Method for manufacturing an extruded body

Abstract

Provided is a method for manufacturing an extruded molded article, which can stably and continuously manufacture a PHA extruded molded article using a polyhydroxyalkanoate (PHA) powder granulate. 【Solution means】The method for manufacturing an extruded molded article includes extruding polyhydroxyalkanoate (PHA) using an extruder. The extrusion molding includes melting a powder granulate containing PHA powder at a plasticizing melting temperature T P (unit: °C) to obtain a melt, extruding the melt from a die, and cooling and solidifying the extruded melt. The plasticizing melting temperature T P is represented by formula (1) T M -10 < T P ≤ T M + 20 (1) (wherein T M (unit: °C) represents the highest melting peak temperature observed in differential scanning calorimetry in which the powder granulate is heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere.) is satisfied.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing an extruded product.

Background Art

[0002] Polyhydroxyalkanoate (PHA) is a biodegradable polyester resin produced by microorganisms in their bodies and is known for its marine biodegradability by microorganisms. On the other hand, PHA is easily decomposed by heat. For example, in a temperature range exceeding 180°C, thermal decomposition significantly progresses. Also, although PHA is a crystalline polymer, due to its slow crystal solidification rate, in extrusion molding, problems such as sticking to the cooling roll, adhesion of the extruded product to the die (referred to as die fouling), and instability of shape and dimensions due to post-shrinkage occur. Therefore, in the extrusion molding of PHA, a crystallization nucleating agent may be added to pellets (hereinafter, sometimes referred to as "melt pellets") produced by melt-kneading raw material PHA powder, or melt pellets produced by compounding PHA with other resins may be used as molding materials. However, the crystallization nucleating agent may cause factors that hinder continuous molding, such as sticking of the extrudate to the cooling roll and deposits on the die (referred to as die fouling). Furthermore, the production of PHA melt pellets by the melt-kneading process requires a large amount of electric power. Products manufactured using melt pellets produced by compounding PHA with other resins generally tend to have a slow marine decomposition rate.

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

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

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] The present disclosure provides a method for manufacturing an extruded article that can stably and continuously manufacture a PHA extruded article using a PHA powder granulate. [Means for Solving the Problems]

[0007] Aspects of the present disclosure include the following. [Aspect 1] A method for manufacturing an extruded article, comprising extruding polyhydroxyalkanoate (PHA) with an extruder, wherein the extrusion molding includes melting a powder granulate containing PHA powder at a plasticizing melting temperature T P (unit: °C) to obtain a melt, extruding the melt from a die, and cooling and solidifying the extruded melt, wherein the plasticizing melting temperature T P satisfies the formula (1) T M -10 < T P ≤ T M +20 (1) (wherein T M (unit: °C) represents the highest melting peak temperature observed in a differential scanning calorimetry measurement in which the powder granulate is heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere.) A method that satisfies the above. [Aspect 2] The method according to Aspect 1, wherein the powder granulate has a melt memory effect. [Aspect 3] The method according to Aspect 1 or 2, wherein the powder granulate is a compression granulate. [Aspect 4] The method according to aspect 3, wherein the powder granule has an outer wall portion formed by melting and solidifying at least a part of the PHA powder located at the outer edge of the powder granule, and the PHA powder compressed inside the outer wall portion is contained therein. [Aspect 5] The die is a T-shaped die, The method according to any one of aspects 1 to 4, wherein the melt extruded from the die is cooled by at least one cooling roll. [Aspect 6] The at least one cooling roll includes a first roll and a second roll that sandwich the melt, The cooled melt is conveyed along the surface of the second roll, The surface temperature T of the first roll R1 (unit: °C), the surface temperature T of the second roll R2 (unit: °C), and the crystallization temperature T of the powder granule C satisfy equations (2), (3), and (4) T C -80 < T R1 ≤ T C (2) T C -60 < T R2 ≤ T C (3) T R1 < T R2 (4) and satisfy The crystallization temperature T of the powder granule C is defined as the peak temperature of the crystallization exothermic peak observed during the temperature drop in differential scanning calorimetry in which the powder granule is heated to 180 °C at a rate of 10 °C / min in a nitrogen atmosphere, held at 180 °C for 2 minutes, and then cooled at a rate of 10 °C / min. The method according to aspect 5. [Aspect 7] The surface temperature T of the second roll R2 is 50 °C to 80 °C. The method according to aspect 6. [Aspect 8] The method according to any one of aspects 1 to 7, wherein the extrusion molding machine has a single-screw flight screw having a supply zone, a compression zone, and a metering zone. [Aspect 9] The method according to aspect 8, wherein the extrusion molding is performed at a screw rotation speed of 100 rpm or less. [Aspect 10] The crystallization temperature T of the powder granulate C (unit: °C) is 80 °C or higher, The crystallization temperature T of the powder granulate C is defined as the peak temperature of the crystallization exothermic peak observed during the temperature decrease in a differential scanning calorimetry measurement in which the powder granulate is heated to 180 °C at a rate of 10 °C / min in a nitrogen atmosphere, held at 180 °C for 2 minutes, and then cooled at a rate of 10 °C / min, according to the method described in any one of aspects 1 to 9. [Aspect 11] The method according to any one of aspects 1 to 4, or aspects 8 to 10 that cite aspects 1 to 4, wherein the extruded body has a tubular shape. [Aspect 12] The crystallization temperature T of the extruded body CA (unit: °C) and the crystallization temperature T of the powder granulate C (unit: °C) satisfy the formula (5) 0.8 ≤ T CA / T C ≤ 1.2 (5) and The crystallization temperature T of the powder granulate C is defined as the peak temperature of the crystallization exothermic peak observed during the temperature decrease in a differential scanning calorimetry measurement in which the powder granulate is heated to 180 °C at a rate of 10 °C / min in a nitrogen atmosphere, held at 180 °C for 2 minutes, and then cooled at a rate of 10 °C / min, The crystallization temperature T of the extruded body CA is defined as the peak temperature of the crystallization exothermic peak observed during the temperature decrease in a differential scanning calorimetry measurement in which 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, according to the method described in any one of aspects 1 to 11. [Aspect 13] The melt flow rate MFR of the PHA powder ORI (unit: g / 10 min), the melt flow rate MFR of the powder granulate GRN(Unit: g / 10 min), and the melt flow rate MFR of the extruded molded article ART (Unit: g / 10 min) is expressed by formulas (a), (b), and (c) 1 ≦ MFR GRN / MFR ORI ≦ 5 (a) 1 ≦ MFR ART / MFR GRN ≦ 5 (b) 1 ≦ MFR ART / MFR ORI ≦ 10 (c) satisfies the condition, and the melt flow rate MFR of the PHA powder ORI , the melt flow rate MFR of the powder granulate GRN , and the melt flow rate MFR of the extruded molded article ART are measured at 165°C under a load of 5 kg in accordance with ISO 1133, and the method according to any one of Aspects 1 to 12

Advantages of the Invention

[0008] According to the present disclosure, there is provided a method for manufacturing an extruded molded article capable of stably and continuously manufacturing an extruded PHA molded article using a PHA powder granulate

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0010] A. Powder Granulate First, the powder granulate used as an extrusion molding material in the method for manufacturing an extruded molded article according to the embodiment will be described

[0011] The powder granulate contains polyhydroxyalkanoate (PHA) powder, preferably contains PHA powder as the main component, more preferably consists essentially of PHA powder, and even more preferably consists of PHA powder. In this specification, "comprising" and "containing" mean that additional components or elements may be included unless otherwise specified, and include "consisting essentially of" and "consisting of". "Consisting essentially of" means that additional components or elements that do not substantially have an adverse effect may be included. "Consisting of" means including only the described materials or elements, but does not exclude further containing inevitable impurities.

[0012] The powder granulate is produced by granulating PHA powder. Such a powder granulate has a melt memory effect. The powder granulate can preferably be produced by a powder compression granulation method (hereinafter also referred to as the compression granulation method). Details of the production method of the powder granulate will be described later.

[0013] In this specification, a powder granulate having a melt memory effect means a powder granulate having the following characteristics i) and ii). i) In the first differential scanning calorimetry (DSC) in which the powder granulate is heated from room temperature to the first hold temperature T at a rate of 10 °C / min in a nitrogen atmosphere, held at the first hold temperature T for 2 minutes, and then cooled at a rate of 10 °C / min, a crystallization exothermic peak of PHA is observed during the cooling process. The first hold temperature T (unit: °C) is higher than the highest melting peak temperature T. Here, the highest melting peak temperature T (unit: °C) is defined as the highest temperature among the peak temperatures of the melting peaks observed in the differential scanning calorimetry in which the powder granulate is heated from room temperature to 10 °C / min in a nitrogen atmosphere. H1 up to, and held at the first hold temperature T H1 for 2 minutes, and then cooled at a rate of 10 °C / min, a crystallization exothermic peak of PHA is observed during the cooling process. The first hold temperature T H1 (unit: °C) has. The first hold temperature T H1 is higher than the highest melting peak temperature T M . Here, the highest melting peak temperature T M (unit: °C) is defined as the highest temperature among the peak temperatures of the melting peaks observed in the differential scanning calorimetry in which the powder granulate is heated from room temperature to 10 °C / min in a nitrogen atmosphere. ii) In the second differential scanning calorimetry in which the powder granulate is heated from room temperature to the second hold temperature T at a rate of 10 °C / min in a nitrogen atmosphere, and held at the second hold temperature T H2 up toH2 In a second DSC where it is held for 2 minutes at [temperature] and cooled at a rate of 10 °C / min, a second holding temperature T H2 (unit: °C) where no crystallization exothermic peak of PHA is observed during cooling. The second holding temperature T H2 is higher than the first holding temperature T H1 .

