Method for producing polyhydroxyalkanoate particles

Abstract

To provide PHA particles which allow efficient drying and ensure excellent handling performance following drying.SOLUTION: A method for producing PHA particles comprises: a crushing step of crushing PHA agglomerates having a moisture content of 5.0-30.0 wt.% (W.B.) by sandwiching them between a screen and a rotary roller positioned above the screen; and a sizing step of allowing the crushed PHA agglomerates to pass through a vibrated screen with an aperture of 1.0-8.0 mm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing polyhydroxyalkanoate particles. [Background technology]

[0002] Polyhydroxyalkanoates (hereinafter sometimes referred to as "PHAs") are known to be biodegradable, and in recent years, their use has been promoted from the viewpoint of environmental considerations.

[0003] One of the advantages of PHA is that it can be produced by microorganisms using renewable plant materials. To utilize PHA produced by microorganisms, it is first necessary to disrupt the microbial cells, extract the PHA from the cells, obtain an aqueous suspension of PHA, and then recover and purify the PHA from this aqueous suspension by filtration or the like. Patent Document 1 discloses a technique for recovering and purifying PHA, in which an aqueous suspension of PHA is subjected to dead-end filtration to obtain PHA aggregates, and the obtained PHA aggregates are dried to obtain particulate PHA (PHA particles). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. WO2023 / 120193 Summary of the Invention [Problem to be solved by the invention]

[0005] Although the above-mentioned technology is excellent, there is room for improvement in terms of the drying time and the handling properties of the PHA particles after drying when drying the PHA agglomerates to remove the remaining moisture.

[0006] In view of the above circumstances, one aspect of the present invention aims to provide a method for producing PHA particles that can be dried efficiently and have excellent handleability after drying. [Means for solving the problem]

[0007] As a result of intensive research to solve the above-mentioned problems, the inventors have discovered a new finding that by crushing PHA agglomerates by clamping them between a screen and a rotating roller, and then passing the resulting crushed PHA agglomerates through the screen having a specified mesh size while vibrating the screen, and sizing the particles, it is possible to provide PHA particles that can be dried efficiently and have excellent handleability after drying, which has led to the completion of the present invention.

[0008] That is, one aspect of the present invention includes the following configuration. [1] A method for producing polyhydroxyalkanoate particles, comprising: a crushing step in which polyhydroxyalkanoate agglomerates having a moisture content of 5.0 to 30.0% by weight (wet basis) are crushed by pinching them between a screen and a rotating roller placed above the screen; and a sizing step in which the crushed polyhydroxyalkanoate agglomerates are passed through the vibrated screen, wherein the openings of the screen are 1.0 to 8.0 mm. [2] The method for producing polyhydroxyalkanoate particles according to [1], wherein the disintegration step further comprises a step of disintegrating polyhydroxyalkanoate agglomerates using a blade installed above the screen. [3] The method for producing polyhydroxyalkanoate particles according to [1] or [2], wherein the range of motion of the roller is 1.0 to 8.0 mm. [4] The method for producing polyhydroxyalkanoate particles according to any one of [1] to [3], wherein the clearance between the roller and the screen is 0.0 to 3.0 mm. [5] The method for producing polyhydroxyalkanoate particles according to [2], wherein the clearance between the blade and the screen is 5 to 30 mm. [6] The method for producing polyhydroxyalkanoate particles according to any one of [1] to [5], wherein the tip speed of the roller is 0.3 to 7.2 m / s. [7] The method for producing polyhydroxyalkanoate particles according to any one of [1] to [6], further comprising a filtration step of filtering an aqueous suspension containing polyhydroxyalkanoate to obtain polyhydroxyalkanoate agglomerates before the disintegration step. [8] The method for producing polyhydroxyalkanoate particles according to any one of [1] to [7], further comprising a drying step of drying the polyhydroxyalkanoate particles after the sizing step. [9] Polyhydroxyalkanoate particles having an average Feret diameter of 0.2 mm to 6.0 mm, a ratio of particles of 100 μm or less of 50% or less, and a moisture content of 5.0 to 30.0% by weight (wet basis). [Effects of the Invention]

[0009] According to one aspect of the present invention, it is possible to provide PHA particles that can be dried efficiently and have excellent handleability after drying. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a side view showing a schematic configuration of a crushing device used in a crushing step and a sizing step according to one embodiment of the present invention. [Figure 2] FIG. 1 is a top view showing a schematic configuration of a crushing device used in a crushing step and a sizing step according to one embodiment of the present invention. [Figure 3] FIG. 10 is a side view showing a schematic configuration of a crushing device used in the crushing step and the particle size regulating step according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a top view showing a schematic configuration of a crushing device used in the crushing step and the particle size regulating step according to a second embodiment of the present invention. [Figure 5] FIG. 10 is a side view showing a schematic configuration of a crushing device used in the crushing step and the particle size regulating step according to a third embodiment of the present invention. [Figure 6] FIG. 10 is a top view showing a schematic configuration of a crushing device used in the crushing step and the particle size regulating step according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] One embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the respective configurations described below, and various modifications are possible within the scope of the claims. Furthermore, embodiments or examples obtained by combining the technical means disclosed in different embodiments or examples are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. All academic literature and patent documents described in this specification are incorporated herein by reference. Furthermore, unless otherwise specified in this specification, the term "A to B" representing a numerical range means "greater than or equal to A (including and greater than A) and less than or equal to B (including and less than B)."

[0012] 1. Overview of the Invention The PHA agglomerates obtained by the above-mentioned conventional techniques contain a certain amount of water in addition to PHA, and therefore, in order to obtain PHA particles suitable for processing, it is necessary to dry the PHA agglomerates to remove the remaining water.

[0013] The present inventors have found that, when drying PHA agglomerates to remove residual moisture, (1) if the particle size of the PHA agglomerates exceeds a certain value, problems may arise, such as the drying time of the agglomerates becoming excessively long, resulting in poor drying efficiency, or the drying being insufficient, resulting in undried PHA being mixed into the PHA particles that are the final product. On the other hand, (2) if the particle size of the PHA agglomerates is below a certain value, fine powder is generated after drying of the agglomerates, which is mixed into the PHA particles that are the final product, resulting in problems such as poor handleability of the PHA particles.

[0014] Having gained the above knowledge, the inventors believed that if the particle size of the PHA agglomerates to be dried could be controlled within a certain range that would avoid both problems (1) and (2) above, the drying efficiency and the handleability of the PHA particles after drying could be improved.Therefore, they attempted to carry out a step of crushing the PHA agglomerates and adjusting (sizing) the particle size to within the above-mentioned certain range before drying the agglomerates.

[0015] While thoroughly investigating the conditions for crushing and sizing PHA agglomerates that can provide PHA agglomerates of particle size within a certain range, while achieving both drying efficiency and ease of handling of the PHA particles after drying, the inventors discovered that PHA agglomerates of particle size within the above-mentioned certain range can be provided by crushing the PHA agglomerates by clamping them between a screen with a specified mesh size and a rotating roller placed above the screen, and then passing the crushed PHA agglomerates through the screen while vibrating it.

[0016] Furthermore, in the crushing and sizing process using this predetermined screen and rotating roller, it was found that (1) if the moisture content of the PHA agglomerates subjected to the crushing and sizing process exceeds a certain value, the agglomerates clog the screen, making it impossible for the agglomerates to pass through, and (2) if the moisture content falls below a certain value, a large amount of fine powder is generated after drying. In other words, it was found that by adjusting the moisture content of the PHA agglomerates subjected to the crushing and sizing process within a predetermined range, it is possible to prevent the crushed agglomerates from clogging the screen while suppressing the generation of excessive fine powder after drying.

[0017] Having gained the above-mentioned findings, the inventors have discovered that a method comprising the steps of crushing PHA agglomerates having a predetermined moisture content by clamping them between a screen having a predetermined mesh size and a rotating roller placed above the screen, and passing the crushed PHA agglomerates through the vibrated screen, can prevent clogging of the screen during the sizing process while achieving both drying efficiency and easy handling of the PHA particles after drying, and has thus completed the present invention.

[0018] Method for Producing PHA Particles The method for producing PHA particles according to an embodiment of the present invention (hereinafter, the "method for producing PHA according to an embodiment of the present invention" may be referred to as the "present production method") is a method in which PHA agglomerates having a water content of 5.0 to 30.0% by weight (wet basis (hereinafter, may be referred to as "W.B")) are crushed by sandwiching them between a screen and a rotary roller installed above the screen, and a sizing step of passing the crushed PHA agglomerates through the vibrated screen, wherein the aperture of the screen is 1.0 to 8.0 mm.

[0019] By including the above-mentioned crushing step and sizing step, the present production method can efficiently dry and provide PHA particles having excellent handling properties after drying.

[0020] <PHA Agglomerates> First, the PHA agglomerates used in the crushing step will be described. In the present specification, the PHA agglomerates refer to a composition containing solid PHA and water, wherein the weight ratio of PHA (solid content) is 60% or more and less than 100% in 100% by weight of the total amount of the PHA agglomerates, and which does not have the properties of a fluid in a stationary state. Further, the water in the PHA agglomerates may contain, in addition to water, other solvents (for example, organic solvents compatible with water), components derived from PHA-producing microorganisms (for example, cell walls, proteins, etc.), and / or other compounds generated during purification. That is, the PHA agglomerates according to the present production method may contain, in addition to PHA and water, each component present in these waters.

