Method of manufacturing resin molding

Abstract

To provide a method of manufacturing a resin molding capable of reducing generation of fine powders.SOLUTION: A method of manufacturing a resin molding includes: a strand preparation step of extruding a wet resin from a die of a granulator to obtain a strand of the wet resin; and a pelletizing step of pelletizing the wet resin by applying a crushing blade at a portion 2 to 20 mm away from a surface of the die with respect to the obtained strand. A contact area between the strand and the crushing blade is 0.3 cm2 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a resin molded article. [Background technology]

[0002] For the purpose of improving the handleability of polymers, resins, or compositions containing them, a pelletizing (granulation) technique is known. As a technique for pelletizing polymers, resins, or compositions containing them, wet granulation is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-159788 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned conventional techniques are not sufficient from the viewpoint of preventing the generation of fine powder from the obtained resin molded article, and there is room for further improvement.

[0005] One embodiment of the present invention has been made in consideration of the above-mentioned problems, and its object is to provide a new method for producing a resin molded body that can provide a resin molded body with reduced generation of fine powder. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems and have completed the present invention.

[0007] An embodiment of the present invention includes the following configuration.

[0008] [1] A method for manufacturing a granulator, comprising: a strand preparation step of extruding a wet resin through a die provided in the granulator to obtain strands of the wet resin; and a sizing step of sizing the wet resin by applying a crushing blade to the obtained strands at a position 2 mm to 20 mm away from the surface of the die, wherein the contact area of ​​the crushing blade with the strands is 0.3 cm. 2 The following is a method for producing a resin molded body.

[0009] [2] The method for producing a resin molded product according to [1], wherein the die hole diameter is 0.3 mm to 10.0 mm.

[0010] [3] The method for producing a resin molded body according to [1] or [2], wherein the crushing blade is any one selected from the group consisting of a piano wire, an inclined paddle blade having an inclination angle of 45°, a round pin, and a propeller blade.

[0011] [4] The method for producing a resin molded product according to any one of [1] to [3], wherein the wet resin has a water content of 30% by weight to 70% by weight.

[0012] [5] The method for producing a resin molded body according to any one of [1] to [4], wherein the wet resin contains, as a resin, biodegradable resin particles (primary particles) having a volume average particle diameter of 1 μm to 200 μm, and / or secondary particles of polymer particles having a volume average particle diameter of 1 μm to 200 μm. [Effects of the Invention]

[0013] According to one embodiment of the present invention, it is possible to provide a novel method for producing a resin molded article, which can provide a resin molded article with reduced generation of fine powder. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a schematic diagram showing the moment when the crushing blade according to one embodiment of the present invention comes into contact with the strand. [Figure 2]FIG. 10 is a schematic diagram showing the moment when the crushing blade according to another embodiment of the present invention comes into contact with the strand. [Figure 3] FIG. 10 is a schematic diagram showing the moment when the crushing blade according to another embodiment of the present invention comes into contact with the strand. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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)."

[0016] 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)."

[0017] In this specification, the term "X unit" contained in a polymer, copolymer, or resin refers to a "structural unit derived from an X monomer."

[0018] Unless otherwise specified in this specification, the structural unit is X 1 Units, X 2 Units, ... and X n A polymer (copolymer) containing units (n is an integer of 2 or more) is called "X 1 / X 2 / ··· / X n Also called "polymer (copolymer)". X 1 / X 2 / ··· / X n Unless otherwise specified, the polymerization mode of the polymer (copolymer) is not particularly limited, and the polymer may be a random copolymer, an alternating copolymer, a block copolymer, or a graft copolymer.

[0019] 1. Method for producing resin molded body A method for producing a resin molded product according to one embodiment of the present invention includes a strand preparation step of extruding a wet resin through a die provided in a granulator to obtain strands of the wet resin, and a sizing step of sizing the wet resin by applying a crushing blade to the obtained strands at a position 2 mm to 20 mm away from the surface of the die, wherein in the sizing step, the contact area of ​​the crushing blade with the strands is 0.3 cm 2 The following is the result.

[0020] In this specification, the "method for manufacturing a resin molded body" may be referred to as the "manufacturing method," and the "method for manufacturing a resin molded body according to one embodiment of the present invention" may be referred to as the "present manufacturing method."

[0021] The present manufacturing method has the above-described configuration, which has the advantage of being able to provide a resin molded product with reduced fine powder generation. The amount of fine powder generated from a resin molded product is referred to as the "fine powder rate" in this specification. That is, the present manufacturing method has the above-described configuration, which has the advantage of being able to provide a resin molded product with a low fine powder rate. Because the resin molded product obtained by this manufacturing method has a low fine powder rate, the amount of fine powder generated during drying, transport, and / or handling of the resin molded product can be reduced. This allows the present manufacturing method to contribute to an increase in the yield of resin molded products and / or the stabilization of subsequent processes (e.g., reducing the occurrence of problems due to fine powder and eliminating the hassle of changing product types). The method for measuring the fine powder rate will be described in detail in the Examples below.

[0022] (1-1. Strand preparation process) (granulator) In the strand preparation step, a granulator equipped with a die is used. The granulator is not particularly limited as long as it is equipped with a die, but for example, an extrusion-type granulator (extrusion granulator) is preferable. Examples of extrusion-type granulators include a screw-type extrusion granulator, a roll-type extrusion granulator, a basket-type extrusion granulator, and a piston-type extrusion granulator. A screw-type extrusion granulator, for example, is equipped with a raw material supply section (sometimes called a "hopper") that supplies the wet resin as a raw material, a screw, and a die having one or more discharge holes.

[0023] When a screw-type extrusion granulator is used, the screw may be a single screw or multiple screws (e.g., two screws). The granulator is preferably equipped with multiple screws (e.g., two screws). When the granulator is equipped with multiple screws, the pressure applied to the wet resin increases, making it possible to obtain a densely packed resin molded product. As a result, there are advantages in that (i) a resin molded product with reduced generation of fine powder can be obtained, and (ii) a resin molded product with a high bulk density can be obtained. When the granulator has multiple screws, the multiple screws may or may not intermesh. Furthermore, when the granulator has multiple screws, the rotation directions of the multiple screws may be the same or different in each combination.

[0024] When a screw extrusion granulator is used, the screw rotation speed is not particularly limited, but is preferably 10 rpm to 100 rpm, more preferably 20 rpm to 80 rpm, even more preferably 25 rpm to 70 rpm, and particularly preferably 30 rpm to 60 rpm. This configuration makes it possible to obtain a densely packed resin molded product.

[0025] When an extrusion granulator is used, the wet resin may be pressurized in the granulator from the time it is fed into the granulator until it is extruded through the die, and the wet resin may be particularly pressurized in the vicinity of the die.

[0026] In a granulator, the pressure applied to the wet resin immediately before the die (for example, within 5 mm from the surface of the die facing the granulator) is not particularly limited and may be set appropriately from the viewpoints of (i) reducing the fine powder content and (ii) obtaining a densely packed resin molding. The pressure applied to the wet resin immediately before the die (for example, within 5 mm from the surface of the die facing the granulator) can be adjusted by, for example, changing the effective area ratio (the ratio of the total area of ​​the discharge holes to the area of ​​the die), the water content in the wet resin, and the linear speed (discharge rate) of the wet resin (strand) extruded from the die.

[0027] (Dice) The wet resin is extruded from the die in the form of a thread or string. In this specification, the wet resin extruded from the die may be referred to as a "strand." In other words, the wet resin is extruded from the die in the form of a strand.

[0028] In this specification, the plane of the strand perpendicular to the extrusion direction of the strand is also referred to as the "cross section of the strand." In this specification, the plane of the discharge hole of the die perpendicular to the extrusion direction of the strand is also referred to as the "cross section of the discharge hole." The cross-sectional shape of the strand (cross-sectional shape) is (substantially) the same as the cross-sectional shape of the discharge hole (cross-sectional shape). In other words, the wet resin is shaped to the cross-sectional shape of the discharge hole of the die and is extruded from the die in the form of a strand.

[0029] In one embodiment of the present invention, the cross-sectional shape of the discharge hole of the die (or the cross-sectional shape of the strand) is not particularly limited. From the viewpoint of maintaining the strand shape, the cross-sectional shape of the discharge hole of the die (or the cross-sectional shape of the strand) is preferably one or more selected from the group consisting of a perfect circle and an ellipse. When the die has multiple discharge holes, each of the multiple discharge holes may have the same cross-sectional shape or different shapes.

[0030] In this specification, the diameter of the smallest circle among perfect circles that have the cross-sectional shapes of all the discharge holes inside and inscribe at least a portion of the cross-sectional shapes of the discharge holes in the perfect circle is also referred to as the "hole diameter of the discharge holes." In one embodiment of the present invention, the diameter of the discharge holes in the die is not particularly limited. From the viewpoint of ease of handling of the resin molded product, the diameter of the discharge holes in the die is preferably 0.3 mm to 10.0 mm, more preferably 0.5 mm to 9.0 mm, more preferably 1.0 mm to 8.0 mm, even more preferably 3.0 mm to 7.0 mm, and particularly preferably 4.0 mm to 6.0 mm. When the die has multiple discharge holes, the phrase "the diameter of the discharge holes in the die is X mm to Y mm" in this specification means that all of the diameters of the multiple discharge holes are within the range of X mm to Y mm. When the die has multiple discharge holes, the diameters of the multiple discharge holes may be the same or different.

