Thermoplastic resin composition and use thereof

Abstract

The present invention addresses the problem of providing a thermoplastic resin composition with which it is possible to provide a molded body having a large tensile strain. The problem is solved by a thermoplastic resin composition containing: a P3HA-based resin component (A) containing P3HA-based copolymers (a-1) having a weight average molecular weight of 200,000 to 1,000,000 and P3HA-based copolymers (a-2) having a weight average molecular weight larger than that of (a-1); and crosslinked resin particles (B) containing a polyhydroxyalkanoate-based resin and having a gel fraction of 50% or more.

Description

Thermoplastic resin composition and its use

[0001] The present invention relates to a thermoplastic resin composition and its use.

[0002] Plastic waste is a source of burden to the global environment, affecting ecosystems, emitting harmful gases when burned, and contributing to global warming due to the large amount of heat generated by combustion. Biodegradable plastics are being actively developed as a material that can solve these problems.

[0003] Patent Document 1 describes a biodegradable and environmentally friendly thermoplastic resin composition that is obtained by blending 0.1 to 20 parts by weight of poly(3-hydroxyalkanoate) particles having an average particle size of 300 μm or less with 100 parts by weight of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0004] Japanese Patent Application Publication No. 2004-161802

[0005] However, the above-mentioned conventional techniques are not sufficient from the viewpoint of tensile strain of molded articles of thermoplastic resin compositions, and there is room for further improvement.

[0006] One embodiment of the present invention has been made in consideration of the above-mentioned current situation, and its object is to provide a thermoplastic resin composition that can provide a molded article with a large tensile strain.

[0007] In order to solve the above-mentioned problems, a thermoplastic resin composition according to one embodiment of the present invention is a thermoplastic resin composition comprising a poly(3-hydroxyalkanoate)-based resin component (A) and crosslinked resin particles (B) containing a polyhydroxyalkanoate-based resin and having a gel fraction of 50% or more, wherein the poly(3-hydroxyalkanoate)-based resin component (A) contains a poly(3-hydroxyalkanoate)-based copolymer (a-1) having a weight-average molecular weight of 200,000 to 1,000,000, and a poly(3-hydroxyalkanoate)-based copolymer (a-2) having a weight-average molecular weight higher than that of the poly(3-hydroxyalkanoate)-based copolymer (a-1).

[0008] According to one embodiment of the present invention, it is possible to provide a thermoplastic resin composition that can provide a molded article having a large tensile strain.

[0009] An 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, "A to B" representing a numerical range means "A or more (including A and greater than A) and B or less (including B and less than B)."

[0010] [1. Thermoplastic Resin Composition] A thermoplastic resin composition according to one embodiment of the present invention is a thermoplastic resin composition comprising a poly(3-hydroxyalkanoate)-based resin component (A) and crosslinked resin particles (B) containing a polyhydroxyalkanoate-based resin and having a gel fraction of 50% or more, wherein the poly(3-hydroxyalkanoate)-based resin component (A) is a thermoplastic resin composition containing a poly(3-hydroxyalkanoate)-based copolymer (a-1) having a weight-average molecular weight of 200,000 to 1,000,000, and a poly(3-hydroxyalkanoate)-based copolymer (a-2) having a weight-average molecular weight higher than that of the poly(3-hydroxyalkanoate)-based copolymer (a-1).

[0011] In this specification, a "poly(3-hydroxyalkanoate)-based resin" may be referred to as a "P3HA-based resin," a "poly(3-hydroxyalkanoate)-based copolymer" may be referred to as a "P3HA-based copolymer," and a "thermoplastic resin composition according to one embodiment of the present invention" may be referred to as the "resin composition."

[0012] Through extensive research into thermoplastic resin compositions containing a P3HA-based resin, the present inventors have discovered that a thermoplastic resin composition containing a P3HA-based resin component and crosslinked resin particles containing a polyhydroxyalkanoate-based resin and having a gel fraction of 50% or more, in which two types of P3HA-based copolymers with different molecular weights are used as the P3HA-based resin component, results in a molded article obtained by molding the thermoplastic resin composition with a greater tensile strain, leading to the completion of the present invention.

[0013] The resin composition is biodegradable because it contains a P3HA-based resin, which is a biodegradable plastic. Therefore, it is expected to be useful as an environmentally friendly thermoplastic resin composition and molded article that can address issues such as plastic waste. More specifically, according to one embodiment of the present invention, a biodegradable thermoplastic resin composition or molded article can be provided, thereby suppressing soil and / or marine pollution when discarded. That is, one embodiment of the present invention is expected to contribute to the achievement of Sustainable Development Goals (SDGs), such as Goal 12 "Ensure sustainable consumption and production patterns" and / or Goal 14 "Conserve and sustainably use the oceans and marine resources for sustainable development."

[0014] Each component that may be contained in the resin composition will be described in detail below.

[0015] [1-1] P3HA-based resin component (A) The present resin composition contains a P3HA-based resin component (A). Hereinafter, the "P3HA-based resin component (A)" may be referred to as "component (A)." Component (A) can also be said to be the matrix resin in the present resin composition.

[0016] Component (A) is a composition containing a poly(3-hydroxyalkanoate) copolymer (a-1) having a weight-average molecular weight of 200,000 to 1,000,000, and a poly(3-hydroxyalkanoate) copolymer (a-2) having a weight-average molecular weight greater than that of the poly(3-hydroxyalkanoate) copolymer (a-1). Hereinafter, the "poly(3-hydroxyalkanoate) copolymer (a-1)" may be referred to as the "copolymer (a-1)," and the "poly(3-hydroxyalkanoate) copolymer (a-2)" may be referred to as the "copolymer (a-2)." Component (A) may be a composition containing at least two P3HA-based resins, copolymer (a-1) and copolymer (a-2), and may be a composition consisting of only the two P3HA-based resins, copolymer (a-1) and copolymer (a-2), or may contain other P3HA-based resins in addition to polymer (a-1) and copolymer (a-2).

[0017] P3HA-based resins have the formula: [-CHR-CH ２ 3-hydroxyalkanoic acid repeating units represented by the formula: —CO—O— (wherein R is C ｎ H ２ｎ＋１ where n is an integer of 1 or more and 15 or less. ) as an essential repeating unit (hereinafter, "repeating unit" may be simply referred to as "unit"). The P3HA-based resin may be a copolymer composed of two or more types of 3-hydroxyalkanoic acid repeating units, or may be a copolymer composed of 3-hydroxyalkanoic acid repeating units and other repeating units. In this specification, "P3HA-based resin" refers to a polymer (copolymer) containing 50 mol % or more of 3-hydroxyalkanoic acid repeating units out of all monomer repeating units (100 mol %). In other words, copolymer (a-1) and copolymer (a-2) are copolymers containing 50 mol % or more of 3-hydroxyalkanoic acid repeating units out of all monomer repeating units (100 mol %).

[0018] The copolymer (a-1) and / or copolymer (a-2) preferably contains 60 mol % or more, and even more preferably 70 mol % or more, of the 3-hydroxyalkanoic acid repeating units of all monomer repeating units (100 mol %).

[0019] The P3HA-based resins as copolymer (a-1) and / or copolymer (a-2) are not particularly limited and may be homopolymers containing the aforementioned repeating units or copolymers containing the aforementioned repeating units. The copolymers may be, for example, copolymers of two or more monomers selected from the group consisting of 3-hydroxybutanoic acid, 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. Alternatively, the copolymers may be copolymers of a monomer mixture containing the above-mentioned monomers as the main monomer and further containing, as a comonomer, a hydroxyalkanoic acid repeating unit other than the 3-hydroxyalkanoic acid repeating unit (e.g., 4-hydroxybutanoic acid, etc.). In this specification, a copolymer containing monomer-derived units X as a main monomer-derived unit and monomer-derived units Y as a comonomer-derived unit may be referred to as "poly(X-co-Y)." Poly(X-co-Y) can also be said to be a copolymer containing X repeat units and Y repeat units.

[0020] More specifically, examples of the P3HA resins that are copolymer (a-1) and / or copolymer (a-2) include poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (hereinafter sometimes referred to as "P3HB3HH"), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (hereinafter sometimes referred to as "P3HB4HB"), poly(3-hydroxybutyrate-co-3-hydroxypropionate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate), poly(3-hydroxybutyrate-co-3-hydroxydecanoate), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate). Furthermore, during the production of P3HA by microorganisms, a small amount (about 1 mol % or less) of a monomer may be copolymerized, but if this does not significantly affect the physical properties of the resulting P3HA, the monomer is considered to be uncopolymerized, and the product will be referred to by a name that does not include that monomer. Copolymer (a-1) and copolymer (a-2) may be the same type of P3HA-based resin, or different types of P3HA-based resins.

[0021] From the viewpoint that the P3HA resins can be industrially produced using plant raw materials by microorganisms and have a lower environmental impact as they contribute to resource recycling (carbon neutrality), it is more preferable that the P3HA resins, such as copolymer (a-1) and / or copolymer (a-2), are copolymers containing a 3-hydroxyalkanoic acid repeating unit in which R is an alkane having one carbon atom in the above formula, i.e., a 3-hydroxybutyrate (3HB) repeating unit, and a hydroxyalkanoic acid repeating unit other than the 3-hydroxybutyrate unit.

[0022] P3HA can be produced by microorganisms. Such microbially produced P3HA is typically composed solely 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.

[0023] When copolymer (a-1) and / or copolymer (a-2) is a copolymer containing a 3HB repeating unit, or a copolymer of a 3HB repeating unit and a hydroxyalkanoate unit other than a 3-hydroxybutyrate unit, from the viewpoint of the balance between flexibility and strength, in copolymer (a-1) and / or copolymer (a-2), the composition ratio of the 3HB repeating unit in all monomer repeating units (100 mol%) is preferably 77 mol% to 99 mol%, more preferably 80 mol% to 98 mol%, and even more preferably 85 mol% to 97 mol%. When the composition ratio of the 3HB repeating unit in copolymer (a-1) and / or copolymer (a-2) is in the above range, it has the advantage that flexibility and strength (rigidity) can be compatible and productivity can also be improved. The monomer composition ratio in the copolymer that is a P3HA-based resin can be measured by gas chromatography or the like (for example, see WO 2014 / 020838). As the copolymer (a-1) and / or the copolymer (a-2), copolymers having the same composition ratio of 3HB repeating units may be used, or two or more different copolymers may be used in combination.

[0024] Furthermore, when copolymer (a-1) and copolymer (a-2) are copolymers containing 3HB repeating units, or copolymers of 3HB repeating units and hydroxyalkanoate units other than 3-hydroxybutyrate units, the composition ratio of 3HB repeating units in all monomer repeating units (100 mol%) in copolymer (a-1) is in the above-mentioned range, and the composition ratio of 3HB repeating units in all monomer repeating units (100 mol%) in copolymer (a-2) is also preferably in the range of 85 mol% to 92 mol%, or 85 mol% to 90 mol%. When the composition ratio of 3HB repeating units in copolymer (a-1) and copolymer (a-2) is in the above-mentioned range, there is an advantage that the tensile strain of the molded article obtained by molding this resin composition is greater.