[0021] The moisture content of the PHA agglomerates subjected to the disintegration step is 5.0 to 30.0 wt% (WB). By setting the moisture content of the PHA agglomerates subjected to the disintegration step to 5.0 wt% (WB) or more, the amount of fine powder generated after drying can be reduced, and PHA particles with excellent handleability can be provided. Furthermore, by setting the moisture content to 30.0 wt% (WB) or less, clogging of the screen mesh by the PHA agglomerates can be suppressed. The moisture content of the PHA agglomerates subjected to the disintegration step is not particularly limited as long as it is 5.0 to 30.0 wt% (WB), but is preferably 8 wt% or more and less than 25 wt% (WB), more preferably 8 to 23 wt% (WB), even more preferably 10 to 20 wt% (WB), and even more preferably 10 to 17 wt% (WB). The water content (WB) of the PHA aggregates is the weight percentage of water in 100% by weight of the total amount of the PHA aggregates, and is a value measured by the method described in the Examples.

[0022] (PHA) The PHA contained in the PHA aggregates subjected to the disintegration step will be specifically described. "PHA" is a general term for polymers containing hydroxyalkanoate as a monomer unit (monomer repeating unit) and is generally biodegradable. In particular, in this specification, "PHA" refers to a (co)polymer containing hydroxyalkanoate repeating units at 50 mol% or more of the total monomer repeating units (100 mol%) and a resin composed of such a (co)polymer. The PHA is preferably a (co)polymer containing 60 mol% or more, and more preferably a (co)polymer containing 70 mol% or more, of the total monomer repeating units (100 mol%). In this specification, the term "(co)polymer" is used to refer to both a homopolymer composed of only one type of monomer and a copolymer composed of two or more types of monomers.

[0023] Examples of PHAs provided by this production method include poly(3-hydroxyalkanoate) (hereinafter sometimes referred to as "P3HA"), poly(4-hydroxyalkanoate), etc. Among these, P3HA is preferred because it is suitable for use in molded articles.

[0024] P3HA is a 3-hydroxyalkanoate repeating unit of the formula: [—CHR—CH—CO—O—] (wherein R is C n H 2n+1 where n is an integer of 1 to 15.) as an essential repeating unit. In this specification, "P3HA" refers to a (co)polymer containing 50 mol % or more of the 3-hydroxyalkanoate repeating units out of all monomer repeating units (100 mol %).

[0025] Specific examples of P3HA include homopolymers of one or more monomers selected from the group consisting of 3-hydroxybutanoic acid (hereinafter sometimes referred to as "3HB"), 3-hydroxypropionic acid, 3-hydroxypentanoic acid, 3-hydroxyhexanoic acid, 3-hydroxyheptanoic acid, 3-hydroxyoctanoic acid, 3-hydroxynonanoic acid, 3-hydroxydecanoic acid, 3-hydroxyundecanoic acid, 3-hydroxydodecanoic acid, 3-hydroxytridecanoic acid, 3-hydroxytetradecanoic acid, 3-hydroxyhexadecanoic acid, and 3-hydroxyoctadecanoic acid, or copolymers of two or more of these monomers. Furthermore, P3HA may also be a copolymer of the above-mentioned P3HA-based repeating unit with a repeating unit other than P3HA. For example, P3HA may be a copolymer of the above-mentioned P3HA-based repeating unit and one or more monomers selected from the group consisting of 4-hydroxybutanoic acid, 4-hydroxypentanoic acid, 4-hydroxyhexanoic acid, 4-hydroxyheptanoic acid, 4-hydroxyoctanoic acid, 4-hydroxynonanoic acid, 4-hydroxydecanoic acid, 4-hydroxyundecanoic acid, 4-hydroxydodecanoic acid, 4-hydroxytridecanoic acid, 4-hydroxytetradecanoic acid, 4-hydroxyhexadecanoic acid, and 4-hydroxyoctadecanoic acid.

[0026] More specifically, examples of P3HA include 3HB homopolymers such as poly(3-hydroxybutyrate) (hereinafter sometimes referred to as "P3HB"), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (hereinafter sometimes referred to as "P3HB3HH"), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (hereinafter sometimes referred to as "P3HB4HB"), and poly(3-hydroxybutyrate-co-3-hydroxypropionate). Among these, P3HB, P3HB3HH, and P3HB4HB are preferred, with P3HB3HH and P3HB4HB being more preferred, due to the ease of industrial production using microorganisms.

[0027] In this specification, "poly(X-co-Y)" refers to a copolymer containing X repeating units and Y repeating units, and is intended to mean a copolymer obtained by copolymerizing a monomer from which the X repeating unit is derived and a monomer from which the Y repeating unit is derived. As described above, the name of a P3HA is determined by the repeating units contained in the P3HA. However, a very small amount (about 1 mol % or less) of a monomer contained in a P3HA may not be reflected in the name of the P3HA, provided that such a monomer does not significantly affect the physical properties of the P3HA. In other words, a P3HA may contain, in addition to the repeating units corresponding to its name, very small amounts of other repeating units.

[0028] When P3HA contains 3HB repeating units, from the viewpoint of the balance between flexibility and strength, the composition ratio of 3HB repeating units to repeating units other than 3HB repeating units (other repeating units) in the total monomer repeating units (100 mol%) in the P3HA (3HB repeating units / other repeating units) is preferably 99 / 1 (mol% / mol%) to 60 / 40 (mol% / mol%), more preferably 97 / 3 (mol% / mol%) to 70 / 30 (mol% / mol%), and even more preferably 95 / 5 (mol% / mol%) to 80 / 20 (mol% / mol%). When the composition ratio of 3HB repeating units in P3HA is 60 mol% or more, it is advantageous in that a resin product with superior rigidity can be provided. On the other hand, when the composition ratio of 3HB repeating units in P3HA is 99 mol% or less, it is advantageous in that a resin product with superior flexibility can be provided. The monomer composition ratio of P3HA can be measured by gas chromatography or the like (see, for example, WO 2014 / 020838).

[0029] P3HA can be produced by microorganisms. Examples of microorganisms capable of producing P3HA include Bacillus megaterium, a P3HB-producing bacterium discovered in 1925, as well as other naturally occurring microorganisms such as Cupriavidus necator (formerly Alcaligenes eutrophus and Ralstonia eutropha) and Alcaligenes latus. These microorganisms accumulate P3HB intracellularly.

[0030] Known microorganisms that produce P3HA, a copolymer of 3HB and other hydroxyalkanoic acids, include Aeromonas caviae, which produces P3HB3HH, and Alcaligenes eutrophus, which produces poly(3-hydroxybutyrate-co-4-hydroxybutyrate). To increase P3HB3HH productivity, Alcaligenes eutrophus AC32 (FERM BP-6038) (T. Fukui, Y. Doi, J. Bateriol., 179, pp. 4821-4830 (1997)) is particularly preferred. In addition to the above, genetically modified microorganisms containing various P3HA synthesis-related genes can also be used depending on the desired physical properties of P3HA.

[0031] (Method of producing PHA aggregates) The PHA agglomerates to be subjected to the disintegration step can be prepared, for example, by removing a portion of the water contained in a PHA aqueous suspension, which is a solution in which PHA is suspended (dispersed) in water. That is, the present production method preferably includes, prior to the disintegration step, a step of removing a portion of the water from the PHA aqueous suspension to prepare PHA agglomerates containing 5 to 30 wt % (WB) of water (PHA agglomerate preparation step).

[0032] A PHA aqueous suspension derived from a culture medium of a microorganism capable of producing PHA can be suitably used as a raw material for PHA aggregates. Such a PHA aqueous suspension derived from a culture medium of a microorganism capable of producing PHA can be prepared, for example, by the following method: (1) culturing a microorganism capable of producing PHA; (2) inactivating the culture medium by heating to obtain an inactivated culture medium; (3) treating the inactivated culture medium with alkali; (4) neutralizing the alkali-treated inactivated culture medium and adding a lytic enzyme (a cell wall-degrading enzyme) to lyse the microorganism cells and disperse the intracellular substances, including PHA, in the culture medium; (5) adding a protease to the culture medium to decompose and / or remove substances derived from the microorganisms other than PHA (particularly proteins); and (6) further adjusting the pH of the culture medium and adding a surfactant to decompose and / or remove substances derived from the microorganisms other than PHA (particularly cell membranes).

[0033] This manufacturing method may include, prior to the PHA aggregate preparation step, a step of culturing a microorganism capable of producing PHA, which includes one or more of the above-mentioned operations, and preparing a PHA aqueous suspension from the culture solution (PHA aqueous suspension preparation step).

[0034] In the PHA aggregate preparation step, the method for removing a portion of the water contained in the PHA aqueous suspension is not particularly limited, and examples thereof include known methods, such as filtering the PHA aqueous suspension and centrifuging the PHA aqueous suspension and then removing the supernatant. Among these, filtering the PHA aqueous suspension is preferred because it has the advantage of easily reducing the water content. In other words, the present production method preferably includes a step (filtration step) of filtering the PHA aqueous suspension to obtain PHA aggregates.

[0035] The method for filtering the aqueous PHA suspension is not particularly limited as long as it can prepare a PHA agglomerate having the desired moisture content, but dead-end filtration is preferred because it has the advantage of reducing the moisture content of the resin cake after dehydration and making it easier to reduce the amount of moisture carried over to the dryer. That is, in the PHA agglomerate preparation step, it is preferable to prepare the PHA agglomerate by dead-end filtering the aqueous PHA suspension. In other words, it is preferable that the PHA agglomerate preparation step includes a dead-end filtration step in which the aqueous PHA suspension is dead-end filtered. In this specification, "dead-end filtration" means "filtration by the dead-end filtration method."

