Thermoplastic resin composition and use thereof

Abstract

Provided is a novel thermoplastic resin composition with which a molded body having excellent impact resistance and hardness and little stickiness can be obtained. Provided is the thermoplastic resin composition which contains a poly(3-hydroxybutyrate) resin (A) and crosslinked resin particles (B). The poly(3-hydroxybutyrate) resin (A) contains a copolymer (a-1), and a copolymer (a-2) or a homopolymer. These copolymers and the homopolymer are different from each other in terms of the percentage of the 3-hydroxybutyrate repeating units, and the percentage of the copolymer (a-1) in the poly(3-hydroxybutyrate) resin (A) is 65 wt% or less. The crosslinked resin particles (B) contain a polyhydroxyalkanoate resin and have 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 burden on 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 in terms of impact resistance, hardness, and stickiness 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-described current situation, and its object is to provide a novel thermoplastic resin composition that can provide a molded article that is excellent in impact resistance, hardness, and anti-stickiness.

[0007] As a result of extensive research, the present inventors have found that a thermoplastic resin composition containing a polyhydroxyalkanoate resin and crosslinked resin particles satisfying a specific gel fraction can provide a molded article that is excellent in impact resistance, hardness, and non-stickiness, and have thus completed one embodiment of the present invention. That is, one embodiment of the present invention has the following configuration: A thermoplastic resin composition comprising a poly(3-hydroxybutyrate) resin (A) and crosslinked resin particles (B), wherein the poly(3-hydroxybutyrate) resin (A) comprises at least one selected from the group consisting of copolymers (a-2) and homopolymers, and copolymer (a-1), wherein the copolymer (a-1) comprises 3-hydroxybutanoic acid repeating units and hydroxyalkanoic acid repeating units other than the 3-hydroxybutanoic acid repeating units, the proportion of 3-hydroxybutanoic acid repeating units in copolymer (a-1) being 76 mol % or less, and the copolymer (a-2) comprises 3-hydroxybutanoic acid repeating units and hydroxyalkanoic acid repeating units other than the 3-hydroxybutanoic acid repeating units, wherein the proportion of 3-hydroxybutanoic acid repeating units in copolymer (a-1) is 76 mol % or less, and the copolymer (a-2) comprises 3-hydroxybutanoic acid repeating units and hydroxyalkanoic acid repeating units other than the 3-hydroxybutanoic acid repeating units. a hydroxyalkanoate repeating unit, wherein the proportion of 3-hydroxybutanoic acid repeating units contained in the copolymer (a-2) is greater than 95 mol %, and the homopolymer is a homopolymer of 3-hydroxybutanoic acid repeating units; when the total of the copolymer (a-1), the copolymer (a-2), and the homopolymer in the poly(3-hydroxybutyrate)-based resin (A) is taken as 100 wt %, the proportion of the copolymer (a-1) is 65 wt % or less and the total proportion of the copolymer (a-2) and the homopolymer is 35 wt % or more; and the crosslinked resin particles (B) contain a polyhydroxyalkanoate-based resin and have a gel fraction of 50% or more.

[0008] According to one embodiment of the present invention, it is possible to provide a novel thermoplastic resin composition that can provide a molded article that is excellent in impact resistance, hardness, and anti-stickiness.