[0025] The microorganism that produces P3HA-based resins is not particularly limited as long as it is capable of producing P3HA-based resins. For example, the first microorganism to produce poly(3-hydroxybutyrate) (P3HB), a homopolymer of 3-hydroxybutanoic acid, was Bacillus megaterium, discovered in 1925. Other known natural microorganisms include Cupriavidus necator (formerly classified as Alcaligenes eutrophus and Ralstonia eutropha) and Alcaligenes latus. In these microorganisms, P3HB accumulates intracellularly.

[0026] Known examples of bacteria that produce copolymers of 3HB repeating units and other hydroxyalkanoic acid repeating units include Aeromonas caviae, a P3HB3HH-producing bacterium, and Alcaligenes eutrophus, a poly(3-hydroxybutyrate-co-4-hydroxybutyrate)-producing bacterium. In particular, Alcaligenes eutrophus AC32 (FERM BP-6038) (T. Fukui, Y. Doi, J. Bateriol., 179, pp. 4821-4830 (1997)), into which genes encoding P3HA synthases have been introduced, is preferred in order to increase the productivity of P3HB3HH. Microbial cells obtained by culturing such microorganisms under appropriate conditions and allowing the P3HA resin to accumulate within the cells are used. In addition to the above, genetically modified microorganisms into which various P3HA synthesis-related genes have been introduced may be used depending on the desired P3HA resin, or the culture conditions, including the type of substrate, may be optimized.

[0027] The weight-average molecular weight of copolymer (a-1) is preferably 200,000 to 1,000,000, more preferably 250,000 to 900,000, and even more preferably 300,000 to 800,000. Having the weight-average molecular weight of copolymer (a-1) within the above range offers the advantage of excellent toughness in molded articles. Furthermore, the weight-average molecular weight of copolymer (a-2) is not particularly limited as long as it is greater than the weight-average molecular weight of copolymer (a-1). A thermoplastic resin composition using, as P3HA-based resin components, copolymer (a-1) having a weight-average molecular weight within the above range and copolymer (a-2) having a weight-average molecular weight greater than that of copolymer (a-1), offers the advantage of greater tensile strain in molded articles obtained by molding the thermoplastic resin composition. The weight-average molecular weight of copolymer (a-2) is preferably 200,000 or more higher than the weight-average molecular weight of copolymer (a-1), more preferably 250,000 or more higher, and even more preferably 300,000 or more higher. The weight-average molecular weight of copolymer (a-2) is not particularly limited as long as it is higher than the weight-average molecular weight of copolymer (a-1), but is preferably 400,000 to 3,000,000, more preferably 450,000 to 2,000,000, and even more preferably 500,000 to 1,500,000. The weight-average molecular weight of copolymer (a-2) may be 600,000 to 1,500,000 or 700,000 to 1,500,000. When the weight average molecular weight of the copolymer (a-2) is within the above range, it has the advantage that the tensile strain of the molded article can be made larger without impairing the processability into the molded article.

[0028] In this specification, the weight average molecular weight of the P3HA resin (i.e., copolymer (a-1) and copolymer (a-2)), and the weight average molecular weight of the polyhydroxyalkanoate resin described below, are values ​​measured by gel permeation chromatography (GPC), for example, using a Shimadzu Corporation "High Performance Liquid Chromatograph 20A System", using a polystyrene gel (e.g., Showa Denko K.K. "K-G 4A", "K-806M", etc.) as a column, and chloroform as a mobile phase, and are values ​​measured in polystyrene equivalent. In the above measurement, a calibration curve obtained by measuring polystyrene of known molecular weight by GPC can be used, and in this case, the calibration curve can be created using polystyrene of weight average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. In addition, as the column in GPC when creating the calibration curve, a column appropriate for measuring the molecular weight of polystyrene may be used.

[0029] The content of copolymer (a-1) in component (A) is not particularly limited, but is preferably 80 to 99 parts by weight, more preferably 83 to 97 parts by weight, and even more preferably 85 to 95 parts by weight, per 100 parts by weight of component (A). By adjusting the content of copolymer (a-1) to 80 to 99 parts by weight per 100 parts by weight of component (A), the tensile strain of the resulting molded article can be increased. Furthermore, the content of copolymer (a-2) in component (A) is also not particularly limited, but is preferably 1 part by weight or more but less than 20 parts by weight, more preferably 3 parts by weight or more but less than 17 parts by weight, and even more preferably 5 parts by weight or more but less than 15 parts by weight.

[0030] The gel fraction of component (A) in the resin composition is not particularly limited, but is preferably less than 50% because this improves moldability, more preferably 40% or less, and even more preferably 30% or less. It may be 20% or less, 10% or less, or even 0%. The gel fraction of component (A) is affected by the amount of crosslinked structures contained in component (A) (in other words, in each P3HA-based resin contained in component (A)). Specifically, the lower the gel fraction of component (A), the smaller the amount of crosslinked structures contained in the P3HA-based resin contained in component (A). In other words, component (A) in the resin composition preferably contains a P3HA-based resin that has a small amount of crosslinked structures or does not have a crosslinked structure. The gel fraction of a P3HA-based resin that is not crosslinked during the production process is usually 0%.

[0031] From the above viewpoints, the gel fractions of both copolymer (a-1) and copolymer (a-2) are preferably less than 50%, more preferably 40% or less, and even more preferably 30% or less, and may be 20% or less, 10% or less, or even 0%. By controlling the gel fractions of the P3HA-based resins contained in component (A) (particularly copolymer (a-1) and copolymer (a-2)) within the above ranges, the gel fraction of component (A) can also be controlled within the same range.

[0032] In this specification, the gel fraction of a P3HA-based resin (composition) is a value measured as follows: (1) A dried P3HA-based resin (composition) is added to chloroform to a concentration of 0.7 wt %. The resulting mixture is then maintained at 60°C for 30 minutes to obtain a chloroform solution. (2) The chloroform solution is then allowed to stand at room temperature for 3 hours, and then filtered through a membrane filter with a pore size of 0.45 μm. During filtration, chloroform is sprayed multiple times on the inside of the container and on the filter to thoroughly wash the solution while filtering, thereby preventing loss. (3) The gel remaining on the filter is dried, and the weight of the dried gel and the filter is measured. The gel fraction is calculated using the following formula: Gel fraction = (weight of filter including dried gel - weight of filter only) / weight of P3HA-based resin (composition) used in measurement × 100 (%).

[0033] Component (A) may contain a P3HA-based resin other than copolymer (a-1) and copolymer (a-2) (another P3HA-based resin). Examples of such other P3HA-based resins include various P3HA-based resins having a weight-average molecular weight of less than 200,000.

[0034] The content of the other P3HA-based resin in component (A) is not particularly limited as long as it does not impair the effects of the present invention, but it is preferably 0.1 to 10 parts by weight, and more preferably 0.5 to 5 parts by weight, per 100 parts by weight of the total amount of component (A).

[0035] [1-2] Crosslinked Resin Particles (B) The present resin composition contains crosslinked resin particles (B) that contain a polyhydroxyalkanoate resin and have a gel fraction of 50% or more. Hereinafter, the "crosslinked resin particles (B)" may be referred to as "component (B)." By including component (B), the present resin composition can provide a molded article with excellent impact resistance. In other words, component (B) can function as a modifier or impact modifier for thermoplastic resins.

[0036] The content of the crosslinked resin particles (B) in the resin composition is 10 to 60 parts by weight per 100 parts by weight of the total amount of the P3HA-based resin component (A) and the crosslinked resin particles (B). This configuration enables the thermoplastic resin composition to provide a molded article with excellent impact resistance. The content of the crosslinked resin particles (B) in the resin composition may be 15 parts by weight or more, 20 parts by weight or more, or even 25 parts by weight or more per 100 parts by weight of the total amount of the P3HA-based resin component (A) and the crosslinked resin particles (B). The content of the crosslinked resin particles (B) in the resin composition is preferably 55 parts by weight or less, more preferably 50 parts by weight or less, and particularly preferably 45 parts by weight or less per 100 parts by weight of the total amount of the P3HA-based resin component (A) and the crosslinked resin particles (B).

[0037] <Polyhydroxyalkanoate Resin> In this specification, the "polyhydroxyalkanoate resin" may also be referred to as a "PHA resin."

[0038] PHA resin is a general term for polymers containing hydroxyalkanoic acid as a monomer unit (monomer repeating unit), and is generally biodegradable. PHA resins are aliphatic polyesters, preferably polyesters that do not contain aromatic rings. In this specification, PHA resins refer to those that contain hydroxyalkanoic acid repeating units in an amount of 50 mol% or more of all monomer repeating units (100 mol%). PHA resins preferably contain hydroxyalkanoic acid repeating units in an amount of 60 mol% or more, more preferably 70 mol% or more, of all monomer repeating units (100 mol%).

[0039] The PHA-based resin is not particularly limited. Examples of PHA-based resins include polyglycolic acid, P3HA-based resins, and poly(4-hydroxyalkanoate)-based resins. One type of PHA-based resin may be used alone, or two or more types may be used in combination. The PHA-based resin preferably contains a P3HA-based resin, and more preferably is a P3HA-based resin (in other words, is composed only of a P3HA-based resin).

[0040] The P3HA-based resin is as described in [1-1] P3HA-based resin component (A). The P3HA-based resin contained in component (B) may be a homopolymer or copolymer containing repeating units derived from the monomers exemplified in [1-1]. More specific examples of the P3HA-based resin contained in component (B) include 3HB homopolymers such as poly(3-hydroxybutyrate) (P3HB), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P3HB3HH), and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB). Only one type of P3HA-based resin may be used, or two or more types may be used in combination.

[0041] It is also preferred that the P3HA-based resin contained in component (B) contains a 3-hydroxybutanoic acid repeating unit. When P3HA contains a 3HB repeating unit, from the viewpoint of the balance between flexibility and strength, the compositional ratio of the 3HB repeating unit to all monomer repeating units (100 mol%) is preferably 60 mol% to 99 mol%, more preferably 61 mol% to 97 mol%, and even more preferably 62 mol% to 95 mol%. When the compositional ratio of the 3HB repeating unit in the P3HA-based resin contained in component (B) is 60 mol% or more, it has the advantage that the rigidity of the crosslinked resin particles (B) can be further improved. On the other hand, when the compositional ratio of the 3HB repeating unit in the P3HA-based resin is 99 mol% or less, it has the advantage that the flexibility of the crosslinked resin particles (B) tends to be further improved. The P3HA-based resin contained in component (B) may be a combination of two or more types having different compositional ratios of the 3HB repeating unit.