[0014] The melt memory effect refers to a phenomenon where when a crystalline polymer is heated and melted (thermoplastified) above its melting point, a pseudo-crystalline phase structure order remains in the melt. The melt memory effect is a unique phenomenon that can occur in crystalline polymers, where, even in the temperature region above the melting point, due to the long relaxation time for changing to a random aggregated state by thermal disturbance, there remains a region that does not reach a disordered random state in a short time. Hereinafter, the pseudo-crystalline phase structure order caused by the melt memory effect may be referred to as a melt memory structure. Such a powder granulate is described in Patent No. 7454097 and can be manufactured by the method described in Patent No. 7454097.

[0015] The melt memory effect of the powder granulate can be evaluated by the method described in Patent No. 7454097. That is, in the cooling DSC curve obtained by differential scanning calorimetry (DSC) where the powder granulate is heated to a temperature above the melting point of PHA and then cooled at a rate of 10 °C / min, the peak temperature of the crystallization exothermic peak observed (i.e., the crystallization temperature of the powder granulate) T C (unit: °C), if it is higher than the crystallization temperature of the PHA powder measured in the same manner, the powder granulate has a high melt memory effect. When the powder granulate has a high melt memory effect, the crystallization exothermic peak of the powder granulate often has a half-width smaller than the half-width of the crystallization exothermic peak of the PHA powder measured in the same manner. The above DSC can be performed, for example, by heating the measurement piece from room temperature to 180 °C at a rate of 10 °C / min in a nitrogen atmosphere, then holding it at 180 °C for 2 minutes, and immediately cooling the measurement piece at a rate of 10 °C / min in a nitrogen atmosphere.

[0016] When the powder granulate having a melt memory effect is heated and melted, the melt memory structure of PHA remaining in the melt functions as nuclei for crystallization during cooling. Since the melt memory structure is a pseudo-crystalline phase structure of PHA itself, the crystallization temperature T C of the powder granulate that crystallizes with the melt memory structure as nuclei is higher than the crystallization temperature of the molten pellet added with a crystallization nucleating agent. Also, the melt memory effect of the powder granulate is excellent in terms of persistence with respect to the melt residence time. On the other hand, when the melt memory structure in the melt is lost due to thermal disturbance and reaches a random agglomerated state, crystallization does not easily proceed during cooling.

[0017] A method for manufacturing an extruded body using a powder granulate having a melt memory effect as an extrusion molding material can be advantageous in the following aspects compared to a method for manufacturing an extruded body using a conventional molten pellet containing a crystallization nucleating agent as an extrusion molding material.

[0018] i) Since the powder granulate is produced under the condition that the temperature of the granulate immediately after granulation is equal to or lower than the melting point of PHA as described in Patent No. 7454097, thermal decomposition of PHA and the resulting decrease in molecular weight during the granulation process are suppressed. Therefore, the PHA contained in the powder granulate can have a larger molecular weight than the PHA contained in the molten pellet. Accordingly, the PHA in the extruded body produced from the powder granulate can also have a large molecular weight, whereby the extruded body can have excellent physical properties.

[0019] ii) The process for producing the powder granulate requires significantly less power consumption compared to the melt kneading granulation process using an extruder for producing the molten pellet. Therefore, by producing an extruded body from the powder granulate, the total power consumption can be significantly reduced.

[0020] iii) By advantageously utilizing the melt memory effect of the powder granulate, the range of the molding processing conditions (set temperatures of the extrusion molding machine and the cooling roll, screw rotation speed, etc.) can be expanded. Therefore, it is easy to control the appearance and crystallinity of the extruded molded article, and the degree of freedom of the shape of the extruded molded article (thickness of the extruded molded article, etc.) can also be increased.

[0021] iv) By using the powder granulate, an extruded molded article containing no crystallization nucleating agent can be produced. Since there is no risk of elution of the crystallization nucleating agent in the produced extruded molded article, it can also be used for applications such as food applications and medical applications. In addition, the crystallization nucleating agent may cause problems such as adhering to the cooling roll, generating eyelets, increasing the adhesiveness of the extrudate and / or the extruded molded article, causing the extrudate to stick to the cooling roll and the extruded molded articles to fuse together, etc., which may prevent continuous extrusion molding. By performing extrusion molding using a powder granulate containing no crystallization nucleating agent, these problems can be avoided, making continuous extrusion molding easier.

[0022] In one embodiment, the powder granule has an outer wall portion formed by melting and solidifying at least a part of the PHA powder located at the outer edge of the powder granule, and compressed PHA powder is contained inside the outer wall portion. In the present application, "melting and solidifying" means solidifying after melting. The outer wall portion is located at the outer edge of the powder granule. In this specification, the outer wall portion is also referred to as a shell portion. At least a part of the compressed PHA powder inside the outer wall portion may be melted and solidified and welded, or at least a part may not be melted and solidified. The compressed PHA powder inside the outer wall portion may be in an unmelted state. That is, at least a part of the compressed PHA powder inside the outer wall portion may include an unmelted compressed powder form, or may include a partially melted and solidified form. The partially melted and solidified form is intended to be a form in which the constituent components of the PHA powder are partially melted and solidified, but do not have a strong welding structure capable of holding the PHA powder like the outer wall portion. In this specification, the inside of the outer wall portion is also referred to as a core portion. Compressed PHA powder is contained in the core portion inside the outer wall portion. In this specification, "compressed" refers to the fact that the density of the PHA powder located in the core portion is higher than the bulk density of the PHA powder before granulation. Such a powder granule is described in Japanese Patent No. 7387950 and can be manufactured by the method described in Japanese Patent No. 7387950. Further, such a powder granule has the above-described melt memory effect.

[0023] The outer wall portion (shell portion) has a dense structure including a melt-solidified product of the PHA powder. On the other hand, the inner core portion, although compressed, has a sparse structure compared to the dense structure (welding structure) of the outer wall portion including the melt-solidified product. Since the outer wall including the melt-solidified product of the PHA powder holds the compressed PHA powder present in the core portion, the powder granule can have a stable structure, less powder loss, excellent handleability and safety, and can also improve the working environment for manufacturing an extruded molded body.

[0024] The outer wall part (shell part) has a welded structure in which at least a part of the thermoplastic resin powder located at the outer edge of the powder granule is melted and solidified. The outer wall part may be a smooth surface to the extent that it has a glossy surface appearance. Also, even though it has not melted to the extent of becoming a smooth surface, the outer wall part may be constituted by a part of the constituent components of the thermoplastic resin powder melting and partially welding to adjacent components. The outer wall part can be formed, in compression granulation, for example, at the contact surface with the die hole, by melting at least a part 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 part can take various thicknesses depending on the manufacturing conditions of the PHA powder granule.

[0025] The core part is a part located inside the outer wall part and is a part in which the compressed thermoplastic resin powder is contained. The PHA powder located in the core part may be in a porous state, or may have a non-welded structure because heat has not reached the core part during granulation. The core part can have a structure in which the PHA powder maintains its powder shape (that is, a non-welded structure or a powder-like structure), or a structure in which a part is welded but the shape of the PHA powder remains.

[0026] In this specification, for the sake of simplicity of explanation, terms such as "outer wall part (shell part)" and "core part" are used. However, as described above, since the outer wall part is formed by melting the PHA powder by heat during granulation, actually, the boundary between the outer wall part (shell part) and the core part does not clearly exist. The outer wall part (shell part) includes the welded structure of the PHA powder and refers to the part located at the outer edge of the powder granule and contributing to maintaining a certain shape of the powder granule. The core part refers to the part located inside the outer wall part (shell part).

[0027] The shape of the powder granule is preferably substantially cylindrical or substantially prismatic, and the powder granule preferably has an outer wall part on the side surface of the powder granule. In the present disclosure, the powder granule has a substantially cylindrical or substantially prismatic shape, and it is preferable that an outer wall part is formed on the side surface of the powder granule having a substantially cylindrical or substantially prismatic shape.

[0028] Since the powder granule having such a shape can be directly supplied to an extruder for a thermoplastic resin, it can be used as a material for extrusion molding.

[0029] The powder granule can be in any suitable shape. Typically, when the powder granule is produced by compression granulation of powder and granulation is performed by passing through a circular die hole, the basic shape of the powder granule is a cylindrical pellet shape.

[0030] In this specification, the "die" used for the production of the powder granule shall be a general term for tools corresponding to the mold for compressing the PHA powder granule to impart a shape.

[0031] When the powder granule is substantially cylindrical, the diameter of the powder granule is, for example, 2 mm to 7 mm, preferably 3 mm to 5 mm. The length (height) of the powder granule is, for example, 1 mm to 10 mm, preferably 2 mm to 7 mm. With such a shape, the powder granule is easy to handle. The diameter of the powder granule can be adjusted, for example, by the diameter of the die hole of the disk plate (die plate) during granulation, and the length can be adjusted by the distance between the disk plate and the cutter. The said distance can be any suitable distance. The distance between the disk plate and the cutter is, for example, 1 mm to 30 mm, preferably 2 mm to 20 mm, preferably 3 mm to 10 mm.

[0032] The breaking strength based on the measurement with a log hardness tester of the powder granulate is preferably 1.0 kg or more, preferably 2.0 kg or more, preferably 3.0 kg or more, preferably 4.0 kg or more, preferably 5.0 kg or more, preferably 6.0 kg or more, preferably 7.0 kg or more, preferably 8.0 kg or more, preferably 9.0 kg or more, preferably 10.0 kg or more. The upper limit may exceed the measurement limit of the log hardness tester (the measurement limit is 10 kg for "WPF1600 - B" manufactured by Shiro Sangyo Co., Ltd.). Within such a range, a powder granulate excellent in handleability and melt processability can be obtained. Here, the breaking strength means the average breaking stress (breaking load) measured by pressing and crushing 20 or more (preferably 25 or more) powder granulates in a direction perpendicular to the longitudinal direction (extrusion direction) of the powder granulate. In the powder granulate, since the shell part is composed of a molten resin, it is possible to maintain a stable shape as a granulate despite being a powder granulate. The diameter of the pressure surface of the pressure attachment of the log hardness tester is, for example, 5 mm.