[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 comprises a poly(3-hydroxybutyrate)-based resin (A) and crosslinked resin particles (B), wherein the poly(3-hydroxybutyrate)-based resin (A) comprises at least one selected from the group consisting of a copolymer (a-2) and a homopolymer, and a copolymer (a-1), wherein the copolymer (a-1) comprises a 3-hydroxybutanoic acid repeating unit and a hydroxyalkanoic acid repeating unit other than the 3-hydroxybutanoic acid repeating unit, the proportion of the 3-hydroxybutanoic acid repeating unit contained in the copolymer (a-1) being 76 mol % or less, and the copolymer (a-2) comprises a 3-hydroxybutanoic acid repeating unit and a hydroxyalkanoic acid repeating unit other than the 3-hydroxybutanoic acid repeating unit, wherein the proportion of the 3-hydroxybutanoic acid repeating unit contained in the copolymer (a-1) is 76 mol % or less, and the copolymer (a-2) comprises a 3-hydroxybutanoic acid repeating unit and a hydroxyalkanoic acid repeating unit other than the 3-hydroxybutanoic acid repeating unit. and a hydroxyalkanoic acid repeating unit other than a butanoic acid repeating unit, the proportion of 3-hydroxybutanoic acid repeating units contained in the copolymer (a-2) is more than 95 mol %, the homopolymer is a homopolymer of 3-hydroxybutanoic acid repeating units, when the total of the copolymer (a-1), the copolymer (a-2), and the homopolymer in the poly(3-hydroxybutyrate) resin (A) is taken as 100 wt %, the proportion of the copolymer (a-1) is 65 wt % or less and the total proportion of the copolymer (a-2) and the homopolymer is 35 wt % or more, and the crosslinked resin particles (B) contain a polyhydroxyalkanoate resin and have a gel fraction of 50% or more.

[0011] In this specification, the "thermoplastic resin composition according to one embodiment of the present invention" may be referred to as the "present resin composition." The crosslinked resin particles (B) contained in the present resin composition may also be referred to as the crosslinked resin particles according to one embodiment of the present invention. In this specification, the "crosslinked resin particles according to one embodiment of the present invention" may be referred to as the "present crosslinked resin particles (B)."

[0012] The present resin composition has the advantage of being able to provide a molded article with excellent impact resistance. In this specification, the impact resistance of a molded article is evaluated as the impact resistance of a structure containing the molded article, and can be evaluated by the value of the "impact attenuation rate (FR%)" using an impact absorption tester conforming to DIN 18032. The "impact attenuation rate (FR%)" is calculated using the following formula: Impact absorption rate (FR%) = (1 - Fs / Fc) x 100, where Fs is the maximum impact force on the structure (subject to evaluation), and Fc is the maximum impact force on a rigid floor (concrete floor). The method for measuring the impact attenuation rate (FR%) will be described in detail in the Examples below. The impact resistance of a molded article of the present resin composition can also be evaluated by a qualitative impact resistance test conducted by a tester, as will be described in detail in the Examples below.

[0013] The present resin composition also has the advantage of being able to provide a molded article having excellent hardness. In this specification, the hardness of the molded article may be a durometer hardness measured using a Type A durometer in accordance with JIS K7215. Durometer hardness is an index indicating the hardness of an elastic body. The hardness of a molded article of the present resin composition can also be evaluated by a qualitative hardness test conducted by a tester, as will be described in detail in the Examples below.

[0014] The present resin composition also has the advantage of being able to provide a molded article that is less sticky. In this specification, the stickiness of the molded article can be evaluated by a qualitative test using a stickiness test conducted by a tester, as will be described in detail in the Examples below.

[0015] The polyhydroxyalkanoate resin contained in the present crosslinked resin particles (B) is a biodegradable resin. Therefore, the present crosslinked resin particles (B) can be biodegradable. The present resin composition is advantageous in terms of biodegradability because it contains the biodegradable crosslinked resin particles (B).

[0016] First, the crosslinked resin particles (B) will be described.

[0017] <Crosslinked Resin Particles (B)> The crosslinked resin particles (B), i.e., the present crosslinked resin particles (B), contain a polyhydroxyalkanoate resin and have a gel fraction of 50% or more. In this specification, "polyhydroxyalkanoate resin" may be referred to as "PHA." By including the present crosslinked resin particles (B), the present resin composition can provide a molded article with excellent impact resistance. In other words, the present crosslinked resin particles (B) can be used as a modifier or impact modifier for thermoplastic resins.

[0018] "PHA" is a general term for polymers containing hydroxyalkanoic acid as a monomer unit (monomer repeating unit), and is generally biodegradable. PHA is an aliphatic polyester, preferably a polyester not containing an aromatic ring. In this specification, "PHA" refers to a polymer containing hydroxyalkanoic acid repeating units in an amount of 50 mol% or more of all monomer repeating units (100 mol%). PHA preferably contains 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%).