[0042] In this specification, "polyglycolic acid" refers to a group of all monomer repeating units (100 mol%) containing [—CH ２ The term "polyglycolic acid" refers to a resin containing 50 mol % or more of repeating units represented by the formula [—CH—CO—O—]. ２ The repeating units represented by the formula [—CO—O—] may account for 60 mol % or more, 70 mol % or more, 80 mol % or more, or 90 mol % or more of all the monomer repeating units (100 mol %).

[0043] The polyglycolic acid may be a homopolymer of glycolic acid, or a copolymer of glycolic acid and a monomer other than glycolic acid (for example, a copolymer of glycolic acid and lactic acid, or a copolymer of glycolic acid and caprolactone).

[0044] Polyglycolic acid can be obtained by known methods such as condensation polymerization of glycolic acid and ring-opening polymerization of glycolide.

[0045] The PHA-based resin may have a glass transition temperature of 0°C or lower, or may have a glass transition temperature higher than 0°C, or may be a mixture of a PHA-based resin having a glass transition temperature of 0°C or lower and a PHA-based resin having a glass transition temperature higher than 0°C. The glass transition temperature of the crosslinked resin particles (B) is preferably 0°C or lower from the viewpoint that rigidity is likely to be high in a temperature range of room temperature or lower. From the viewpoint of making the glass transition temperature of the crosslinked resin particles (B) 0°C or lower, the PHA-based resin contained in the crosslinked resin particles (B) preferably contains a PHA-based resin having a glass transition temperature of 0°C or lower. The PHA-based resin contained in the crosslinked resin particles (B) preferably contains 60% by weight or more, more preferably 70% by weight or more, even more preferably 80% by weight or more, and particularly preferably 90% by weight or more of a PHA-based resin having a glass transition temperature of 0°C or lower, based on 100% by weight of all the PHA-based resins contained in the crosslinked resin particles (B).

[0046] The glass transition temperature of the PHA resin is determined as the midpoint between the temperatures at which a baseline shift occurs when 2 mg to 3 mg of the PHA resin is filled in an aluminum pan, the pan is heated in a differential scanning calorimeter under a nitrogen stream from −80° C. to 180° C. at a rate of 10° C. / min to completely melt the resin, the pan is cooled from 180° C. to −80° C. at a rate of 10° C. / min, and the pan is heated again from −80° C. to 180° C. at a rate of 10° C. / min to completely melt the resin, and the glass transition temperature of the PHA resin is determined as the midpoint between the temperatures at which a baseline shift begins and ends.

[0047] For example, the Tg of a copolymer of P3HA with 3HB and a monomer other than 3HB may depend on the type and content of the monomer other than 3HB in the copolymer. For example, P3HB3HH, which contains 10 mol% or more of 3HH repeating units out of 100 mol% of P3HB3HH repeating units, has a Tg of less than 0°C. For example, P3HB4HB, which contains 6 mol% or more of 4HB repeating units out of 100 mol% of P3HB4HB repeating units, has a Tg of less than 0°C.

[0048] The weight-average molecular weight of the PHA-based resin is not particularly limited. The weight-average molecular weight of the PHA-based resin is preferably 50,000 to 3,000,000, more preferably 100,000 to 2,000,000, and more preferably 150,000 to 1,500,000. A weight-average molecular weight of 50,000 or more has the advantage of reducing or avoiding the tendency of the crosslinked resin particles (B) to have low strength. Furthermore, a weight-average molecular weight of 50,000 or more has the advantage of reducing or avoiding the tendency of stickiness due to low-molecular-weight components. On the other hand, a PHA-based resin having a weight-average molecular weight of 3,000,000 or less has the advantage of being easy to manufacture and / or easy to handle, which is effective in achieving the objective of one embodiment of the present invention. The weight-average molecular weight of the PHA-based resin is a value obtained by measuring the PHA-based resin before crosslinking.

[0049] <Gel Fraction> In this specification, the term "crosslinked resin particles" refers to particles having a crosslinked structure in which molecular chains of resins constituting the resin particles are bonded intramolecularly and / or intermolecularly. That is, "crosslinked resin particles" may have a crosslinked structure in which molecular chains of resin components including a PHA-based resin are bonded together. The amount of crosslinked structures in the crosslinked resin particles affects the gel fraction of the crosslinked resin particles; specifically, the more crosslinked structures there are, the higher the gel fraction. Since the crosslinked resin particles (B) have a certain amount or more of crosslinked structures, they exhibit a high gel fraction, specifically a gel fraction of 50% or more. When the gel fraction of the crosslinked resin particles (B) is 50% or more, the crosslinked resin particles (B) have excellent hardness, heat resistance, and solvent resistance.

[0050] The gel fraction value is preferably 60% or more, more preferably 70% or more, even more preferably 75% or more, and particularly preferably 80% or more. It may also be 85% or more, or 90% or more. The upper limit of the gel fraction is not particularly limited, as long as it is 100% or less. From the viewpoint of production efficiency of the crosslinked resin particles (B), the upper limit of the gel fraction is preferably 99.5% or less, more preferably 99% or less. The upper limit of the gel fraction may also be 98% or less, 97% or less, or 96% or less.

[0051] The gel fraction is a value measured as follows: (1) A dried product of crosslinked resin particles (B) is added to chloroform so that the concentration becomes 0.7% by weight, and the resulting mixture is maintained at 60°C for 30 minutes to obtain a chloroform solution; (2) The chloroform solution is then allowed to stand at room temperature for 3 hours, and the chloroform solution is then filtered through a membrane filter having a pore size of 0.45 µm; (3) The gel remaining on the filter is dried, and the weight of the dried gel together with the filter is measured, and the gel fraction is calculated using the following formula: Gel fraction (%) = {(Weight of filter including dried gel - Weight of filter only) / Weight of dried product of crosslinked resin particles (B) used for measurement} x 100.

[0052] <Volume average particle diameter> The volume average particle diameter of the crosslinked resin particles (B) is preferably 0.10 μm to 10.00 μm. This configuration allows the crosslinked resin particles to be suitably used in various applications, as described below. From the viewpoint of practical use opportunities, the lower limit of the volume average particle diameter is more preferably 0.15 μm or more, and even more preferably 0.20 μm or more. Furthermore, from the viewpoint of productivity (such as PHA production and / or crosslinking treatment), the upper limit of the volume average particle diameter is more preferably 8.00 μm or less, and even more preferably 5.00 μm or less.

[0053] In this specification, the volume average particle diameter (MV) of the crosslinked resin particles is a value obtained by measuring an aqueous dispersion in which the crosslinked resin particles are dispersed in an aqueous medium. More specifically, the volume average particle diameter (MV) of the crosslinked resin particles is a value calculated by the following formula (1), i.e., formula (2), when the particle diameters of the individual crosslinked resin particles contained in a population of k crosslinked resin particles in total are denoted as d1, d2, ..., di... dk in ascending order, and the volumes of these individual crosslinked resin particles are denoted as V1, V2, ..., Vi... Vk (where Vi is the volume of the crosslinked resin particle with particle diameter di):

[0054] A general-purpose measuring device can be used to measure the volume average particle diameter of the crosslinked resin particles in the aqueous dispersion (in other words, the particle diameter and volume of the crosslinked resin particles). One example of such a device is Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd.

[0055] <Peroxide> The crosslinked structure in the crosslinked resin particles (B) is not particularly limited, but is preferably one crosslinked using a peroxide. That is, the crosslinked resin particles (B) are preferably one crosslinked using a peroxide. When a peroxide is used, radicals generated by decomposition of the peroxide act on the molecules of the resin (e.g., PHA-based resin) constituting the resin particles. As a result, molecular chains of the resin constituting the resin particles are directly bonded to each other, thereby forming a crosslinked structure.

[0056] When the crosslinked resin particles (B) are crosslinked using a peroxide, the aqueous dispersion containing the crosslinked resin particles (B) may contain substances derived from the peroxide used to introduce the crosslinked structure (such as decomposition products of the peroxide and unreacted peroxide). Alternatively, when the crosslinked resin particles (B) are crosslinked using a peroxide, substances derived from the peroxide used to introduce the crosslinked structure (such as decomposition products of the peroxide and unreacted peroxide) may adhere to the surface of the resulting crosslinked resin particles (B). In other words, when the crosslinked resin particles (B) are crosslinked using a peroxide, the crosslinked resin particles (B) or the present resin composition may contain substances derived from the peroxide (such as decomposition products of the peroxide and unreacted peroxide). When the crosslinked resin particles (B) or the present resin composition contain substances derived from a peroxide, analysis of the crosslinked resin particles (B) or the resin composition reveals that the crosslinked resin particles (B) are crosslinked using a peroxide.

[0057] The peroxide may be an organic peroxide or an inorganic peroxide, but is preferably an organic peroxide because it can increase the gel fraction more efficiently.

[0058] As the organic peroxide, it is preferable to use at least one selected from the group consisting of diacyl peroxides, alkyl peroxy esters, dialkyl peroxides, hydroperoxides, peroxyketals, peroxycarbonates, and peroxydicarbonates, taking into consideration the heating temperature and / or heating time during the crosslinking treatment.

