallized and could not be removed from the mold with an ejector pin. Therefore, the molded body was removed from the mold manually, and the crystallization temperature of the molded body T ＣＡ The appearance was also evaluated in the same manner as in Example A1. The results are shown in Table 1.

[0364] The molded product exhibited severe orange peel texture and shrinkage. Furthermore, a broad exothermic peak was observed in the cooling DSC curve of the molded product, with a peak temperature of approximately 73°C. This corresponds to the crystallization temperature T of the powder granules.Ｃ This differs significantly from (95°C), indicating that the crystallization temperature was not maintained during the injection molding process.

[0365]

[0366] (Example of the second embodiment) Example B1 (1) Preparation of raw material powder A commercially available copolymer polyester of 3-hydroxybutyrate and 3-hydroxyhexanoate, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), was prepared as powder (PHA powder). The hydroxyhexanoate content of the PHA powder was 6 mol%, the bulk density was 0.33 kg / L, the maximum melting peak temperature was 145°C, the crystallization temperature was 85°C, and the melt flow rate MFR ＯＲＩ The concentration was 3.0 g / 10 min. The weight-average molecular weight of PHBH was 500,000 (polystyrene equivalent).

[0367] The bulk density of the PHA powder was measured using the same method as that used for the bulk density of the powder granules described later.

[0368] The maximum melting peak temperature and crystallization temperature of PHA powder are determined using 5 mg of PHA powder, and the maximum melting peak temperature T of the powder granules described later is used. Ｍ and crystallization temperature T Ｃ The same procedure was used for measurement (see Figures 4 and 5).

[0369] Melt flow rate MFR of PHA powder ＯＲＩ The measurement was performed in accordance with ISO 1133, using a melt indexer (Yasuda Seiki Seisakusho Co., Ltd. "No. 120-FWP"), with a cylinder set temperature of 165°C, a load of 5 kg, and preheating for 4 minutes.

[0370] (2) Production of powder granules 100 parts by mass of PHA powder was put into an FM mixer (manufactured by Nippon Coke Industries Co., Ltd., product name "5FM5C / I"; processing volume: 5L), and 20 parts by mass of tap water was continuously sprayed in for 5 minutes while the stirring blades were rotated at a speed of 2,000 rpm to obtain a water-containing powder.

[0371] A water-containing powder was fed into a disc pelletizer (Dalton Co., Ltd., product name "Disc Pelletizer F-5 / 11-175"), and a roughly cylindrical granular precursor was produced under conditions of a roller rotation speed of 108 rpm. The thickness of the die plate of the disc pelletizer was 15 mm, and the hole diameter was 3 mmφ. The length of the water-containing powder that receives compressive stress from the die hole wall inside the die plate (referred to as the effective length) was 10 mm. The granulation rate was 43 kg / h.

[0372] The obtained granule precursor was dried at 100°C for 4 hours using a hot air circulating dryer (manufactured by ESPEC, product name "PH-402") to obtain powdered granules.

[0373] (3) Evaluation of powder granules i) Bulk density The bulk density of the powder granules was calculated by measuring the mass of 1 liter of powder granules obtained by letting the dried powder granules fall naturally into a 1-liter measuring cup. The bulk density of the powder granules was 0.40 kg / L.

[0374] ii) Moisture content: The amount of moisture remaining in the powder granules was measured using an infrared moisture meter (FD-660, manufactured by Kett Scientific Laboratories). The moisture content of the powder granules was 0.5% by mass.

[0375] iii) The fracture stress (unit: kg) of 25 powder granules was measured using a Kiya-type hardness tester (manufactured by Shiro Sangyo Co., Ltd., product name "WPF1600-B"), and the average of the measured values ​​was calculated. The fracture stress was measured by setting the powder granule with the side facing downwards in the hardness tester and crushing the powder granule from the side using a 5 mmφ cylindrical press. In other words, the fracture stress was measured by crushing the powder granule perpendicular to the longitudinal direction (extrusion direction). The average fracture stress of the powder granules was 1.5 kg, indicating that the powder granules had excellent handling properties.

[0376] iv) Maximum melting peak temperature T Ｍ and crystallization temperature T ＣA 5 mg sample was obtained by cutting the powder granules perpendicular to the longitudinal direction (extrusion direction) with a razor blade. Differential scanning calorimetry (DSC) was performed on the sample using a DSC6220 manufactured by SII Nanotechnology, Inc. Specifically, the sample was heated from room temperature to 180°C at a rate of 10°C / min in a nitrogen atmosphere, held at 180°C for 2 minutes, and then DSC was performed while cooling at a rate of 10°C / min to obtain the DSC curves shown in Figures 4 and 5. In the DSC curve during heating shown in Figure 4, a melting endothermic peak was observed, and its highest peak temperature (i.e., the highest melting peak temperature) T Ｍ The temperature was 147°C. In the DSC curve during cooling shown in Figure 5, a clear crystallization exothermic peak was observed, and its peak temperature (i.e., crystallization temperature) T Ｃ The temperature was 95°C. Crystallization temperature T of powder granules Ｃ The temperature was higher than the crystallization temperature of the raw material PHA powder (85°C). Furthermore, when the measurement sample was heated from room temperature to 200°C at a rate of 10°C / min in a nitrogen atmosphere, held at 200°C for 2 minutes, and then cooled at a rate of 10°C / min while DSC was performed, no crystallization exothermic peak was observed. These results indicate that a high melt memory effect is present in the powder granules. In addition, the full width at half maximum (FMAX) of the crystallization exothermic peak of the powder granules was smaller than that of the crystallization exothermic peak of the PHA powder.