[0036] Specific modes of dead-end filtration are not particularly limited, and examples include suction filtration, pressure filtration, centrifugal filtration, and gravity filtration. Among these, pressure filtration is preferred because it has the advantage of easily reducing the water content, and filter press filtration (FP filtration) is more preferred. That is, the PHA aggregate preparation step preferably includes a filter press filtration step in which the aqueous PHA suspension is filtered through a filter press. Note that filter press filtration is an operation in which the aqueous PHA suspension is squeezed and dehydrated, and a residue (in this production method, PHA aggregates) is obtained.

[0037] The FP filtration step, which may be included in the PHA agglomerate preparation step, is described below. The FP step is a step in which an aqueous PHA suspension is squeezed and dehydrated, and the residue is solidified to obtain a PHA agglomerate.

[0038] In the FP filtration step, the pressure at which the aqueous PHA suspension is compressed is preferably 0.2 to 1.0 MPa, more preferably 0.25 to 0.9 MPa, and even more preferably 0.3 to 0.8 MPa. Compressing the aqueous PHA suspension at the above pressures has the advantage of making it easier to reduce the water content.

[0039] In the FP filtration step, the above-mentioned squeezing operation may be carried out only once or may be carried out two or more times. When squeezing is carried out two or more times, the squeezing pressure may be changed for each squeezing operation.

[0040] The FP filtration step may include an air blowing step in which the compressed PHA agglomerates are blown with air to adjust the moisture content of the compressed PHA agglomerates to a desired value. The air blowing step is a step in which moisture is further pushed out of the compressed PHA agglomerates with air blown.

[0041] The air blowing pressure in the air blowing step is not particularly limited, but is preferably 0.01 to 1.5 MPa, more preferably 0.05 to 1.3 MPa, and even more preferably 0.10 to 1.0 MPa, since this has the advantages of making it easier to reduce the moisture content and improving peelability from the filter cloth.

[0042] The air blowing time in the air blowing step can be appropriately set depending on the air blowing pressure and the desired water content of the PHA aggregates, but is, for example, 1 to 50 minutes, preferably 5 to 40 minutes.

[0043] The filter press filtration operation (and air blowing operation) in the FP filtration step can be carried out using a known filter press filtration device.

[0044] In the PHA aggregate preparation step, the obtained PHA aggregates may be roughly crushed to a size that allows them to be easily fed into a crusher and efficiently crushed in the subsequent crushing step. In other words, the PHA aggregate preparation step may include a crushing step in which the obtained PHA aggregates are roughly crushed.

[0045] The average Feret diameter of the PHA agglomerates is preferably 9 mm to 500 mm, more preferably 50 to 400 mm, and even more preferably 100 to 300 mm, since this allows for efficient disintegration in the subsequent disintegration step. That is, in the disintegration step, the PHA agglomerates are preferably disintegrated so that the average Feret diameter of the PHA agglomerates after disintegration falls within the above-mentioned range. The average Feret diameter of the PHA agglomerates is a value measured by the method described in the Examples.

[0046] In the crushing step, the method for crushing the PHA agglomerates is not particularly limited, but examples thereof include mechanically breaking the agglomerates using a crusher or screw, or breaking the agglomerates by impact such as dropping them.

[0047] <Crushing process and sizing process> This manufacturing method includes a crushing step in which PHA agglomerates having a moisture content of 5.0 to 30.0 wt% (WB) are crushed by pinching them between a screen and a rotating roller installed above the screen, and a sizing step in which the crushed PHA agglomerates are passed through a vibrated screen.

[0048] The present production method includes the above-mentioned crushing step and sizing step, and therefore can provide PHA particles that are excellent in drying efficiency and handleability after drying while preventing clogging of the screen during the sizing process.

[0049] (Embodiment 1) Specific embodiments of the crushing step and sizing step in this production method will be described in detail with reference to Figures 1 and 2. Figure 1 is a side view showing the schematic configuration of a crushing device used in the crushing step and sizing step in this production method, and Figure 2 is a top view showing the schematic configuration of the crushing device.

[0050] 1, the disintegrator 100 is an apparatus including a motor 1, a rotary shaft 2 connected to the motor, two sets of rotary rollers 3 connected diagonally to the rotary shaft 2, a cylindrical outer container 5 in which a screen 4 is disposed, and a vibration drive unit 6 connected to the outer container 5. For ease of explanation, the PHA agglomerates are not shown.

[0051] The rotary roller 3 is installed above the screen 4, and has a structure in which a central shaft 32 passes through the annular hollow portion of one or more double cylindrical rollers 31. The outer container 5 has an inlet 51 and an outlet 52, and the vibration drive unit 6 has a vibration motor 61, a spring 62, and a weight 63 connected to the vibration motor 61.

[0052] The specific steps of the disintegration step using the disintegrator 100 will now be described. First, PHA agglomerates are supplied into the disintegrator 100 via the inlet 51. The supplied PHA agglomerates are placed on the screen 4. Next, the motor 1 is driven. In conjunction with the driving of the motor 1, the rotary shaft 2 and the rotary roller 3 rotate in the rotational direction, and in conjunction with the rotation of the rotary roller 3, the roller 31 rotates in the rotational direction. As the rotating rotary roller 3 passes over the PHA agglomerates on the screen 4, the PHA agglomerates are sandwiched between the screen 4 and the rotary roller 3 (the roller 31 portion of the rotary roller 3), and are thereby disintegrated.

[0053] The rotating roller 3 consists of one or more double cylindrical rollers 31 and one central shaft 32. In this specification, a structure consisting of one or more rollers and one central shaft is referred to as one set of rotating rollers. Note that while FIG. 1 shows an example in which there are two sets of rotating rollers in total, the number of rotating rollers provided in the disintegrator 100 is not limited to this, and there may be only one set, or three or more sets.

[0054] The number of rollers 31 included in one set of rotary rollers 3 is not particularly limited as long as it is one or more, and may be, for example, 1 to 30, 5 to 25, or 8 to 15. The height (width) of the rollers 31 is also not particularly limited, and may be, for example, 5 to 50 mm, 10 to 40 mm, or 15 to 30 mm. The outer diameter of the rollers 31 is also not particularly limited, and may be, for example, 30 to 150 mm, 35 to 120 mm, or 40 to 90 mm. The inner diameter of the rollers 31 is also not particularly limited, and may be, for example, 5 to 80 mm, 10 to 70 mm, or 15 to 60 mm.

[0055] The material of the roller 31 is not particularly limited, and may be a fluororesin such as PTFE (polytetrafluoroethylene) or PVDF (polyvinylidene fluoride), a thermoplastic resin such as urethane or vinyl chloride, or a biodegradable resin such as PHA (polyhydroxyalkanoic acid) or PLA (polylactic acid).

[0056] The diameter of the central shaft 32 of one set of rotary rollers 3 is not particularly limited and may be, for example, 4 to 79 mm, 9 to 69 mm, or 14 to 59 mm. The length of the central shaft 32 is also not particularly limited and can be set appropriately according to the size of the outer container 5, but may be, for example, 50 to 560 mm, 100 to 530 mm, or 150 to 500 mm.

[0057] The material of the center shaft 32 is not particularly limited, and may be a metal such as stainless steel, a fluororesin such as PTFE (polytetrafluoroethylene) or PVDF (polyvinylidene fluoride), a thermoplastic resin such as urethane or vinyl chloride, or a biodegradable resin such as PHA (polyhydroxyalkanoic acid) or PLA (polylactic acid).

[0058] In the disintegrator 100, the movable range of the rotary roller 3 is preferably 1.0 to 8.0 mm, more preferably 1.1 to 6.0 mm, and even more preferably 1.2 to 5.0 mm. In this specification, the movable range of the rotary roller 3 refers to the range within which the roller 31 of the rotary roller 3 can move up and down, and is the distance between the rotary roller 3 (the lower end of the roller 31) and the screen 4 when the PHA agglomerates are sandwiched between the rotary roller 3 (the lower end of the roller 31) and the screen 4, pushing the rotary roller 3 up to its limit, in other words, when the lower end of the annular hollow portion of the roller 31 is in contact with the central shaft 32.

[0059] The size of the PHA agglomerates to be crushed is determined by the size of the range of motion of the rotary roller 3. Specifically, PHA agglomerates with a particle size larger than the range of motion of the rotary roller 3 are crushed by the rotary roller 3, and as a result, the particle size of the crushed PHA agglomerates becomes smaller than the range of motion of the rotary roller 3. Therefore, from the viewpoint of crushing the PHA agglomerates so that they can pass through a screen with a mesh size of 1.0 to 8.0 mm, it is preferable that the range of motion of the rotary roller 3 is 1.0 to 8.0 mm. The range of motion of the rotary roller 3 can be adjusted by adjusting the inner and outer diameters of the roller 31, the diameter of the central shaft, the installation height, etc.