[0019] The PHA is not particularly limited. Examples of PHA include polyglycolic acid, poly(3-hydroxyalkanoate)-based resin (hereinafter sometimes referred to as "P3HA"), and poly(4-hydroxyalkanoate)-based resin. One type of PHA may be used alone, or two or more types may be used in combination. The PHA preferably contains a poly(3-hydroxyalkanoate)-based resin, and more preferably is a poly(3-hydroxyalkanoate)-based resin (in other words, composed solely of a poly(3-hydroxyalkanoate)-based resin).

[0020] 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—]. ２The 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 %).

[0021] 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).

[0022] Polyglycolic acid can be obtained by known methods such as condensation polymerization of glycolic acid and ring-opening polymerization of glycolide.

[0023] The P3HA has 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.) is a polyhydroxyalkanoate containing the 3-hydroxyalkanoic acid repeating unit as an essential repeating unit. In this specification, "P3HA" refers to a resin containing 50 mol % or more of the 3-hydroxyalkanoic acid repeating units out of all monomer repeating units (100 mol %). The P3HA preferably contains 60 mol % or more, and more preferably 70 mol % or more, of all monomer repeating units (100 mol %).

[0024] P3HA is not particularly limited and may be a homopolymer containing the repeating unit described above, or a copolymer containing the repeating unit described above. Examples of the copolymer include copolymers of 3-hydroxybutanoic acid (hereinafter sometimes referred to as "3HB") and one or more monomers selected from the group consisting of 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, another example of the copolymer may be a copolymer of 3HB and one or more monomers selected from the group consisting of 4-hydroxybutanoic acid, 4-hydroxypentanoic acid, 4-hydroxyhexanoic acid, 4-hydroxyheptanoic acid, 4-hydroxyoctanoic acid, 4-hydroxynonanoic acid, 4-hydroxydecanoic acid, 4-hydroxyundecanoic acid, 4-hydroxydodecanoic acid, 4-hydroxytridecanoic acid, 4-hydroxytetradecanoic acid, 4-hydroxyhexadecanoic acid, and 4-hydroxyoctadecanoic acid.

[0025] Examples of P3HA include poly(3-hydroxybutyrate) (hereinafter sometimes referred to as "P3HB"), which is a homopolymer of 3HB, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (hereinafter sometimes referred to as "P3HB3HH"), and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (hereinafter sometimes referred to as "P3HB4HB"). Only one type of P3HA may be used, or two or more types may be used in combination. As used herein, "poly(X-co-Y)" refers to a copolymer containing X repeating units and Y repeating units, and is intended to mean a copolymer obtained by copolymerizing a monomer from which the X repeating unit is derived and a monomer from which the Y repeating unit is derived. Furthermore, during the production of P3HA by microorganisms, a small amount (less than 1 mol%) of a monomer may be copolymerized. However, if this does not significantly affect the physical properties of the resulting P3HA, the monomer is considered to be uncopolymerized, and the product will be referred to by a name that does not include that monomer.

[0026] 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.

[0027] It is also preferred that P3HA contains 3-hydroxybutanoic acid (3HB) repeating units. When P3HA contains 3HB repeating units, from the viewpoint of the balance between flexibility and strength, the composition ratio of 3HB repeating units in 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 composition ratio of 3HB repeating units in P3HA is 60 mol% or more, there is an advantage that the rigidity of the crosslinked resin particles can be further improved. On the other hand, when the composition ratio of 3HB repeating units in P3HA is 99 mol% or less, there is an advantage that the flexibility of the crosslinked resin particles tends to be further improved. The monomer composition ratio of P3HA can be measured by gas chromatography or the like (see, for example, WO 2014 / 020838). As P3HA, two or more types having different composition ratios of 3HB repeating units may be used in combination.

[0028] The microorganism that produces P3HA is not particularly limited as long as it has the ability to produce P3HA. For example, the first P3HB-producing bacterium was Bacillus megaterium, discovered in 1925, and other naturally occurring microorganisms such as Cupriavidus necator (formerly classified as Alcaligenes eutrophus and Ralstonia eutropha) and Alcaligenes latus are known. In these microorganisms, P3HB accumulates intracellularly.