[0031] In this specification, the surface of the die perpendicular to the extrusion direction of the strand is also referred to as the "die cross section." In this specification, the area of ​​the die cross section is also referred to as the "die area." In this specification, the sum of the cross-sectional areas of the discharge holes in the die is also referred to as the "total area of ​​the discharge holes." When the die has multiple discharge holes, the sum of the cross-sectional areas of all the discharge holes is the "total area of ​​the discharge holes." In this specification, the ratio of the area of ​​the die to the total area of ​​the discharge holes, i.e., the area of ​​the die / the total area of ​​the discharge holes, is also referred to as the "effective area ratio."

[0032] The effective area ratio can affect the fine powder ratio, but is not particularly limited. The effective area ratio is preferably 2.0 to 100.0, more preferably 2.5 to 100.0, even more preferably 2.9 to 20.0, and particularly preferably 3.3 to 10.0. The area of ​​the die can also be said to be the area where the wet resin comes into contact with the die inside the granulator (inside the die). When the effective area ratio is 2.0 or more, the pressure applied to the wet resin inside the granulator is not too small but is appropriate, resulting in an advantage of reducing the fine powder ratio. When the effective area ratio is 100 or less, the pressure applied to the wet resin inside the granulator is not excessive but moderate, which has the advantage that there is no risk of water seeping out onto the surface of the extruded strands. However, if water seeps out onto the surface of the extruded strands and a drying step is performed, there is a risk that the resin moldings will adhere to each other and become integrated (coalesced) during the drying step.

[0033] In this specification, "the amount of wet resin extruded from each discharge hole of the die per unit time (for example, per hour)" is also referred to as "discharge rate of wet resin." In one embodiment of the present invention, the discharge rate of wet resin is not particularly limited. Since a densely packed resin molded body can be obtained, the discharge rate of wet resin per hour is preferably 20 kg / hour to 105 kg / hour, more preferably 30 kg / hour to 100 kg / hour, even more preferably 40 kg / hour to 95 kg / hour, and particularly preferably 50 kg / hour to 90 kg / hour.

[0034] In this specification, the "speed at which the wet resin is extruded from each discharge hole of the die per unit time (for example, per hour)" is also referred to as the "linear speed of the wet resin." In one embodiment of the present invention, the linear speed of the wet resin is not particularly limited. From the viewpoint of productivity, the linear speed of the wet resin per second is preferably 1.6 cm / sec to 8.1 cm / sec, more preferably 2.3 cm / sec to 7.8 cm / sec, even more preferably 3.1 cm / sec to 7.4 cm / sec, and particularly preferably 3.9 cm / sec to 7.0 cm / sec.

[0035] (wet resin) The wet resin is not particularly limited, but may be, for example, a mixture containing a liquid component and a resin.

[0036] (liquid component) The liquid component is not particularly limited, but from the viewpoint of reducing environmental pollution, it preferably contains water, and may be composed only of water. In other words, the wet resin preferably contains water.

[0037] (resin) The resin is not particularly limited, but examples thereof include natural resins such as natural rubber, thermoplastic resins, and thermosetting resins.

[0038] The thermoplastic resin is not particularly limited, but examples thereof include polyolefin resins (e.g., polyester resins, polyethylene resins, etc.), cyclic polyolefin resins, polystyrene resins, (meth)acrylic polymers (also referred to as "(meth)acrylic resins"), vinyl polymers, polyvinyl chloride, polytetrafluoroethylene, acrylonitrile / butadiene / styrene polymers (also referred to as "acrylonitrile / butadiene / styrene resin" and "ABS resin"), acrylonitrile / styrene polymers (also referred to as "acrylonitrile / styrene resin" and "AS resin"), polyacetal, polycarbonate, polyamide, polyester resins (e.g., polycarbonate / polyethylene terephthalate, polyethylene terephthalate / glycol-modified polyethylene terephthalate, and polyethylene terephthalate / copolymerized polyethylene terephthalate), polyphenylene ether, modified polyphenylene ether, polyurethane, and polyvinyl acetate.

[0039] In this specification, "(meth)acrylic" means "methacrylic and / or acrylic." For example, "(meth)acrylic polymer" means "methacrylic polymer and / or acrylic polymer."

[0040] Thermosetting resins are not particularly limited, but examples thereof include epoxy resins, epoxidized oils and fats, phenolic resins, polyimide resins, oxetane resins, polyol resins, and amino / formaldehyde resins (also referred to as "melamine resins"). Polymers obtained by polymerizing these thermosetting resins with monomers having ethylenically unsaturated bonds (hereinafter also referred to as "ethylenically unsaturated monomers"), and resins having one or more ethylenically unsaturated bonds (carbon-carbon double bonds) derived from the ethylenically unsaturated monomers in the molecule, are also included in thermosetting resins.

[0041] In this specification, unless otherwise specified, "X-based resin" and "poly X-based resin" refer to a resin having the highest content of X units among all the structural units constituting the resin. In this specification, "X-based polymer" and "poly X-based copolymer" refer to a polymer and copolymer having the highest content of X units among all the structural units constituting the polymer and copolymer, respectively.

[0042] Resins also include elastomers (rubbers), such as rubbers containing farnesene units, diene rubbers, (meth)acrylate rubbers, and organosiloxane rubbers.

[0043] Examples of the resin include (i) acrylonitrile / α-methylstyrene polymers and (ii) copolymers having aromatic vinyl units and unsaturated nitrile units as structural units.

[0044] The resin may also be a biodegradable resin, and may include, but is not limited to, aliphatic polyesters and aliphatic aromatic polyesters.

[0045] Examples of the aliphatic polyesters include (i) polyhydroxyalkanoate resins (also referred to as "PHA"), (ii) polylactic acid (also referred to as "PLA"), (iii) polycaprolactone (also referred to as "PCL"), and (iv) aliphatic polyesters other than PHA, PLA, and PCL.

[0046] "PHA" is a general term for polymers containing hydroxyalkanoic acid as a monomer unit (monomer repeating unit), and is generally biodegradable. PHA is an aliphatic polyester, preferably a polyester that does not contain an aromatic ring. PHA preferably contains hydroxyalkanoic acid repeating units in an amount of 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more of the total monomer repeating units (100 mol%).

[0047] The PHA is not particularly limited. Examples of PHA include polyglycolic acid, poly(3-hydroxyalkanoate)-based resin (hereinafter sometimes referred to as "P3HA"), poly(4-hydroxyalkanoate)-based resin, etc. One type of PHA may be used alone, or two or more types may be used in combination. The PHA preferably contains a poly(3-hydroxyalkanoate)-based resin, and more preferably is a poly(3-hydroxyalkanoate)-based resin (in other words, composed solely of a poly(3-hydroxyalkanoate)-based resin).

[0048] The P3HA is a 3-hydroxyalkanoic acid repeating unit represented by 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. The P3HA preferably contains 50 mol % or more of the 3-hydroxyalkanoic acid repeating units, more preferably 60 mol % or more, and even more preferably 70 mol % or more of the total monomer repeating units (100 mol %).

[0049] Examples of P3HA include 3HB homopolymers such as poly(3-hydroxybutyrate) (also referred to as "P3HB"), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (also referred to as "P3HB3HH"), and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (also referred to as "P3HB4HB"). A single P3HA may be used, or two or more may be used in combination. As used herein, "poly(X-co-Y)" refers to a copolymer containing X repeating units and Y repeating units, obtained by copolymerizing a monomer from which the X repeating units are derived with a monomer from which the Y repeating units are derived. During microbial P3HA production, trace amounts (approximately 1 mol% or less) of a monomer may be copolymerized. However, if this does not significantly affect the physical properties of the resulting P3HA, the monomer is considered to be uncopolymerized, and the resulting P3HA will be referred to without including that monomer.

[0050] P3HA can be produced by microorganisms. Such microbially produced P3HA is usually P3HA composed only of D-form (R-form) 3-hydroxyalkanoic acid repeating units. Among microbially produced P3HAs, P3HB, P3HB3HH, and P3HB4HB are preferred, with P3HB3HH and P3HB4HB being more preferred, due to ease of industrial production.

[0051] The aliphatic polyesters other than PHA, PLA, and PCL are not particularly limited, but examples thereof include aliphatic polyesters having a structure in which an aliphatic diol and an aliphatic dicarboxylic acid are polycondensed. The aliphatic polyesters having a structure in which an aliphatic diol and an aliphatic dicarboxylic acid are polycondensed are not particularly limited, but examples thereof include polyethylene succinate, polybutylene succinate (also referred to as "PBS"), polyhexamethylene succinate, polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polybutylene succinate adipate (also referred to as "PBSA"), polyethylene sebacate, polybutylene sebacate, etc.