[0059] Specific examples of such organic peroxides include butyl peroxy neododecanoate, octanoyl peroxide, dilauroyl peroxide, succinic peroxide, a mixture of toluoyl peroxide and benzoyl peroxide, benzoyl peroxide, bis(butylperoxy)trimethylcyclohexane, butyl peroxylaurate, dimethyldi(benzoylperoxy)hexane, bis(butylperoxy)methylcyclohexane, bis(butylperoxy)cyclohexane, and butylperoxybenzo ester, butyl bis(butylperoxy)valerate, dicumyl peroxide, di-t-hexyl peroxide, t-butylperoxy 2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxypivalate, t-hexylperoxypivalate, t-butylperoxymethyl monocarbonate, t-pentylperoxymethyl monocarbonate, t-hexylperoxymethyl monocarbonate, t-heptylperoxymethyl monocarbonate, t-octylperoxymethyl monocarbonate, 1 , 1,3,3-tetramethylbutylperoxymethyl monocarbonate, t-butylperoxyethyl monocarbonate, t-pentylperoxyethyl monocarbonate, t-hexylperoxyethyl monocarbonate, t-heptylperoxyethyl monocarbonate, t-octylperoxyethyl monocarbonate, 1,1,3,3-tetramethylbutylperoxyethyl monocarbonate, t-butylperoxy n-propyl monocarbonate, t-pentylperoxy n-propyl monocarbonate, t-hexylperoxy peroxy isopropyl monocarbonate, t-heptylperoxy isopropyl monocarbonate, t-octylperoxy isopropyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy isopropyl monocarbonate, t-butylperoxy isopropyl monocarbonate, t-pentylperoxy isopropyl monocarbonate, t-hexylperoxy isopropyl monocarbonate, t-heptylperoxy isopropyl monocarbonate, t-octylperoxy isopropyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy isopropyl monocarbonate, t-butylperoxy n-butyl monocarbonate, t-pentylperoxy n-butyl monocarbonate, t-hexylperoxy n-butyl monocarbonate, t-heptylperoxy n-butyl monocarbonate, t-octylperoxy n-butyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy n-butyl monocarbonate, t-butylperoxy isobutyl monocarbonate, t-pentylperoxy isobutyl monocarbonate, t -Hexylperoxy isobutyl monocarbonate, t-heptylperoxy isobutyl monocarbonate, t-octylperoxy isobutyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy isobutyl monocarbonate, t-butylperoxy sec-butyl monocarbonate, t-pentylperoxy sec-butyl monocarbonate, t-hexylperoxy sec-butyl monocarbonate, t-heptylperoxy sec-butyl monocarbonate, t-octylperoxy sec-butyl monocarbonate t-butylperoxy t-butyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy sec-butyl monocarbonate, t-butylperoxy t-butyl monocarbonate, t-pentylperoxy t-butyl monocarbonate, t-hexylperoxy t-butyl monocarbonate, t-heptylperoxy t-butyl monocarbonate, t-octylperoxy t-butyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy t-butyl monocarbonate, t-butylperoxy 2-ethylhexyl monocarbonate, t-pentylperoxy 2-ethylhexyl monocarbonate ethylhexyl monocarbonate, t-hexylperoxy 2-ethylhexyl monocarbonate, t-heptylperoxy 2-ethylhexyl monocarbonate, t-octylperoxy 2-ethylhexyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexyl monocarbonate, diisobutyl peroxide, cumyl peroxy neodecanoate, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, bis(4-t-butylcyclohexyl) peroxydicarbonate, bis(2-ethylhexyl) peroxydicarbonate, t-hexyl peroxyneodecanoate, t-butyl peroxyneodecanoate, t-butyl peroxyneoheptanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, di(3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, disuccinic acid peroxide, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy) Examples of organic peroxides include hexane, t-hexylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, dibenzoyl peroxide, t-butylperoxy-2-ethylhexyl carbonate, t-butylperoxyisopropyl carbonate, 1,6-bis(t-butylperoxycarbonyloxy)hexane, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxyacetate, t-butylperoxybenzoate, t-amylperoxy-3,5,5-trimethylhexanoate, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, and 2,2-di-t-butylperoxybutane. One organic peroxide may be used alone, or two or more organic peroxides may be used in combination.

[0060] Among these, t-butylperoxyisopropyl monocarbonate, t-pentylperoxyisopropyl monocarbonate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy2-ethylhexyl monocarbonate, t-pentylperoxy2-ethylhexyl monocarbonate, t-hexylperoxy2-ethylhexyl monocarbonate, t-amylperoxyisopropyl monocarbonate, di-t-hexyl peroxide, t-butylperoxy2-ethylhexanoate Peroxymethylbutylperoxyisobutyrate, t-hexylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, t-butylperoxypivalate, t-hexylperoxypivalate, t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, and 1,1,3,3-tetramethylbutylperoxyneodecanoate are preferred organic peroxides because they can efficiently promote crosslinking of the resin that constitutes the resin particles.

[0061] Since the heating temperature during the crosslinking treatment can be set low, the peroxide is preferably a compound exhibiting a one-hour half-life temperature of 200° C. or less, more preferably a compound exhibiting a one-hour half-life temperature of 170° C. or less, and even more preferably a compound exhibiting a one-hour half-life temperature of 140° C. or less. The lower limit of the one-hour half-life temperature of the peroxide may be 50° C. or more, 60° C. or more, or 70° C. or more.

[0062] Particularly preferred organic peroxides exhibiting such a one-hour half-life temperature include t-butylperoxyisopropyl monocarbonate, t-butylperoxy 2-ethylhexyl monocarbonate, di-sec-butylperoxydicarbonate, t-butylperoxy 2-ethylhexanoate, t-butylperoxyisobutyrate, t-hexylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, t-butylperoxypivalate, t-hexylperoxypivalate, t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, and 1,1,3,3-tetramethylbutylperoxyneodecanoate.

[0063] The case where the peroxide is an inorganic peroxide will be described. Examples of the inorganic peroxide include hydrogen peroxide, potassium peroxide, calcium peroxide, sodium peroxide, magnesium peroxide, potassium persulfate, sodium persulfate, and ammonium persulfate, taking into consideration the heating temperature and / or time during the crosslinking treatment. Among these, hydrogen peroxide, potassium persulfate, sodium persulfate, and ammonium persulfate are preferred because they are easy to handle and have decomposition temperatures suitable for the heating temperature during the crosslinking treatment. The inorganic peroxide may be used alone or in combination of two or more. Furthermore, an organic peroxide and an inorganic peroxide may be used in combination.

[0064] <Multifunctional Compound> The crosslinked structure in the crosslinked resin particles (B) may be introduced using only peroxide, but it is preferable that it is introduced using both peroxide and a multifunctional compound. That is, it is preferable that the crosslinked resin particles (B) are crosslinked in the presence of peroxide and a multifunctional compound. When both peroxide and a multifunctional compound are used, the gel fraction of the crosslinked resin particles (B) can be increased with a smaller amount of peroxide than when only peroxide is used.

[0065] The polyfunctional compound refers to a compound having two or more functional groups (e.g., radical reactive groups) per molecule that can crosslink the resin (e.g., PHA-based resin) that constitutes the resin particles. The polyfunctional compound is not particularly limited, but is preferably a compound that is reactive with radicals generated from peroxides, and is particularly preferably a compound having two or more radical reactive groups per molecule. The radical reactive group is preferably at least one selected from the group consisting of a vinyl group, an allyl group, an acryloyl group, and a methacryloyl group.

[0066] Such polyfunctional compounds are not particularly limited, but examples thereof include allyl (meth)acrylate, allyl alkyl (meth)acrylates, allyloxyalkyl (meth)acrylates, polyfunctional (meth)acrylates having two or more (meth)acrylic groups such as ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol (meth)acrylate, divinylbenzene, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene. Preferably, the polyfunctional compound is one or more selected from the group consisting of allyl methacrylate, triallyl isocyanurate, butanediol di(meth)acrylate, and divinylbenzene, and more preferably, the polyfunctional compound is one or more selected from the group consisting of allyl methacrylate and triallyl isocyanurate.

[0067] When a crosslinked structure is formed in the presence of a polyfunctional compound, the resulting crosslinked resin particles (B) usually contain a structure derived from the polyfunctional compound, and in this case, the molecular chains of the resin constituting the resin particles are bonded to each other via the structure derived from the polyfunctional compound.

[0068] <Other Components> The crosslinked resin particles (B) may be composed solely of a PHA-based resin having a crosslinked structure, or may further contain components other than the PHA-based resin. Examples of the components other than the PHA-based resin having a crosslinked structure include resins other than the PHA-based resin, antioxidants, hydrolysis inhibitors, antiblocking agents, crystal nucleating agents, lubricants, and ultraviolet absorbers.

[0069] The proportion of the PHA resin in the crosslinked resin particles (B) is not particularly limited. The content of the PHA resin in 100% by weight of the resin components of the crosslinked resin particles (B) may be 50% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more, particularly preferably 95% by weight or more, and may even be 99% by weight or more. The upper limit of the content of the PHA resin in 100% by weight of the resin components of the crosslinked resin particles (B) is not particularly limited, as long as it is 100% by weight or less. Note that the term "resin component of the crosslinked resin particles (B)" refers to the resin that essentially constitutes the crosslinked resin particles (B), and does not include components that crosslink the molecular chains of the resin (e.g., structures derived from polyfunctional compounds) or residues of components used to crosslink the molecular chains of the resin (e.g., unreacted peroxides, decomposition products of peroxides, unreacted polyfunctional compounds, etc.).

[0070] Examples of resins other than PHA-based resins include aliphatic polyesters and aliphatic aromatic polyesters other than PHA-based resins. Examples of aliphatic polyesters other than PHA include (i) polycaprolactone (PCL), (ii) polylactic acid (PLA), and (iii) aliphatic polyesters having a structure in which an aliphatic diol and an aliphatic dicarboxylic acid are polycondensed. Specific examples of aliphatic polyesters having a structure in which an aliphatic diol and an aliphatic dicarboxylic acid are polycondensed include polyethylene succinate, polybutylene succinate (hereinafter also referred to as "PBS"), polyhexamethylene succinate, polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polybutylene succinate adipate (hereinafter also referred to as "PBSA"), polyethylene sebacate, polybutylene sebacate, etc. Examples of the aliphatic aromatic polyester include aliphatic aromatic polyesters obtained by copolymerizing both aliphatic and aromatic compounds as monomers (both aliphatic and aromatic compounds as monomers). Examples of the aliphatic aromatic polyester include polybutylene adipate terephthalate (hereinafter sometimes referred to as "PBAT"), polybutylene sebacate terephthalate (hereinafter sometimes referred to as "PBSeT"), polybutylene azelate terephthalate (hereinafter sometimes referred to as "PBAzT"), polybutylene succinate terephthalate (hereinafter sometimes referred to as "PBST"), and polybutylene succinate adipate terephthalate (hereinafter sometimes referred to as "PBSAT"). These resins other than the PHA-based resin may be used alone or in combination of two or more. In the crosslinked resin particles (B), the resins other than the PHA-based resin may be crosslinked or uncrosslinked.

[0071] The crosslinked resin particles (B) are preferably non-expanded and are different from the expanded resin particles disclosed in WO 2007 / 049694 and WO 2019 / 146555. In other words, the crosslinked resin particles (B) preferably contain substantially no air bubbles inside the particles. The phrase "substantially no air bubbles inside the particles" means that the volume of air bubbles (voids) is 10% or less of the 100% volume of the crosslinked resin particles.

[0072] When the crosslinked resin particles (B) are not expanded, the apparent density of the crosslinked resin particles (B) is relatively large. The apparent density of the crosslinked resin particles (B) is 0.6 g / cm ３ It is preferable that the density exceeds 0.7 g / cm ３ More preferably, it is 0.9 g / cm or more. ３ The apparent density of the crosslinked resin particles (B) can be determined by the method described in JIS K0061 (Method for measuring density and specific gravity of chemical products) or JIS Z8807 (Method for measuring density and specific gravity of solids).

[0073] The average weight per particle of the crosslinked resin particles (B) is not particularly limited. For example, when the volume average particle diameter of the crosslinked resin particles (B) is 10.00 μm or less, the average weight per particle of the crosslinked resin particles (B) can be much less than 0.1 mg.

[0074] The crosslinked resin particles (B) may be dried, and the shape of the dried particles may be powder, pellets, crumbs, a film, a sheet, or the like, depending on the drying method.

[0075] <Method for producing crosslinked resin particles (B)> An example of a method for producing crosslinked resin particles (B) will be specifically described. The crosslinked resin particles (B) can be produced by crosslinking resin molecular chains in an aqueous dispersion containing resin particles before crosslinking treatment in the presence of a peroxide. Note that the term "resin particles" refers to particles composed of the resin component that essentially constitutes the crosslinked resin particles. When the resin component is composed only of a PHA-based resin, the resin particles can also be called PHA-based resin particles. In order to efficiently crosslink the resin molecular chains, it is preferable to heat the aqueous dispersion of resin particles containing a peroxide to a temperature suitable for decomposing the peroxide.