[0060] From the viewpoint of more efficiently disintegrating PHA agglomerates, the clearance between the rotating roller 3 and the screen 4 in the disintegrator 100 is preferably 0.0 to 3.0 mm, more preferably 0.0 to 1.5 mm, and even more preferably 0.0 to 0.5 mm. In this specification, the clearance between the rotating roller 3 and the screen 4 refers to the distance between the rotating roller 3 (the lower end of the roller 31) and the screen 4 in a stationary state, i.e., when the disintegrator 100 is not operating and no PHA agglomerates or the like are present below the rotating roller 3; in other words, when the upper end of the annular hollow portion of the roller 31 is in contact with the central shaft 32. A clearance of 0.0 mm means that the rotating roller 3 and the screen 4 are in contact with each other in a stationary state, whereas a clearance of more than 0.0 mm means that the rotating roller 3 and the screen 4 are not in contact with each other in a stationary state.

[0061] In the disintegrator 100, the tip speed of the roller 3 is not particularly limited, but from the viewpoint that a high speed will cause wear of the roller when it comes into contact with the screen, it is preferably 0.3 to 7.2 m / s, more preferably 0.7 to 6.0 m / s, and even more preferably 1.0 to 5.0 m / s. The tip speed of the roller 3 is a value measured by the method described in the Examples.

[0062] Next, the specific steps of the sizing process using the crushing device 100 will be described. First, the vibration motor 61 is driven. The vibration of the vibration motor 61 is transmitted via the spring 62 to the outer container 5 and the screen 4 inside the outer container 5, vibrating the screen 4. A portion of the PHA agglomerates crushed in the crushing process passes through the vibrated screen 4 and is discharged and collected from the discharge port 52 as PHA particles having the desired particle size.

[0063] Normally, when PHA agglomerates containing a relatively high amount of water, such as a water content of 5.0 to 30.0% by weight, are crushed and sized, the PHA agglomerates may clog the screen, making sizing difficult. However, in the present manufacturing method, the vibration of screen 4 prevents the PHA agglomerates from clogging the openings of screen 4, while allowing PHA particles that can pass through the openings of screen 4 to be screened out.

[0064] The opening of the screen 4 in the disintegrator 100 is 1.0 to 8.0 mm, preferably 1.1 to 6.0 mm, and more preferably 1.3 to 5.0 mm. By setting the opening of the screen 4 to 1.0 to 8.0 mm, it is possible to selectively sieve out PHA particles having a particle size that satisfies both drying efficiency and handling properties of the PHA particles after drying (i.e., an average Feret size of 0.2 mm to 6.0 mm).

[0065] (Embodiment 2) FIG. 3 is a side view showing a schematic configuration of a crushing device used in the crushing step and sizing step according to another aspect (embodiment 2) of the present production method, and FIG. 4 is a top view showing a schematic configuration of the crushing device.

[0066] As shown in FIG. 3 , the crusher 101 according to the second embodiment is a device including a motor 1, a rotating shaft 2 connected to the motor, a set of rotating rollers 3a and blades 7 connected to the rotating shaft 2, a cylindrical outer container 5 in which a screen 4 is disposed, and a vibration drive unit 6 connected to the outer container 5.

[0067] The specific aspects of the crushing process and sizing process, as well as the crushing device, of embodiment 2 are the same as those of the crushing process and sizing process of embodiment 1 described above, except that the crushing device 101 has blade 7 as described above, in other words, the crushing process includes, in addition to crushing by a rotating roller, a step of crushing the PHA agglomerates by blade 7 installed on the top of the screen.

[0068] In the crushing process and sizing process of embodiment 2, the crushing process includes a step of crushing the PHA agglomerates using a blade installed above the screen, thereby making it possible to more efficiently crush the PHA agglomerates in the crushing process.

[0069] In the disintegrator 101, the clearance between the blade 7 and the screen 4 is preferably 5 to 30 mm, more preferably 6 to 20 mm, and even more preferably 8 to 15 mm. In this specification, the clearance between the blade 7 and the screen 4 refers to the distance between the blade 7 (the lower end of the blade 7) and the screen 4 in a stationary state, that is, when the disintegrator 101 is not operating and no PHA agglomerates or the like are present below the blade 7. Unlike the rotating roller 3, the blade 7 is not movable, and therefore, to prevent contact with the vibrating screen 4 and damage to the screen 4 due to such contact, it is preferable that the blade 7 have a clearance of 5 mm or more.

[0070] The length of the blade 7 provided in the disintegrator 101 is not particularly limited and may be, for example, 50 to 560 mm, 100 to 530 mm, or 150 to 500 mm. The width of the blade 7 is also not particularly limited and may be, for example, 10 to 500 mm, 50 to 300 mm, or 70 to 200 mm.

[0071] The installation angle of the blade 7 in the disintegrator 101 is not particularly limited, but from the viewpoint of more efficiently disintegrating the PHA agglomerates, it is preferable that the blade 7 be installed at an angle of 30 to 60° relative to the screen 4, and it is more preferable that the blade 7 be installed at an angle of 40 to 50°.

[0072] The material of the blade 7 is not particularly limited, and may be metal such as stainless steel, or fluororesin such as PTFE (polytetrafluoroethylene) or PVDF (polyvinylidene fluoride), thermoplastic resin such as urethane or vinyl chloride, or biodegradable resin such as PHA (polyhydroxyalkanoic acid) or PLA (polylactic acid).

[0073] Although Figures 3 and 4 show an example in which there is one set of rotating rollers 3a and one blade 7, the number of rotating rollers 3a and blades 7 provided in the crushing device according to the present manufacturing method is not limited to this, and for example, the crushing device according to the present manufacturing method may be provided with two or more sets of rotating rollers 3a and / or blades 7.

[0074] (Embodiment 3) FIG. 5 is a side view showing a schematic configuration of a crushing device used in the crushing step and sizing step according to another aspect (embodiment 3) of the present production method, and FIG. 6 is a top view showing a schematic configuration of the crushing device.

[0075] As shown in FIG. 3 , the crushing device 102 according to the third embodiment is a device including a motor 1, a rotating shaft 2 connected to the motor, a cylindrical outer container 5 in which a total of four sets of rotating rollers 3b and a screen 4 connected to the rotating shaft 2 are arranged, and a vibration drive unit 6 connected to the outer container 5.

[0076] The specific aspects of the crushing process and sizing process, as well as the crushing device, in embodiment 3 are the same as those of the crushing process and sizing process in embodiment 1 described above, except that the crushing device 102 has four sets of rotating rollers 3b as described above, in other words, the crushing process includes a step of crushing PHA agglomerates using four sets of rotating rollers.

[0077] In the crushing process and sizing process of embodiment 3, the crushing process includes a step of crushing the PHA agglomerates using four sets of rotating rollers installed above the screen, thereby making it possible to more efficiently crush the PHA agglomerates.

[0078] The specific configuration of the rotary roller 3b in the crusher 102 is the same as the configuration of the rotary roller 3 according to the first embodiment described above.

[0079] <Second crushing process and sizing process> In the present production method, the crushing step and the sizing step may be repeated. In other words, the present production method may include a second crushing step in which the PHA particles obtained in the step of crushing and sizing the PHA aggregates (first crushing step and sizing step) are further crushed, and a second sizing step in which the crushed PHA particles are sizing.

[0080] By carrying out the second crushing step and sizing step, i.e., by carrying out two-stage crushing and sizing, it is possible to more efficiently provide PHA particles with a relatively small particle size (e.g., PHA particles with an average Feret diameter of 2.0 mm).

[0081] The specific aspects of the second crushing step and sizing step are the same as those of the first crushing step and sizing step described above as embodiments 1 to 3, except that instead of PHA agglomerates, the PHA particles obtained in the first crushing step and sizing step are subjected to the crushing step (and subsequent sizing step).

[0082] When the present production method includes two stages of crushing and sizing, from the viewpoint of more efficiently providing PHA particles with a relatively small particle size, it is preferable that the mesh size of the screen used in the first crushing and sizing step (first screen) be larger than the mesh size of the screen used in the subsequent second crushing and sizing step (second screen). Specifically, it is preferable that the mesh size of the screen used in the first crushing and sizing step is 3.0 to 8.0 mm, and that the mesh size of the screen used in the second crushing and sizing step is 1.0 mm or more and less than 3.0 mm. It is more preferable that the mesh size of the screen used in the first crushing and sizing step is 2.5 to 8.0 mm, and that the mesh size of the screen used in the second crushing and sizing step is 1.0 mm or more and less than 2.5 mm.

[0083] According to another preferred embodiment of the present invention, a method for producing PHA particles comprising two stages of crushing and sizing steps may include the following configuration: a first crushing step in which PHA agglomerates having a water content of 5.0 to 30.0 wt % (WB) are crushed by being sandwiched between a first screen and a rotating roller installed above the first screen; a first sizing step in which the crushed PHA agglomerates are passed through the vibrated first screen; and a second sizing step in which the PHA agglomerates obtained by the first sizing step are crushed by being sandwiched between a first screen and a rotating roller installed above the first screen. A method for producing PHA particles, comprising: a second crushing step in which PHA particles having a water content of 5.0 to 30.0 weight % (WB) are crushed by pinching them between a second screen and a rotating roller installed above the second screen; and a second sizing step in which the crushed PHA particles are passed through the vibrated second screen, wherein the openings of the first screen are 3.0 to 8.0 mm, and the openings of the second screen are 1.0 mm or more and less than 3.0 mm.

[0084] <Drying process> The present production method preferably includes, after the sizing step, a drying step in which the PHA particles obtained in the sizing step are dried. The drying step can also be considered as a step in which dried PHA particles (dried PHA particles) are obtained.

[0085] In the drying step, the method for drying the PHA particles is not particularly limited, and examples thereof include drying methods using a tray dryer, band dryer, conveyor dryer, rotary dryer, or the like.