[0052] The aliphatic aromatic polyester is not particularly limited, but examples thereof include aliphatic aromatic polyesters obtained using both an aliphatic compound and an aromatic compound as monomers (using both an aliphatic compound and an aromatic compound as monomers).

[0053] The aliphatic aromatic polyester is not particularly limited, but examples thereof include polybutylene adipate terephthalate (also referred to as "PBAT"), polybutylene sebacate terephthalate (also referred to as "PBSeT"), polybutylene azelate terephthalate (also referred to as "PBAzT"), polybutylene succinate terephthalate (also referred to as "PBST"), and polybutylene succinate adipate terephthalate (also referred to as "PBSAT").

[0054] The biodegradable resin (i) preferably contains an aliphatic polyester and / or an aliphatic aromatic polyester, and more preferably consists of only an aliphatic polyester and / or an aliphatic aromatic polyester, and (ii) preferably contains one or more selected from the group consisting of PHA, PLA, PCL, PBS, PBSA, PBAT, PBSeT, PBAzT, PBST, and PBSAT, and more preferably consists of only one or more selected from the group.

[0055] The PHA preferably (i) contains P3HA, more preferably consists of only P3HA, or (ii) contains one or more selected from the group consisting of P3HB, P3HB3HH and P3HB4HB, more preferably consists of only one or more selected from the group.

[0056] The wet resin may contain one of the above-mentioned resins alone or two or more of them in combination.

[0057] In this specification, a "particulate resin" may be referred to as a "resin particle," and a "particulate polymer" may be referred to as a "polymer particle." When a resin is a polymer particle, the resin can also be considered a resin particle. In other words, in a wet resin, the resin may contain resin particles (e.g., polymer particles and / or biodegradable resin particles), or may be composed only of resin particles (in other words, it may be resin particles).

[0058] When the wet resin contains a biodegradable resin as a resin, the biodegradable resin preferably has a particulate shape. In other words, the wet resin preferably contains biodegradable resin particles (primary particles) as a resin. The volume average particle diameter (Mv) of the biodegradable resin particles (primary particles) is not particularly limited, but is preferably 1 μm to 200 μm, more preferably 5 μm to 150 μm, even more preferably 15 μm to 100 μm, and particularly preferably 20 μm to 90 μm. This configuration has the advantage of being able to obtain a densely packed resin molded product.

[0059] (polymer particles) The polymer particles may be composites made of two or more polymers with different constitutional unit compositions. In polymer particles (composites) made of two or more polymers with different constitutional unit compositions, each polymer may have a layer structure. For example, in a polymer particle (composite) made of two polymers, polymer A and polymer B, with different constitutional unit compositions, the phrase "polymer A and polymer B have a layer structure" means that at least a portion of polymer A is coated with at least a portion of polymer B. In other words, in a polymer particle (composite) made of two polymers, polymer A and polymer B, with different constitutional unit compositions, the phrase "polymer A and polymer B have a layer structure" means that at least a portion of polymer A is present at the innermost part of the polymer particle, and at least a portion of polymer B is present at the outermost part of the polymer particle. In a polymer particle (composite) made of two polymers, polymer A and polymer B, with different constitutional unit compositions, polymer A and polymer B may or may not be chemically bonded to each other. In a polymer particle (composite) composed of two types of polymers, polymer A and polymer B, which differ in the composition of their structural units, polymer A and polymer B may be chemically bonded to each other, for example, polymer B may be graft-bonded to polymer A. A copolymer (polymer particle) containing polymer A and polymer B graft-bonded to polymer A is sometimes referred to as a "graft copolymer." In a graft copolymer, polymer B is sometimes referred to as the "graft portion."

[0060] In this specification, a graft copolymer in which polymer A is an elastomer may also be referred to as a "rubber-containing graft copolymer." Polymer particles that are graft copolymers may be rubber-containing graft copolymers having an elastomer (polymer A) and a graft portion (polymer B) graft-bonded to the elastomer. In the rubber-containing graft copolymer, each of the elastomer and the graft portion may be a single layer, or a multi-layer consisting of two or more layers. The rubber-containing graft copolymer may be, for example, a polymer obtained by polymerizing a first elastomer, a second elastomer, and a graft portion in this order.

[0061] In the rubber-containing graft copolymer, the elastomer is preferably one or more selected from the group consisting of rubbers containing farnesene units, diene-based rubbers, (meth)acrylate-based rubbers, and organosiloxane-based rubbers.

[0062] The diene rubber is preferably butadiene rubber (also called polybutadiene rubber) consisting of structural units derived from 1,3-butadiene, or butadiene-styrene rubber (also called polystyrene-butadiene) which is a copolymer of 1,3-butadiene and styrene, with butadiene rubber being more preferred.

[0063] The (meth)acrylate rubber is preferably at least one selected from the group consisting of methyl (meth)acrylate rubber, ethyl (meth)acrylate rubber, butyl (meth)acrylate rubber, and 2-ethylhexyl (meth)acrylate rubber, more preferably at least one selected from the group consisting of methyl (meth)acrylate rubber and butyl (meth)acrylate rubber, even more preferably at least one selected from the group consisting of butyl (meth)acrylate rubber, and particularly preferably butyl acrylate.

[0064] Examples of organosiloxane rubbers include (i) organosiloxane polymers composed of alkyl or aryl di-substituted silyloxy units, such as dimethylsilyloxy, diethylsilyloxy, methylphenylsilyloxy, diphenylsilyloxy, and dimethylsilyloxy-diphenylsilyloxy, and (ii) organosiloxane polymers composed of alkyl or aryl mono-substituted silyloxy units, such as organohydrogensilyloxy in which some of the alkyl groups in the side chains are substituted with hydrogen atoms.

[0065] In this specification, a polymer composed of dimethylsilyloxy units is referred to as dimethylsilyloxy rubber, a polymer composed of methylphenylsilyloxy units is referred to as methylphenylsilyloxy rubber, and a polymer composed of dimethylsilyloxy units and diphenylsilyloxy units is referred to as dimethylsilyloxy-diphenylsilyloxy rubber. The organosiloxane rubber is preferably one or more selected from the group consisting of dimethylsilyloxy rubber, methylphenylsilyloxy rubber, and dimethylsilyloxy-diphenylsilyloxy rubber, because (i) the resulting resin composition containing the powder or granule can provide a molded article or cured product with excellent heat resistance, and (ii) dimethylsilyloxy rubber is more preferred because it is easily available and economical.

[0066] In the rubber-containing graft copolymer, a crosslinked structure may be introduced into the elastomer. A commonly used method can be used to introduce a crosslinked structure into the elastomer, and examples thereof include the following methods. That is, in the production of the elastomer, a method can be used in which a crosslinkable monomer such as a polyfunctional monomer and / or a mercapto group-containing compound is mixed with a monomer capable of constituting the elastomer, followed by polymerization.

[0067] A polyfunctional monomer can also be said to be a monomer having two or more radically polymerizable reactive groups in the same molecule. The radically polymerizable reactive group is preferably a carbon-carbon double bond. Examples of polyfunctional monomers include (meth)acrylates having an ethylenically unsaturated double bond, such as allyl (meth)acrylate, allyl alkyl (meth)acrylates, and allyloxy alkyl (meth)acrylates, and the like, excluding butadiene.

[0068] In the rubber-containing graft copolymer, the graft portion preferably contains one or more structural units selected from the group consisting of an aromatic vinyl unit, a vinylcyan unit, and a (meth)acrylate unit.

[0069] Specific examples of monomers from which aromatic vinyl units are derived include styrene, α-methylstyrene, p-methylstyrene, and divinylbenzene.

[0070] Specific examples of monomers from which vinylcyan units are derived include acrylonitrile and methacrylonitrile.

[0071] Specific examples of monomers from which (meth)acrylate units are derived include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hydroxyethyl (meth)acrylate, and hydroxybutyl (meth)acrylate. In this specification, the term "(meth)acrylate" refers to acrylate and / or methacrylate.

[0072] When the wet resin contains polymer particles as a resin, the polymer particles preferably have the shape of secondary particles formed by aggregation of primary particles. In other words, the wet resin preferably contains secondary particles of polymer particles as a resin. The volume average particle diameter (Mv) of the secondary particles of the polymer particles is not particularly limited, but is preferably 1 μm to 200 μm, more preferably 5 μm to 150 μm, even more preferably 15 μm to 100 μm, and particularly preferably 20 μm to 90 μm. This configuration has the advantage of being able to obtain a densely packed resin molded product.

[0073] The wet resin preferably contains biodegradable resin particles (primary particles) having a volume average particle diameter of 1 μm to 200 μm and / or secondary particles of polymer particles having a volume average particle diameter of 1 μm to 200 μm. More preferably, the resin in the wet resin is composed only of biodegradable resin particles (primary particles) having a volume average particle diameter of 1 μm to 200 μm and / or secondary particles of polymer particles having a volume average particle diameter of 1 μm to 200 μm.