[0076] More specifically, the method for producing the crosslinked resin particles (B) preferably includes the steps of: (1) preparing an aqueous dispersion of resin particles in which pre-crosslinked resin particles (e.g., PHA-based resin particles) are dispersed in water; (2) adding a peroxide to the aqueous dispersion of resin particles to impregnate the resin particles with the peroxide; and (3) heating the aqueous dispersion of resin particles impregnated with the peroxide to a heating temperature to crosslink the resin molecular chains (e.g., PHA-based resin molecular chains). Furthermore, the method more preferably includes the step of maintaining the heating temperature after all the peroxide has been added.

[0077] In step (1), for example, the aqueous dispersion of PHA-based resin particles may be an aqueous dispersion obtained by culturing a PHA-producing microorganism to accumulate a PHA-based resin in the cells, disrupting the cells in the culture solution, and separating and removing the cell components, or an aqueous dispersion obtained by concentrating or diluting the aqueous dispersion. According to such a method, the process from producing PHA-based resin particles by culturing a PHA-producing microorganism to crosslinking treatment can be carried out without separating the PHA-based resin particles from water.

[0078] Alternatively, the aqueous dispersion of resin particles (for example, PHA-based resin particles) can be prepared by dispersing dried resin particles (for example, PHA-based resin particles) in water.

[0079] The aqueous medium contained in the aqueous dispersion may be water alone or a mixed solvent of water and a water-compatible organic solvent. In the mixed solvent, the concentration of the water-compatible organic solvent is not particularly limited as long as it is equal to or lower than the solubility of the organic solvent in water.

[0080] The organic solvent is not particularly limited, but examples thereof include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, pentanol, hexanol, and heptanol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; nitriles such as acetonitrile and propionitrile; amides such as dimethylformamide and acetamide; dimethyl sulfoxide; pyridine; piperidine; and the like. Among these, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, acetonitrile, and propionitrile are preferred because they are easily removable. Furthermore, methanol, ethanol, 1-propanol, 2-propanol, butanol, and acetone are more preferred because they are easily available. Furthermore, methanol, ethanol, and acetone are particularly preferred.

[0081] The water content in the entire aqueous medium (100% by weight) constituting the aqueous dispersion is preferably 5% by weight to 100% by weight. The water content in 100% by weight of the aqueous medium is more preferably 10% by weight or more, more preferably 30% by weight or more, even more preferably 50% by weight or more, and particularly preferably 70% by weight or more. The water content in 100% by weight of the aqueous medium may be 90% by weight or more, or may be 95% by weight or more.

[0082] In the aqueous dispersion, the volume average particle diameter of the resin particles is preferably within the same range as that of the crosslinked resin particles (B) described above. In the case of PHA-based resin particles produced by a PHA-producing microorganism, the volume average particle diameter can usually be within the above range, so that an aqueous dispersion of PHA-based resin particles having a desired volume average particle diameter can be obtained without carrying out a special step for adjusting the particle diameter.

[0083] The concentration of the resin particles in the aqueous dispersion is not particularly limited and can be set as appropriate, but may be, for example, about 1 to 70% by weight, and preferably about 5 to 50% by weight.

[0084] The aqueous dispersion of resin particles preferably contains a dispersant to improve the dispersibility of the resin particles and promote the crosslinking reaction uniformly. Examples of dispersants include anionic surfactants such as dioctyl sodium sulfosuccinate, sodium dodecyl sulfate, sodium lauryl sulfate, and sodium oleate; cationic surfactants such as lauryl trimethylammonium chloride; nonionic surfactants such as glycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene polyoxypropylene glycol; and water-soluble polymers such as polyvinyl alcohol, ethylene-modified polyvinyl alcohol, polyvinylpyrrolidone, methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, polyacrylic acid, sodium polyacrylate, potassium polyacrylate, polymethacrylic acid, and sodium polymethacrylate. These dispersants may be used alone or in combination of two or more.

[0085] When a dispersant is used, the content (addition amount) of the dispersant in the aqueous dispersion is not particularly limited. The content of the dispersant in the aqueous dispersion may be, for example, 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, and particularly preferably 0.5 to 3 parts by weight, relative to 100 parts by weight of the resin particles.

[0086] In step (2), a peroxide is added to the aqueous dispersion of resin particles obtained in step (1) to impregnate the resin particles with the peroxide. The peroxide may be any of those described above. The peroxide may be added in various forms, such as a solid or liquid. Alternatively, a liquid diluted with a diluent may be added. The peroxide may be added all at once, continuously, or in portions.

[0087] When a peroxide and the polyfunctional compound are used in combination, it is preferable to add the polyfunctional compound to the aqueous dispersion of resin particles in step (2). The polyfunctional compound can be any of those described above. The polyfunctional compound can be added in various forms, such as solid or liquid. Alternatively, a liquid diluted with a diluent or the like may be added. The polyfunctional compound may be added all at once, continuously, or in portions.

[0088] In step (2), the resin particles are impregnated with the peroxide and any polyfunctional compound by, for example, setting the temperature of the aqueous dispersion to, for example, 0°C or higher but lower than a temperature suitable for decomposing the peroxide employed in the next step (3) after or while adding these compounds to the aqueous dispersion of the resin particles, and maintaining this temperature for, for example, about 1 minute to 5 hours while stirring the aqueous dispersion. Specifically, the temperature of the aqueous dispersion during impregnation may be about 0°C to 80°C.

[0089] The amount of peroxide used can be appropriately set in consideration of the gel fraction of the crosslinked resin particles (B), and is, for example, preferably 0.01 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, even more preferably 0.3 to 5 parts by weight, and particularly preferably 0.5 to 3 parts by weight, per 100 parts by weight of the resin particles.

[0090] According to the production method of crosslinking resin particles in an aqueous dispersion using a peroxide, crosslinking can be easily carried out while maintaining the particle size (volume) before crosslinking to obtain crosslinked resin particles (B). On the other hand, it may be difficult to achieve this in the method of crosslinking a resin by melt-kneading in the presence of a peroxide.

[0091] Furthermore, the production method in which resin particles are crosslinked in an aqueous dispersion using a peroxide has the advantage that it is easy to control the temperature rise caused by the heat generated during the crosslinking reaction, and crosslinked resin particles (B) having a safe and stable crosslinked structure (quality) can be efficiently obtained.

[0092] The amount of the polyfunctional compound used may also be appropriately determined in consideration of the gel fraction of the crosslinked resin particles (B). The amount of the polyfunctional compound used is, for example, preferably 0.01 to 20 parts by weight, more preferably 0.05 to 15 parts by weight, even more preferably 0.1 to 10 parts by weight, still more preferably 0.2 to 5 parts by weight, and particularly preferably 0.3 to 3 parts by weight, per 100 parts by weight of the resin particles.

[0093] In step (3), the aqueous dispersion of resin particles impregnated with peroxide is heated to a temperature suitable for decomposing the peroxide. The heating temperature is preferably within a range of approximately 25°C above or below the one-hour half-life temperature of the peroxide (one-hour half-life temperature -25°C to one-hour half-life temperature +25°C). Specifically, the heating temperature is preferably 30°C to 140°C, more preferably 50°C to 135°C, and even more preferably 60°C to 130°C. This method allows crosslinking of the resin (e.g., PHA-based resin) at a temperature lower than the melting temperature of the resin, thereby avoiding resin degradation due to heating during the crosslinking process. The melting temperature of PHA-based resins is, for example, 50°C to 210°C.

[0094] In the subsequent step (4), it is preferable to maintain the heating temperature. This allows the crosslinking reaction using the peroxide to proceed sufficiently. The time for maintaining the heating temperature is not particularly limited, but is preferably 1 minute to 15 hours, and more preferably 1 hour to 10 hours.

[0095] After the crosslinking reaction is completed, the crosslinked resin particles (B) are separated from the aqueous dispersion, and water is removed from the separated crosslinked resin particles (B) to obtain dried crosslinked resin particles (B). The method for separating the crosslinked resin particles (B) from the aqueous dispersion is not particularly limited, and examples thereof include filtration, centrifugation, heat drying, freeze drying, and spray drying. For example, spray drying can be used to obtain dried crosslinked resin particles (B) directly from the aqueous dispersion. Furthermore, by extruding the crosslinked resin particles (B) alone after separation from the aqueous dispersion, residual water can be completely removed, and crosslinked resin particles (B) can be obtained in pellet form. Furthermore, an aggregation step using a coagulant and / or adjusting the pH may be performed.

[0096] [1-3] Other Components Included in the Resin Composition <Crystal Nucleating Agent> The resin composition may further contain a crystal nucleating agent. When the thermoplastic resin composition contains a crystal nucleating agent, crystallization during molding is promoted when the P3HA-based resin component (A) is a crystalline resin, and molding processability, productivity, and the like can be improved. When the resin composition contains a crystal nucleating agent, there is also the advantage that a thermoplastic resin composition and a molded article thereof having excellent heat resistance or mechanical properties can be obtained.

[0097] The crystal nucleating agent is not particularly limited, and conventionally known ones can be used. Examples of the crystal nucleating agent include inorganic substances such as talc, kaolinite, montmorillonite, mica, synthetic mica, clay, zeolite, silica, carbon black, graphite, boron nitride, zinc oxide, titanium oxide, tin oxide, calcium carbonate, magnesium carbonate, aluminum oxide, neodymium oxide, barium sulfate, sodium chloride, and metal phosphates; sugar alcohol compounds derived from natural products such as erythritol, pentaerythritol, galactitol, mannitol, and arabitol; polysaccharides such as chitin and chitosan; polyols such as aliphatic alcohols (polyols), polyvinyl alcohol, and polyethylene oxide; sodium benzoate, potassium benzoate, lithium benzoate, calcium benzoate, magnesium benzoate, barium benzoate, lithium terephthalate, sodium terephthalate, and terephthalic acid salts. metal salts of organic carboxylic acids such as potassium phosphate, calcium oxalate, sodium laurate, potassium laurate, sodium myristate, potassium myristate, calcium myristate, sodium octacosanoate, calcium octacosanoate, sodium stearate, potassium stearate, lithium stearate, calcium stearate, magnesium stearate, barium stearate, sodium montanate, calcium montanate, sodium toluate, sodium salicylate, potassium salicylate, zinc salicylate, aluminum dibenzoate, potassium dibenzoate, lithium dibenzoate, sodium β-naphthalate, and sodium cyclohexanecarboxylate; organic sulfonates such as sodium p-toluenesulfonate and sodium sulfoisophthalate;Carboxylic acid amides such as ethylene stearic acid amide, ethylene bislauric acid amide, palmitic acid amide, hydroxystearic acid amide, erucic acid amide, and trimesic acid tris(t-butylamide), lauric acid esters, palmitic acid esters, oleic acid esters, stearic acid esters, erucic acid esters, N-oleyl palmitic acid ester, N-oleyl oleic acid ester, N-oleyl stearate, N-stearyl oleic acid ester, N-stearyl stearate, N-stearyl erucic acid ester, methylene bisstearate, ethylene bislauric acid ester, ethylene biscapric acid ester, ethylene bisoleic acid ester, ethylene bisstearate, ethylene biserucic acid ester, ethylene Examples of suitable crystal nucleating agents include carboxylic acid esters such as butylene bisisostearate, butylene bisstearate, and p-xylylene bisstearate; dicarboxylic acid derivatives such as dimethyl adipate, dibutyl adipate, diisodecyl adipate, and dibutyl sebacate; cyclic compounds having a functional group C═O and one or more functional groups selected from the group consisting of NH, S, and O in the molecule, such as indigo, quinacridone, and quinacridone magenta; sorbitol derivatives such as bisbenzylidene sorbitol and bis(p-methylbenzylidene)sorbitol; compounds containing a nitrogen-containing heteroaromatic nucleus, such as pyridine, triazine, and imidazole; phosphate ester compounds, bisamides of higher fatty acids, and metal salts of higher fatty acids; branched polylactic acid; and low-molecular-weight poly(3-hydroxybutyrate). These crystal nucleating agents may be used alone or in combination of two or more.