[0086] In the drying step, the PHA particles are preferably dried until the moisture content of the resulting PHA dry particles is 0.5% by weight or less. By keeping the moisture content of the resulting PHA dry particles at 0.5% by weight or less, it is possible to suppress a decrease in the molecular weight of the PHA when the PHA particles are melted for pelletization. From the above perspective, the moisture content of the PHA dry particles obtained in the drying step is preferably 0.5% by weight or less, more preferably 0.4% by weight or less, and even more preferably 0.3% by weight or less. The moisture content of PHA particles is the weight percentage of water in a total amount of 100% by weight of the PHA particles on a wet basis, and is a value measured by the method described in the Examples.

[0087] In the drying process, the temperature at which the PHA particles are dried is not particularly limited, but from the viewpoint of efficiently providing dried PHA particles with a sufficiently low moisture content (0.5% by weight or less), it is preferably 60°C or higher, and more preferably 80°C or higher.

[0088] [3.PHA particles] In one embodiment of the present invention, PHA particles (hereinafter sometimes referred to as "the present PHA particles") are provided which have an average Feret diameter of 0.2 mm to 6.0 mm, a proportion of particles of 100 μm or less of 50% or less, and a water content of 5.0 to 30.0 wt% (WB).

[0089] Because the PHA particles have the above-mentioned structure, they can be dried efficiently, and the generation of fine powder after drying is suppressed, making it possible to provide dried PHA particles that are easy to handle.

[0090] The present PHA particles can be suitably produced by the present production method. In other words, the PHA particles produced by the present production method are the present PHA particles. Therefore, the description of the present PHA particles, including preferred embodiments, also applies to the PHA particles produced by the present production method.

[0091] The average Feret diameter of the PHA particles is 0.2 mm to 6.0 mm, preferably 0.4 to 4 mm, and more preferably 0.8 to 2.5 mm. When the average Feret diameter of the PHA particles is 0.2 mm to 6.0 mm, efficient drying is possible and generation of fine powder after drying is suppressed. The average Feret diameter of the PHA particles is a value measured by the method described in the Examples.

[0092] The proportion of particles of 100 μm or less (PHA particles) in the present PHA particles is 50% or less, preferably 40% or less, and more preferably 33% or less. The proportion of particles of 100 μm or less in the present PHA particles means the amount of fine powder in the PHA particles, and a proportion of particles of 100 μm or less of 50% means that the PHA particles and the amount of fine powder after drying of the PHA particles are sufficiently small.

[0093] From the viewpoint of providing PHA particles with less fine powder content after drying, it is preferable that the proportion of particles of 100 μm or less in the PHA particles is as low as possible, and the lower limit is not particularly limited, but may be, for example, 10% or more, 5% or more, or 1% or more, or even 0%.

[0094] The water content of the PHA particles is 5.0 to 30.0 wt% (WB), preferably 8 wt% or more and less than 25 wt% (WB), more preferably 8 to 23 wt% (WB), even more preferably 10 to 20 wt% (WB), and even more preferably 10 to 17 wt% (WB). Having a water content of 5.0 to 30.0 wt% (WB) of the PHA particles allows for efficient drying and suppresses the generation of fine powder after drying. The water content (WB) of the PHA particles is the weight percentage of water in 100 wt% of the total amount of PHA particles, and is a value measured by the method described in the Examples.

[0095] The particle shape of the present PHA particles is not particularly limited, and may be cylindrical, elliptical, spherical, cubic, rectangular, or the like.

[0096] The present PHA particles and the dried PHA particles obtained by drying the present PHA particles can be molded by a known molding method, such as injection molding, extrusion molding, blow molding, or compression molding, and used as molded articles.The present PHA particles and the dried PHA particles obtained by drying the present PHA particles can also be foamed by a known method and further molded, and used as foamed molded articles.The molded articles and foamed molded articles made from these present PHA particles and the dried PHA particles obtained by drying the present PHA particles can be used for various purposes, such as paper, film, sheet, tube, plate, rod, container (e.g., bottle container), bag, parts, etc. [Example]

[0097] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, "P3HB3HH" is used as "PHA," and "PHA" in the examples can also be read as "P3HB3HH."

[0098] [Measurement method] Measurements in the examples and comparative examples were carried out by the following methods.

[0099] (moisture content) The moisture content of the PHA agglomerates and PHA particles was measured using a heat-drying moisture meter ML-50 (manufactured by A&D Co., Ltd.). Specifically, the weight (w1) of the target PHA agglomerates or PHA particles was first measured, and the target PHA agglomerates or PHA particles after weight measurement were heated at 105°C. The heating was terminated when the rate of weight change fell below 0.05 wt% (WB) / min. The weight (w2) of the target PHA agglomerates or PHA particles at the end of heating was measured, and the change in weight of the target PHA agglomerates or PHA particles before and after heating (= w1 - w2) was taken as the amount of water contained in the weight of the target PHA agglomerates or PHA particles. The moisture content of the target PHA agglomerates or PHA particles was calculated using the following formula: Moisture content (wt%) of the target PHA agglomerates or PHA particles = {(w1-W2) / (w1)} x 100.

[0100] (pH of PHA aqueous suspension) The pH of the PHA aqueous suspension was measured using a pH meter (9652-10D, manufactured by HORIBA).

[0101] (Average Feret diameter of PHA aggregates) The average Feret diameter of the PHA agglomerates was measured as follows. 5 kg of PHA agglomerates were weighed out, and the cumulative undersize distribution of the 5 kg of PHA particles was measured using a metal sieve. The 5 kg of PHA agglomerates were sieved again using a metal sieve with a mesh size equal to or larger than D50 of the measured cumulative undersize distribution, and images of the 10 PHA agglomerates remaining on the sieve were taken. The captured images were analyzed using ImageJ (ver. 1.50), and the Feret diameters of the individual 10 PHA agglomerates were calculated. The simple average of the Feret diameters of the 10 PHA agglomerates was taken as the average Feret diameter of the PHA agglomerates.

[0102] (Average Feret diameter of PHA particles) The average Feret diameter of PHA particles was measured as follows. 1 kg of PHA particles was weighed out, and the cumulative undersize distribution of the 1 kg of PHA particles was measured using a metal sieve. 1 kg of PHA particles was sieved again using a metal sieve with a mesh size equal to or larger than D50 of the measured cumulative undersize distribution, and images of 10 PHA particles remaining on the sieve were taken. The captured images were analyzed using ImageJ (ver. 1.50), and the individual Feret diameters of the 10 PHA particles were calculated. The simple average of the Feret diameters of the 10 PHA particles was used as the average Feret diameter of the PHA particles.

[0103] (Processing volume) First, for the disintegrator used in each example, the screen was vibrated and the rotary roller (and blade) was rotated without any PHA agglomerates being added. A predetermined amount (W [kg]) of PHA agglomerates was added to the disintegrator within 5 seconds, and the time (T [sec]) required for PHA particles equivalent to 90% by weight of the added PHA agglomerates to be discharged was recorded. The throughput [kg / hr] was calculated based on the following formula: Processing capacity [kg / hr] = W [kg] / T [sec] × 3600 [sec / hr].

[0104] The larger the throughput, the more efficient the disintegration and granulation of PHA agglomerates becomes, in other words, the more efficiently PHA particles can be provided.

[0105] (Tip speed of rotating roller) The tip speed of the rotating roller was calculated as follows: The maximum radius of the rotating part of the rotating roller (i.e., the length of the central axis of the rotating roller) was measured and defined as R [m], and the number of rotations of the rotating part per second was measured and defined as ω [rpm]. The tip speed of the rotating roller was calculated based on the following formula: Tip speed of the rotating roller [m / s] = 2 × pi × R × ω ÷ 60 [m / s].

[0106] (Fine powder rate) After the sizing process, 10 g of the PHA particles were placed on a metal sieve with 710 μm openings, and PHA particles with a particle size of 710 μm or less were selected and their weight was measured as W g. The resulting PHA particles with a particle size of 710 μm or less were then placed in a MASTERSIZER 3000 laser diffraction / scattering particle size distribution analyzer (Malvern) connected to an Aero S dry dispersion unit, and their particle size distribution was measured. From the measured volume-based particle size distribution, the volume fraction of PHA particles with a size of 100 μm or less was calculated and designated P as P%. The fine powder fraction of the PHA particles was calculated using the following formula: PHA particle fine powder fraction [%] = W × P / 10.

[0107] (Drying time) After the sizing process, 10 g of PHA particles were placed in a stainless steel tray (length x width x depth = 150 mm x 125 mm x 2 mm). Fifteen stainless steel trays containing 10 g of PHA particles were prepared, and the particle surfaces were smoothed to prevent crushing. Each stainless steel tray was then placed in a shelf dryer (EYELA WFO-700) heated to 90°C to dry the PHA particles. Each tray was removed every 5 minutes from the start of loading, and the PHA particles in the tray were thoroughly stirred. The moisture content of the PHA particles in the tray was then measured using an infrared moisture meter (manufactured by A&D Co., Ltd.). The time it took for the moisture content of the measured PHA particles to reach 0.5% or less was defined as the drying time of the PHA particles.

[0108] Example 1 (Preparation of bacterial culture solution) Ralstonia eutropha, as described in International Publication No. WO 2019 / 142717, was cultured using the method described in paragraphs

[0041] to

[0048] of the same document to obtain a bacterial cell culture broth containing PHA. The obtained PHA was a copolymer consisting of 3HB repeating units and 3HH repeating units (i.e., poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)), and the composition ratio of the repeating units in the PHA (3HB unit / 3HH unit composition ratio) was 94 / 6 (mol / mol).