[0074] In one embodiment of the present invention, the resin preferably contains one or more selected from the group consisting of the following (1) to (3), and more preferably consists of only one or more selected from said group (in other words, consists of only one or more selected from said group): (1) Secondary particles of polymer particles, which are rubber-containing graft copolymers having an elastomer and a graft portion graft-bonded to the elastomer; (2) Secondary particles of polymer particles that are composites of two or more polymers with different constitutional unit compositions, which are not chemically bonded to each other; (3) Biodegradable resin particles (primary particles).

[0075] (Wet resin preparation process) The present production method may further include a wet resin preparation step for obtaining a wet resin prior to the strand preparation step. The method for obtaining the wet resin is not particularly limited. When the resin particles are polymer particles, the wet resin preparation step may include, for example, an aqueous dispersion preparation step for preparing an aqueous dispersion containing an aqueous medium and resin particles, and an aggregation step for aggregating the resin particles. In this specification, the "aqueous dispersion containing an aqueous medium and resin particles" may also be referred to as "aqueous latex."

[0076] (Aqueous dispersion preparation process) When the resin particles are polymer particles, an aqueous latex containing the polymer particles is prepared in the aqueous dispersion preparation step.

[0077] When the resin particles are polymer particles, the aqueous dispersion preparation step may be, for example, a step of preparing polymer particles by a known method such as emulsion polymerization, suspension polymerization, or microsuspension polymerization. The emulsion polymerization method is preferred as a method for preparing (producing) polymer particles. The emulsion polymerization method has the following advantages: (i) the composition of the polymer particles can be easily designed; (ii) industrial production of the polymer particles can be easily carried out; and (iii) an aqueous latex containing the polymer particles can be easily obtained.

[0078] When preparing polymer particles by emulsion polymerization, known emulsifiers (dispersants) can be used. Examples of emulsifiers include anionic emulsifiers, nonionic emulsifiers, polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone, and polyacrylic acid derivatives. Examples of anionic emulsifiers include sulfur-based emulsifiers, phosphorus-based emulsifiers, sarcosinic acid-based emulsifiers, and carboxylic acid-based emulsifiers. Examples of sulfur-based emulsifiers include sodium dodecylbenzenesulfonate (abbreviated as SDBS). Examples of phosphorus-based emulsifiers include sodium polyoxyethylene lauryl ether phosphate.

[0079] When preparing polymer particles by emulsion polymerization, a thermally decomposable initiator can be used as the polymerization initiator. Examples of the thermally decomposable initiator include known initiators such as (i) 2,2'-azobisisobutyronitrile and (ii) peroxides, such as organic peroxides and inorganic peroxides. Examples of the organic peroxides include t-butylperoxyisopropyl carbonate, paramenthane hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, and t-hexyl peroxide. Examples of the inorganic peroxides include hydrogen peroxide, potassium persulfate, and ammonium persulfate.

[0080] When preparing polymer particles by emulsion polymerization, a redox initiator can also be used as the polymerization initiator. The redox initiator is an initiator that combines (i) a peroxide, such as an organic peroxide or an inorganic peroxide, with (ii) a transition metal salt, such as iron(II) sulfate, or a reducing agent, such as sodium formaldehyde sulfoxylate or glucose. If necessary, a chelating agent, such as disodium ethylenediaminetetraacetate, and a phosphorus-containing compound, such as sodium pyrophosphate, may also be used in combination.

[0081] When a redox initiator is used, polymerization can be carried out at a low temperature where the peroxide does not substantially decompose thermally, allowing the polymerization temperature to be set over a wide range. Therefore, it is preferable to use a redox initiator. Among redox initiators, redox initiators using organic peroxides such as cumene hydroperoxide, dicumyl peroxide, paramenthane hydroperoxide, and t-butyl hydroperoxide as the peroxide are preferred. The amount of the initiator used, as well as the amounts of the reducing agent, transition metal salt, chelating agent, etc. used when a redox initiator is used, can be within known ranges.

[0082] In addition to the above-mentioned components, a surfactant may be used in the preparation (manufacture) of polymer particles. The type and amount of the surfactant used are within known ranges.

[0083] In preparing (producing) the polymer particles, conditions within known numerical ranges can be appropriately applied as the polymerization conditions such as polymerization temperature, pressure, and deoxidation.

[0084] As described above, an aqueous latex containing polymer particles can be obtained by producing polymer particles, for example, by emulsion polymerization. The aqueous dispersion obtained by this process may be further concentrated or diluted.

[0085] (Agglutination process) The aggregation step will be described using an example in which the resin particles are polymer particles. When the resin particles are polymer particles, the aggregation step can be said to be a step of aggregating the polymer particles. The aggregates of polymer particles obtained in the aggregation step can also be said to be secondary particles of the polymer particles.

[0086] The method for aggregating polymer particles is not particularly limited. For example, polymer particles can be aggregated by adding a coagulant and / or an aqueous solution containing a coagulant to an aqueous latex containing polymer particles. Alternatively, polymer particles can be aggregated by mixing an aqueous latex containing polymer particles with a highly hydrophobic organic solvent. Applying shear stress to the aqueous latex containing polymer particles can weaken the emulsification of the polymer particles in the aqueous latex by the emulsifier, thereby aggregating the polymer particles. Alternatively, polymer particles can be aggregated by rapidly freezing the aqueous latex containing polymer particles (e.g., within 1 second to less than 20 minutes) and then thawing the frozen aqueous latex. In other words, the aggregation process may include (i) a coagulant addition process in which a coagulant is added to the aqueous latex containing polymer particles, (ii) a shearing process in which shear stress is applied to the aqueous latex containing polymer particles, or (iii) a process in which the aqueous latex containing polymer particles is rapidly frozen and then thawed.

[0087] The coagulant that can be used in the coagulation step is not particularly limited as long as it has the property of being able to coagulate (coagulate) the polymer particles in the aqueous latex containing the polymer particles, and examples thereof include inorganic acids (e.g., hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc.), inorganic salts (e.g., sodium chloride, potassium chloride, calcium chloride, magnesium chloride, etc.), organic acids, organic salts, and polymer coagulants.

[0088] When a coagulant is used to aggregate polymer particles, a mixture of the aqueous latex and the coagulant and / or an aqueous solution containing the coagulant may be stirred. A known stirring device (stirring blade) can be used to stir the mixture. Examples of stirring blades include inclined paddle blades, propeller blades, turbine blades, anchor blades, ribbon blades, and large blades.

[0089] When the resin particles are polymer particles, the above-mentioned aqueous dispersion preparation step and aggregation step can be carried out to obtain aggregates of the polymer particles (secondary particles). More specifically, when the resin particles are polymer particles, the above-mentioned aqueous dispersion preparation step and aggregation step can be carried out to obtain a slurry containing aggregates of the polymer particles (secondary particles).

[0090] In the aggregation step, by appropriately changing the temperature of the aggregation step, the time of the aggregation step, the shape of the stirring blades, the stirring speed, etc., it is possible to adjust (i) the water content in the wet resin and (ii) the volume average particle size of the secondary particles of the polymer particles, etc.

[0091] Examples of the temperature in the aggregation step include (a) the ambient temperature when the aggregation step is carried out (e.g., room temperature in the work space), (b) the temperature of the aqueous latex containing polymer particles, (c) in the case where a coagulant is used, (c-1) the temperature of the coagulant and / or the aqueous solution containing the coagulant, and (c-2) the temperature of the mixture of the aqueous latex and the coagulant and / or the aqueous solution containing the coagulant, (d) in the case where shear stress is applied to the latex, the temperature of the aqueous latex when shear stress is applied, (e) in the case where the aqueous latex is frozen, the temperature when the frozen aqueous latex is thawed (thawing temperature), and (f) in the case where the aqueous latex is sprayed, the temperature of the aqueous latex when the aqueous latex is sprayed and the temperature of the aqueous latex (droplets) after spraying. Examples of the aggregation step time include (a) the time required for the aggregation step, (b) the time required for the aqueous latex to be held at a predetermined temperature, (c) the time required for the mixture of the aqueous latex and the coagulant and / or aqueous solution containing the coagulant to be held at a predetermined temperature, (d) the time required for the mixture to be stirred, (e) the time required for the application of shear stress to the coagulation step latex (the shear (stirring) time of the latex) when shear stress is applied to the coagulation step latex, (f) the time required for the freezing of the coagulation step latex and the time required for the thawing of the frozen coagulation step latex (the time required for the frozen coagulation step latex to be exposed to the thawing temperature) when shear stress is applied to the aqueous latex, etc. Examples of the agitation frequency during the aggregation step include (a) the agitation frequency of the aqueous latex, (b) the agitation frequency of the mixture of the aqueous latex and the coagulant and / or aqueous solution containing the coagulant when a coagulant is used, and (c) the agitation frequency of the aqueous latex when shear stress is applied to the aqueous latex. The temperature, duration, shape of the stirring blades, and stirring speed in the aggregation step can be appropriately set depending on (i) the desired water content in the wet resin, and (ii) the desired volume average particle size of the secondary particles of the polymer particles, etc.