[0033] The bulk density of the powder granulate can be any appropriate bulk density, but is preferably 0.3 kg / L to 2.0 kg / L, and preferably 0.5 kg / L to 1.0 kg / L. By increasing the bulk density, the supply speed and supply stability of the powder granulate to the extrusion molding machine are enhanced.

[0034] The bulk density of the powder granulate is calculated by allowing the powder granulate to naturally fall into a 1 - liter measuring cylinder until it is full, accurately weighing out the powder granulate with a volume of 1 liter, and measuring its mass (unit: kg / L).

[0035] B.PHA powder The PHA powder, which is the raw material of the powder granulate, is a powdery polyhydroxyalkanoate (PHA) resin. PHA can be, for example, a compound produced in the body by microorganisms using carbohydrates, oils and fats, etc. as food. Such PHA is primarily taken out as a powdery polymer from microorganisms.

[0036] PHA contains hydroxyalkanoic acid as a raw material component as a polymerization component and has at least repeating units derived from hydroxyalkanoic acid. PHA may be artificially synthesized or biosynthesized by microorganisms. Examples of hydroxyalkanoic acid include glycolic acid, 3-hydroxybutyrate, 3-hydroxypropionate, 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyheptanoate, 3-hydroxyoctanoate, 3-hydroxynonanoate, 3-hydroxydecanoate, 3-hydroxytetradecanoate, 3-hydroxyhexadecanoate, 3-hydroxyoctadecanoate, 4-hydroxybutyrate, 4-hydroxyvalerate, 5-hydroxyvalerate, or 6-hydroxyhexanoate, etc. The carbon number of hydroxyalkanoic acid may be 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, or 8 or more, preferably 3 or more. The carbon number of hydroxyalkanoic acid may be 15 or less, 12 or less, 10 or less, 8 or less, 6 or less, or 4 or less, preferably 10 or less, particularly 6 or less. Hydroxyalkanoic acid may be used alone or in combination of two or more.

[0037] Preferred examples of PHA include poly(3-hydroxyalkanoate) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0038] In the PHA powder, the weight average molecular weight (Mw) of PHA is 200,000 or more, preferably 300,000 or more, preferably 500,000 or more, preferably 700,000 or more. Since the melt memory effect is manifested by the time lag in the process of the polymer molecular chain transitioning from the crystalline ordered state to the random state in the molten state, the larger the molecular weight, the longer the relaxation time (the transition time to the random chain), which is advantageous in terms of the persistence of the effect. When the weight average molecular weight of PHA is 200,000 or more, it is preferable because the decrease or deactivation of the melt memory effect due to thermal disturbance can be effectively delayed. On the other hand, if the molecular weight of PHA becomes too large, the viscosity becomes too high, which is disadvantageous for causing solid phase deformation, and there is also a tendency for powder granulation to be difficult. Therefore, the weight average molecular weight of PHA is preferably 3,000,000 or less, preferably 2,000,000 or less, preferably 1,500,000 or less, preferably 1,000,000 or less.

[0039] The above-mentioned weight average molecular weight (Mw) can be determined as the weight average molecular weight in terms of polystyrene by gel permeation chromatography (GPC). For example, as a GPC device, "Shodex GPC-101" manufactured by Showa Denko KK can be used, and as a column packing agent, polystyrene gel ("Shodex K-804" manufactured by Showa Denko KK) can be used, and it can be evaluated by GPC using an organic solvent mobile phase (for example, chloroform). Note that the column device, column packing agent, and organic solvent mobile phase can be appropriately selected. For example, chloroform can be used.

[0040] The PHA powder may be a powdery resin obtained through its manufacturing process, that is, it may be powdery due to the manufacturing process, or it may be obtained by pulverizing a non-powdery PHA resin such as pellets, lumps, or molded articles. The PHA powder can be obtained, for example, by cooling a molded article, pellets, trimming end materials generated in extrusion molding, or sprues or runners generated in injection molding at room temperature or using dry ice or liquid nitrogen as needed, and then pulverizing using a pulverizer (e.g., manufactured by Dalton, trade names "Near Mill", "Sil Feed Mill", "Atomizer", or "Impact Mill", etc.).

[0041] As long as the effects of this embodiment can be obtained, the particle size of the PHA powder can be any appropriate particle size according to its form. The maximum diameter of the particles of the PHA powder before granulation is preferably 5 mm or less, and the minimum diameter is preferably 0.0001 mm or more.

[0042] The average particle size of the PHA powder is, for example, 0.001 mm or more and 1.0 mm or less. The average particle size of the PHA powder is preferably 1.0 mm or less, preferably 0.01 mm or more and 0.8 mm or less, and preferably 0.1 mm or more and 0.5 mm or less. In this specification, the average particle size can be measured by the laser diffraction method. The average particle size of the PHA powder can be the median diameter (d50) at which the cumulative 50% in the cumulative particle size distribution based on volume is reached. The median diameter (d50) may be a mixture of primary particles and aggregated particles. The PHA powder may be used alone or in combination of two or more kinds.

[0043] The PHA powder before granulation can have any bulk density, but the bulk density of the PHA powder is preferably 0.05 kg / L to 1.0 kg / L, more preferably 0.1 kg / L to 0.8 kg / L, and even more preferably 0.2 kg / L to 0.6 kg / L. When the bulk density of the PHA powder is within this range, compression granulation is easy to perform.

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

[0045] C. Other components contained in the PHA powder granulate The powder granulate may contain any suitable additive as required. The additive may be in solid form such as powder or in liquid form. Examples of the additive include a binder, a dispersant, a crystallization nucleating agent, an antioxidant, a light stabilizer, a foaming agent, an ultraviolet absorber, an antiblocking agent, a heat stabilizer, an impact modifier, an antibacterial agent, a compatibilizer, a processing aid, a lubricant, a coupling agent, a hydrolysis inhibitor, a deoxidizer, or a colorant (dyestuff or pigment), etc. The additive may be used alone or in combination of two or more kinds.

[0046] 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.

[0047] The powder granulate may contain a binder as an additive. Here, the "binder" generally refers to a compound that exists between the PHA powder particles in addition to the constituent components of the raw material PHA powder and can bind the powders together and exhibit the effect of enhancing the breaking strength of the granulate. However, if necessary, various compounds having a binding effect, preferably water-dispersible or water-soluble polymer compounds, polysaccharides, etc. can be appropriately selected and used as the binder.

[0048] In one embodiment, it is preferable to melt and bind a part of the constituent components of the PHA powder to form a powder granulate, and it is preferable not to blend a binder.

[0049] 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.

[0050] 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 about effects such as improving the productivity (discharge rate) of the powder granulate, reducing the frictional heat during granulation, and enhancing the cleanability of the granulation apparatus.

[0051] Examples of the dispersant include fatty acids, fatty acid metal salts, fatty acid sulfonates, fatty acid amides, acrylamide, polyhydric alcohol fatty acid esters, and polyglycerin fatty acid esters. The dispersant may be used alone or in combination of two or more.

[0052] In one embodiment, the dispersant is at least one selected from the group consisting of polyhydric alcohol fatty acid esters, fatty acid amides, polyglycerin fatty acid esters, condensed hydroxy fatty acids, and alcohol esters of condensed hydroxy fatty acids.

[0053] 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.

[0054] A fatty acid amide is a compound having a structure formed by dehydration condensation of a fatty acid and ammonia or a primary or secondary amine. Examples of fatty acid amides include saturated fatty acid monoamides such as lauric acid amide, palmitic acid amide, stearic acid amide, and behenic acid amide.

[0055] A polyglycerol fatty acid ester is an ester compound composed of polyglycerol and a fatty acid. Examples of polyglycerol fatty acid esters include diglycerol palmitate, diglycerol stearate, diglycerol oleate, decaglycerol palmitate, decaglycerol stearate, decaglycerol oleate, and the like.

[0056] The content of the dispersant is usually 0% by mass to 10.0% by mass, preferably 0.01% by mass to 9.0% by mass, preferably 0.1% by mass to 7.0% by mass, and more preferably 0.3% by mass to 5.0% by mass with respect to the total mass of the powder granulated product. Also, the content of the dispersant is usually 10.0% by mass or less, preferably 5.0% by mass or less, preferably 3.0% by mass or less, preferably 1.0% by mass or less, preferably 0.5% by mass or less, preferably 0.1% by mass or less, and preferably 0% by mass (undetectable) with respect to the total mass of the powder granulated product.

[0057] It is possible to incorporate a crystallization nucleating agent as an additive into the powder granulated product. Examples of crystallization nucleating agents that can be incorporated into the powder granulated product include organometallic salt compounds such as metal phosphates, metal benzoates, metal pimelates, metal rosins, metal oxalates, and metal fatty acid salts; aliphatic organic esters, triallyl phosphate, polyalkylene glycols or their derivatives, aliphatic polyesters, organic compounds such as benzylidene sorbitol; dyestuffs and pigments such as pentaerythritol, quinacridone, cyanine blue, and carbon black; minerals such as talc, mica, kaolin, clay, carbonate minerals, metal oxides, and metal sulfates; ionomers, or high melting point polyamides and other polymer compounds.

[0058] In one embodiment, as the crystallization nucleating agent, talc, mica, kaolin, calcium carbonate, or the like is used. The crystallization nucleating agent may be used alone or in combination of two or more.

[0059] The content of the crystallization nucleating agent in the powder granulate is, for example, 0.1% by mass or more and 10.0% by mass or less, preferably more than 0.1% by mass and less than 10.0% by mass, preferably 0.2% by mass or more and 7.0% by mass or less, preferably 0.3% by mass or more and 5.0% by mass or less.

[0060] In one embodiment, the powder granulate substantially does not contain a crystallization nucleating agent. Since the powder granulate can exhibit a melt memory effect, excellent crystallization characteristics can be exhibited in the molding process without using a crystallization nucleating agent.