[0098] The content of the nucleating agent is not particularly limited as long as it can promote the crystallization of the thermoplastic resin. The content of the nucleating agent is preferably 0.05 to 12.00 parts by weight, more preferably 0.10 to 10.00 parts by weight, and even more preferably 0.50 to 8.00 parts by weight, per 100 parts by weight of the P3HA-based resin component (A). When the content of the nucleating agent is within the above range, the effect of the nucleating agent can be obtained while suppressing a decrease in viscosity during molding and in the physical properties of the molded product.

[0099] <Lubricant> The resin composition may further contain a lubricant. When the thermoplastic resin composition contains a lubricant, the surface smoothness of the obtained molded article can be improved. The lubricant is not particularly limited. Examples of the lubricant include, but are not limited to, fatty acid metal salts such as magnesium stearate and calcium stearate; fatty acid amides such as behenic acid amide, stearic acid amide, erucic acid amide, oleic acid amide, methylenebisstearic acid amide, and ethylenebisstearic acid amide; polyethylene wax, oxidized polyester wax, glycerin monofatty acid esters such as glycerin monostearate, glycerin monobehenate, and glycerin monolaurate; organic acid monoglycerides such as succinic acid saturated fatty acid monoglycerides; sorbitan fatty acid esters such as sorbitan behenate, sorbitan stearate, and sorbitan laurate; polyglycerin fatty acid esters such as diglycerin stearate, diglycerin laurate, tetraglycerin stearate, tetraglycerin laurate, decaglycerin stearate, and decaglycerin laurate; and higher alcohol fatty acid esters such as stearyl stearate. Lubricants may be used alone or in combination of two or more.

[0100] The content of the lubricant (when multiple lubricants are used, the total content) is not particularly limited as long as it can impart lubricity to the molded article. The content of the lubricant is preferably 0.01 to 20.00 parts by weight, more preferably 0.05 to 10.00 parts by weight, even more preferably 0.10 to 10.00 parts by weight, even more preferably 0.20 to 5.00 parts by weight, and particularly preferably 0.30 to 4.00 parts by weight, per 100 parts by weight of the P3HA-based resin component (A). When the content of the lubricant is within the above range, it is possible to obtain the effect of the lubricant while avoiding bleeding out of the lubricant onto the surface of the molded article.

[0101] <Other Components> The present resin composition may contain other components such as plasticizers; organic fillers; inorganic fillers; antioxidants; hydrolysis inhibitors; ultraviolet absorbers; colorants such as dyes and pigments; and antistatic agents, to the extent that the functionality of the resulting molded article is not impaired.

[0102] The plasticizer is not particularly limited. Examples of the plasticizer include polyester-based plasticizers such as polypropylene glycol sebacate ester; aliphatic dibasic acid ester-based plasticizers such as di-1-butyl adipate, di-n-butyl sebacate, and di-2-ethylhexyl azelate; glycerin-based plasticizers such as glycerin diacetomonolaurate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate; polycarboxylic acid ester-based plasticizers such as tri-2-ethylhexyl acetylcitrate and tributyl acetylcitrate; polyolefin plasticizers such as polyethylene glycol, polypropylene glycol, poly(ethylene oxide-propylene oxide) block and / or random copolymers, and polytetramethylene glycol. alkylene glycol-based plasticizers; phosphate ester-based plasticizers such as diphenyl-2-ethylhexyl phosphate and diphenyloctyl phosphate; epoxy-based plasticizers such as epoxidized soybean oil and epoxidized linseed oil fatty acid butyl esters; and castor oil-based plasticizers such as castor oil fatty acid esters, methyl ricinoleate, ethyl ricinoleate, isopropyl ricinoleate, butyl ricinoleate, ethylene glycol monoricylate, propylene glycol monoricylate, trimethylolpropane monoricylate, sorbitan monoricylate, castor oil fatty acid polyethylene glycol esters, castor oil ethylene oxide adducts, castor oil-based polyols, castor oil-based toluene, and castor oil-based diols. These plasticizers may be used alone or in combination of two or more.

[0103] The organic filler is not particularly limited. Examples of the organic filler include fillers made of naturally-derived materials such as wood-based materials (e.g., wood chips, wood flour, sawdust, etc.), rice husks, rice flour, starch, corn starch, rice straw, wheat straw, and natural rubber; organic fibers such as natural plant fibers, natural animal fibers, and synthetic fibers; and fillers made of synthetic resin materials such as polyester, polyacrylic, polyamide, nylon, polyethylene, polyolefin, polyvinyl alcohol, polyvinyl chloride, polyurethane, polyacetal, aramid, PBO (poly-p-phenylene benzobisoxazole), polyphenylene sulfide, acetyl cellulose, polybenzazole, polyarylate, polyvinyl acetate, and synthetic rubber.

[0104] The natural plant fibers are not particularly limited. Examples of the natural plant fibers include kenaf fiber, abaca fiber, bamboo fiber, jute fiber, hemp fiber, linen fiber, henequen (sisal), ramie fiber, hemp, cotton, banana fiber, coconut fiber, palm, paper mulberry, Mitsumata, bagasse, etc. Other examples include regenerated fibers such as pulp, cellulose fiber, and rayon processed from plant fibers. Examples of natural animal fibers include wool, silk, cashmere, and mohair.

[0105] The inorganic filler is not particularly limited. Examples of the inorganic filler include silica-based inorganic fillers (e.g., quartz, fumed silica, silicic anhydride, fused silica, crystalline silica, amorphous silica, fillers formed by condensing alkoxysilanes, and ultrafine amorphous silica), alumina, zircon, iron oxide, zinc oxide, titanium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, glass, silicone rubber, silicone resin, titanium oxide, carbon fiber, mica, graphite, carbon black, ferrite, graphite, diatomaceous earth, clay, clay, talc, calcium carbonate, manganese carbonate, magnesium carbonate, barium sulfate, and silver powder. These inorganic fillers may be surface-treated to improve dispersibility in the thermoplastic resin composition. These inorganic fillers may be used alone or in combination of two or more.

[0106] The antioxidant is not particularly limited. Examples of the antioxidant include phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. These antioxidants may be used alone or in combination of two or more.

[0107] The hydrolysis inhibitor is not particularly limited. Examples of the hydrolysis inhibitor include carbodiimide compounds, epoxy compounds, isocyanate compounds, and oxazoline compounds. These hydrolysis inhibitors may be used alone or in combination of two or more.

[0108] The ultraviolet absorber is not particularly limited. Examples of the ultraviolet absorber include benzophenone compounds, benzotriazole compounds, triazine compounds, salicylic acid compounds, cyanoacrylate compounds, and nickel complex salt compounds. These ultraviolet absorbers may be used alone or in combination of two or more.

[0109] The colorants such as pigments and dyes are not particularly limited. Examples of colorants include inorganic colorants such as titanium oxide, calcium carbonate, chromium oxide, cuprous oxide, calcium silicate, iron oxide, carbon black, graphite, titanium yellow, and cobalt blue; soluble azo pigments such as lake red, lithol red, and brilliant carmine; insoluble azo pigments such as dinitrile orange and fast yellow; phthalocyanine pigments such as monochlorophthalocyanine blue, polychlorophthalocyanine blue, and polybromophthalocyanine green; condensed polycyclic pigments such as indigo blue, perylene red, isoindolinone yellow, and quinacridone red; and dyes such as oracet yellow. These colorants may be used alone or in combination of two or more.

[0110] The antistatic agent is not particularly limited. Examples of the antistatic agent include low molecular weight antistatic agents such as fatty acid ester compounds, aliphatic ethanolamine compounds, and aliphatic ethanolamide compounds, and polymeric antistatic agents. These antistatic agents may be used alone or in combination of two or more.

[0111] The resin composition may further contain any of the following additives: catalyst deactivators (hindered phenol compounds, thioether compounds, vitamin compounds, triazole compounds, polyamine compounds, hydrazine derivative compounds, phosphorus compounds, etc.), mold release agents (montanic acid and its salts, esters thereof, half esters thereof, stearyl alcohol, stearamide, polyethylene wax, etc.), color inhibitors (phosphites, hypophosphites, etc.), silane coupling agents (epoxy silane coupling agents, amino silane coupling agents, (meth)acrylic silane coupling agents, isocyanate silane coupling agents, etc.), flame retardants (red phosphorus, phosphate esters, brominated polystyrene, brominated polyphenylene ether, brominated polyisocyanate, methyl methyl silane ... The composition may also contain: polycarbonate, aluminum hydroxide, magnesium hydroxide, melamine and cyanuric acid or salts thereof, silicon compounds, etc.), conductive agents (carbon black, etc.), sliding property improvers (graphite, fluororesin, etc.), epoxy compounds (glycidyl ether compounds, glycidyl ester compounds, polymer compounds grafted or copolymerized with a glycidyl compound, etc.), acid anhydride compounds (maleic anhydride, succinic anhydride, polymer compounds grafted or copolymerized with an acid anhydride, etc.), carbodiimide compounds (N,N'-di-2,6-diisopropylphenylcarbodiimide, 2,6,2',6'-tetraisopropyldiphenylcarbodiimide, polycarbodiimide, etc.), etc.

[0112] The content of each of the other components described above is not particularly limited as long as the effect of one embodiment of the present invention is exhibited, and can be appropriately determined by a person skilled in the art.