[0377] v) Meltflow rate MFR ＧＲＮ Melt flow rate (MFR) of powder granules ＧＲＮ The melt flow rate (MFR) of the powder granules was measured in accordance with ISO 1133, using a melt indexer (Yasuda Seiki Seisakusho Co., Ltd. "No. 120-FWP"), with a cylinder set temperature of 165°C, a load of 5 kg, and preheating for 4 minutes. ＧＲＮ The value was 3.0 g / 10 min.

[0378] (4) The powder granules were dried at 100°C for 8 hours using an extrusion dryer (ESPEC, product name "PH-402") to reduce the moisture content of the powder granules to 0.05% by mass or less. After drying, the powder granules were molded using an extrusion machine as shown in Figure 3. The extrusion machine was equipped with a pair of cooling rolls consisting of a first roll and a second roll, a conveying roll consisting of a third roll located downstream of the second roll and a pair of pinch rolls located downstream of the third roll, and a winding roll. A 40 mmφ single-screw extruder (GSI Creos, product name "691C-EF049") equipped with a full-flight screw with L / D = 28 was used as the extruder. For the first roll, a roll with a silicone rubber outer layer was used. The surface temperature of the first roll was controlled by water cooling. For the second and third rolls, metal mirror-finish rolls with chrome-plated surfaces were used. The second and third rolls share a hot water temperature control system, allowing for integrated control of the surface temperatures of both rolls.

[0379] The extruder cylinder was divided into five regions C1 to C5 in the flow direction of the powder granules and their molten material, from upstream to downstream, and the temperature of each region was controlled independently. Region C1 was the region below the hopper into which the powder granules were fed. The T-type die was divided into three regions D1 to D3 in the width direction of the molten material extruded from the T-type die, and the temperature of each region was controlled independently. Region D2 was the region sandwiched between regions D1 and D3, including the center of the T-type die. The set temperatures for regions C1 to C5 of the cylinder, the die head (HD) and adapter (AD) attached to the tip of the cylinder, and regions D1 to D3 of the T-type die were as shown in Table 2 below.

[0380]

[0381] The temperature of the molten material inside the die head, i.e., the plasticizing melt temperature T, is measured by a thermocouple attached to the die head. Ｐ The results were as shown in Table 6.

[0382] Screw rotation speed S ＲAt 30 rpm, a sheet of molten material was continuously extruded from a T-type die with a die width of 300 mm, and the molten material was cooled by being sandwiched between a pair of cooling rolls, consisting of a first roll and a second roll, positioned directly below the T-type die. The surface temperature of the first roll was set to 20°C. The surface temperature of the first roll, measured with a contact thermocouple (ST-41-K-1000-3C / A, manufactured by Rika Kogyo Co., Ltd.), was 30°C. The surface temperatures of the second and third rolls were set to 70°C. The surface temperatures of the second and third rolls, measured with the same contact thermocouple, were both 63°C. Upon contact with the second roll, the molten material was rapidly cooled to 63°C, yielding a single-layer sheet (extruded product) with a thickness of 80 μm. The sheet was fed to a winding roll via the third roll and pinch rolls and wound up. The winding speed of the sheet was 1.3 m / min. The winding speed was controlled by the rotation speed of the second roll, thereby controlling the thickness of the sheet.

[0383] (5) Evaluation of extruded articles i) Resistance to adhesion to the second roll The resistance of the sheet to adhesion to the second roll was evaluated according to the following criteria. The results are shown in Table 6.

[0384] A: The sheet did not stick to the second roll. B: The sheet stuck to the second roll, or was likely to stick to it.

[0385] ii) The width of the region in the effective width sheet having a thickness within ±10 μm of the design thickness (80 μm in Example B1) (hereinafter referred to as "effective width") was measured. Here, width means the length in the direction perpendicular to the conveying direction (machine direction, MD) (TD). The results are shown in Table 6.