[0061] "Substantially does not contain a crystallization nucleating agent" means, for example, that the content of the crystallization nucleating agent in the powder granulate is 0.1% by mass or less, preferably that the content of the crystallization nucleating agent in the powder granulate is less than 0.1% by mass, preferably that the content of the crystallization nucleating agent in the powder granulate is 0.01% by mass or less, preferably that the content of the crystallization nucleating agent in the powder granulate is 0.005% by mass or less, preferably that the content of the crystallization nucleating agent in the powder granulate is 0.001% by mass or less, preferably that the content of the crystallization nucleating agent in the powder granulate is 0% by mass (undetectable).

[0062] Those skilled in the art should understand that the powder granulate may contain a crystallization nucleating agent or the powder granulate may be used together with a crystallization nucleating agent. When the powder granulate contains a crystallization nucleating agent or the powder granulate is used together with a crystallization nucleating agent, in addition to the crystallization promoting action by the melt memory effect, the crystallization promoting action by the crystallization nucleating agent can be obtained.

[0063] Method for producing D.PHA powder granulate The powder granulated product can be produced by various powder granulators. For example, compression granulators such as the disk pelletizer method, screw extrusion method, briquetting method, compaction method, and tabletting method are mentioned as preferable granulators. The powder granulated product produced by the compression granulator is considered to have an outer wall portion containing oriented crystals due to the strong shear stress from the wall surface of the die holes during the granulation process. Therefore, the powder granulated product (i.e., the compression granulated product) produced by the compression granulation method can particularly have a high melt memory effect.

[0064] Among those exemplified above, from the viewpoints of granulation productivity and the quality and shape uniformity of the obtained powder granulated product, the disk pelletizer method is preferably adopted. In the disk pelletizer method, a semi-wet granulation method in which appropriate moisture is contained in the PHA powder can be adopted. There may also be cases where granulation can be performed without using water. When granulation is performed without using water, the subsequent drying treatment after granulation may become unnecessary. When granulation is performed without using water, the amount of energy required in the drying process can be reduced, and the emission amount of carbon dioxide generated during the manufacturing process can be significantly reduced.

[0065] As described above, the PHA powder granulated product can be advantageously obtained by the granulation method described in Patent No. 7454097 or Patent No. 7387950.

[0066] When the powder granulate is a mixture containing two or more types of PHA powder raw materials, or when it contains any components other than PHA, it is preferably uniformly mixed using any appropriate mixer. Examples of mixers include Henschel mixers, Nauta mixers, kneaders for powders (KDH, KDA, CKD, CPM) (Dalton), Spartan mixers (SPM) (Dalton), and SP granulators (SPG) (Dalton). In order to obtain a preferable mixture with excellent granulation properties, it is preferable to use a mixing and stirring device equipped with appropriate stirring blades. For example, when using a Henschel mixer type of mixer, the mixer blades are a combination of upper blades and lower blades. The upper blades are preferably Y1 blades (trade name, manufactured by Nippon Coke Industry Co., Ltd.), and the lower blades are preferably S0 blades (trade name, manufactured by Nippon Coke Industry Co., Ltd.). Also, it is preferable to install a deflector in the stirring tank and mix. That is, by using a mixing device capable of uniformly dispersing each component throughout the mixture, it is advantageous for enhancing the productivity and quality stability of the finally obtained powder granulate.

[0067] When manufacturing a powder granulate by the semi-wet granulation method described above, the blending amount of water can be any appropriate amount depending on the properties of the powder (e.g., water absorption). In this case, the blending amount of water is 3 to 30 parts by mass, preferably 5 to 25 parts by mass, and more preferably 5 to 20 parts by mass with respect to 100 parts by mass of the crystalline polymer powder. The semi-wet method can be adopted to improve the stability of granulation properties.

[0068] In the granulation process of the powder granulate, since local heat generation leads to die clogging, it may be advantageous for continuous granulation to include an appropriate amount of moisture in the PHA powder and suppress excessive temperature rise during granulation by the heat of vaporization of water.

[0069] The powder granulate can be dried after granulation, but the moisture content of the final powder granulate is preferably 10% by mass or less, preferably 5.0% by mass or less, preferably 3.0% by mass or less, preferably 1.0% by mass or less, and preferably 0.5% by mass or less. The moisture content of the final powder granulate can be appropriately selected according to the intended use.

[0070] The powder granulate is preferably granulated without adding water. When the moisture content of the powder granulate is low, the drying process after granulation may not be required. If granulation can be carried out without using water, the drying process is not required, so the carbon dioxide emissions generated in the powder granulation process can be greatly reduced.

[0071] The moisture content of the powder granulate granulated without adding water is, for example, 1.0% by mass or less, preferably 0.5% by mass or less, preferably 0.3% by mass or less, and preferably 0.2% by mass or less.

[0072] When the powder granulate is produced by a compression granulator using a screw extrusion method, since it is easy to attach a temperature control device to the compression granulator and compression granulation can be performed at a low screw rotation speed, local heat generation due to rapid shear heat generation during granulation can be reduced. When the powder granulate is produced by a compression granulator using a briquetting method, a compaction method, or a tabletting method, since the shear stress received by the powder from the wall surface of the die hole is smaller than that of the disk pelleter method, local heat generation during granulation can be reduced. Therefore, in the screw extrusion method, the briquetting method, the compaction method, and the tabletting method, the powder granulate can be continuously and stably produced without causing die clogging due to local heat generation even without adding water. When granulation is carried out without adding water, the drying process after granulation is not required, so the manufacturing process can be simplified and the energy consumption for the drying process can be reduced.

[0073] The moisture content of the powder granulate is measured using an infrared moisture meter.

[0074] The granulator of the disk pelleter method has, as its basic structure, one (flat die) or two disks (indicating cylindrical dies) with many holes of 2 mm to 30 mm, and a roller for pumping the raw material into the holes of the disks. The PHA powder (which may contain moisture) supplied between the disk and the roller or between the two disks is pressed into the holes of the disk as the roller rotates, and a cylindrical extrudate is formed. By cutting the extrudate with a cutter or the like on the back surface of the disk, a pellet-shaped powder granulate can be obtained. The length of the granulate can be adjusted by the distance between the back surface of the disk and the cutter, the rotation speed of the roller, etc. The distance between the disk plate and the cutter can be any appropriate distance. The distance between the disk plate and the cutter is, for example, 1 mm to 30 mm, more preferably 2 mm to 20 mm, and even more preferably 3 mm to 10 mm.

[0075] More specifically, examples of the disk pelleter method include the roller-disk die method, the roller-ring die method, the double die method, the flat die method, etc. Examples of commercially available granulators of the disk pelleter method include the disk pelleter F series manufactured by Dalton.

[0076] The powder granulate may be sufficiently dried immediately before being used as an extrusion molding material. Thereby, the decrease in the molecular weight of PHA accompanying the extrusion molding and / or the appearance defect of the extrusion molded body can be effectively suppressed. The moisture content of the powder granulate immediately before being used 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 preferably carried out at 70°C to 110°C, 75°C to 100°C, or 80°C to 90°C until a predetermined moisture content is reached. The moisture content of the powder granulate is measured using an infrared moisture meter.

[0077] E. Method for manufacturing an extrusion molded body by extrusion molding The method for manufacturing an extruded article according to the embodiment includes using a powder granulate containing PHA as a molding material and extruding the PHA with an extruder. The extrusion molding includes melting the powder granulate charged into the extruder to obtain a melt, extruding the melt from a die, and cooling and solidifying the extruded melt. The extruded article may have a sheet-like or tubular shape, but is not limited thereto.

[0078] In this specification, the "die" used for extrusion molding is a general term for tools corresponding to a mold that discharges the PHA melt in a desired shape.

[0079] E-1. Method for manufacturing a sheet-like extruded article When manufacturing a sheet-like extruded article, for example, the extruded article can be manufactured using the extruder 1 shown in FIG. 1. The extruder 1 includes an extruder 10, at least one cooling roll 30, at least one conveying roll 50, and a winding roll 70. The extruder 10 includes a cylinder 12, a screw 14 housed in the cylinder 12, a hopper 16 for supplying the powder granulate 92 to the cylinder 12, a die head 17, an adapter 19, and a T-die 18. The hopper 16 is provided at the most upstream part of the extruder 10. The die head 17, the adapter 19, and the T-die 18 are connected in this order downstream of the cylinder 12. The T-die 18 is provided at the most downstream part of the extruder 10. The cooling roll 30 is provided below the T-die 18 in the gravitational direction. In the extruder 1 shown in FIG. 1, at least one cooling roll 30 includes a first roll 32 and a second roll 34, and at least one conveying roll 50 includes a third roll 52 provided downstream of the second roll 34 and a pair of pinch rolls 54 provided downstream of the third roll 52. The temperature of each part of the extruder 1 can be controlled by a heating heater (not shown) and / or a cooling unit (not shown) provided at each part.

[0080] The powder granulates 92 charged into the hopper 16 are supplied into the cylinder 12. The powder granulates 92 are 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.

[0081] The plasticizing melt temperature T of the powder granulates 92 in the extruder 10 P (unit: °C) is given by formula (1) T M -10 < T P ≦ T M +20 (1) (wherein T M (unit: °C) represents the highest melting peak temperature observed in a differential scanning calorimetry (DSC) in which the powder granulates are heated from room temperature at a rate of 10 °C / min in a nitrogen atmosphere.) is satisfied.

[0082] Incidentally, when multiple melting peaks are observed by DSC for the highest melting peak temperature T M it means the highest temperature among the peak temperatures of those melting peaks, and when one melting peak is observed by DSC, it means the peak temperature of that melting peak.

[0083] 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.

[0084] By the plasticizing melt temperature T P satisfying formula (1), disappearance of the melt memory effect of the powder granulates 92 due to thermal disturbance, mechanical mixing, etc. can be suppressed, and thereby extrusion molding utilizing the melt memory effect effectively can be performed.