[0092] On the other hand, when the resin is a resin (e.g., PHA) produced in the body of a microorganism, the wet resin preparation process may include, for example, (i) a bacterial cell culture process in which resin-producing microorganisms (e.g., PHA-producing microorganisms) are cultured to accumulate the resin in the bacterial cells, and (ii) a bacterial cell removal process in which the bacterial cells are destroyed and the bacterial components are removed by performing one or more treatments selected from the group consisting of enzyme treatment, alkali washing, surfactant treatment, and crushing treatment. Note that a "resin produced in the body of a microorganism" can be said to be a biodegradable resin.

[0093] (Bacterial cell culture process) The resin-producing microorganism is not particularly limited as long as it is capable of producing a resin (e.g., PHA) intracellularly. For example, microorganisms isolated from nature or microorganisms deposited in strain depositories (e.g., IFO, ATCC, etc.), or mutants or transformants prepared from them, can be used. More specifically, examples include bacteria of the genera Cupriavidus, Alcaligenes, Ralstonia, Pseudomonas, Bacillus, Azotobacter, Nocardia, and Aeromonas. Among these, microorganisms belonging to the genera Aeromonas, Alcaligenes, Ralstonia, or Cupriavidus are preferred. In particular, strains such as Alcaligenes lipolytica (A. lipolytica), Alcaligenes latus (A. latus), Aeromonas caviae (A. caviae), Aeromonas hydrophila (A. hydrophila), and C. necator are more preferred, with C. necator being the most preferred.

[0094] Furthermore, when a microorganism does not inherently have the ability to produce a resin (e.g., PHA) or produces only a small amount of resin (e.g., PHA), a transformant can be used by introducing a gene encoding a synthase of the desired resin (e.g., PHA) and / or its mutant into the microorganism. The PHA synthase gene used to prepare such a transformant is not particularly limited, but the P3HA synthase gene derived from Aeromonas caviae is preferred.

[0095] By culturing the above-mentioned microorganisms under appropriate conditions, a culture solution of the cells containing a resin (e.g., PHA) can be prepared (obtained). The method for culturing the microbial cells is not particularly limited, but for example, the method described in JP-A-05-93049 can be used.

[0096] The resin (e.g., PHA)-containing bacterial cells are preferably inactivated. The inactivation method is not particularly limited, but an example thereof includes a method in which a culture solution containing the resin (e.g., PHA)-containing bacterial cells is heated and stirred at 70°C to 80°C for 8 hours.

[0097] (Bacterial body removal process) In the bacterial cell removal step, one or more treatments selected from the group consisting of enzyme treatment, alkaline washing, surfactant treatment, and crushing treatment are carried out to destroy the bacterial cells and remove bacterial components.

[0098] The enzyme treatment is a step in which the bacterial cells are treated with an alkaline protease. The term "alkaline protease" refers to a protease that has the activity of degrading proteins in an alkaline environment (e.g., in a solution of pH 8.5).

[0099] The alkaline protease is not particularly limited as long as it has the activity of degrading proteins in an alkaline environment, and examples thereof include peptidoglycan-degrading enzymes (e.g., lysozyme), serine-specific proteases (e.g., subtilisin, chymotrypsin, trypsin), cysteine-specific proteases (e.g., papain, bromelain, cathepsin), and aspartic acid-specific proteases (e.g., pepsin, cathepsin D, HIV protease). From the viewpoint of economical advantage, serine-specific proteases, particularly subtilisins (e.g., alcalase), are preferred. These enzymes may be used alone or in combination of two or more.

[0100] Alkaline washing is a process in which an alkaline aqueous solution is added to the bacterial cell culture solution to adjust the pH of the bacterial cell culture solution. In alkaline washing, the alkaline aqueous solution is preferably added to adjust the pH of the bacterial cell culture solution to 10.0 to 12.0. This method dissolves bacterial cell-derived impurities, allowing a more pure resin (e.g., PHA) to be separated from the bacterial cells.

[0101] The surfactant treatment is a step in which the bacterial cells in the bacterial cell culture solution are treated with a surfactant. Treating the bacterial cells with a surfactant allows for efficient removal of impurities contained in the bacterial cells, particularly cell membranes, and allows for the removal of a larger amount of bacterial-derived impurities, enabling the separation of a higher-purity resin from the bacterial cells.

[0102] The surfactant used in the surfactant treatment is not particularly limited, but examples thereof include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. Among these, anionic surfactants are preferred from the viewpoint of their high cell membrane removal ability. These surfactants may be used alone or in combination of two or more.

[0103] The disruption treatment is a step of disrupting bacterial components in a bacterial cell culture solution. The disruption treatment has the advantage of facilitating the removal of bacterial cells decomposed by the enzyme. Specific modes of the disruption treatment are not particularly limited, and examples include methods of applying a certain shear force to the bacterial cell culture solution using a homogenizer, ultrasonic treatment, pump transfer, etc.

[0104] When the resin is a resin (e.g., PHA) produced in the body of a microorganism, the resin (e.g., PHA) particles (primary particles) can be obtained through the above-mentioned bacterial cell culture step and bacterial cell removal step. More specifically, when the resin is a resin (e.g., PHA) produced in the body of a microorganism, the resin (e.g., PHA) particles can be obtained through the above-mentioned bacterial cell culture step and bacterial cell removal step.

[0105] During each treatment in the bacterial cell removal step, the resin (e.g., PHA) or a mixture containing bacterial cells (including disrupted bacterial cells) and resin (e.g., PHA) may be stirred. By appropriately changing the shape of the stirring blades and the stirring speed during stirring of the mixture, it is possible to adjust (i) the water content in the wet resin and (ii) the volume average particle size of the biodegradable resin particles (primary particles).

[0106] (Heat treatment process) The wet resin preparation step may include a heat treatment step of heat-treating (i) a slurry containing aggregates (secondary particles) of polymer particles obtained through the above-mentioned aqueous dispersion preparation step and aggregation step, or (ii) a slurry containing biodegradable resin particles (primary particles) obtained through the above-mentioned bacterial cell culture step and bacterial cell removal step. When the wet resin preparation step includes a heat treatment step, it has the advantage of being able to obtain a densely packed resin molded body.

[0107] When the resin in the wet resin contains polymer particles, the heat treatment step is not essential, but is preferably carried out because it makes it easier to remove impurities in the wet resin in the washing step, while it is preferable not to carry out the heat treatment step from the viewpoint of reducing the number of steps and saving energy.When the resin in the wet resin contains a biodegradable resin, it is preferable not to carry out the heat treatment step from the viewpoint of reducing the number of steps and saving energy, but it may be carried out from other viewpoints.

[0108] In the heat treatment step, the temperature at which the slurry containing polymer particle aggregates (secondary particles) or the slurry containing biodegradable resin particles (primary particles) is treated is also referred to as the “heat treatment temperature.” In addition, in the heat treatment step, the time for which the slurry containing polymer particle aggregates (secondary particles) or the slurry containing biodegradable resin particles (primary particles) is heat treated is also referred to as the “heat treatment time.”

[0109] The heat treatment temperature in the heat treatment step is not particularly limited, but is, for example, preferably 65° C. to 110° C., more preferably 70° C. to 105° C., even more preferably 75° C. to 100° C., and particularly preferably 80° C. to 95° C. This configuration has the advantage that a densely packed resin molded body can be obtained.

[0110] The heat treatment time in the heat treatment step is not particularly limited, but is preferably 5 seconds to 20 minutes, more preferably 10 seconds to 15 minutes, even more preferably 20 seconds to 10 minutes, and particularly preferably 30 seconds to 5 minutes. This configuration has the advantage of being able to obtain a densely packed resin molded body.

[0111] The specific embodiment of the heat treatment step, in other words, the method for heat-treating a slurry containing polymer particle aggregates (secondary particles) or a slurry containing biodegradable resin particles (primary particles), is not particularly limited. Examples of heat-treating methods for the slurry include a method of directly adding steam to the slurry to heat it, a method of indirectly heating the slurry with heated oil or water, and a method of treating the slurry with microwaves or near-infrared rays. The slurry may also be heated in a sealed space (sealed container). By heating the slurry in a sealed space (sealed container), the temperature within the sealed space increases, allowing the slurry temperature to be raised to a temperature above 100°C. Therefore, when the slurry is heated in a sealed space (sealed container), it can also be referred to as a "pressure heat treatment step." The slurry may also be stirred during the heat treatment step.

[0112] The fluidity of the slurry can be adjusted by changing the temperature and time of the heat treatment step, and, when stirring the slurry, the shape of the stirring blades and the stirring speed, etc. As a result, it is possible to adjust (i) the water content in the wet resin and (ii) the volume average particle size of the polymer particle aggregates (secondary particles) or the biodegradable resin particles (primary particles), etc.