[0386] iii) Crystallization temperature T ＣＡ A 5 mg sample was cut from the center of the sheet using a razor blade. The crystallization temperature T of the sheet was determined using the same method as described above for the melt memory effect of powder granules. ＣＡ The following was measured. The results are shown in Table 6. Crystallization temperature T of the sheet. ＣＡ The temperature is 99°C, and the crystallization temperature of powder granules is T Ｃ It was 4°C higher than (95°C).

[0387] iv) Meltflow rate MFR ＡＲＴ A sample is cut from the sheet, and the melt flow rate (MFR) of the sheet is measured using this sample. ＡＲＴ The following measurements were taken. The measurements were performed in accordance with ISO 1133, using a melt indexer (Yasuda Seiki Seisakusho Co., Ltd. "No. 120-FWP"), with a cylinder set temperature of 165°C, a load of 5 kg, and preheating for 4 minutes. The results are shown in Table 6.

[0388] v) Appearance The appearance of the sheets was evaluated according to the following criteria. In the following criteria, an appearance defect refers to wavy, orange peel, etc. The results are shown in Table 6.

[0389] AA: Almost no cosmetic defects. A+: Some cosmetic defects were observed (minor defects). A: Cosmetic defects were easily observed (moderate defects). B: Severe cosmetic defects (severe defects).

[0390] vi) A 120 mm x 120 mm square piece was cut from the heat-shrinkable sheet, and two lines were drawn on the surface of the piece. The two lines intersected perpendicularly at the center of the piece and each had a length of 100 mm. One of the two lines was parallel to the sheet's conveying direction (machine direction, MD), and the other line was parallel to the direction perpendicular to MD (TD). The piece was placed in an oven set to 150°C, near the melting point of PHA, or 170°C, above the melting point of PHA, for 30 minutes. After that, the length of the lines drawn on the piece was measured to determine the amount of sheet shrinkage in MD and TD, respectively. The results are shown in Table 6.

[0391] As shown in Table 6, the sheet could be wound stably onto the second roll without sticking. The sheet had a stable shape and dimensions with virtually no cosmetic defects. The sheet did not shrink when heated.

[0392] In Example B2, a sheet was manufactured in the same manner as in Example B1, except that the sheet winding speed was set to 1.5 m / min and the design thickness of the sheet was set to 50 μm during extrusion molding. The sheet was evaluated in the same manner as in Example B1. The results are shown in Table 6. The sheet could be wound stably without sticking to the second roll. The sheet had a stable shape and dimensions with almost no appearance defects. The sheet did not shrink when heated.

[0393] In Example B3, a sheet was manufactured in the same manner as in Example B1, except that the sheet winding speed was set to 3.0 m / min and the sheet design thickness was set to 30 μm during extrusion molding. The sheet was evaluated in the same manner as in Example B1. The results are shown in Table 6. The sheet could be wound stably without sticking to the second roll. The sheet had a stable shape and dimensions with almost no appearance defects. The sheet did not shrink when heated.

[0394] Example B4 In extrusion molding, the set temperatures for regions C1 to C5 of the cylinder, the die head (HD) attached to the tip of the cylinder, the adapter (AD), and regions D1 to D3 of the T-type die are as shown in Table 3 below, and the plasticizing melt temperature T Ｐ Except for setting the temperature to 160°C and the winding speed to 1.2 m / min, the sheet was prepared and evaluated in the same manner as in Example B1. The results are shown in Table 6. The sheet could be wound stably without sticking to the second roll. The sheet had minor cosmetic defects. The sheet did not shrink when heated.

[0395]

[0396] Example B5: A sheet was produced in the same manner as in Example B1, except that the surface temperature of the second and third rolls was set to 40°C during extrusion molding. The measured surface temperatures of both the second and third rolls were 37°C. The obtained sheet was evaluated in the same manner as in Example B1. The results are shown in Table 6. The sheet could be wound stably without sticking to the second roll. The sheet had moderate surface defects. The sheet did not shrink when heated.

[0397] Comparative Example B1 In extrusion molding, the set temperatures for regions C1 to C5 of the cylinder, the die head (HD) attached to the tip of the cylinder, the adapter (AD), and regions D1 to D3 of the T-type die are as shown in Table 4 below, and the plasticizing melt temperature T Ｐ Except for setting the temperature to 170°C, a sheet was prepared in the same manner as in Example B1, and the degree of adhesion of the sheet to the second roll and the crystallization temperature T were measured. ＣＡ The appearance and other aspects were evaluated in the same manner as in Example B1. The results are shown in Table 6. The sheet stuck to the second roll and could not be wound up stably.

[0398]

[0399] Comparative Example 2 In extrusion molding, the set temperatures for regions C1 to C5 of the cylinder, the die head (HD) attached to the tip of the cylinder, the adapter (AD), and regions D1 to D3 of the T-type die are as shown in Table 5 below, and the plasticizing melt temperature T Ｐ The sheet was prepared in the same manner as in Example B1, except that the temperature was set to 135°C. Unmelted PHA was present in the molten material extruded from the T-die, and the resulting sheet had wrinkles and holes.