[0085] The plasticizing melt temperature T P is preferably T M -8 < T P ≦ TM +15 satisfies, and more preferably, T M -5 < T P ≤ T M +10 satisfies, and even more preferably, T M -5 < T P ≤ T M +5 satisfies.

[0086] In conventional extrusion molding using a molten pellet of PHA as a molding material, if the plasticizing melting temperature T P is less than the melting peak temperature of the molten pellet, it will not only impose an excessive load on the extruder, but also result in insufficient plasticization, and the remaining unmelted materials may be mixed into the extruded molded body, or surface defects such as sink marks, poor transfer, flow unevenness, thickness non-uniformity, orange peel, etc. are likely to occur due to insufficient flow.

[0087] On the contrary, in the method according to this embodiment using the powder granulated product 92 of PHA as a molding material, due to the large porosity of the powder granulated product 92, the load on the extruder 10 is alleviated, so that even when the plasticizing melting temperature T P is T M -10 < T P < T M is satisfied, the powder granulated product 92 can be sufficiently plasticized and extrusion molding can be performed without imposing an excessive load on the molding machine.

[0088] Inside the extruder 10, a flow field is formed as the screw 14 for plasticizing and metering rotates. The maximum temperature at which the melt memory effect in the flow field is maintained can be lower than the maximum temperature at which the melt memory effect in the stationary field is maintained. The plasticizing melting temperature T P is, T P > T MWhen it satisfies +20, due to the action of the flow field, the melt memory effect decreases or disappears, and the crystallization and solidification of the melt 94 extruded from the T-die 18 slow down. As a result, various problems such as poor mold release from the cooling roll 30, sticking of the extruded molded bodies to each other, deformation of the extruded molded bodies associated therewith, difficulty in thinning the extruded molded bodies, reduction of the effective sheet width, and post-shrinkage may occur, and the productivity may decrease. The effective sheet width refers to the width of the region having a thickness within the set range in the sheet-shaped extruded molded body.

[0089] 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 from the upstream to the downstream in the flow direction of the powder granulated product and its melt. Such a single-screw flight screw can suppress the decrease 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 extruder is a single-screw flight screw, the rotation speed S of the screw 14 R 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 S of the screw 14 R the decrease or disappearance of the melt memory effect due to the flow field caused by mechanical mixing can be suppressed. The rotation speed S of the screw 14 R may be 10 rpm or more.

[0090] The sheet-shaped melt 94 extruded from the T-die 18 is pulled down between the first roll 32 and the second roll 34 constituting the cooling roll 30. The melt 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 melt 94 is cooled by the cooling roll 30 and crystallizes and solidifies. Thereby, the sheet-shaped extruded molded body 96 is formed. The extruded molded body 96 is conveyed to the winding roll 70 via the conveying roll 50 and wound by the winding roll 70. The winding speed of the extruded molded body 96 can be controlled by the rotation speed of the second roll 34.

[0091] The first roll 32 may have an outermost layer made of an elastomer. When the outermost layer of the first roll 32 is made of an elastomer, the first roll 32 can be deformed to press the entire melt 94 against the second roll 34, and the thickness of the extruded molded body 96 can be efficiently controlled. The surfaces of the first roll 32 and / or the second roll 34 may be mirror surfaces, 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 molded body 96.

[0092] The surface temperatures of the cooling rolls 30 (i.e., the first roll 32 and the second roll 34) and the conveying roll 50 can be set as appropriate. The surface temperature T R1 of the first roll 32 and the surface temperature T R2 of the second roll 34 are preferably controlled independently of each other. The surface temperature T R1 of the first roll 32 and the surface temperature T R2 of the second roll 34 may be controlled integrally. The surface temperature T R2 of the second roll 34 may be controlled integrally with the surface temperature T R3 of the third roll 52. The surface temperature of each roll can be controlled by a temperature control device (for example, a water cooling device, an oil cooling device, a heater) provided on each roll. A plurality of rolls may share one temperature control device, whereby the surface temperatures of the plurality of rolls are controlled integrally. The surface temperature of each roll is measured by a contact thermometer (for example, a thermocouple) provided on the surface of each roll.

[0093] In one embodiment, the surface temperature T R1 (unit: °C) of the first roll 32, the surface temperature T R2 (unit: °C) of the second roll 34, and the crystallization temperature T C (unit: °C) of the powder granulated product 92 are represented by formulas (2), (3), and (4) T C -80 < T R1 ≤ T C (2) T C -60 < T R2 ≤ T C (3) T R1 < TR2 (4) may be satisfied. Note that the crystallization temperature T C is defined as the peak temperature of the crystallization exothermic peak observed during cooling in a differential scanning calorimetry (DSC) in which the powder granule 92 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.

[0094] The surface temperature T R1 of the first roll 32 is lower than the surface temperature T R2 of the second roll 34, so that the melt 94 is prevented from sticking to the first roll 32 and is conveyed along the surface of the second roll 34 with high reliability. The difference (T R2 - T R1 ) between the surface temperature T R2 of the second roll 34 and the surface temperature T R1 of the first roll 32 may be 5° C. to 60° C., 10° C. to 50° C., or 20° C. to 40° C.

[0095] The surface temperature T R1 of the first roll 32, the surface temperature T R2 of the second roll 34, and the crystallization temperature T C of the powder granule 92 are preferably T C -75 < T R1 ≤ T C , and T C -60 < T R2 ≤ T C More preferably, T C -70 < T R1 ≤ T C , and T C -55 < T R2 ≤ T C Even more preferably, T C -70 < T R1 ≤ T C , and T C -50 < T R2 ≤ T C Particularly preferably, T C -70 < T R1 ≤ T C and T C -45 < T R2 ≤ T C is satisfied.

[0096] The surface temperature T of the second roll 34 R2 is made lower than the crystallization temperature T of the powder granulate 92, C so that the crystallization and solidification of the melt 94 extruded from the T-die 18 can proceed rapidly, and an extruded molded article 96 excellent in quality and appearance can be produced with high productivity. As described above, the crystallization temperature T of the powder granulate 92 having the melt memory effect C is higher than the crystallization temperature of the molten pellet added with the crystallization nucleating agent. Therefore, when extrusion molding is performed using the powder granulate 92 having the melt memory effect as a molding material, compared with the conventional extrusion molding using the molten pellet, the surface temperature T of the second roll 34 R2 can be made higher. A high surface temperature T of the second roll 34 R2 is advantageous for improving the crystallinity of the produced extruded molded article 96. The improvement of the crystallinity leads to the production of an extruded molded article 96 having high heat resistance, a high elastic modulus (rigidity), and high shape and dimensional stability and few appearance defects. Note that high heat resistance means a high heat shrinkage start temperature. High shape and dimensional stability means that there is no shrinkage or little shrinkage after the production of the extruded molded article 96, no undulation occurs, and even if shrinkage occurs, the anisotropy thereof is small.

[0097] In one embodiment, the maximum melting peak temperature T of the powder granulate 92 M is 140°C or higher, and the powder granulate 92 may have a high crystallization temperature T of 80°C or higher due to the melt memory effect. C In this case, the surface temperature T of the second roll 34 R2While setting the temperature of the melt 94 in contact with the second roll 34 to a high temperature of 50°C to 80°C, the melt 94 can be rapidly crystallized and solidified. As a result, the extruded molded body 96 can be produced with high productivity without sticking to the second roll 34, and the extruded molded body 96 having excellent quality and appearance can be obtained.

[0098] For example, the powder granulated product used in the examples described later has a maximum melting peak temperature T M of 147°C and a crystallization temperature T C of 95°C. When extrusion molding is performed using this powder granulated product, while setting the surface temperature T R2 of the second roll 34 to 63°C, the melt 94 in contact with the second roll 34 can be rapidly crystallized and solidified. As a result, the extruded molded body 96 can be produced with high productivity without sticking to the second roll 34, and the extruded molded body 96 having excellent quality and appearance can be obtained.

[0099] The surface temperature of each roll of the extrusion molding machine 1 may be appropriately set according to the crystallization temperature T C of the powder granulated product 92. For example, when the crystallization temperature T C of the powder granulated product 92 is 95°C to 100°C, the surface temperature T R1 of the first roll 32 is preferably 20°C to 60°C, more preferably 30°C to 50°C, and the surface temperature T R2 of the second roll 34 is preferably 50°C to 95°C, more preferably 55°C to 90°C, still more preferably 58°C to 85°C, and most preferably 60°C to 80°C.

[0100] For example, when the crystallization temperature T C of the powder granulated product 92 is 80°C to 95°C, the surface temperature T R1 of the first roll 32 is preferably 10°C to 50°C, more preferably 20°C to 45°C, and the surface temperature T R2 of the second roll 34 is preferably 50°C to 85°C, more preferably 40°C to 80°C, still more preferably 40°C to 80°C, and most preferably 40°C to 70°C.

[0101] Thus, the crystallization temperature T of the powder granulated productC According to this, the surface temperature T of the first roll 32 R1 and the surface temperature T of the second roll 34 R2 are appropriately selected, so that the melt memory effect can be effectively utilized to rapidly crystallize the melt 94. Thereby, various advantages such as improvement of the releasability from the cooling roll 30, prevention of sticking between the extrusion molded articles 96, prevention or reduction of deformation of the extrusion molded article 96 associated therewith, improvement of the ease of thinning of the extrusion molded article 96, increase of the effective sheet width, reduction of shrinkage after extrusion molding, etc. occur, and efficient extrusion molding becomes possible. Further, since the extrusion molded article 96 to be manufactured can have a high degree of crystallinity, it can have high heat resistance, elastic modulus, and stability of shape and dimensions, and there are few appearance defects.

[0102] The surface temperature T of the second roll 34 R2 is 60 °C or more lower than the crystallization temperature T of the powder granulated product 92 C In this case, the extrusion molded article 96 to be manufactured cannot have a sufficient degree of crystallinity, and the dimensional and shape stability of the extrusion molded article 96 decreases due to shrinkage after extrusion molding, and it may cause an increase in appearance defects such as waviness of the sheet, transfer defects, and non-uniformity of thickness.