[0109] (inactivation) The bacterial culture solution obtained above was sterilized by heating and stirring at an internal temperature of 60 to 70°C for 7 hours, and then ion-exchanged water at room temperature was added to dilute the solution, followed by cooling to 55°C to obtain an inactivated culture solution.

[0110] (alkali treatment) To the inactivated culture solution obtained above, a 30 wt % aqueous solution of sodium hydroxide was added to adjust the pH to 9.5. While maintaining this solution at 70°C, the pH was maintained at 9.5 for 6 hours by continuing to add a 30 wt % aqueous solution of sodium hydroxide, thereby obtaining a PHA aqueous suspension.

[0111] (Neutralization and cell wall decomposition enzyme treatment) To the PHA aqueous suspension obtained above, 10% sulfuric acid was added to adjust the pH to 6.5. To the neutralized PHA aqueous suspension, 0.05 phr of lysozyme (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), a cell wall decomposing enzyme, was added, and the suspension was kept at 50°C for 2 hours.

[0112] (Proteolytic enzyme treatment) The pH of the PHA aqueous suspension was adjusted to 8.5±0.2 using 30% by weight sodium hydroxide, followed by the addition of 0.2 phr of Alcalase (Novozymes), a protease, and the suspension was maintained at 50°C for 2 hours or more while controlling the pH at 8.5 with 30% by weight sodium hydroxide.

[0113] (Surfactant addition treatment) An alkaline aqueous solution was added to the aqueous PHA suspension after the enzyme treatment obtained above to adjust the pH to 11 or higher, and then 1.0 wt% of sodium dodecyl sulfate (Kao) based on the weight of the aqueous PHA suspension was added, followed by holding at 45°C for 2 hours. At this time, the solids concentration of the aqueous PHA suspension was 15%.

[0114] (Centrifugal washing) The aqueous PHA suspension was centrifuged (4000 G, 10 minutes), and the supernatant was removed to obtain a 2x concentrated aqueous PHA suspension. To this concentrated aqueous PHA suspension, an equal amount of sodium hydroxide to the removed supernatant was added, and the mixture was centrifuged again (4000 G, 10 minutes), and the supernatant was removed. This procedure was repeated four times, and the aqueous PHA suspension was centrifuged and washed.

[0115] (pH adjustment) The PHA aqueous suspension obtained above was diluted with ion-exchanged water so that the solid content concentration in the suspension became 15% by weight, and the suspension was kept at 60° C. Then, 10% sulfuric acid was added to adjust the pH to 3.0.

[0116] (filter press filtration) The PHA aqueous suspension was compressed at a pressure of 0.4 MPa using a filter press (ISD type 360, filter chamber thickness 25 mm, manufactured by Ishigaki Co., Ltd.) to obtain a filter cake. This filter cake was compressed again at a pressure of 0.7 MPa, and the air blow pressure was adjusted to 0.4 MPa and air blown for 20 minutes to obtain a PHA aggregate. The water content of the obtained PHA aggregate was 15.0 wt% (WB).

[0117] (coarse crushing) The resulting PHA aggregates were fractured to an average Feret diameter of 200 mm.

[0118] (Crushing process and granulation process) 6.0 kg of the PHA agglomerates were placed in a crusher (vibrating sieve with crusher 70M-1S (manufactured by KS Links Co., Ltd.)) with the structure shown in Figure 1. The PHA agglomerates were crushed and sized while the vibrating sieve was running (the screen was vibrating). The crusher was equipped with a stainless steel wire screen with a mesh size of 4.0 mm (4.7 mesh) and two sets of rotating rollers attached diagonally from the rotating shaft. Each set of rotating rollers had eight rollers mounted on a Teflon double cylinder (25 mm high, 50 mm outer diameter, 30 mm inner diameter) attached to a stainless steel central shaft with a shaft diameter of 21 mm. The range of motion of the rotating rollers was 4.5 mm, and the clearance between the screen and the rotating rollers was 2.0 mm. The tip speed of the rotating rollers was 1.2 m / s. The processing speed in the crushing and sizing processes, the average Feret diameter of the resulting PHA particles, the amount of fine powder, and the drying time were measured and evaluated. The results are shown in Table 1. The dried PHA particles obtained after drying contained little fine powder and were easy to handle.

[0119] Example 2 The same procedures as in Example 1 were carried out up to the crushing step.

[0120] (Crushing process and granulation process) 6.0 kg of the coarsely crushed PHA agglomerates were placed in a crusher (vibrating sieve with crusher 70M-1S (manufactured by KS Links Co., Ltd.)) with the structure shown in Figure 3. The PHA agglomerates were crushed and sized while the vibrating sieve was running (the screen was vibrating). The crusher was equipped with a stainless steel wire screen with a mesh size of 4.0 mm (4.7 mesh), a set of rotating rollers, and blades attached diagonally to the rotating rollers. Each set of rotating rollers had eight rollers attached to a stainless steel central shaft with a shaft diameter of 21 mm, each roller being a double cylinder made of Teflon (25 mm high, 50 mm outer diameter, 30 mm inner diameter). The range of motion of the rotating rollers was 4.5 mm, and the clearance between the screen and the rotating rollers was 2.0 mm. The tip speed of the rotating rollers was 1.2 m / s. The blade was made of stainless steel, 0.2 m long and 3 mm thick, and had a plate shape. It was attached to the rotating shaft at a 45° angle to the screen. The clearance between the blade and the screen was 10 mm. The processing speed in the crushing and sizing processes, as well as the average Feret diameter, amount of fine powder, and drying time of the resulting PHA particles were measured and evaluated. The results are shown in Table 1. The dried PHA particles obtained after drying contained little fine powder and were easy to handle.

[0121] Example 3 (Preparation of bacterial culture solution) Capriavidus necator, described in International Publication No. WO 2021 / 206155, was cultured using the method described in paragraphs

[0051] to

[0054] of the same document to obtain a bacterial cell culture broth containing PHA. The obtained PHA was a copolymer consisting of 3HB repeating units and 3HH repeating units (i.e., poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)), and the composition ratio of the repeating units in the PHA (composition ratio of 3HB units / 3HH units) was 84 / 16 (mol / mol).

[0122] (inactivation) The bacterial culture solution obtained above was sterilized by heating and stirring at an internal temperature of 60 to 70°C for 7 hours, and then ion-exchanged water at room temperature was added to dilute the solution, followed by cooling to 55°C to obtain an inactivated culture solution.

[0123] (alkali treatment) To the inactivated culture solution obtained above, a 30 wt % aqueous solution of sodium hydroxide was added to adjust the pH to 9.5. The solution was maintained at 70°C for 6 hours by continuing to add the 30 wt % aqueous solution of sodium hydroxide, to obtain a PHA aqueous suspension.

[0124] (Neutralization treatment) To the PHA aqueous suspension obtained above, 10% sulfuric acid was added to adjust the pH to 8.5.

[0125] (Proteolytic enzyme treatment) The pH of the PHA aqueous suspension was adjusted to 8.5±0.2 using 30% by weight sodium hydroxide, followed by the addition of 0.2 phr of Alcalase (Novozymes), a protease, and the suspension was maintained at 50°C for 2 hours or more while controlling the pH at 8.5 with 30% by weight sodium hydroxide.

[0126] (Surfactant addition treatment) An alkaline aqueous solution was added to the aqueous PHA suspension after the enzyme treatment obtained above to adjust the pH to 11 or higher, and then 1.0 wt% of sodium dodecyl sulfate (Kao) based on the weight of the aqueous PHA suspension was added, followed by holding at 45°C for 2 hours. At this time, the solids concentration of the aqueous PHA suspension was 15%.

[0127] (Centrifugal washing) The aqueous PHA suspension was centrifuged (4000 G, 10 minutes), and the supernatant was removed to obtain a 2x concentrated aqueous PHA suspension. To this concentrated aqueous PHA suspension, an equal amount of sodium hydroxide to the removed supernatant was added, and the mixture was centrifuged again (4000 G, 10 minutes), and the supernatant was removed. This procedure was repeated four times, and the aqueous PHA suspension was centrifuged and washed.

[0128] (pH adjustment) The PHA aqueous suspension obtained above was diluted with ion-exchanged water so that the solid content concentration in the suspension became 15% by weight, and the suspension was kept at 60° C. Then, 10% sulfuric acid was added to adjust the pH to 3.0.

[0129] (filter press filtration) The PHA aqueous suspension was compressed at a pressure of 0.4 MPa using a filter press (ISD type 360, filter chamber thickness 25 mm, manufactured by Ishigaki Co., Ltd.) to obtain a filter cake. This filter cake was compressed again at a pressure of 0.7 MPa, and the air blow pressure was adjusted to 0.4 MPa and air blown for 20 minutes to obtain a PHA aggregate. The water content of the obtained PHA aggregate was 15.0 wt% (WB).

[0130] (coarse crushing) The resulting PHA aggregates were fractured to an average Feret diameter of 200 mm.