[0029] Known examples of bacteria that produce copolymers of 3HB and other hydroxyalkanoic acids include Aeromonas caviae, which produces P3HB3HH, and Alcaligenes eutrophus, which produces poly(3-hydroxybutyrate-co-4-hydroxybutyrate). In particular, Alcaligenes eutrophus AC32 (FERM BP-6038) (T. Fukui, Y. Doi, J. Bacteriol., 179, pp. 4821-4830 (1997)), into which genes encoding P3HA synthases have been introduced, is preferred for increasing P3HB3HH productivity. Microbial cells obtained by culturing such microorganisms under appropriate conditions and allowing P3HA 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 P3HA to be produced, or culture conditions, including the type of substrate, may be optimized.

[0030] The weight-average molecular weight of the PHA is not particularly limited. The weight-average molecular weight of the PHA is preferably 50,000 to 3,000,000, preferably 100,000 to 2,000,000, and more preferably 150,000 to 1,500,000. A PHA with a weight-average molecular weight of 50,000 or more has the advantage of reducing or avoiding the tendency for the crosslinked resin particles to have low strength. Furthermore, a PHA with a weight-average molecular weight of 50,000 or more has the advantage of reducing or avoiding the tendency for the PHA to become sticky due to low molecular weight components. On the other hand, a PHA with a weight-average molecular weight of 3,000,000 or less may have the advantage of being easy to manufacture and / or easy to handle in order to achieve the object of one embodiment of the present invention. The numerical value of the weight-average molecular weight of the PHA is a value obtained by measurement using the PHA before crosslinking treatment.

[0031] The weight-average molecular weight can be measured using gel permeation chromatography (GPC) (Shimadzu Corporation's "High Performance Liquid Chromatograph 20A System"), a polystyrene gel column (Showa Denko K.K.'s "K-G 4A" or "K-806M" or the like), and chloroform as the mobile phase. The weight-average molecular weight can be determined as a polystyrene-equivalent molecular weight using a calibration curve obtained by measuring polystyrenes with known molecular weights using the same measurement method. In this case, the calibration curve can be prepared using polystyrenes with weight-average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. As the column for the GPC, a column appropriate for measuring the molecular weight can be used.

[0032] (Gel Fraction) In this specification, the term "crosslinked resin particles" refers to particles having a crosslinked structure in which molecular chains of the resin constituting the resin particles are bonded intramolecularly and / or intermolecularly. That is, the present crosslinked resin particles (B) may have a crosslinked structure in which molecular chains of PHA 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. The present crosslinked resin particles (B) have a certain amount or more of crosslinked structures, and therefore exhibit a high gel fraction, specifically a gel fraction of 50% or more. Since the present crosslinked resin particles (B) have a gel fraction of 50% or more, the crosslinked resin particles have excellent hardness, heat resistance, and solvent resistance.

[0033] 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, and may be 100% or less. From the viewpoint of production efficiency of crosslinked resin particles, 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.

[0034] The gel fraction is a value measured as follows: (1) A dried product of crosslinked resin particles is added to chloroform so that the concentration becomes 0.7% by weight, and the resulting mixture is kept at 60°C for 30 minutes to obtain a chloroform solution; (2) The chloroform solution is then left to stand at room temperature for 3 hours, and then the chloroform solution is filtered through a membrane filter with 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 used for measurement} x 100.

[0035] (Volume average particle diameter) The volume average particle diameter of the present crosslinked resin particles is preferably 0.10 μm to 10.00 μm. This configuration enables 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.

[0036] 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):

[0037]

[0038] 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.

[0039] (Peroxide) The crosslinked structure in the present crosslinked resin particles (B) is not particularly limited, but is preferably crosslinked using a peroxide. That is, the present crosslinked resin particles (B) are preferably 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) that constitute the resin particles. As a result, molecular chains of the resin that constitutes the resin particles are directly bonded to each other, thereby forming a crosslinked structure.