[0103] In the method according to the embodiment, the powder granulated product 92 containing no crystallization nucleating agent can be used as a molding material. The crystallization nucleating agent may cause problems such as adhering to the cooling roll, generating eyelets, increasing the adhesiveness of the extrudate and / or the extrusion molded article to cause sticking of the extrudate to the cooling roll and fusion of the extrusion molded articles to each other, and may prevent continuous extrusion molding. Further, the crystallization nucleating agent is also a factor in lowering the heat resistance of the extrusion molded article to be manufactured. By performing extrusion molding using a powder granulated product containing no crystallization nucleating agent, these problems can be avoided.

[0104] In one embodiment, the crystallization temperature T of the extrusion molded article 96 CA (unit: °C) and the crystallization temperature T of the powder granulated product 92 C (unit: °C) satisfy the formula (5) 0.8 ≦ T CA / T C≦1.2 (5) satisfies the condition. Here, the crystallization temperature T C of the powder granulate 92 is defined as the peak temperature of the crystallization exothermic peak observed during the temperature decrease in a DSC in which the powder granulate 92 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 crystallization temperature T CA of the extrusion molded body 96 is defined as the peak temperature of the crystallization exothermic peak observed during the temperature decrease in a DSC in which the extrusion molded body 96 (specifically, a measurement piece cut out from the extrusion molded body 96) 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.

[0105] The above formula (5) indicates that the crystallization temperature T CA of the extrusion molded body 96 is substantially equivalent to the crystallization temperature T C of the powder granulate 92, that is, the change in the crystallization temperature due to extrusion molding is small, indicating that the melt memory effect of the powder granulate 92 is effectively exerted in the extrusion molding. Effectively exerting the melt memory effect is advantageous for improving the crystallinity of the extrusion molded body 96 as described above. As a result, the extrusion molded body 96 can have a large effective sheet width, reduced shrinkage after extrusion molding, and high heat resistance.

[0106] The crystallization temperature T CA of the extrusion molded body 96 may be higher than the crystallization temperature T C of the powder granulate 92. In that case, it is considered that the extrusion molded body 96 has a higher melt memory effect than the powder granulate 92, which can be advantageous when further processing the extrusion molded body 96.

[0107] In one embodiment, the powder granulate 92 is produced under conditions such that the temperature of the granulate immediately after granulation is equal to or lower than the melting point of the PHA. In this case, the melt flow rate MFR ORI (unit: g / 10 min) of the PHA powder, the melt flow rate MFR GRN (unit: g / 10 min) of the powder granulate 92, and the melt flow rate MFR ART(Unit: g / 10min) is expressed by formulas (a), (b), and (c). 1 ≤ MFR GRN / MFR ORI ≤ 5 (a) 1 ≤ MFR ART / MFR GRN ≤ 5 (b) 1 ≤ MFR ART / MFR ORI ≤ 10 (c) can be satisfied. The melt flow rate MFR of the PHA powder ORI , the melt flow rate MFR of the powder granulate 92 GRN , and the melt flow rate MFR of the extrusion molded article 96 ART are measured at 165 °C under a load of 5 kg in accordance with ISO 1133.

[0108] The above formulas (a), (b), and (c) indicate that the decrease in the molecular weight of PHA during the process of manufacturing the extrusion molded article 96 of PHA from the PHA powder is sufficiently suppressed. By suppressing the decrease in the molecular weight of PHA, it becomes possible to manufacture an extrusion molded article 96 having more excellent mechanical properties.

[0109] E-2. Method for manufacturing a tubular extrusion molded article Examples of the tubular extrusion molded article include elongated cylindrical molded articles having a cavity inside, such as a straw and a pipe. The extrusion molded article has a substantially circular cross-sectional shape.

[0110] The tubular extrusion molded article can be manufactured using an extruder including a cylinder, a screw accommodated in the cylinder, a hopper for supplying the powder granulate to the cylinder, and an annular die. The extruder has the same configuration as the above-described extruder 10 shown in FIG. 1, except that it is provided with an annular die instead of a T-shaped die. The plasticizing and melting temperature in this extruder is set in the same manner as the plasticizing and melting temperature T P in the extruder shown in FIG. 1. By melting the powder granulate in the cylinder, extruding the tubular melt from the annular die into water, and cooling and crystallizing the melt in water, a tubular extrusion molded article can be manufactured.

[0111] When the extruded molded article is used as a drinking straw, from the viewpoint of ease of drinking a beverage, the extruded molded article preferably has an outer diameter of 2 mm to 10 mm, more preferably 4 mm to 8 mm, still more preferably 5 mm to 7 mm, and preferably has an average thickness of 0.005 mm to 0.5 mm, more preferably 0.01 mm to 0.3 mm, still more preferably 0.02 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 granulated product, the melt can be rapidly crystallized and solidified without a crystallization nucleating agent. Therefore, an extruded molded article 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 the extruded molded article is used as a drinking straw, the cross section of the extruded molded article is preferably as close to a perfect circle as possible.

[0112] When the extruded molded article is used as a drinking straw, the extruded molded article may be subjected to secondary processing for forming a stopper portion and / or a bellows portion or the like.

[0113] E-3. Extruded Molded Articles of Other Shapes By the method according to the embodiment, an extruded molded article that can be used as a bottle or a container can also be manufactured. Specifically, using an extruder equipped with a cylinder, a screw housed in the cylinder, a hopper for supplying the powder granulated product to the cylinder, and an annular die, the powder granulated product is melted in the cylinder, a tubular melt is extruded from the annular die, and sent into an open mold. The mold is closed to close one end of the tubular melt, and air is blown into the melt to bring the melt into close contact with the mold, and the melt is cooled and crystallized and solidified. Thereby, an extruded molded article that can be used as a bottle or a container can be manufactured.

[0114] The use of the extruded product manufactured by the method according to the embodiment is not particularly limited. The extruded product can be used for various purposes such as medical materials, tableware materials, agricultural materials, fishery materials, forestry materials, OA parts, home appliance parts, automotive members, daily sundries, stationery, preforms for bottle molding, and the like. The powder granulate used in the method according to the embodiment can be manufactured with lower energy compared to the molten pellets used in conventional extrusion molding. Further, the extruded product manufactured by the method according to the embodiment has excellent physical properties and appearance, and also has seawater decomposability. Therefore, the method according to the embodiment can contribute to the reduction of the amount of greenhouse gas generated and the improvement of environmental problems caused by the ocean dumping of plastics.

Examples

[0115] Hereinafter, the present embodiment will be specifically described with reference to examples, but the present embodiment is not limited to these examples at all. In addition, parts and % are based on mass standards unless otherwise specified.

[0116] Example 1 (1) Preparation of raw material powder Powder of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), which is a commercially available copolymer polyester of 3-hydroxybutyric acid and 3-hydroxyhexanoic acid (PHA powder), was prepared. The hydroxyhexanoate content of the PHA powder was 6 mol%, the bulk density was 0.33 kg / L, the highest melting peak temperature was 145 °C, the crystallization temperature was 85 °C, and the melt flow rate MFR ORI was 3.0 g / 10 min. The weight average molecular weight of PHBH was 500,000 (in terms of polystyrene).

[0117] The bulk density of the PHA powder was measured in the same manner as the bulk density of the powder granulate described later.

[0118] The highest melting peak temperature and crystallization temperature of the PHA powder were measured using 5 mg of the PHA powder by the highest melting peak temperature T of the powder granulate described later M and crystallization temperature T CMeasured in the same manner (see FIGS. 2 and 3).

[0119] Melt flow rate MFR of the PHA powder ORI was measured in accordance with ISO 1133 using a melt indexer (“No. 120 - FWP” manufactured by Yasuda Seiki Seisakusho Co., Ltd.), with a cylinder set temperature of 165° C., a load of 5 kg, and preheating for 4 minutes.

[0120] (2) Production of the powder granulated product 100 parts by mass of the PHA powder was charged into an FM mixer (manufactured by Nippon Coke & Engineering Co., Ltd., trade name “5FM5C / I”; processing volume: 5 L), and while rotating the stirring blades at a rotational speed of 2,000 rpm, 20 parts by mass of tap water was continuously spray - injected for 5 minutes to obtain a water - containing powder.

[0121] The water - containing powder was charged into a disk pelletizer (manufactured by Dalton Co., Ltd., trade name “Disk Pelletizer F - 5 / 11 - 175”), and a substantially cylindrical granulated product precursor was produced under the condition of a roller rotational speed of 108 rpm. The thickness of the die plate of the disk pelletizer was 15 mm, and the hole diameter was 3 mmφ. The length (referred to as the effective length) of the water - containing powder receiving compressive stress from the die hole wall surface inside the die plate was 10 mm. The granulation speed was 43 kg / h.

[0122] The obtained granulated product precursor was dried at 100° C. for 4 hours using a hot - air circulation dryer (manufactured by Espec Co., Ltd., trade name “PH - 402”) to obtain a powder granulated product.

[0123] (3) Evaluation of the powder granulated product i) Bulk density The mass of 1 liter of the powder granulated product obtained by allowing the dried powder granulated product to fall naturally into a 1 - liter graduated cylinder was measured to calculate the bulk density of the powder granulated product. The bulk density of the powder granulated product was 0.40 kg / L.

[0124] ii) Moisture content The moisture content remaining in the powder granulated product was measured using an infrared moisture meter (FD - 660 manufactured by Kett Science Laboratory Co., Ltd.). The moisture content of the powder granulated product was 0.5 mass%.