[0131] (Crushing process and granulation process) 6.0 kg of the PHA agglomerates were placed in a crusher (vibrating sieve with crusher 70M-1S (manufactured by KS Links Co., Ltd.)) with the structure shown in Figure 1. The PHA agglomerates were crushed and sized with the vibrating sieve in operation (the screen was vibrating). The crusher was equipped with a stainless steel wire screen with a mesh size of 4.0 mm (4.7 mesh) and two sets of rotating rollers attached diagonally from the rotating shaft. Each set of rotating rollers had eight rollers mounted on a Teflon double cylinder (25 mm high, 50 mm outer diameter, 30 mm inner diameter) attached to a stainless steel central shaft with a shaft diameter of 21 mm. The range of motion of the rotating rollers was 1.5 mm, and the clearance between the screen and the rotating rollers was 0.1 mm. The tip speed of the rotating rollers was 1.2 m / s. The processing speed in the crushing and sizing processes, the average Feret diameter of the resulting PHA particles, the amount of fine powder, and the drying time were measured and evaluated. The results are shown in Table 1. The dried PHA particles obtained after drying contained little fine powder and were easy to handle.

[0132] Example 4 The same procedures as in Example 1 were carried out up to the crushing step.

[0133] (Crushing process and granulation process) 6.0 kg of the coarsely crushed PHA agglomerates were placed in a crusher (vibrating sieve with crusher 70M-1S (manufactured by KS Links Co., Ltd.)) with the structure shown in Figure 3. The PHA agglomerates were crushed and sized while the vibrating sieve was running (the screen was vibrating). The crusher was equipped with a stainless steel wire screen with a mesh size of 4.0 mm (4.7 mesh), a set of rotating rollers, and blades attached diagonally to the rotating rollers. Each set of rotating rollers had eight rollers attached to a stainless steel central shaft with a shaft diameter of 21 mm, each roller being a double cylinder made of Teflon (25 mm high, 50 mm outer diameter, 30 mm inner diameter). The range of motion of the rotating rollers was 4.5 mm, and the clearance between the screen and the rotating rollers was 2.0 mm. The tip speed of the rotating rollers was 1.2 m / s. The blade was made of stainless steel, 0.2 m long and 3 mm thick, and had a plate shape. It was attached to the rotating shaft at a 45° angle to the screen. The clearance between the blade and the screen was 40 mm. The processing speed in the crushing and sizing processes, as well as the average Feret diameter, amount of fine powder, and drying time of the resulting PHA particles were measured and evaluated. The results are shown in Table 1. The dried PHA particles obtained after drying contained little fine powder and were easy to handle.

[0134] Example 5 The same procedures as in Example 1 were carried out up to the crushing step.

[0135] (Crushing process and granulation process) 6.0 kg of the coarsely crushed PHA agglomerates were placed in a crusher (vibrating sieve with crusher 70M-1S (manufactured by KS Links Co., Ltd.)) with the structure shown in Figure 3. The PHA agglomerates were crushed and sized with the vibrating sieve in operation (the screen was vibrating). The crusher was equipped with a stainless steel wire screen with a mesh size of 5.4 mm (4 mesh), a set of rotating rollers, and blades attached diagonally to the rotating rollers. Each set of rotating rollers had eight rollers mounted on a stainless steel central shaft with a shaft diameter of 21 mm, each roller being a double cylinder made of Teflon (25 mm high, 50 mm outer diameter, 30 mm inner diameter). The range of motion of the rotating rollers was 4.5 mm, and the clearance between the screen and the rotating rollers was 2.0 mm. The tip speed of the rotating rollers was 1.2 m / s. The blade was made of stainless steel, 0.2 m long and 3 mm thick, and had a plate shape. It was attached to the rotating shaft at a 45° angle to the screen. The clearance between the blade and the screen was 10 mm. The processing speed in the crushing and sizing processes, as well as the average Feret diameter, amount of fine powder, and drying time of the resulting PHA particles were measured and evaluated. The results are shown in Table 1. The dried PHA particles obtained after drying contained little fine powder and were easy to handle.

[0136] Example 6 The same procedures as in Example 1 were carried out up to the crushing step.

[0137] (Crushing process and granulation process) 6.0 kg of the coarsely crushed PHA agglomerates were placed in a crusher (vibrating sieve with crusher 70M-1S (manufactured by KS Links Co., Ltd.)) with the structure shown in Figure 1. The PHA agglomerates were crushed and sized while the vibrating sieve was running (the screen was vibrating). The crusher was equipped with a stainless steel wire screen with a mesh size of 1.4 mm (12 mesh) and two sets of rotating rollers attached diagonally from the rotating shaft. Each set of rotating rollers had eight rollers attached to a stainless steel central shaft with a shaft diameter of 21 mm, each on a Teflon double cylinder (25 mm high, 50 mm outer diameter, 30 mm inner diameter). The range of motion of the rotating rollers was 1.5 mm, and the clearance between the screen and the rotating rollers was 0.1 mm. The tip speed of the rotating rollers was 1.2 m / s. The processing speed in the crushing and sizing processes, the average Feret diameter of the resulting PHA particles, the amount of fine powder, and the drying time were measured and evaluated. The results are shown in Table 1. The dried PHA particles obtained after drying contained little fine powder and were easy to handle.

[0138] Comparative Example 1 The same procedures as in Example 1 were carried out up to the crushing step.

[0139] (Crushing and granulation) 6.0 kg of the coarsely crushed PHA agglomerates were placed in a crusher (vibrating sieve with crusher 70M-1S (manufactured by KS Links Co., Ltd.)) with the structure shown in Figure 1. The PHA agglomerates were crushed and sized without moving the vibrating sieve (vibrating the screen). The crusher was equipped with a stainless steel wire screen with a mesh size of 4.0 mm (4.7 mesh) and two sets of rotating rollers attached diagonally from the rotating shaft. Each set of rotating rollers had eight rollers mounted on a Teflon double cylinder (25 mm high, 50 mm outer diameter, 30 mm inner diameter) attached to a stainless steel central shaft with a shaft diameter of 21 mm. The range of motion of the rotating rollers was 4.5 mm, and the clearance between the screen and the rotating rollers was 2.0 mm. The tip speed of the rotating rollers was 1.2 m / s. However, in this disintegration operation, the screen was clogged with the PHA agglomerates that were added, and it was not possible to obtain PHA particles.

[0140] Comparative Example 2 The same procedures as in Example 1 were carried out up to the crushing step.

[0141] The crushed PHA aggregates were allowed to stand for 4 days in a room at 30° C. to remove moisture. The water content of the resulting PHA aggregates was 4%.

[0142] (Crushing and granulation) 6.0 kg of the PHA agglomerates with a moisture content of 4.0 wt% were placed in a crusher (vibrating sieve with crusher 70M-1S (manufactured by KS Links Co., Ltd.)) with the structure shown in Figure 1. The PHA agglomerates were crushed and sized while the vibrating sieve was running (the screen was vibrating). The crusher was equipped with a stainless steel wire screen with a mesh size of 1.4 mm (12 mesh) and two sets of rotating rollers attached diagonally from the rotating shaft. Each set of rotating rollers had eight rollers mounted on a Teflon double cylinder (25 mm high, 50 mm outer diameter, 30 mm inner diameter) attached to a stainless steel central shaft with a shaft diameter of 21 mm. The range of motion of the rotating rollers was 1.5 mm, and the clearance between the screen and the rotating rollers was 0.1 mm. The tip speed of the rotating rollers was 1.2 m / s. The processing speed in the crushing and sizing processes, the average Feret diameter of the resulting PHA particles, the amount of fine powder, and the drying time were measured and evaluated. The results are shown in Table 1. The dried PHA particles obtained after drying contained a large amount of fine powder and were difficult to handle.

[0143] Comparative Example 3 The same procedures as in Example 1 were carried out up to the pH adjustment procedure.

[0144] (filter press filtration) The pH-adjusted PHA aqueous suspension was compressed at a pressure of 0.4 MPa using a filter press (ISD type 360, filter chamber thickness 25 mm, manufactured by Ishigaki Co., Ltd.) to obtain a filter cake. This filter cake was compressed again at a pressure of 0.7 MPa, and the air blow pressure was adjusted to 0.4 MPa and air blown for 10 minutes to obtain a PHA aggregate. The water content of the obtained PHA aggregate was 35.0 wt% (WB).

[0145] (coarse crushing) The resulting PHA aggregates were fractured to an average Feret diameter of 200 mm.

[0146] (Crushing and granulation) 6.0 kg of the PHA agglomerates with a moisture content of 35.0 wt% were placed in a crusher (vibrating sieve with crusher 70M-1S (manufactured by KS Links Co., Ltd.)) with the structure shown in Figure 1. The PHA agglomerates were crushed and sized while the vibrating sieve was running (the screen was vibrating). The crusher was equipped with a stainless steel wire screen with a mesh size of 1.4 mm (12 mesh) and two sets of rotating rollers attached diagonally from the rotating shaft. Each set of rotating rollers had eight rollers mounted on a Teflon double cylinder (25 mm high, 50 mm outer diameter, 30 mm inner diameter) attached to a stainless steel central shaft with a shaft diameter of 21 mm. The range of motion of the rotating rollers was 1.5 mm, and the clearance between the screen and the rotating rollers was 0.1 mm. The tip speed of the rotating rollers was 1.2 m / s. However, in this disintegration operation, the screen was clogged with the PHA agglomerates that were added, and it was not possible to obtain PHA particles.

[0147] Comparative Example 4 The same procedures as in Example 1 were carried out up to the crushing step.