[0040] When the crosslinked resin particles are crosslinked using a peroxide, the aqueous dispersion containing the crosslinked resin particles 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 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. That is, when the present crosslinked resin particles (B) are crosslinked using a peroxide, the present 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 present crosslinked resin particles (B) or the present resin composition contain substances derived from a peroxide, analysis of the crosslinked resin particles or the resin composition reveals that the crosslinked resin particles are crosslinked using a peroxide.

[0041] 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.

[0042] 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 time during the crosslinking treatment.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] (Polyfunctional Compound) The crosslinked structure in the present crosslinked resin particles (B) may be introduced using only a peroxide, or may be introduced using both a peroxide and a polyfunctional compound. That is, the present crosslinked resin particles (B) may be crosslinked in the presence of a peroxide and a polyfunctional compound. When both a peroxide and a polyfunctional compound are used, the gel fraction of the crosslinked resin particles can be increased with a smaller amount of peroxide than when only a peroxide is used.

[0049] 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) 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.

[0050] 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.

[0051] When a crosslinked structure is formed in the presence of a polyfunctional compound, the resulting crosslinked resin particles usually contain a structure derived from the polyfunctional compound, in which case the molecular chains of the resin constituting the resin particles are bonded to each other via the structure derived from the polyfunctional compound.

[0052] (Other Components) The present crosslinked resin particles (B) are crosslinked resin particles containing PHA. Therefore, the present crosslinked resin particles (B) may be crosslinked resin particles containing only PHA, or may be crosslinked resin particles containing other components other than PHA. Examples of the other components include resins other than PHA, antioxidants, hydrolysis inhibitors, antiblocking agents, crystal nucleating agents, lubricants, and ultraviolet absorbers.

[0053] The proportion of PHA in the present crosslinked resin particles (B) is not particularly limited. The content of PHA in 100% by weight of the resin component of the present 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 PHA in 100% by weight of the resin component of the present 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" refers to the resin that essentially constitutes the crosslinked resin particles, 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.).

[0054] Examples of the resin other than PHA include aliphatic polyesters other than PHA and aliphatic aromatic polyesters. Examples of aliphatic polyesters other than PHA include (i) polycaprolactone (PCL), (ii) polylactic acid (PLA), and (iii) aliphatic polyesters having a structure obtained by polycondensation of an aliphatic diol and an aliphatic dicarboxylic acid. Specific examples of the aliphatic polyesters having a structure obtained by polycondensation of an aliphatic diol and an aliphatic dicarboxylic acid 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 an aliphatic compound and an aromatic compound as monomers (both aliphatic compounds and aromatic compounds are used 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 PHA may be used alone or in combination of two or more. In the crosslinked resin particles (B), the resin other than PHA may be crosslinked or uncrosslinked.

[0055] The present crosslinked resin particles (B) are different from the expanded resin particles disclosed in WO 2007 / 049694 and WO 2019 / 146555, and are preferably not expanded. In other words, the present crosslinked resin particles (B) preferably contain substantially no air bubbles inside the particles. "Substantially no air bubbles inside the particles" means that the volume of air bubbles (voids) is 10% or less of the volume of 100% of the crosslinked resin particles.

[0056] When the crosslinked resin particles (B) are not expanded, the apparent density of the crosslinked resin particles 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).

[0057] The average weight per particle of the present crosslinked resin particles (B) is not particularly limited. For example, when the volume average particle size of the present crosslinked resin particles (B) is 10.00 μm or less, the average weight per particle of the crosslinked resin particles can be much less than 0.1 mg.

[0058] The crosslinked resin particles (B) may be dried, and the shape after drying may be powder, pellets, crumbs, a film, a sheet, or the like, depending on the drying method.

[0059] (Method for producing crosslinked resin particles) An example of a method for producing the present crosslinked resin particles (B) will now be described in detail. The present 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 PHA, the resin particles can also be called PHA particles. In order to efficiently crosslink the resin molecular chains, it is preferable to heat the aqueous dispersion of resin particles containing peroxide to a temperature suitable for decomposing the peroxide.

[0060] 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 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 molecular chains). Furthermore, the method more preferably includes the step of maintaining the heating temperature after all the peroxide has been added.