[0113] [2. Method for producing a thermoplastic resin composition] In one embodiment of the present invention, there is provided a method for producing a thermoplastic resin composition, comprising a mixing step of mixing component (A) and component (B). In this specification, the "method for producing a thermoplastic resin composition according to one embodiment of the present invention" may be referred to as the "method for producing the present resin composition." The "method for producing the present resin composition" can be suitably used as a method for producing the "present resin composition."

[0114] Specific aspects of component (A), component (B), and other components used in the method for producing the resin composition are the same as those described in the above section [1. Thermoplastic resin composition]. Therefore, the description therein is incorporated by reference and will not be repeated in this section.

[0115] <Mixing Step> The method for producing the resin composition includes a mixing step of mixing component (A), component (B), and, if necessary, other components. The amount of each component blended in the mixing step determines the content of each component in the resulting thermoplastic resin composition. Therefore, in the mixing step, each component is mixed so that the content of each component in the resulting thermoplastic resin composition is the desired amount.

[0116] The mixing step is not particularly limited as long as it is a method for mixing component (A) and component (B), and can be carried out by a known method. The mixing step can be carried out, for example, by mixing the P3HA-based resin component (A), crosslinked resin particles (B), optionally a crystal nucleating agent and / or nucleating agent, and other components using an extruder, kneader, Banbury mixer, kneading roll, or the like. The mixing step may also include a melt-kneading step in which the crosslinked resin particles (B) and the P3HA-based resin component (A) are melt-kneaded. When melt-kneading, it is preferable to mix the components while taking care to avoid a decrease in the molecular weight of component (A) due to thermal decomposition. Alternatively, a thermoplastic resin composition can be produced by dissolving each component in a soluble solvent and then removing the solvent.

[0117] When producing a thermoplastic resin composition by melt-kneading, each component may be charged individually into an extruder, etc., or each component may be mixed in advance and the resulting mixture may be charged into an extruder, etc. For example, an aqueous dispersion of the P3HA-based resin component (A) and an aqueous dispersion of the crosslinked resin particles (B) may be mixed, and then the resulting mixture may be dried in a dryer to obtain a mixed powder, which may then be charged into an extruder, etc.

[0118] When melt-kneading is performed using an extruder, the obtained thermoplastic resin composition may be extruded from the extruder into a strand shape and then cut, thereby processing the thermoplastic resin composition into particle shapes such as a bar shape, a cylindrical shape, an elliptical cylindrical shape, a sphere shape, a cube shape, a rectangular parallelepiped shape, or the like.

[0119] The resin temperature during melt-kneading cannot be generally defined because it depends on the melting point and melt viscosity of the resin used, etc. The resin temperature during melt-kneading is preferably 140°C to 250°C, more preferably 150°C to 230°C, and even more preferably 160°C to 210°C, from the viewpoint of uniformly dispersing the crosslinked resin particles (B) in the P3HA-based resin component (A) while avoiding thermal decomposition of the P3HA-based resin component (A).

[0120] [3. Molded Article] In one embodiment of the present invention, a molded article containing the present resin composition is provided. Hereinafter, the "molded article according to one embodiment of the present invention" may be referred to as the "present molded article." The present molded article can also be said to be a molded article obtained by molding the present resin composition. In providing the present molded article, the molding method of the present resin composition is not particularly limited, and commonly used molding methods can be applied. Specific molding methods include inflation film molding, extrusion blow molding, injection blow molding, extrusion molding, calendar molding, vacuum molding, and injection molding. The molded article obtained by molding the present resin composition can also be said to be a molded article containing the present resin composition.

[0121] By carrying out the above-described molding method using the present resin composition, molded articles having excellent tensile impact strength, specifically, film molded articles, sheet molded articles, blow molded articles, extrusion molded articles, vacuum molded articles, and injection molded articles, can be produced with good productivity. In other words, the present molded articles can be film molded articles, sheet molded articles, blow molded articles, extrusion molded articles, vacuum molded articles, or injection molded articles. In this specification, the term "film molded article" refers to an article conforming to JIS 20108:2012, specifically a thin film-like article having a thickness of less than 0.25 mm. In this specification, the term "sheet molded article" refers to an article conforming to JIS 20108:2012, specifically a thin plate-like article having a thickness of 0.25 mm or more.

[0122] The molded article can be suitably used in agriculture, fisheries, forestry, horticulture, medicine, hygiene products, the food industry, clothing, non-clothing, packaging, automobiles, building materials, and other fields.

[0123] <Tensile strain> The present molded article is a molded article improved so as to increase the tensile strain. In this specification, the tensile strain of the molded article can be evaluated by a tensile test. A specific method for measuring the tensile strain will be described in detail in the Examples below.

[0124] It can be said that the larger the tensile strain measured by the above method, the more excellent the impact fracture resistance (the less likely it is to be broken by impact) of the molded article being measured.

[0125] The tensile strain of the present molded body is preferably 16% or more, more preferably 18% or more, and even more preferably 20% or more. A tensile strain of 16% or more of the molded body means that the molded body has excellent toughness. The upper limit of the tensile strain of the present molded body is not particularly limited, but can be, for example, 200% or less.

[0126] <Summary> One embodiment of the present invention includes the following configuration.

[0127] [1] A thermoplastic resin composition comprising a poly(3-hydroxyalkanoate)-based resin component (A) and crosslinked resin particles (B) containing a polyhydroxyalkanoate-based resin and having a gel fraction of 50% or more, wherein the poly(3-hydroxyalkanoate)-based resin component (A) contains a poly(3-hydroxyalkanoate)-based copolymer (a-1) having a weight-average molecular weight of 200,000 to 1,000,000, and a poly(3-hydroxyalkanoate)-based copolymer (a-2) having a weight-average molecular weight higher than that of the poly(3-hydroxyalkanoate)-based copolymer (a-1).

[0128] [2] The thermoplastic resin composition according to [1], wherein the poly(3-hydroxyalkanoate) copolymer (a-2) is a copolymer of 3-hydroxybutyrate units and hydroxyalkanoate units other than 3-hydroxybutyrate units, and the composition ratio of the 3-hydroxybutyrate units is 77 mol% to 99 mol%.

[0129] [3] The thermoplastic resin composition according to [1] or [2], wherein the content of the poly(3-hydroxyalkanoate) copolymer (a-1) in 100 parts by weight of the poly(3-hydroxyalkanoate) resin component (A) is 80 parts by weight to 99 parts by weight.

[0130] [4] The thermoplastic resin composition according to any one of [1] to [3], wherein the weight average molecular weight of the poly(3-hydroxyalkanoate) copolymer (a-2) is 200,000 or more greater than the weight average molecular weight of the poly(3-hydroxyalkanoate) copolymer (a-1).

[0131] [5] The thermoplastic resin composition according to any one of [1] to [4], wherein the poly(3-hydroxyalkanoate) copolymer (a-1) and / or (a-2) is at least one selected from the group consisting of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxypropionate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate), poly(3-hydroxybutyrate-co-3-hydroxydecanoate), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate).

[0132] [6] The thermoplastic resin composition according to any one of [1] to [5], wherein the poly(3-hydroxyalkanoate) copolymer (a-1) and / or (a-2) is poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0133] [7] The thermoplastic resin composition according to any one of [1] to [6], wherein the poly(3-hydroxyalkanoate) copolymer (a-1) is a copolymer of 3-hydroxybutyrate units and hydroxyalkanoate units other than 3-hydroxybutyrate units, and the composition ratio of the 3-hydroxybutyrate units is 77 mol% to 99 mol%.

[0134] [8] The thermoplastic resin composition according to any one of [1] to [7], wherein the crosslinked resin particles (B) are contained in an amount of 10 parts by weight to 60 parts by weight per 100 parts by weight of the total amount of the poly(3-hydroxyalkanoate)-based resin component (A) and the crosslinked resin particles (B).

[0135] [9] The thermoplastic resin composition according to any one of [1] to [8], wherein the crosslinked resin particles (B) have a volume average particle diameter of 0.10 μm to 10.00 μm.

[0136]

[10] The thermoplastic resin composition according to any one of [1] to [9], wherein the crosslinked resin particles (B) are crosslinked using a peroxide.

[0137]

[11] The thermoplastic resin composition according to

[10] , wherein the crosslinked resin particles (B) are crosslinked in the presence of the peroxide and a polyfunctional compound.

[0138]

[12] The thermoplastic resin composition according to any one of [1] to

[11] , wherein the proportion of the polyhydroxyalkanoate resin in 100% by weight of the resin component of the crosslinked resin particles (B) is 80% by weight or more.

[0139]

[13] A molded article comprising the thermoplastic resin composition according to any one of [1] to

[12] .

[0140]

[14] The molded article according to

[13] , which is a sheet, a film, a blow molded article, an extrusion molded article, a vacuum molded article, or an injection molded article.

[0141] The present invention will be specifically explained below with reference to examples, but the technical scope of the present invention is not limited to these examples.

[0142] [Measurement Method] <Measurement of Monomer Composition Ratio of P3HB3HH> The monomer composition ratio of P3HB3HH was determined by the following method. 1 mL of a concentrated sulfuric acid (98%)-methanol mixture (volume ratio 15:85) and 1 mL of chloroform were added to approximately 20 mg of P3HB3HH, the mixture was sealed, and heated at 100°C for 140 minutes to obtain a methyl ester of the P3HB3HH decomposition product. After cooling the resulting mixture containing the decomposition product, 0.5 mL of deionized water was added, mixed thoroughly, and allowed to stand until the aqueous and organic layers separated. The monomer composition of the P3HB3HH decomposition product in the separated organic layer was then analyzed by capillary gas chromatography. The ratio of 3-hydroxyhexanoate was calculated from the obtained peak area.

[0143] <Weight-Average Molecular Weight> The resin to be measured was added to chloroform, and the resulting mixture was heated in a hot water bath at 60°C for 30 minutes. The resulting mixture (chloroform solution) was filtered through a disposable PTFE filter with a 0.45 μm pore size. The resulting filtrate was then subjected to GPC measurement under the following conditions to determine the weight-average molecular weight. GPC measurement device: High-performance liquid chromatograph 20A system manufactured by Shimadzu Corporation Columns: K-G 4A (1 column), K-806M (2 columns) manufactured by Showa Denko K.K. Sample concentration: 1 mg / ml Free solution: chloroform solution Free solution flow rate: 1.0 ml / min Sample injection volume: 100 μL Analysis time: 30 minutes Standard sample: standard polystyrene.

[0144] <Volume average particle diameter> The volume average particle diameter of the crosslinked resin particles was measured using an aqueous dispersion of crosslinked resin particles as a sample. The measuring device used was a Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd. Specifically, the particle diameter and volume of each crosslinked resin particle in the aqueous dispersion of crosslinked resin particles were measured using the above device, and the volume average particle diameter was calculated from the measurement results based on the above-mentioned formula (1), i.e., formula (2).