[0113] The wet resin may be (i) (i-1) a slurry containing polymer particle agglomerates (secondary particles) obtained through the above-mentioned aqueous dispersion preparation step and aggregation step, or (i-2) a slurry containing biodegradable resin particles (primary particles) obtained through the above-mentioned bacterial cell culture step and bacterial cell removal step, or (ii) (ii-1) a slurry containing polymer particle agglomerates (secondary particles) that has been subjected to the above-mentioned heat treatment step, or (ii-2) a slurry containing biodegradable resin particles (primary particles) that has been subjected to the above-mentioned heat treatment step. The water content of the wet resin can be adjusted by removing the liquid component from the slurry containing polymer particle agglomerates (secondary particles) or biodegradable resin particles (primary particles), in other words, by recovering the polymer particle agglomerates (secondary particles) or biodegradable resin particles (primary particles) from the slurry. The method for removing liquid components from a slurry containing polymer particle aggregates (secondary particles) or biodegradable resin particles (primary particles) is not particularly limited, and examples thereof include centrifugal dehydration, static separation, filtration dehydration, compression dehydration, and water evaporation. Furthermore, the equipment used to carry out the various separation methods can be appropriately selected according to the desired separation method. For example, a screw press, roller press, belt screen, filter press, vibrating sieve, multi-plate vibrating filter, vacuum dehydrator, pressure dehydrator, belt press, centrifugal dehydrator, etc. can be used.

[0114] (Cleaning process) The present production method preferably further includes a washing step of washing the wet resin obtained in the wet resin preparation step described above before the strand preparation step. By carrying out the washing step, it is possible to obtain a resin molded product containing fewer impurities.

[0115] The method for washing the wet resin is not particularly limited, and examples thereof include (i) simply pouring washing water onto the wet resin, and (ii) mixing the wet resin with washing water and removing the washing water from the mixture. As a method for removing the washing water from the wet resin from the mixture, the above-mentioned method for removing liquid components from a slurry containing aggregates of polymer particles (secondary particles) or biodegradable resin particles (primary particles) may be used.

[0116] The washing water used in the washing step is not particularly limited, but examples thereof include pure water, distilled water, RO water, ion-exchanged water, and ultrapure water.

[0117] (Physical properties of wet resin) The wet resin preferably has a water content of 30 to 70% by weight, more preferably 40 to 65% by weight, even more preferably 45 to 60% by weight, and particularly preferably 50 to 55% by weight, based on 100% by weight of the wet resin. If the water content is 30% by weight or more, water will be present in the resulting resin molded body (for example, water will be present between the resin particles (polymer particles)). When a drying step (described later) is performed, the presence of water in the resin molded body has the advantage of improving the strength of the resin molded body after drying. If the water content is 70% by weight or less, water may seep onto the surface of the extruded strand. In such a case, when a drying step is performed, the resin molded bodies will adhere to each other and will not be integrated (coalesced) during the drying step, which has the advantage.

[0118] When the liquid component in the wet resin is composed only of water, the difference obtained by subtracting the water content of the wet resin from 100% by weight can be considered to be the concentration (% by weight) of the resin in the wet resin.

[0119] The water content of the wet resin can be adjusted by appropriately setting the temperature, time, and stirring speed of the aggregation step, as described above. The water content of the wet resin can also be adjusted by removing liquid components from a slurry containing agglomerates (secondary particles) of resin particles (polymer particles), as described above. For example, the water content of the wet resin can be adjusted by monitoring the amount of slurry input and the amount of filtrate when removing liquid components from a slurry containing agglomerates (secondary particles) of resin particles (polymer particles) using equipment such as a screw press, roller press, belt screen, filter press, vibrating sieve, multi-plate vibrating filter, vacuum dehydrator, pressure dehydrator, belt press, or centrifugal dehydrator.

[0120] (1-2. Sizing process) In the sizing step, the strands obtained in the strand preparation step are sized by applying a crushing blade to the strands at a distance of 2 mm to 20 mm from the surface of the die. The sizing step can also be said to be a step of adjusting the wet resin (strands) to a desired length, for example, by folding (or cutting) the wet resin strands. The sizing step allows for the production of a sized wet resin, i.e., a resin molded product.

[0121] (Crushing blade) The crushing blade is designed so that the contact area between the crushing blade and the strands is 0.3cm2 during the sizing process. 2 There are no particular limitations on the crushing blades as long as they satisfy the following conditions: The contact area of ​​the crushing blade with the strands is affected by the inclination angle of the crushing blade, the material of the crushing blade, the moving speed of the crushing blade, and the like.

[0122] The material of the crushing blade is not particularly limited. Preferred materials for the crushing blade include general structural rolled steel (also called SS material), stainless steel (also called SUS material), Teflon (registered trademark), other metal materials, plastic materials, and glass materials. This configuration has the advantages of (i) being able to obtain a resin molded product with a lower fine powder ratio, and / or (ii) reducing the amount of wet resin adhering to the crushing blade.

[0123] The surface structure of the crushing blade is not particularly limited, and the surface of the crushing blade may be smooth, may have irregularities, or may be wavy.

[0124] The shape of the crushing blade is not particularly limited. Examples of the crushing blade include linear (rod-like), rectangular, trapezoidal, polygonal, and arc-shaped blades. Examples of linear crushing blades include piano wire and round pins. Examples of rectangular, trapezoidal, polygonal, and arc-shaped crushing blades include paddle blades and propeller blades. It is also possible to use stirring blades used in stirring devices as crushing blades.

[0125] In this specification, the "inclination angle of the crushing blade" means "the angle formed between the crushing blade and the extrusion direction of the strand when the crushing blade and the strand come into contact, and the angle formed on the side opposite to the granulator." The inclination angle of the crushing blade will be explained in more detail using drawings. FIG. 1 is a schematic diagram showing the moment of contact between the crushing blade and the strand according to one embodiment of the present invention. FIG. 2 is a schematic diagram showing the moment of contact between the crushing blade and the strand according to another embodiment of the present invention. FIG. 3 is a schematic diagram showing the moment of contact between the crushing blade and the strand according to another embodiment of the present invention. In FIGS. 1 to 3, the strand 1 is extruded from a die provided in the granulator 10. In FIGS. 1 to 3, X represents the extrusion direction of the strand 1. In FIGS. 1 to 3, the strand 1 extruded from the granulator 10 comes into contact with the crushing blade 2 in the sizing process. 1 to 3, no particular dimensions are shown, but the strand 1 and the crushing blade 2 are in contact with each other at a surface portion of the strand 1 that is 2 mm to 20 mm away from the surface of the die provided in the granulator 10. Also, in FIGS. 1 to 3, the contact area of ​​the crushing blade 2 with the strand 1 is 0.3 cm 2The crushing blades shown in FIGS. 1 and 2 are plate-shaped, and the surface of the crushing blade 2 shown in FIGS. 1 and 2 is a cross section perpendicular to the plate surface of the crushing blade. In FIG. 1, the angle θ formed between the crushing blade 2 and the extrusion direction X of the strand 1, which is the angle formed on the side opposite the granulator 10, is referred to in this specification as the "inclination angle of the crushing blade." In other words, in the embodiment shown in FIG. 1, the crushing blade has an inclination angle. On the other hand, as shown in FIG. 2, when the plate surface of the plate-shaped crushing blade 2 and the strand 1 come into contact, no angle is formed between the crushing blade 2 and the extrusion direction X of the strand 1. In other words, in the embodiment shown in FIG. 2, the crushing blade does not have an inclination angle. Furthermore, the crushing blade shown in FIG. 3 is intended for piano wire. When the cross section of the crushing blade is circular or approximately circular, as in the embodiment shown in FIG. 3, it is considered in this specification that no angle is formed between the crushing blade 2 and the extrusion direction X of the strand 1. As the crushing blade shown in FIG. 3, examples of the crushing blade having a circular or nearly circular cross section include round bar pins in addition to piano wire.

[0126] The inclination angle of the crushing blade is between 0° and 180°. When the inclination angle of the crushing blade is 0°, it can be said that "the crushing blade has no inclination angle." When the inclination angle of the crushing blade is greater than 0°, it can be said that "the crushing blade has an inclination angle." The crushing blade preferably has an inclination angle of 30° to 90°, more preferably an inclination angle of 35° to 90°, even more preferably an inclination angle of 40° to 90°, and particularly preferably an inclination angle of 45° to 90°. This configuration has the advantage of further reducing the fine powder ratio.

[0127] In the sizing process, the contact area between the crusher blade and the strand is 0.3 cm 2 Less than or equal to 0.25cm 2 Preferably, it is less than 0.20 cm 2 More preferably, it is 0.15 cm or less. 2 More preferably, it is 0.10 cm or less. 2The following is particularly preferable. This configuration has the advantage of further reducing the fine powder rate. The method for measuring the contact area between the crushing blade and the strands will be described in detail in the examples below.

[0128] In the sizing step, the portion of the strand where the crushing blades come into contact is a portion 2 mm to 20 mm away from the surface of the die along the strand, preferably a portion 3 mm to 18 mm away, more preferably a portion 4 mm to 16 mm away, even more preferably a portion 5 mm to 14 mm away, and particularly preferably a portion 5 mm to 10 mm away. This configuration has the advantage of further reducing the fine powder ratio.