[0400]

[0401] Comparative Example B3: A sheet was prepared in the same manner as in Example B1, except that a commercially available PHA molten pellet (manufactured by BluePHA, product name "BP-330-05") with a crystallization nucleating agent added was used instead of powder granules. The sheet's resistance to adhesion to the second roll and its crystallization temperature T were evaluated. ＣＡ Melt flow rate MFR ＡＲＴThe appearance and other aspects were evaluated in the same manner as in Example B1. The maximum melting peak temperature T of the molten pellet. Ｍ , crystallization temperature T Ｃ , and melt flow rate MFR ＰＬＴ The results were as shown in Table 6. The evaluation results are shown in Table 6. The sheet stuck to the second roll and could not be wound continuously.

[0402] Comparative Example B4: In extrusion molding, a sheet was manufactured in the same manner as in Comparative Example B3, except that the surface temperature of the second and third rolls was set to 40°C, the sheet winding speed was set to 2.0 m / min, and the design thickness of the sheet was set to 80 μm. The measured surface temperatures of the second and third rolls were both 37°C. The obtained sheet was evaluated in the same manner as in Example B1. The results are shown in Table 6. The sheet sometimes stuck to the second roll, but it was barely possible to manufacture sheets continuously. However, the sheet had a small effective width, was wavy, and had poor shape and dimensional stability. In addition, the sheet shrank at MD and stretched at TD at 170°C, and had poor heat resistance.

[0403]

[0404] (Examples of the third embodiment) Examples C1 to C11 (1) Raw material powder A commercially available copolymer polyester of 3-hydroxybutyrate and 3-hydroxyhexanoate, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), was prepared as a powder (PHA powder). The hydroxyhexanoate content of the PHA powder was 6 mol%, the bulk density was 0.33 kg / L, the maximum melting peak temperature was 145°C, the crystallization temperature was 73°C, and the melt flow rate MFR was 3.0 g / 10 min. The weight-average molecular weight of PHBH was 500,000 (polystyrene equivalent).

[0405] The bulk density of the PHA powder was measured using the same method as that used for the bulk density of the powder granules described later.

[0406] The maximum melting peak temperature and crystallization temperature of PHA powder are determined using 5 mg of PHA powder, and the maximum melting peak temperature T of the powder granules described later is used. Ｍand crystallization temperature T Ｃ It was measured in the same manner.

[0407] The melt flow rate (MFR) of PHA powder was measured in accordance with ISO 1133 using a melt indexer (Yasuda Seiki Seisakusho Co., Ltd. "No. 120-FWP"), with a cylinder set temperature of 165°C, a load of 5 kg, and a preheating time of 4 minutes.

[0408] (2) Production of powder granules 100 parts by mass of PHA powder was put into an FM mixer (5FM5C / I manufactured by Nippon Coke Industries Co., Ltd.), and 15 parts by mass of tap water was continuously sprayed in for 5 minutes while the stirring blades were rotated at a speed of 2,000 rpm to obtain a water-containing powder.

[0409] A water-containing powder was fed into a disc pelletizer (Dalton Co., Ltd. "Disc Pelletizer F-5 / 11-175"), and a roughly cylindrical granular precursor was produced under conditions of a roller rotation speed of 108 rpm. The thickness of the die plate of the disc pelletizer was 15 mm, and the hole diameter was 3 mmφ. The length of the water-containing powder that receives compressive stress from the die hole wall inside the die plate (referred to as the effective length) was 12 mm. The granulation rate was 40 kg / h.

[0410] The obtained granular precursor was dried at 100°C for 4 hours using a hot air circulating dryer (PH-402, manufactured by ESPEC Corporation) to obtain powdered granules.

[0411] (3) Evaluation of powder granules i) Bulk density The bulk density of the powder granules was calculated by measuring the mass of 1 liter of powder granules obtained by letting the dried powder granules fall naturally into a 1-liter measuring cup. The bulk density of the powder granules was 0.40 kg / L.

[0412] ii) Moisture content: The amount of moisture remaining in the powder granules was measured using an infrared moisture meter (FD-660, manufactured by Kett Scientific Research Institute Co., Ltd.). The moisture content of the powder granules was 0.5% by mass.

[0413] iii) The fracture stress (unit: kg) of 25 powder granules was measured using a Kiya-type hardness tester (WPF1600-B, manufactured by Shiro Sangyo Co., Ltd.), and the average of the measured values ​​was calculated. The fracture stress was measured by setting the powder granule with the side facing downwards in the hardness tester and crushing the powder granule from the side using a 5 mmφ cylindrical press. In other words, the fracture stress was measured by crushing the powder granule perpendicular to the longitudinal direction (extrusion direction). The average fracture stress of the powder granules was 2.1 kg, indicating that the powder granules had excellent handling properties.