[0145] <Gel Fraction> Dried crosslinked resin particles were added to chloroform to a concentration of 0.7 wt % and dissolved at 60°C for 30 minutes to obtain a chloroform solution. After allowing to stand at room temperature for 3 hours, the chloroform solution was filtered through a membrane filter with a pore size of 0.45 μm. Losses were prevented by pouring chloroform over the inside of the container and the filter multiple times while thoroughly washing. The gel remaining on the filter was dried and weighed together with the filter, and the gel fraction was calculated using the following formula: Gel fraction = (weight of filter including dried gel - weight of filter only) / weight of crosslinked resin particles used in measurement × 100 (%).

[0146] <Evaluation of Tensile Strain> The thermoplastic resin compositions obtained in Examples 1 to 6 and Comparative Examples 1 to 4 were kneaded for 2 minutes using a test roll machine (diameter: 8 inches, length: 20 inches) manufactured by Kansai Roll Co., Ltd. under conditions of a set temperature of 140 ° C. and a rotation speed (front roll: 17 rpm, rear roll: 16 rpm), and a sheet was prepared so that the sheet thickness was 0.5 mm. Two sheet pieces cut out from the obtained sheet were stacked alternately at right angles and hot-pressed to a thickness of 1 mm using a compression molding machine (ASFA-37H / C) manufactured by Shinto Metal Industries Co., Ltd. at a set temperature of 160 ° C. and a pressure of 10 MPa to prepare a pressed sheet. The obtained pressed sheet was cut into a JIS K-6251-2 shape to prepare a test specimen for a tensile test. A tensile test was performed on the test specimen using an Autograph AG-X manufactured by Shimadzu Corporation under the following conditions, and the tensile strain was evaluated. Test piece size: thickness 1.0 mm, length (between chucks) 50 mm or more, width 20 mm Temperature: 23°C Tensile speed: 2 mm / min Distance between chucks: 50 mm Distance between gauge lines: 20 mm

[0147] [Production Example: Production of Crosslinked Resin Particles] <Raw Materials for Crosslinked Resin Particles> (Uncrosslinked Resin Particles) P3HB3HH-28: P3HB3HH (average content ratio 3HB / 3HH=72 / 28 (mol % / mol %), weight average molecular weight 700,000, Tg -7°C, manufactured by Kaneka Corporation) The weight average molecular weight of the uncrosslinked resin particles was measured by the method described above.

[0148] (Peroxide) Di-sec-butyl peroxydicarbonate ("Luperox (registered trademark) 225" manufactured by Arkema Yoshitomi Co., Ltd., one-hour half-life temperature: 69°C).

[0149] (Polyfunctional Compound) Triallyl isocyanurate.

[0150] <Production of Crosslinked Resin Particles> An aqueous dispersion (100 parts by weight of solids) of uncrosslinked resin particles dispersed in water, 200 parts by weight of deionized water, 2 parts by weight of peroxide, 2 parts by weight of sodium dioctyl sulfosuccinate, and 0.5 parts by weight of a polyfunctional compound were added to an autoclave equipped with a stirrer, baffles, a nitrogen inlet / outlet, and a thermometer to prepare an aqueous dispersion. Stirring of the resulting aqueous dispersion was initiated at room temperature, and the atmosphere inside the autoclave was simultaneously purged with nitrogen. The aqueous dispersion in the autoclave was then stirred at room temperature (20-25°C) for 1 hour to allow the peroxide and polyfunctional compound to impregnate the interior of the uncrosslinked resin particles.

[0151] Thereafter, the temperature of the aqueous dispersion was raised to 75° C. After the temperature of the aqueous dispersion reached 75° C., the reaction was carried out at the reaction temperature for 3.5 hours while maintaining the heating temperature, thereby obtaining an aqueous dispersion in which crosslinked resin particles were dispersed in water.

[0152] After adjusting the pH of the aqueous dispersion, the dispersion was dried in an oven to obtain solidified crosslinked resin particles.

[0153] The volume average particle size and gel fraction of the resulting crosslinked resin particles were measured by the above-mentioned measuring methods, and the volume average particle size was found to be 1.70 μm and the gel fraction was found to be 95%.

[0154] [Examples 1 to 6, Comparative Examples 1 to 4: Production of Thermoplastic Resin Compositions] <Raw Materials for Thermoplastic Resin Compositions> (Poly(3-hydroxyalkanoate)-Based Resin Component) P3HB3HH-6: Powder of P3HB3HH (average content ratio 3HB / 3HH=94 / 6 (mol % / mol %), weight average molecular weight 400,000, manufactured by Kaneka Corporation, Kaneka Biodegradable Polymer GreenPlanet (registered trademark)) was used. P3HB3HH-6H: Powder of P3HB3HH (average content ratio 3HB / 3HH=94 / 6 (mol % / mol %), weight average molecular weight 760,000, manufactured by Kaneka Corporation, Kaneka Biodegradable Polymer GreenPlanet (registered trademark)) was used. P3HB3HH-11H: Powder of P3HB3HH (average content ratio 3HB / 3HH=89.5 / 10.5 (mol % / mol %), weight average molecular weight 780,000, manufactured by Kaneka Corporation, Kaneka Biodegradable Polymer GreenPlanet (registered trademark)) was used. (The weight average molecular weight of the poly(3-hydroxyalkanoate) resin was measured by the method described above.)

[0155] (Crosslinked resin particles) Crosslinked resin particles prepared in the production examples (Nucleating agent) Erucamide: Neutron-S manufactured by Nippon Fine Chemicals Co., Ltd. (Lubricant) Behenamide: BNT22H manufactured by Nippon Fine Chemicals Co., Ltd.

[0156] <Production of Thermoplastic Resin Composition> (Examples 1 to 6, Comparative Examples 1 to 4) For each Example, a mixture was obtained by mixing the poly(3-hydroxyalkanoate) resin, crystal nucleating agent, and lubricant shown in Table 1 in the amounts shown in Table 1 with the crosslinked resin particles shown in Table 1 in the amount shown in Table 1. The resulting mixture was melt-kneaded for 180 seconds in a small twin-screw kneader (Xplore MC5 manufactured by DSM) with the barrel temperature heated to 175°C and a screw rotation speed of 100 rpm to obtain a melt-kneaded product (mixture). Using the resulting melt-kneaded product, a sheet was produced using the method described above for evaluating tensile strain, and tensile strain was evaluated. The results are shown in Table 1.

[0157] From Table 1, it can be seen that Examples 1 to 3 had significantly improved tensile strain compared to Comparative Examples 1, 3, and 4. Furthermore, it can be seen that Examples 4 to 6 had significantly improved tensile strain compared to Comparative Examples 2, 3, and 4.

[0158] The above results show that when the P3HA-based resin (a-1), the P3HA-based resin (a-2), and the crosslinked resin particles were used in combination, as in Examples 1 to 6, the tensile strain was significantly improved compared to when they were not used in combination, as in Comparative Examples 1 to 4.

[0159] Furthermore, a comparison between Examples 1 to 3, which used a P3HA-based resin having an average 3HB / 3HH content ratio of 94 / 6 (mol% / mol%) as the P3HA-based resin (a-2), and Examples 4 to 6, which used a P3HA-based resin having an average 3HB / 3HH content ratio of 89.5 / 10.5 (mol% / mol%), shows that Examples 4 to 6, which used a P3HA-based resin having an average 3HB / 3HH content ratio of 89.5 / 10.5 (mol% / mol%), showed results that showed even greater improvements in tensile strain.

[0160] According to one embodiment of the present invention, a novel thermoplastic resin composition capable of providing a molded article having a large tensile strain can be provided, and therefore, this embodiment of the present invention can be suitably used in fields such as agriculture, fisheries, forestry, horticulture, medicine, hygiene products, the food industry, clothing, non-clothing, packaging, automobiles, building materials, and other fields.

Claims

1. A thermoplastic resin composition comprising a poly(3-hydroxyalkanoate)-based resin component (A) and crosslinked resin particles (B) containing a polyhydroxyalkanoate-based resin and having a gel fraction of 50% or more, wherein the poly(3-hydroxyalkanoate)-based resin component (A) contains a poly(3-hydroxyalkanoate)-based copolymer (a-1) having a weight average molecular weight of 200,000 to 1,000,000, and a poly(3-hydroxyalkanoate)-based copolymer (a-2) having a weight average molecular weight higher than that of the poly(3-hydroxyalkanoate)-based copolymer (a-1).

2. The thermoplastic resin composition according to claim 1, wherein the poly(3-hydroxyalkanoate) copolymer (a-2) is a copolymer of 3-hydroxybutyrate units and hydroxyalkanoate units other than 3-hydroxybutyrate units, and the composition ratio of the 3-hydroxybutyrate units is 77 mol % to 99 mol %.

3. The thermoplastic resin composition described in claim 1, wherein the content of the poly(3-hydroxyalkanoate) copolymer (a-1) in 100 parts by weight of the poly(3-hydroxyalkanoate) resin component (A) is 80 to 99 parts by weight.

4. The thermoplastic resin composition according to claim 1, wherein the weight average molecular weight of the poly(3-hydroxyalkanoate) copolymer (a-2) is at least 200,000 greater than the weight average molecular weight of the poly(3-hydroxyalkanoate) copolymer (a-1).

5. The thermoplastic resin composition according to claim 1, wherein the poly(3-hydroxyalkanoate)-based copolymer (a-1) and / or (a-2) is at least one selected from the group consisting of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxypropionate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate), poly(3-hydroxybutyrate-co-3-hydroxydecanoate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate).

6. The thermoplastic resin composition according to claim 1, wherein the poly(3-hydroxyalkanoate)-based copolymer (a-1) and / or (a-2) is poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

7. The thermoplastic resin composition according to claim 1, wherein the poly(3-hydroxyalkanoate) copolymer (a-1) is a copolymer of 3-hydroxybutyrate units and hydroxyalkanoate units other than 3-hydroxybutyrate units, and the composition ratio of the 3-hydroxybutyrate units is 77 mol % to 99 mol %.

8. The thermoplastic resin composition according to claim 1, comprising 10 to 60 parts by weight of the crosslinked resin particles (B) per 100 parts by weight of the total amount of the poly(3-hydroxyalkanoate) resin component (A) and the crosslinked resin particles (B).

9. The thermoplastic resin composition according to claim 1, wherein the crosslinked resin particles (B) have a volume average particle size of 0.10 μm to 10.00 μm.

10. The thermoplastic resin composition according to claim 1, wherein the crosslinked resin particles (B) are crosslinked using a peroxide.

11. The thermoplastic resin composition according to claim 10, wherein the crosslinked resin particles (B) are crosslinked in the presence of the peroxide and a polyfunctional compound.

12. The thermoplastic resin composition according to claim 1, wherein the proportion of said polyhydroxyalkanoate resin in 100% by weight of the resin component of said crosslinked resin particles (B) is 80% by weight or more.

13. A molded article comprising the thermoplastic resin composition according to claim 1.

14. The molded article according to claim 13, which is a sheet, a film, a blow molded article, an extrusion molded article, a vacuum molded article, or an injection molded article.

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