[0129] In the sizing step, the moving speed of the crushing blade is not particularly limited. When the crushing blade rotates coaxially with the extrusion shaft of the strand, the rotation speed of the crushing blade is, for example, preferably 50 rpm to 400 rpm, more preferably 100 rpm to 350 rpm, even more preferably 150 rpm to 300 rpm, and particularly preferably 200 rpm to 250 rpm. This configuration has the advantage of further reducing the fine powder ratio.

[0130] In the present production method, the ratio of the linear velocity of the wet resin to the rotational velocity of the crushing blade (linear velocity of the wet resin (cm / min) / rotational velocity of the crushing blade (rpm)) is not particularly limited, but is preferably 0.71 to 5.64, more preferably 0.81 to 2.82, even more preferably 0.94 to 1.88, and particularly preferably 1.13 to 1.41. This configuration has the advantage of further reducing the fine powder ratio.

[0131] When the crushing blade moves linearly, the movement speed of the crushing blade is, for example, preferably 2000 cm / min to 5500 cm / min, more preferably 2500 cm / min to 5000 cm / min, further preferably 3000 cm / min to 4500 cm / min, and particularly preferably 3500 cm / min to 4000 cm / min. This configuration has the advantage of further reducing the fine powder ratio.

[0132] In the present manufacturing method, the ratio of the linear velocity of the wet resin to the moving velocity of the crushing blade (linear velocity of the wet resin (cm / hour) / moving velocity of the crushing blade (cm / min)) is not particularly limited, but is preferably 0.05 to 0.14, more preferably 0.06 to 0.11, even more preferably 0.06 to 0.09, and particularly preferably 0.07 to 0.08. This configuration has the advantage of further reducing the fine powder ratio.

[0133] The crushing blade is preferably any one selected from the group consisting of piano wire, paddle blades with an inclination angle (also referred to as "inclined paddle blades"), round pins, and propeller blades, more preferably any one selected from the group consisting of piano wire, paddle blades with an inclination angle of 30° to 90°, round pins, and propeller blades, even more preferably any one selected from the group consisting of piano wire, paddle blades with an inclination angle of 40° to 90°, round pins, and propeller blades, and particularly preferably any one selected from the group consisting of piano wire, paddle blades with an inclination angle of 45°, round pins, and propeller blades. This configuration has the advantage of further reducing the fine powder rate.

[0134] In the sizing step, it is preferable that the strands are cut on the granulator side of the part where the crushing blade contacts the strands. In other words, it is preferable that the crushing blade does not cut the strands by passing through the strands, but that the crushing blade contacts (comes into contact with) the strands so that the strands are cut, for example, so as to be broken, at a part that is not the part where the crushing blade contacts (comes into contact with) the strands but is closer to the granulator side of the part where the crushing blade contacts (comes into contact with) the strands.

[0135] (1-4. Drying process) The present production method may further include a drying step of drying the resin molded body obtained after the sieving step.

[0136] By carrying out the drying step, it is possible to remove water contained in the resin molded body and also to promote fusion between polymer particles in the resin molded body.

[0137] In the drying step, the method for drying the resin molded body is not particularly limited, and a known method can be used. For example, the resin molded body may be dried by heat-treating the resin molded body by leaving it in a dryer.

[0138] [2. Resin Molded Body] The resin molded article obtained by this manufacturing method is also one embodiment of the present invention.

[0139] The length in the extrusion direction of the resin molded product obtained by this manufacturing method is not particularly limited, but is preferably 1 cm to 10 cm, more preferably 2 cm to 8 cm, even more preferably 3 cm to 7 cm, and particularly preferably 4 cm to 6 cm. This configuration has the advantage of further reducing the fine powder ratio.

[0140] The resin molding obtained by this manufacturing method preferably has a fine powder content of 5% or less, more preferably 4.5% or less, even more preferably 4.0% or less, even more preferably 3.5% or less, and particularly preferably 3.0% or less. [Example]

[0141] [Evaluation method] First, various measurement methods and evaluation methods will be described below.

[0142] <Measurement of the volume average particle size (Mv) of elastomers, primary particles of polymer particles, secondary particles of polymer particles, and primary particles of biodegradable resin> For the primary particles of the elastomer and polymer particles, the aqueous latex after polymerization was diluted with deionized water to serve as the measurement sample. For the secondary particles of the polymer particles, the slurry after heat treatment was diluted with deionized water to serve as the measurement sample. For the primary particles of the biodegradable resin, the slurry containing biodegradable resin particles obtained through the bacterial culture and bacterial removal processes was diluted with deionized water to serve as the measurement sample. The particle size of each particle was measured using a Nanotrac Wave II-EX150 (manufactured by Microtrackbell Co., Ltd.), and the particle size distribution was calculated from the volume cumulative frequency percentage. The particle size measurements were performed by inputting the refractive index of water and the elastomer, polymer particles, and biodegradable resin obtained in each manufacturing example, adjusting the sample concentration so that the loading index was within the range of 1 to 10, and measuring for 120 seconds. The particle size (D50) at which the volume cumulative frequency reached 50% in the obtained particle size distribution was defined as the volume-average particle size (Mv).

[0143] <Measurement of moisture content of wet resin> The weight of the wet resin obtained in the following production example (weight of the wet resin before drying) was measured. Next, the wet resin was dried in an oven at 120°C for 1 hour, and the weight of the resin after drying was measured. The moisture content of the wet resin was measured using the following formula: Moisture content = {(weight of wet resin before drying - weight of resin after drying) / weight of wet resin before drying} x 100.

[0144] <Measurement of the contact area between the crusher blade and the strand> The contact area between the crushing blade and the strand was measured as follows: A crushing blade with fine powder (baby powder) attached to its surface was used to carry out the sizing process. After the process, the fine powder was removed from the part of the crushing blade that came into contact with the strand (the fine powder that had adhered to the crushing blade adheres to the strand side). Therefore, after the sizing process, the area of ​​the part of the crushing blade where the fine powder did not adhere was measured and used as the contact area.

[0145] <Length of resin molded body in extrusion direction> The length of the resin molding in the extrusion direction was measured as follows: 100 resin moldings obtained were randomly selected, and the length of each resin molding in the extrusion direction was measured with a vernier caliper. The minimum to maximum values ​​of the measurement results are shown in the table.

[0146] <Whether or not wet resin is attached to the crushing blade> After the production of the resin molded body, the surface of the crushing blade was visually inspected to determine whether or not the wet resin had adhered to the crushing blade.

[0147] <Measurement of fine powder ratio> After producing the resin molded body, the weight of the entire resin molded body obtained was measured. Next, the entire resin molded body obtained was placed on a 30-mesh sieve, and the sieve was used in a vibrating sieve for 5 minutes to classify the resin molded body. The resin molded body that passed through the 30-mesh sieve was collected, and the weight of the resin molded body was measured. The fine powder ratio was calculated using the following formula: Fine powder ratio = {weight of resin molded product passing through a 30-mesh sieve / (weight of resin molded product passing through a 30-mesh sieve + weight of the total amount of resin molded products obtained)} x 100 [Production Example 1] <Wet resin preparation process> (Aqueous Dispersion Preparation Step (Preparation of Aqueous Latex Containing Polymer Particles)) (Polymerization of the first elastic body) A mixture of the following composition was charged into a glass reactor: Mixture composition: (parts by weight) Ion-exchanged water 220 Boric acid 0.3 Sodium carbonate 0.03 Sodium N-lauroyl sarcosinate 0.09 Sodium formaldehyde sulfoxylate 0.09 Disodium ethylenediaminetetraacetic acid 0.006 Ferrous sulfate heptahydrate 0.002.

[0148] Next, the air in the glass reactor was replaced with nitrogen. Subsequently, the raw materials charged into the glass reactor were stirred in a nitrogen stream while the temperature inside the glass reactor was raised to 80°C. Then, a mixed solution was prepared containing a first monomer mixture consisting of 25 parts by weight of methyl methacrylate (MMA) and 0.1 parts by weight of allyl methacrylate (AMA), 0.1 parts by weight of t-dodecyl mercaptan as a chain transfer agent, and 0.1 parts by weight of t-butyl hydroperoxide (BHPO) as a polymerization initiator. Next, 25% by weight of the prepared mixed solution (100% by weight) was charged into the glass reactor all at once, and polymerization was carried out for 45 minutes.

[0149] Subsequently, the remaining 75% by weight of the mixed solution was continuously added to the glass reactor over 1 hour. After the continuous addition was completed, the temperature in the glass reactor was maintained at 80°C for another 2 hours to complete the polymerization, thereby obtaining an aqueous latex containing an elastomer (the first elastomer, which can also be considered the innermost layer elastomer). During the temperature maintenance period (2 hours at 80°C) after the addition of the mixed solution, 0.2 parts by weight of sodium N-lauroyl sarcosinate was added to the glass reactor. The average particle size of the resulting first elastomer was 0.16 μm, and the polymerization conversion rate (amount of polymer produced / amount of monomer charged) was 98%.