[0414] iv) Maximum melting peak temperature T Ｍ and crystallization temperature T Ｃ A 5 mg sample was obtained by cutting the powder granules perpendicular to the longitudinal direction (extrusion direction) with a razor blade. Differential scanning calorimetry (DSC) was performed on the sample using a Hitachi High-Tech Analysis Co., Ltd. "DSC200". Specifically, the sample was heated from room temperature to 180°C at a rate of 10°C / min in a nitrogen atmosphere, held at 180°C for 2 minutes, and then DSC was performed while cooling at a rate of 10°C / min to obtain a DSC curve. As shown in Figure 9B, a melting endothermic peak was observed in the DSC curve during heating, and its highest peak temperature (i.e., the highest melting peak temperature) T Ｍ The temperature was 146°C. As shown in Figures 8 and 9A, a clear crystallization exothermic peak was observed in the DSC curve during cooling, and its peak temperature (i.e., crystallization temperature) T Ｃ The temperature was 84°C. Crystallization temperature T of powder granules Ｃ The temperature was higher than the crystallization temperature of the raw material PHA powder (73°C). Furthermore, the full width at half maximum (FWHM) of the crystallization exothermic peak of the powder granules was smaller than that of the crystallization exothermic peak of the PHA powder. In addition, when the sample was heated from room temperature to 200°C at a rate of 10°C / min in a nitrogen atmosphere, held at 200°C for 2 minutes, and then cooled at a rate of 10°C / min while DSC was performed, no crystallization exothermic peak was observed. These findings confirm that a high melt memory effect is present in the powder granules.

[0415] v) Melt Flow Rate MFR The melt flow rate MFR of the powder granules was measured in accordance with ISO 1133 using a melt index tester (Yasuda Seiki Seisakusho Co., Ltd. "No. 120-FWP") with a cylinder setting temperature of 165°C, a load of 5 kg, and preheating for 4 minutes. The melt flow rate MFR of the powder granules was 3.0 g / 10 min.

[0416] (4) Using a fiber manufacturing dryer (PH-402 manufactured by ESPEC Corporation), the powder granules were dried at 100°C for 8 hours to reduce the moisture content of the powder granules to 0.05% by mass or less. Using the dried powder granules, fibers were manufactured using the apparatus shown in Figure 7 (Capillograph 1D manufactured by Toyo Seiki Seisakusho Co., Ltd.). The manufacturing apparatus used in the example consisted of an extruder equipped with a cylinder with a barrel inner diameter of 9.55 mm and a length of 350 mm, and a die with a die hole (orifice) of 1.0 mm in diameter mounted on the lower end of the cylinder, two pulleys equipped with load cells (not shown) located below the die hole in the direction of gravity, and a rubber take-up roll located downstream of the pulleys.

[0417] The plasticization and melting temperature T of the powder granules inside the cylinder is as shown in Tables 7 and 8. Ｐ The material was melted (plasticized) and extruded through the die holes in a continuous fibrous manner at the extrusion speeds shown in Tables 7 and 8. The residence time in the cylinder was 4 minutes. In addition, the manufacturing apparatus used in the example had a plasticization melting temperature T Ｐ This corresponds to the die temperature. The extruded molten material was taken up by a take-up roll via a pulley. The take-up speed was as shown in Tables 7 and 8. The take-up speed was controlled by the rotation speed of the take-up roll. The transport distance from the die hole to the take-up roll was 75 cm. The molten material was air-cooled at room temperature (20°C) and solidified while being transported from the die hole to the take-up roll. This produced the fibers.

[0418] The tension (melt tension) when drawing molten material from the die hole was measured using a load cell (standard 4N) attached to a pulley. The results are shown in Tables 7 and 8.

[0419] In Example C11, the plasticizing melt temperature T ＰThe highest melting peak temperature T of the powder granules Ｍ Although the amount was less than 50%, it was possible to extrude the molten material from the die hole in a continuous fibrous manner.

[0420] (5) Evaluation of fibers i) The fusion properties of fusible fibers were evaluated according to the following criteria. The results are shown in Table 7.

[0421] A: A single fiber (monofilament) could be easily drawn out without the fibers fusing to the take-up roll. B: The fibers fused to the take-up roll and were wound up, and the fibers self-fused together. When attempting to draw out a single fiber (monofilament), the fibers cohesively broke.

[0422] ii) Crystallization temperature T ＣＡ，１ , T ＣＡ，２ A 5 mg sample was cut from the fiber using a melt memory effect razor blade. Differential scanning calorimetry (DSC) was performed on the sample using a Hitachi High-Tech Analysis Co., Ltd. "DSC200". Specifically, in a nitrogen atmosphere, the sample was heated from room temperature to 180°C at a rate of 10°C / min, held at 180°C for 2 minutes, cooled to 30°C at a rate of 10°C / min, then heated from 30°C to 180°C at a rate of 10°C / min, held at 180°C for 2 minutes, and DSC was performed while cooling to 30°C at a rate of 10°C / min to obtain the DSC curve. Figure 8 shows the first and second cooling DSC curves for the fiber of Example C9, Figure 9A shows the first and second cooling DSC curves for the fiber of Example C10, and Figure 9B shows the first heating DSC curve for the fiber of Example C10.