[0148] (Crushing and granulation) 6.0 kg of the coarsely crushed PHA agglomerates were placed in a crusher (vibrating sieve with crusher 70M-1S (manufactured by KS Links Co., Ltd.)) with the structure shown in Figure 1. The PHA agglomerates were crushed and sized while the vibrating sieve was in operation (the screen was vibrating). The crusher was equipped with a stainless steel wire screen with a mesh size of 10.8 mm (2 mesh) and two sets of rotating rollers attached diagonally from the rotating shaft. Each set of rotating rollers had eight rollers mounted on a Teflon double cylinder (25 mm high, 50 mm outer diameter, 30 mm inner diameter) attached to a stainless steel central shaft with a shaft diameter of 21 mm. The range of motion of the rotating rollers was 4.5 mm, and the clearance between the screen and the rotating rollers was 2.0 mm. The tip speed of the rotating rollers was 1.2 m / s. The processing speed in the crushing step and the sieving step, the average Feret diameter of the obtained PHA particles, the amount of fine powder, and the drying time were measured or evaluated. The results are shown in Table 1.

[0149] [Table 1]

[0150] Example 7 PHA aggregates were obtained by the same procedure as in Example 5, and then subjected to the crushing and sizing steps (first crushing step and sizing step).

[0151] (Second crushing process and sizing process) 6.0 kg of the PHA particles obtained in the first crushing and sizing steps were again placed in a crusher (vibrating sieve with crusher 70M-1S (manufactured by KS Links Co., Ltd.)) having the structure shown in Figure 1. The vibrating sieve was operated (the screen was vibrating) to crush and size the PHA agglomerates. The crusher was equipped with a stainless steel wire screen with a mesh size of 1.4 mm (12 mesh) and two sets of rotating rollers attached diagonally from the rotating shaft. Each set of rotating rollers had eight rollers mounted on a Teflon double cylinder (25 mm high, 50 mm outer diameter, 30 mm inner diameter) attached to a stainless steel central shaft with a shaft diameter of 21 mm. The range of motion of the rotating rollers was 1.5 mm, and the clearance between the screen and the rotating rollers was 0.1 mm. The tip speed of the rotating rollers was 1.2 m / s. The processing speed in the second crushing step and the sizing step, and the average Feret diameter, amount of fine powder, and drying time of the PHA particles obtained in the second crushing step and the sizing step were measured and evaluated. The results are shown in Table 2. The dried PHA particles obtained after drying contained little fine powder and were easy to handle.

[0152] Example 8 PHA aggregates were obtained by the same procedure as in Example 5, and then subjected to the crushing and sizing steps (first crushing step and sizing step).

[0153] (Second crushing process and sizing process) 6.0 kg of the PHA particles obtained in the first crushing and sizing steps were again placed in a crusher (vibrating sieve with crusher 70M-1S (manufactured by KS Links Co., Ltd.)) having the structure shown in Figure 1, and the PHA agglomerates were crushed and sized while the vibrating sieve was running (the screen was vibrating). The crusher was equipped with a stainless steel wire screen with a mesh size of 1.4 mm (12 mesh) and four sets of rotating rollers attached at positions of 0°, 90°, 180°, and 270° from the rotation axis. Each set of rotating rollers had eight rollers attached to a stainless steel central shaft with a shaft diameter of 21 mm, each on a Teflon double cylinder (25 mm high, 50 mm outer diameter, 30 mm inner diameter). The range of motion of the rotating rollers was 1.5 mm, and the clearance between the screen and the rotating rollers was 0.1 mm. The tip speed of the rotating roller was 1.2 m / s. The processing speed in the second crushing step and sizing step, as well as the average Feret diameter, amount of fine powder, and drying time of the PHA particles obtained in the second crushing step and sizing step were measured and evaluated. The results are shown in Table 2. The dried PHA particles obtained after drying contained little fine powder and were easy to handle.

[0154] Example 9 PHA aggregates were obtained by the same procedure as in Example 5, and then subjected to the crushing and sizing steps (first crushing step and sizing step).

[0155] (Second crushing process and sizing process) 6.0 kg of the PHA particles obtained in the first crushing and sizing steps were again placed in a crusher (vibrating sieve with crusher 70M-1S (manufactured by KS Links Co., Ltd.)) having the structure shown in Figure 1. The vibrating sieve was operated (the screen was vibrating) to crush and size the PHA agglomerates. The crusher was equipped with a stainless steel wire screen with a mesh size of 1.4 mm (12 mesh) and two sets of rotating rollers attached diagonally from the rotating shaft. Each set of rotating rollers had eight rollers attached to a stainless steel central shaft with a shaft diameter of 21 mm, each on a Teflon double cylinder (25 mm high, 50 mm outer diameter, 30 mm inner diameter). The range of motion of the rotating rollers was 15.0 mm, and the clearance between the screen and the rotating rollers was 0.1 mm. The tip speed of the rotating rollers was 1.2 m / s. The processing speed in the second crushing step and the sizing step, and the average Feret diameter, amount of fine powder, and drying time of the PHA particles obtained in the second crushing step and the sizing step were measured and evaluated. The results are shown in Table 2. The dried PHA particles obtained after drying contained little fine powder and were easy to handle.

[0156] Example 10 PHA aggregates were obtained by the same procedure as in Example 5, and then subjected to the crushing and sizing steps (first crushing step and sizing step).

[0157] (Second crushing process and sizing process) 6.0 kg of the PHA particles obtained in the first crushing and sizing steps were again placed in a crusher (vibrating sieve with crusher 70M-1S (manufactured by KS Links Co., Ltd.)) having the structure shown in Figure 1. The vibrating sieve was operated (the screen was vibrating) to crush and size the PHA agglomerates. The crusher was equipped with a stainless steel wire screen with a mesh size of 1.4 mm (12 mesh) and two sets of rotating rollers attached diagonally from the rotating shaft. Each set of rotating rollers had eight rollers mounted on a Teflon double cylinder (25 mm high, 50 mm outer diameter, 30 mm inner diameter) attached to a stainless steel central shaft with a shaft diameter of 21 mm. The range of motion of the rotating rollers was 1.5 mm, and the clearance between the screen and the rotating rollers was 4.0 mm. The tip speed of the rotating rollers was 1.2 m / s. The processing speed in the second crushing step and the sizing step, and the average Feret diameter, amount of fine powder, and drying time of the PHA particles obtained in the second crushing step and the sizing step were measured and evaluated. The results are shown in Table 2. The dried PHA particles obtained after drying contained little fine powder and were easy to handle.

[0158] [Table 2]

[0159] (summary) A comparison of Examples 1 to 10 with Comparative Examples 1 to 4 showed that in order to provide PHA particles that can be dried efficiently (in a short drying time), have little fine powder, and are easy to handle after drying, (1) it is necessary to vibrate the screen during the sizing process, (2) it is necessary to adjust the moisture content of the PHA agglomerates to 5.0 to 30.0% by weight, and (3) it is necessary to use a screen with a mesh size of 1.0 to 8.0 mm to perform sizing. [Industrial Applicability]

[0160] This production method can provide PHA particles that can be dried efficiently and have excellent handleability after drying. Furthermore, the PHA particles produced by this production method and molded articles using dried PHA particles obtained by drying the PHA particles produced by this production method can be suitably used in agriculture, fisheries, forestry, horticulture, medicine, hygiene products, clothing, non-clothing, packaging, automobiles, building materials, and other fields. [Explanation of symbols]

[0161] 1 motor 2 rotation axes 3, 3a, 3b Rotating roller 4 screens 5 Outer packaging 6 Vibration drive unit 7 Blades 31, 31a, 31b rollers 32, 32a, 32b center axis 51 Inlet 52 Outlet 61 Vibration motor 62 Spring 63 weight 100, 101, 102 Crushing device

Claims

1. a crushing step of crushing polyhydroxyalkanoate agglomerates having a moisture content of 5.0 to 30.0% by weight (wet basis) by sandwiching the agglomerates between a screen and a rotating roller installed above the screen; and a sizing step of passing the disintegrated polyhydroxyalkanoate agglomerates through the vibrated screen, The method for producing polyhydroxyalkanoate particles, wherein the opening of the screen is 1.0 to 8.0 mm.

2. 2. The method for producing polyhydroxyalkanoate particles according to claim 1, wherein the disintegration step further comprises a step of disintegrating polyhydroxyalkanoate agglomerates with a blade installed above the screen.

3. 2. The method for producing polyhydroxyalkanoate particles according to claim 1, wherein the range of motion of the roller is 1.0 to 8.0 mm.

4. 2. The method for producing polyhydroxyalkanoate particles according to claim 1, wherein the clearance between the roller and the screen is 0.0 to 3.0 mm.

5. 3. The method for producing polyhydroxyalkanoate particles according to claim 2, wherein the clearance between the blade and the screen is 5 to 30 mm.

6. 2. The method for producing polyhydroxyalkanoate particles according to claim 1, wherein the tip speed of the roller is 0.3 to 7.2 m / s.

7. 2. The method for producing polyhydroxyalkanoate particles according to claim 1, further comprising a filtration step of filtering the aqueous suspension containing the polyhydroxyalkanoate to obtain polyhydroxyalkanoate agglomerates before the disintegration step.

8. 2. The method for producing polyhydroxyalkanoate particles according to claim 1, further comprising a drying step of drying the polyhydroxyalkanoate particles after the sizing step.

9. The average Feret diameter is 0.2 mm to 6.0 mm, The proportion of particles of 100 μm or less is 50% or less, and Polyhydroxyalkanoate particles having a moisture content of 5.0 to 30.0% by weight (wet basis).

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