[0150] (Polymerization of the second elastic body) The glass reactor used in the polymerization of the first elastomer was used in the polymerization of the second elastomer. First, the glass reactor containing the aqueous latex of the first elastomer was maintained at 80°C under a nitrogen stream. After adding 0.1 parts by weight of potassium persulfate to the aqueous latex, a second monomer mixture consisting of 41 parts by weight of n-butyl acrylate (n-BA), 9 parts by weight of styrene (St), and 1 part by weight of AMA was continuously added to the aqueous latex over a period of 5 hours. During the continuous addition of the second monomer mixture, potassium oleate was added to the aqueous latex in three portions, totaling 0.1 parts by weight. After the continuous addition of the second monomer mixture was completed, an additional 0.05 parts by weight of potassium persulfate was added to the aqueous latex to complete the polymerization. The temperature inside the glass reactor was maintained at 80°C for an additional 2 hours. By this procedure, an aqueous latex containing a multi-stage polymerized elastomer (rubber-like polymer) was obtained by multi-stage polymerization of the first elastomer and the second elastomer in this order. The average particle size of the obtained multi-stage polymerized elastomer was 0.23 μm, and the polymerization conversion rate was 99%.

[0151] (Polymerization of grafted portion) The glass reactor used in the polymerization of the second elastomer was used for the polymerization of the graft moiety. First, the temperature inside the glass reactor containing the aqueous latex of the multistage elastomer was maintained at 80°C. After adding 0.02 parts by weight of potassium persulfate to the aqueous latex, a mixture of a graft monomer mixture consisting of 24 parts by weight of MMA and 1 part by weight of n-BA and 0.1 parts by weight of t-dodecyl mercaptan was continuously added over 1 hour. After the addition of the mixture was completed, the temperature inside the glass reactor was maintained at 80°C for another 1 hour. This procedure yielded an aqueous latex containing a rubber-containing graft copolymer (polymer particles) having a multistage elastomer and a graft moiety grafted to the multistage elastomer. The average particle size of the resulting polymer particles was 0.25 μm, and the polymerization conversion rate was 99%.

[0152] (Aggregation step (preparation of aggregates (secondary particles))) While stirring 285 parts by weight of an aqueous latex of polymer particles (containing 100 parts by weight of polymer particles), 2.86 parts by weight of an aqueous calcium chloride solution (containing 1 part by weight of calcium chloride) was added to the aqueous latex as a coagulant, thereby flocculating the polymer particles in the aqueous latex. By this operation, aggregates of polymer particles, i.e., secondary particles, were obtained.

[0153] (Heat treatment process) Subsequently, the temperature of the slurry containing the aggregates (secondary particles) was raised to 80° C. while stirring, and the slurry was heat-treated at 80° C. for 5 minutes. Using the heat-treated slurry, the volume average particle size of the secondary particles of the polymer particles was measured by the method described above, and was found to be 87 μm.

[0154] Next, the slurry containing the aggregates (secondary particles) was filtered and dehydrated under reduced pressure to obtain a wet resin containing polymer particle aggregates (secondary particles) and a small amount of water. Furthermore, 600 parts by weight of water at 60°C per 100 parts by weight of the wet resin was poured onto the wet resin to remove remaining impurities. The wet resin thus obtained was used in Examples 1 and 2, Comparative Examples 1 and 2, which will be described below.

[0155] The water content of the obtained wet resin was measured by the above-mentioned method and was found to be 53% by weight.

[0156] [Production Example 2] <Wet resin preparation process> (Bacterial cell culture process) Based on the method described in Example 1 of International Publication No. WO2019 / 142845, the PHA-producing microorganism Ralstonia eutropha (currently classified as Capriavidus necator) was cultivated to obtain a culture medium containing PHA-containing fungal cells.

[0157] (Bacterial body removal process) The resulting culture solution containing PHA-containing bacterial cells was treated under the conditions described in paragraphs

[0114] to

[0118] of the specification of WO 2023 / 120310 to obtain an aqueous PHA suspension.

[0158] The PHA aqueous suspension obtained by the above procedure was dehydrated by pressure filtration using a pressure filter (YTO type filter press, manufactured by Yabuta Kikai) to obtain a wet resin containing PHA as a resin and water as a liquid component.

[0159] The obtained PHA was poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), and the composition ratio of its repeating units (3HB units / 3HH units) was 94 / 6 (mol % / mol %).

[0160] The water content of the obtained wet resin was measured by the above-mentioned method and was found to be 54% by weight.

[0161] <Production of resin molded body> In the following Examples 1 and 2 and Comparative Examples 1 and 2, a screw-type extrusion granulator equipped with a die and a twin screw was used as the granulator. The cross-sectional shape of the discharge hole equipped in the die was (almost) perfect circle, and the hole diameter of the discharge hole was 5.0 mm.

[0162] The crushing blades used in the following examples and comparative examples were as follows: Piano wire: 0.2mm diameter Inclined paddle blades: These paddle blades have an inclination angle of 45° and have four blades. Paddle blades: Paddle blades with no inclination angle, with six blades.

[0163] Example 1 (Strand preparation process) The wet resin containing polymer particles obtained in Production Example 1 was fed to a granulator, and extruded from a die provided in the granulator at a screw rotation speed of 45 rpm to obtain strands of the wet resin.

[0164] (Sizing process) The strands obtained in the preparation process were subjected to rotation of a crushing blade attached perpendicular to a shaft installed coaxially with the strands to size the wet resin and obtain a resin molded product. The crushing blades used, their rotation speeds, and the distance between the die surface and the crushing blades are as shown in Table 1.

[0165] The length of the obtained resin molding, the presence or absence of adhesion of the wet resin to the crushing blade, and the fine powder ratio were measured and evaluated by the methods described above. The results are shown in Table 1.

[0166] Example 2 (Strand preparation process) The same method as in Example 1 was used to obtain strands of wet resin.

[0167] (Sizing process) The wet resin was sized in the same manner as in Example 1, except that the crushing blade used was changed as shown in Table 1, to obtain a resin molded body.

[0168] The length of the obtained resin molding, the presence or absence of adhesion of the wet resin to the crushing blade, and the fine powder ratio were measured and evaluated by the methods described above. The results are shown in Table 1.

[0169] Example 3 (Strand preparation process) Wet resin strands were obtained in the same manner as in Example 1, except that the wet resin containing the biodegradable resin obtained in Production Example 2 was used instead of the wet resin obtained in Production Example 1.

[0170] (Sizing process) The wet resin was sized in the same manner as in Example 1, except that the crushing blade used was changed as shown in Table 1, to obtain a resin molded body.

[0171] The length of the obtained resin molding, the presence or absence of adhesion of the wet resin to the crushing blade, and the fine powder ratio were measured and evaluated by the methods described above. The results are shown in Table 1.

[0172] (Comparative Example 1) (Strand preparation process) The same method as in Example 1 was used to obtain strands of wet resin.

[0173] (Sizing process) The wet resin was granulated in the same manner as in Example 1, except that the distance between the die surface and the crushing blade was changed as shown in Table 1, to obtain a resin molded body.

[0174] The length of the obtained resin molding, the presence or absence of adhesion of the wet resin to the crushing blade, and the fine powder ratio were measured and evaluated by the methods described above. The results are shown in Table 1.

[0175] (Comparative Example 2) (Strand preparation process) The same method as in Example 1 was used to obtain strands of wet resin.

[0176] (Sizing process) The wet resin was granulated in the same manner as in Example 1, except that the crushing blades and the rotational speeds of the crushing blades used were changed as shown in Table 1, to obtain resin molded bodies.

[0177] The length of the obtained resin molding, the presence or absence of adhesion of the wet resin to the crushing blade, and the fine powder ratio were measured and evaluated by the methods described above. The results are shown in Table 1.

[0178] [Table 1] [Industrial Applicability]

[0179] According to one embodiment of the present invention, a method for producing a resin molded product that can reduce the generation of fine powder can be provided, which is suitable for use in fields such as food, medicine, chemistry, batteries and electronic materials, cosmetics, pesticides, fertilizers, and feed, as well as the environment and recycling. [Explanation of symbols]

[0180] 1 strand 2 Crusher blade 10 Granulator X: Strand extrusion direction

Claims

1. a strand preparation step of extruding the wet resin through a die provided in the granulator to obtain strands of the wet resin; a sizing step of sizing the wet resin by applying a crushing blade to the obtained strand at a position 2 mm to 20 mm away from the surface of the die, In the sizing step, the contact area of ​​the crushing blade with the strands is 0.3 cm ２ The following is a method for producing a resin molded body.

2. The method for producing a resin molded article according to claim 1, wherein the die hole diameter is 0.3 mm to 10.0 mm.

3. 3. The method for producing a resin molded product according to claim 1, wherein the crushing blade is any one selected from the group consisting of a piano wire, an inclined paddle blade having an inclination angle of 45°, a round bar pin, and a propeller blade.

4. 3. The method for producing a resin molded article according to claim 1, wherein the wet resin has a water content of 30% by weight to 70% by weight.

5. 3. The method for producing a resin molded product according to claim 1, wherein the wet resin contains, as a resin, biodegradable resin particles (primary particles) having a volume average particle diameter of 1 μm to 200 μm, and / or secondary particles of polymer particles having a volume average particle diameter of 1 μm to 200 μm.

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