[0423] In each example, a clear crystallization exothermic peak was observed in the first cooling DSC curve, and its peak temperature (i.e., the first crystallization temperature) T ＣＡ，１ The results were as shown in Tables 7 and 8. In each example, a clear crystallization exothermic peak was observed in the second cooling DSC curve, and its peak temperature (i.e., second crystallization temperature) T ＣＡ，２ The results were as shown in Tables 7 and 8. Note that a "-" in Tables 7 and 8 indicates that measurement was not performed.

[0424] In each example, melting peaks were observed in the first and second heating DSC curves. The highest melting peak temperature T of the fiber was determined from the first heating DSC curve. ＭＡ The results were as shown in Tables 7 and 8. The highest melting peak temperature T of the fiber. ＭＡ T is the highest melting peak temperature of the powder granules. Ｍ The values ​​were approximately the same as or higher than those of the processed raw material. Furthermore, as shown in Figure 9B, the melting peak of the fibers was sharper than that of the powder granules. These results are presumed to be due to the increased crystal orientation of the fibers compared to the processed raw material.

[0425] Similarly, a 5 mg sample cut from the fiber was heated in a nitrogen atmosphere from room temperature to 200°C at a rate of 10°C / min, held at 200°C for 2 minutes, and then subjected to DSC while cooling at a rate of 10°C / min. No crystallization exothermic peak was observed. As an example, the cooling DSC curve from 200°C for the fiber of Example C10 is shown in Figure 10. A crystallization exothermic peak was observed in the cooling DSC curve from 180°C, but no crystallization exothermic peak was observed in the cooling DSC curve from 200°C, confirming that the fiber of the example possesses a melt memory effect.

[0426] First crystallization temperature T of the fibers in each example ＣＡ，１ The crystallization temperature T of powder granules is Ｃ The temperature was more than 4°C higher than (84°C). This indicates that the manufactured fibers had a higher melt memory effect than the powder granules, suggesting that the melt memory effect was further improved in the process of manufacturing fibers from powder granules. Furthermore, the fibers of Examples C9 and C10, which had a higher take-up rate compared to Examples C1 to C8, showed a particularly high first crystallization temperature T ＣＡ，１ This was due to the high take-up rate, which stretched the fibrous molten material, thereby increasing the orientation of PHA within the fibers.

[0427] iii) Fiber diameter: Optical microscope images of the fibers in each example were observed, and the fiber thickness was measured at 10 randomly selected locations. The arithmetic mean was calculated. The results are shown in Tables 7 and 8. Optical microscope images of the fibers in Examples C9 and C10 are shown in Figures 11 and 12, respectively.

[0428] Comparative Examples C1 and C2: Fibers were manufactured and evaluated in the same manner as in Example C3, except that commercially available PHBH molten pellets (Bluepha® PHA BP330-05, manufactured by Bluepha) with a crystallization nucleating agent added were used instead of powder granules, and the extrusion rate was as shown in Table 8. The hydroxyhexanoate content of the molten pellets was 6 mol%, and the maximum melting peak temperature was T Ｍ and crystallization temperature T Ｃ The results are as shown in Table 8, and the melt flow rate (MFR) was 3.0 g / 10 min. The evaluation results of the manufactured fibers are shown in Table 8. Note that the manufactured fibers adhered to the take-up roll and self-fused, so the fiber diameter was not measured. The first crystallization temperature T of the fibers of Comparative Examples C1 and C2. ＣＡ、１ The crystallization temperature for both was 49°C. This crystallization temperature is attributed to the crystallization nucleating agent. The fibers of Comparative Examples C1 and C2 did not exhibit the melt memory effect.

[0429] Comparative Example C3: Fibers were manufactured and evaluated in the same manner as in Example C3, except that commercially available PHBH molten pellets (Bluepha® PHA BP350-05, manufactured by Bluepha) with a crystallization nucleating agent added were used instead of powder granules. The hydroxyhexanoate content of the molten pellets was 10 mol%, and the maximum melting peak temperature was T Ｍ and crystallization temperature T Ｃ The results were as shown in Table 8. The evaluation results of the manufactured fibers are shown in Table 8. Note that the manufactured fibers adhered to the take-up roll and self-fused, so the fiber diameter was not measured. The first crystallization temperature of the fibers T ＣＡ、１ The peak melting temperature was 58°C, which was attributed to the crystallization nucleating agent. Furthermore, the fibers did not exhibit a melt memory effect. The highest melting peak temperature of the fibers was T. ＭＡ The temperature was 130°C, which did not satisfy equation (C2).