[0125] iii) Fracture stress Using a wooden hardness tester (manufactured by Shiro Sangyo Co., Ltd., product name "WPF1600-B"), the fracture stress (unit: kg) of 25 powder granules was measured, and the average of the measured values was calculated. The fracture stress was measured by setting the powder granule on the hardness tester with the side surface facing down and pressing and crushing the powder granule from the side using a 5 mmφ cylindrical pressing tool. In other words, the fracture stress was measured by pressing and crushing the powder granule in a direction perpendicular to the longitudinal direction (extrusion direction). The average fracture stress of the powder granule was 1.5 kg, and the powder granule had excellent handleability.

[0126] iv) Maximum melting peak temperature T M and crystallization temperature T C The powder granule was cut perpendicular to the longitudinal direction (extrusion direction) with a razor blade to obtain a measurement piece weighing 5 mg. Differential scanning calorimetry (DSC) of the measurement piece was performed using "DSC6220" manufactured by SII NanoTechnology Inc. Specifically, in a nitrogen atmosphere, the temperature of the measurement piece was raised from room temperature to 180°C at a rate of 10°C / min, held at 180°C for 2 minutes, and DSC was performed while cooling at a rate of 10°C / min to obtain the DSC curves shown in FIGS. 2 and 3. In the DSC curve during heating shown in FIG. 2, an endothermic melting peak was observed, and the highest peak temperature (i.e., the maximum melting peak temperature) T M was 147°C. In the DSC curve during cooling shown in FIG. 3, a distinct exothermic crystallization peak was observed, and the peak temperature (i.e., the crystallization temperature) T C was 95°C. The crystallization temperature T C of the powder granule was higher than the crystallization temperature (85°C) of the raw material PHA powder. Also, when DSC was performed while raising the temperature of the measurement piece from room temperature to 200°C at a rate of 10°C / min, holding at 200°C for 2 minutes, and cooling at a rate of 10°C / min in a nitrogen atmosphere, no exothermic crystallization peak was observed. From these facts, it was shown that a high melt memory effect was exhibited in the powder granule. Also, the full width at half maximum of the exothermic crystallization peak of the powder granule was smaller than that of the exothermic crystallization peak of the PHA powder.

[0127] v) Melt flow rate MFR GRN Melt flow rate MFR of the powder granulate GRN was measured in accordance with ISO 1133 using a melt indexer (“No. 120 - FWP” manufactured by Yasuda Seiki Seisakusho Co., Ltd.) at a cylinder set temperature of 165°C, a load of 5 kg, and preheating for 4 minutes. The melt flow rate MFR of the powder granulate GRN was 3.0 g / 10 min.

[0128] (4) Extrusion molding Using a dryer (manufactured by Espec, product name “PH - 402”), the powder granulate was dried at 100°C for 8 hours to make the moisture content of the powder granulate 0.05 mass% or less. After drying, the powder granulate was molded using an extrusion molding machine as shown in Fig. 1. The extrusion molding machine included a pair of cooling rolls consisting of a first roll and a second roll, a conveying roll consisting of a third roll provided downstream of the second roll and a pair of pinch rolls provided downstream of the third roll, and a winding roll. As the extruder, a 40 mmφ single - screw extruder equipped with a full - flight screw with L / D = 28 (manufactured by GSI Creos Co., Ltd., product name “691C - EF049”) was used. As the first roll, a roll with the outermost layer made of silicone rubber was used. The surface temperature of the first roll was controlled by water cooling. As the second roll and the third roll, metal mirror rolls with chromium plating on the surface were used. The second roll and the third roll shared a temperature control device using warm water, and the surface temperatures of the second roll and the third roll were controlled integrally.

[0129] The cylinder of the extruder was divided into five regions C1 to C5 from the upstream to the downstream in the flow direction of the powder granulate and its melt, and the temperature of each region was independently controlled. Region C1 was the region under the hopper for charging the powder granulate. The T-die was divided into three regions D1 to D3 in the width direction of the melt extruded from the T-die, and the temperature of each region was independently controlled. Region D2 was the region sandwiched between Region D1 and Region D3 and including the center of the T-die. The set temperatures of 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-die were as shown in Table 1 below.

[0130]

Table 1

[0131] The temperature of the melt in the die head measured by the thermocouple attached to the die head, that is, the plasticized melt temperature T P was as described in Table 5.

[0132] Screw rotation speed S R At 30 rpm, a sheet-like melt was continuously extruded from a T-die with a die width of 300 mm, and the melt was sandwiched and cooled by a pair of cooling rolls consisting of a first roll and a second roll arranged immediately below the T-die. The set temperature of the surface of the first roll was 20°C. The surface temperature of the first roll measured by a contact-type thermocouple (manufactured by Rika Denki Co., Ltd., ST-41-K-1000-3C / A) was 30°C. The set temperatures of the surfaces of the second roll and the third roll were 70°C. The surface temperatures of the second roll and the third roll measured by the same contact-type thermocouple as above were both 63°C. The melt was quickly cooled to 63°C when it came into contact with the second roll, and a single-layer sheet (extruded molded body) with a thickness of 80 μm was obtained. The sheet was sent 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.

[0133] (5) Evaluation of the Extruded Product i) Difficulty in Adhering to the Second Roll The difficulty of the sheet adhering to the second roll was evaluated according to the following criteria. The results are shown in Table 5.

[0134] A: The sheet did not adhere to the second roll. B: The sheet adhered to the second roll or there was a possibility of adhesion.

[0135] ii) Effective Width The width of the region having a thickness within ±10 μm of the designed thickness (80 μm in Example 1) in the sheet (hereinafter referred to as "effective width") was measured. Here, the width means the length in the direction perpendicular to the conveyance direction (machine direction, MD) (TD). The results are shown in Table 5.

[0136] iii) Crystallization Temperature T CA Using a razor blade, a measurement piece weighing 5 mg was cut out from the central part of the sheet. In the same manner as the melt memory effect of the above-mentioned powder granulated product, the crystallization temperature T of the sheet CA was measured. The results are shown in Table 5. The crystallization temperature T of the sheet CA was 99 °C, which was 4 °C higher than the crystallization temperature T of the powder granulated product C (95 °C).

[0137] iv) Melt Flow Rate MFR ART A measurement piece was cut out from the sheet, and the melt flow rate MFR of the sheet was measured using the measurement piece. ART The measurement was carried out in accordance with ISO1133, using a melt indexer ("No. 120-FWP" manufactured by Yasuda Seiki Seisakusho Co., Ltd.), at a cylinder setting temperature of 165 °C, a load of 5 kg, and preheating for 4 minutes. The results are shown in Table 5.

[0138] v) Appearance The appearance of the sheet was evaluated according to the following criteria. Note that the appearance defects in the following criteria mean waviness, orange peel, etc. The results are shown in Table 5.

[0139] AA: There were almost no appearance defects. A+: Appearance defects were occasionally seen (the appearance defects were mild). A: Appearance defects were easily confirmed (the appearance defects were moderate). B: Appearance defects were severe (the appearance defects were severe).

[0140] vi) Heat shrinkage A 120 mm × 120 mm square piece was cut out from the sheet, and two lines were drawn on the surface of the piece. The two lines were perpendicular to each other at the center of the piece and each had a length of 100 mm. One of the two lines was parallel to the conveyance direction (machine direction, MD) of the sheet, and the other of the two lines was parallel to the direction perpendicular to MD (TD). The piece was placed in an oven set at 150°C, which is a temperature near the melting point of PHA, or 170°C, which is a temperature exceeding the melting point of PHA, for 30 minutes. Thereafter, the lengths of the lines drawn on the piece were measured to obtain the shrinkage amounts of the sheet in MD and TD, respectively. The results are shown in Table 5.

[0141] As shown in Table 5, the sheet could be stably wound up without sticking to the second roll. The sheet had a stable shape and dimensions with almost no appearance defects. The sheet did not shrink even when heated.

[0142] Example 2 In the extrusion molding, a sheet was produced in the same manner as in Example 1 except that the winding speed of the sheet was 1.5 m / min and the designed thickness of the sheet was 50 μm, and the sheet was evaluated in the same manner as in Example 1. The results are shown in Table 5. The sheet could be stably wound up without sticking to the second roll. The sheet had a stable shape and dimensions with almost no appearance defects. The sheet did not shrink even when heated.

[0143] Example 3 In the extrusion molding, a sheet was produced in the same manner as in Example 1 except that the winding speed of the sheet was 3.0 m / min and the designed thickness of the sheet was 30 μm, and the sheet was evaluated in the same manner as in Example 1. The results are shown in Table 5. The sheet could be stably wound without sticking to the second roll. The sheet had a stable shape and dimensions with almost no appearance defects. The sheet did not shrink even when heated.

[0144] Example 4 In the extrusion molding, the set temperatures of the regions C1 to C5 of the cylinder, the die head (HD) attached to the tip of the cylinder, the adapter (AD), and the regions D1 to D3 of the T-die were as shown in Table 2 below, and the plasticizing melting temperature T P was 160°C and the winding speed of the sheet was 1.2 m / min. A sheet was produced in the same manner as in Example 1 and the sheet was evaluated in the same manner as in Example 1. The results are shown in Table 5. The sheet could be stably wound without sticking to the second roll. The sheet had slight appearance defects. The sheet did not shrink even when heated.

[0145] [Table 2]

[0146] Example 5 In the extrusion molding, a sheet was produced in the same manner as in Example 1 except that the set temperatures of the surfaces of the second roll and the third roll were 40°C. The actually measured surface temperatures of the second roll and the third roll were both 37°C. The obtained sheet was evaluated in the same manner as in Example 1. The results are shown in Table 5. The sheet could be stably wound without sticking to the second roll. The sheet had moderate appearance defects. The sheet did not shrink even when heated.

[0147] Comparative Example 1 In extrusion molding, the set temperatures of the regions C1 to C5 of the cylinder, the die head (HD) attached to the tip of the cylinder, the adapter (AD), and the regions D1 to D3 of the T-die were made as shown in Table 3 below, and the plasticizing melting temperature T P was set at 170 °C. Otherwise, a sheet was produced in the same manner as in Example 1, and the difficulty of sticking the sheet to the second roll, the crystallization temperature T CA , and the appearance were evaluated in the same manner as in Example 1. The results are shown in Table 5. The sheet could not be stably wound up while sticking to the second roll.