[0430] Comparative Example C4: Fibers were manufactured and evaluated in the same manner as in Example C3, except that commercially available PHBH molten pellets ("Green Planet® X131A" manufactured by Kaneka Corporation) with a crystallization nucleating agent added were used instead of powder granules. The hydroxyhexanoate content of the molten pellets was 5.8 mol%, and the maximum melting peak temperature was T Ｍ and crystallization temperature T Ｃ The results were as shown in Table 8. The evaluation results of the manufactured fibers are shown in Table 8. Note that the manufactured fibers adhered to the take-up roll and self-fused, so the fiber diameter was not measured. The first crystallization temperature of the fibers T ＣＡ、１ The temperature was 81°C, which is attributed to the crystallization nucleating agent. Furthermore, a crystallization exothermic peak (peak temperature 51°C) was observed in the DSC cooling curve of the fiber from 200°C, confirming that the fiber does not exhibit a melt memory effect.

[0431] Comparative Example C5: 100 parts by mass of commercially available PHBH powder, the same as used in Example C1, was mixed with 1 part by mass of pentaerythritol (Mitsubishi Chemical Corporation's "Neurizer P"), a crystallization nucleating agent, and powder granules were produced in the same manner as in Example C1. The maximum melting peak temperature T of the produced powder granules was... Ｍ and crystallization temperature T Ｃ The results were as shown in Table 8.

[0432] Using the manufactured powder granules, fibers were produced and evaluated in the same manner as in Example C3. The results are shown in Table 8. Note that the manufactured fibers adhered to the take-up roll and self-fused, so fiber diameter measurement was not performed. The first crystallization temperature of the fibers T ＣＡ、１ The temperature was 83°C, but this was due to the crystallization nucleating agent, and the crystallization temperature T of the powder granules used as processing raw material was different. Ｃ To the same extent (i.e., T ＣＡ，１ / T Ｃ The result was 1.00. Furthermore, a crystallization exothermic peak (peak temperature 80°C) was observed in the DSC cooling curve of the fiber from 200°C, confirming that the fiber does not exhibit a melt memory effect.

[0433]

[0434]

[0435] In Examples C1 to C11, which used powder granules without a crystallization nucleating agent and possessing a melt memory effect as the processing material, fiber fusion was suppressed and the fibers reached a higher first crystallization temperature T compared to Comparative Examples C1 to C5, which used molten pellets or powder granules with added crystallization nucleating agents as the processing material. ＣＡ，１ The inventors speculated that the reason for this was as follows, although they are not bound by theory: When a processing material to which a crystallization nucleating agent has been added is used, the molten material extruded into fibers crystallizes from the center (core). The heat generated by crystallization in the core is conducted to the surface, causing the crystallization of the surface to be delayed compared to the core. Self-fusion is more likely to occur in the amorphous portion. On the other hand, when a powder granule with a melt memory effect is used as a processing material, the crystallization rate is high, and in addition, crystallization proceeds almost simultaneously in the core and surface of the fibrous molten material, or even starting from the surface. As a result, the entire fiber is crystallized uniformly, and crystallization is particularly sufficient in the surface, so it is presumed that fusion is suppressed.

[0436] In this specification, a numerical range represented by the symbol "~" includes the numbers before and after the symbol "~" as the lower and upper limits, respectively, unless otherwise specified. Furthermore, the upper and / or lower limits of the numerical ranges described in this specification can be arbitrarily combined to define a preferred range. For example, a preferred range can be defined by arbitrarily combining the upper and lower limits of a numerical range, by arbitrarily combining the upper limits of a numerical range, and by arbitrarily combining the lower limits of a numerical range.

[0437] In this application, the term "and / or" refers to at least one of the enumerated items and all possible combinations thereof.

[0438] Although this embodiment has been described in detail above, the specific configuration is not limited to this embodiment, and any design changes that do not depart from the gist of this disclosure are also included in this disclosure.

[0439] This specification incorporates the disclosures of Japanese Patent Application Nos. 2024-205593, 2024-205462, and 2025-092166, which form the basis of the priority claim of this application. All publications, patents, and patent applications cited herein are incorporated herein by direct reference.

[0440] 1 Extrusion molding machine, 10 Extruder, 12 Cylinder, 14 Screw, 16 Hopper, 17 Die head, 18 T-type die, 19 Adapter, 30 Cooling roll, 32 First roll, 34 Second roll, 50 Conveyor roll, 52 Third roll, 54 Pinch roll, 70 Winding roll, 92 Powder granules, 94 Molten material, 96 Extruded molded body, 101, 102 Manufacturing equipment, 110, 120 Extruder, 112, 122 Cylinder, 114 Screw, 116 Hopper, 117 Die head, 118, 128 Die, 119 Adapter, 124 Piston, 130 Collector, 132 Conveyor belt, 134 Conveyor roll, 136 Pulley, 150 Take-up roll, 170 Winding roll, 192 Powder granules, 194 Molten material, 196 Nonwoven fabric, 198 Monofilament or multifilament

Claims

1. A method for manufacturing a molded article, comprising injection molding polyhydroxyalkanoate (PHA) using an injection molding machine, wherein the injection molding process involves plasticizing the powder granules containing PHA powder at a melting temperature T Ｐ The process includes melting at a temperature of (°C) to obtain a molten material, pouring the molten material into a mold, and cooling the molten material to solidify it, wherein the plasticizing melt temperature T Ｐ However, equation (A1) T Ｍ -20<T Ｐ ≦T Ｍ +20 (A1) (where T Ｍ A method that satisfies the following conditions: (Unit: °C) represents the highest melting peak temperature observed in differential scanning calorimetry where the powder granules are heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere.

2. The method according to claim 1, wherein the powder granules have a melt memory effect.

3. The method according to claim 1 or 2, wherein the powder granules are compressed granules.

4. The method according to claim 3, wherein the powder granules have an outer wall portion formed by the melting and solidification of at least a portion of the PHA powder located at the outer edge of the powder granules, and compressed PHA powder is contained inside the outer wall portion.

5. The maximum melting peak temperature T of the powder granulated product Ｍ is 140°C or higher, and the injection molding is carried out at a screw rotation speed S Ｒ ×V Ｉ satisfying the formula (A2): 10 ≤ S Ｒ (unit: rpm) and an injection speed V Ｉ (unit: mm / sec), according to any one of claims 1 to 4.

6. The method according to any one of claims 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.

7. Screw rotation speed S of 100 rpm or less Ｒ The method according to claim 6, wherein the injection molding is performed.

8. The injection molding is performed at an injection speed V of 100 mm / second or less. Ｉ The method according to any one of claims 1 to 7, performed in [location].

9. The set temperature T of the mold ＭＯＬＤ (Unit: °C) and the crystallization temperature T of the powder granules. Ｃ However, formula (A3) T Ｃ -60<T ＭＯＬＤ ≦T Ｃ (A3) is satisfied, and the crystallization temperature T of the powder granules is satisfied. Ｃ The method according to any one of claims 1 to 8, wherein the powder granules are 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, and the peak temperature of the crystallization exothermic peak observed during cooling is defined as the peak temperature of the crystallization exothermic peak observed during cooling.

10. Crystallization temperature T of the powder granules Ｃ The temperature (in °C) is 80°C or higher, and the crystallization temperature T of the powder granules is 80°C or higher. Ｃ The method according to any one of claims 1 to 9, wherein the powder granules are 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, and the peak temperature of the crystallization exothermic peak observed during cooling is defined as the peak temperature of the crystallization exothermic peak observed during cooling.

11. The set temperature T of the mold ＭＯＬＤ The method according to claim 10, wherein the temperature is 60°C to 80°C.

12. Crystallization temperature T of the molded body ＣＡ (Unit: °C) and the crystallization temperature T of the powder granules. Ｃ (Unit: °C) is given by equation (A4) 0.8 ≤ T ＣＡ / T Ｃ The following conditions must be met: ≤ 1.2 (A4), and the crystallization temperature T of the powder granules must be met. Ｃ However, in differential scanning calorimetry in which the powder granules are 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 peak temperature of the crystallization exothermic peak observed during cooling is defined as the crystallization temperature T of the molded body. ＣＡ The method according to any one of claims 1 to 11, wherein 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, and the peak temperature of the crystallization exothermic peak observed during cooling is defined as the peak temperature of the crystallization exothermic peak observed during cooling.

13. The method according to any one of claims 1 to 12, wherein the molded body has a load deflection temperature of 100°C or higher, and the load deflection temperature is measured at a load of 0.45 MPa in accordance with ISO 75.

14. Melt flow rate MFR of the PHA powder ＯＲＩ (Unit: g / 10 min), Melt flow rate MFR of the powder granules ＧＲＮ (Unit: g / 10 min), and the melt flow rate MFR of the molded body. ＡＲＴ (Unit: g / 10 min) is given by equations (a), (b), and (c) 1 ≤ MFR ＧＲＮ / MFR ＯＲＩ ≦5 (a) 1≦MFR ＡＲＴ / MFR ＧＲＮ ≦5 (b) 1≦MFR ＡＲＴ / MFR ＯＲＩ The following conditions must be met: ≤ 10 (c), and the melt flow rate MFR of the PHA powder ＯＲＩ , the melt flow rate MFR of the powder granules ＧＲＮ , and the melt flow rate MFR of the molded body ＡＲＴ The method according to any one of claims 1 to 13, wherein the measurement is performed at 165°C and a load of 5 kg in accordance with ISO 1133.

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