[0148]

Table 3

[0149] Comparative Example 2 In extrusion molding, the set temperatures of the regions C1 to C5 of the cylinder, the die head (HD) attached to the tip of the cylinder, the adapter (AD), and the regions D1 to D3 of the T-die were made as shown in Table 4 below, and the plasticizing melting temperature T P was set at 135 °C. Otherwise, a sheet was produced in the same manner as in Example 1. The melt extruded from the T-die contained unmelted PHA, and the produced sheet had wrinkles and holes.

[0150]

Table 4

[0151] Comparative Example 3 A sheet was produced in the same manner as in Example 1, except that a commercially available PHA melt pellet (manufactured by BluePHA, trade name "BP-330-05") to which a crystallization nucleating agent was added was used instead of the powder granulated product. The difficulty of sticking the sheet to the second roll, the crystallization temperature T CA , the melt flow rate MFR ART , and the appearance were evaluated in the same manner as in Example 1. The highest melting peak temperature T M of the melt pellet, the crystallization temperature T C , and the melt flow rate MFR PLTIt was as described in Table 5. The evaluation results are shown in Table 5. The sheet could not be continuously wound up while sticking to the second roll.

[0152] Comparative Example 4 In the extrusion molding, a sheet was produced in the same manner as in Comparative Example 3, except that the set temperatures of the surfaces of the second roll and the third roll were 40°C, the winding speed of the sheet was 2.0 m / min, and the designed thickness of the sheet was 80 μm. The actually measured surface temperatures of the second roll and the third roll were both 37°C. The obtained sheet was evaluated in the same manner as in Example 1. The results are shown in Table 5. The sheet sometimes stuck to the second roll, but barely managed to continuously produce the sheet. However, the sheet had a small effective width, was wavy, and was inferior in shape and dimensional stability. Also, the sheet shrank in the MD at 170°C and elongated in the TD, and was inferior in heat resistance.

[0153]

Table 5

[0154] In this specification, a numerical range represented by the symbol "~" includes the numerical values described before and after the symbol "~" as the lower limit and the upper limit, respectively, unless otherwise specified. Also, the upper limit value and / or the lower limit value of the numerical range described in this specification can define a preferable range by arbitrarily combining them. For example, the upper limit value and the lower limit value of the numerical range can be arbitrarily combined to define a preferable range, the upper limit values of the numerical range can be arbitrarily combined to define a preferable range, and the lower limit values of the numerical range can be arbitrarily combined to define a preferable range.

[0155] In this application, the term "and / or" represents at least one and all possible combinations of the listed items.

[0156] Although the present embodiment has been described in detail above, the specific configuration is not limited to this embodiment, and even if there are design changes within the scope not departing from the gist of the present disclosure, they are included in the present disclosure.

Explanation of Reference Numerals

[0157] 1 Extrusion machine, 10 Extruder, 12 Cylinder, 14 Screw, 16 Hopper, 17 Die head, 18 T-die, 19 Adapter, 30 Cooling roll, 32 First roll, 34 Second roll, 50 Conveyor roll, 52 Third roll, 54 Pinch roll, 70 Take-up roll, 92 Powder granule, 94 Melt, 96 Extruded product

Claims

1. A method for producing an extrusion molded body, comprising the steps of: The method includes extruding a polyhydroxyalkanoate (PHA) through an extruder having a single flight screw having a feed zone, a compression zone, and a metering zone; The extrusion molding is performed by heating the powder granules containing the PHA powder to a plasticization melting temperature T Ｐ (unit: °C) to obtain a melt, extruding the melt through a die, and cooling the extruded melt to solidify, The plasticizing melting temperature T Ｐ But, formula (1) T Ｍ -10<T Ｐ ≦T Ｍ +20 (1) (In the formula, T Ｍ (unit: ° C.) represents the highest melting peak temperature observed in differential scanning calorimetry in which the powder granule is heated from room temperature at a rate of 10° C. / min in a nitrogen atmosphere.

2. A method for producing an extrusion molded product, comprising the steps of: The method includes extruding polyhydroxyalkanoate (PHA) through an extruder, The extrusion molding includes melting a powder granule containing a PHA powder at a plasticizing melting temperature T P (unit: ° C.) to obtain a melt, extruding the melt from a T-shaped die, and sandwiching the extruded melt between a first roll and a second roll to cool and solidify the melt, The plasticization melting temperature T P is expressed by the formula (1) T M -10<T P ≦T M +20 (1) (wherein T M (unit: ° C.) represents the highest melting peak temperature observed in differential scanning calorimetry in which the powder granule is heated from room temperature at a rate of 10° C. / min in a nitrogen atmosphere), The cooled melt is conveyed along the surface of the second roll; The surface temperature T R1 (unit: ° C.) of the first roll, the surface temperature T R2 (unit: ° C.) of the second roll, and the crystallization temperature T C of the powder granulated product are expressed by the following formulas (2), (3), and (4): T C -80<T R1 ≦T C (2) T C -60<T R2 ≦T C (3) T R1 < T R2 (4) Fulfilling The crystallization temperature T C of the powder granule is defined as a peak temperature of a crystallization exothermic peak observed during temperature decrease in a differential scanning calorimetry measurement in which the powder granule is heated to 180° C. at a rate of 10° C. / min in a nitrogen atmosphere, held at 180° C. for 2 minutes, and then cooled at a rate of 10° C. / min.

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

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

5. The method according to any one of claims 1 to 4, wherein the powder granule has a melt memory effect.

6. The method according to any one of claims 1 to 4, wherein the powder granules are compressed granules.

7. The method according to claim 6, wherein the powder granulation product has an outer wall portion formed by melting and solidifying at least a portion of the PHA powder located at the outer edge of the powder granulation product, and the compressed PHA powder is contained inside the outer wall portion.

8. The die is a T-die, 5. The method of claim 1, 3 or 4, wherein the melt extruded from the die is cooled with at least one chill roll.

9. the at least one chill roll includes a first roll and a second roll that sandwich the melt; The cooled melt is conveyed along the surface of the second roll; The surface temperature T of the first roll Ｒ１ (unit: ° C.), the surface temperature T of the second roll Ｒ２ (unit: ° C.), and the crystallization temperature T Ｃ Formula (2), Formula (3), and Formula (4) T Ｃ -80<T Ｒ１ ≦T Ｃ (2) T Ｃ -60<T Ｒ２ ≦T Ｃ (3) T Ｒ１ <T Ｒ２ (4) Fulfilling The crystallization temperature T Ｃ The method according to claim 8, wherein the peak temperature is defined as the peak temperature of a crystallization exothermic peak observed during cooling in a differential scanning calorimetry measurement in which the powder granule is heated to 180°C at a rate of 10°C / min in a nitrogen atmosphere, held at 180°C for 2 minutes, and cooled at a rate of 10°C / min.

10. The surface temperature T of the second roll Ｒ２ The method according to claim 2, wherein the temperature is from 50° C. to 80° C.

11. The method according to claim 9, wherein the surface temperature T R2 of the second roll is 50°C to 80°C.

12. The method of any one of claims 2 to 4, wherein the extruder has a single flight screw having a feed zone, a compression zone, and a metering zone.

13. 10. The method of claim 1, wherein the extrusion is carried out at a screw speed of 100 rpm or less.

14. The method of claim 12, wherein the extrusion is performed at a screw speed of 100 rpm or less.

15. The crystallization temperature T Ｃ (unit: °C) is 80 °C or more, The crystallization temperature T Ｃ The method according to any one of claims 1 to 4, wherein the peak temperature is defined as a peak temperature of a crystallization exothermic peak observed during temperature reduction in a differential scanning calorimetry measurement in which the powder granule is heated to 180°C at a rate of 10°C / min in a nitrogen atmosphere, held at 180°C for 2 minutes, and cooled at a rate of 10°C / min.

16. The method of any one of claims 1 to 4, wherein the extrudate has a tubular shape.

17. The crystallization temperature T ＣＡ (unit: ° C.) and the crystallization temperature T Ｃ (unit: ° C.) is expressed by the formula (5) 0.8≦T ＣＡ / T Ｃ ≦1.2 (5) Fulfilling The crystallization temperature T Ｃ is defined as the peak temperature of the crystallization exothermic peak observed during temperature drop in a differential scanning calorimetry measurement in which the powder granule is heated to 180° C. at a rate of 10° C. / min in a nitrogen atmosphere, held at 180° C. for 2 minutes, and then cooled at a rate of 10° C. / min, The crystallization temperature T ＣＡ is defined as the peak temperature of a crystallization exothermic peak observed during cooling in a differential scanning calorimetry measurement in which the extrusion molded body is heated to 180°C at a rate of 10°C / min in a nitrogen atmosphere, held at 180°C for 2 minutes, and cooled at a rate of 10°C / min.

18. Melt flow rate (MFR) of the PHA powder ＯＲＩ (Unit: g / 10 min), the melt flow rate MFR of the powder granule ＧＲＮ (unit: g / 10 min), and the melt flow rate MFR of the extruded product ＡＲＴ (Unit: g / 10 min) is represented by the formulas (a), (b), and (c) 1≦MFR ＧＲＮ / MFR ＯＲＩ ≦5 (a) 1≦MFR ＡＲＴ / MFR ＧＲＮ ≦5 (b) 1≦MFR ＡＲＴ / MFR ＯＲＩ ≦10 (c) and the melt flow rate MFR of the PHA powder is ＯＲＩ The melt flow rate MFR of the powder granule ＧＲＮ and the melt flow rate MFR of the extruded product ＡＲＴ The method according to any one of claims 1 to 3, wherein the thermal expansion coefficient is measured at 165 ° C and a load of 5 kg in accordance with ISO 1133.

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