[0061] In step (1), for example, the aqueous dispersion of PHA particles may be an aqueous dispersion obtained by culturing a PHA-producing microorganism to accumulate PHA in the cells, disrupting the cells in the culture solution, and then 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 particles by culturing a PHA-producing microorganism to crosslinking treatment can be carried out without separating the PHA particles from water.

[0062] Alternatively, the aqueous dispersion of resin particles (for example, PHA particles) can be prepared by dispersing dried resin particles (for example, PHA particles) in water.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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. In the case of PHA 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 particles having a desired volume average particle diameter can be obtained without carrying out a special step for adjusting the particle diameter.

[0067] The concentration of the resin particles in the aqueous dispersion is not particularly limited and can be set appropriately, but may be, for example, about 1 to 70% by weight, and preferably about 5 to 50% by weight.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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, or about 10°C to 60°C.

[0073] The amount of peroxide used can be appropriately set in consideration of the gel fraction of the crosslinked resin particles, 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.

[0074] In 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, thereby obtaining crosslinked resin particles. On the other hand, in the method of crosslinking a resin by melt-kneading in the presence of a peroxide, this can be difficult to achieve.

[0075] Furthermore, the manufacturing method of crosslinking resin particles 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 having a safe and stable crosslinked structure (quality) can be efficiently obtained.

[0076] The amount of the polyfunctional compound used may also be appropriately determined in consideration of the gel fraction of the crosslinked resin particles. 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, relative to 100 parts by weight of the resin particles.

[0077] 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 the resin (e.g., PHA) to be crosslinked at a temperature lower than its melting temperature, thereby avoiding resin degradation due to heating during the crosslinking process. The melting temperature of PHA is, for example, 50°C to 210°C.

[0078] 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.

[0079] After the crosslinking reaction is complete, the crosslinked resin particles are separated from the aqueous dispersion, and water is removed from the separated crosslinked resin particles to obtain dried crosslinked resin particles. The method for separating the crosslinked resin particles 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 directly from the aqueous dispersion. Furthermore, by extruding the crosslinked resin particles alone after separation from the aqueous dispersion, residual water can be completely removed, and crosslinked resin particles can be obtained in pellet form. Furthermore, an aggregation step using a coagulant and / or pH adjustment may be performed.

[0080] The content of the crosslinked resin particles (B) in the resin composition is preferably 1 part by weight or more and 60 parts by weight or less, based on 100 parts by weight of the total of the poly(3-hydroxybutyrate)-based resin (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 5 parts by weight or more, 7 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, 25 parts by weight or more, or 30 parts by weight or more, based on 100 parts by weight of the total of the poly(3-hydroxybutyrate)-based resin (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 53 parts by weight or less, and even more preferably 50 parts by weight or less, based on 100 parts by weight of the total of the poly(3-hydroxybutyrate)-based resin (A) and the crosslinked resin particles (B). The content of the crosslinked resin particles (B) in the present resin composition may be 45 parts by weight or less, 40 parts by weight or less, 30 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, 12 parts by weight or less, or 10 parts by weight or less, based on 100 parts by weight of the total of the poly(3-hydroxybutyrate)-based resin (A) and the crosslinked resin particles (B).

[0081] <Poly(3-hydroxybutyrate)-based resin (A)> In the present resin composition, the poly(3-hydroxybutyrate)-based resin (A) can also be considered a matrix resin. The poly(3-hydroxybutyrate)-based resin (A) preferably has a gel fraction of less than 50%. The poly(3-hydroxybutyrate)-based resin (A) is preferably not crosslinked. In the present resin composition, the poly(3-hydroxybutyrate)-based resin (A) is preferably not crosslinked by the peroxide used in the crosslinked resin particles (B) described above, or by the peroxide and polyfunctional compound described above.

[0082] The poly(3-hydroxybutyrate) resin (A) contains a copolymer of a 3-hydroxybutanoic acid repeating unit and a hydroxyalkanoic acid repeating unit other than a 3-hydroxybutanoic acid repeating unit. The hydroxyalkanoic acid repeating unit other than a 3-hydroxybutanoic acid repeating unit may be at least one selected from the units (hydroxyalkanoic acid repeating units) derived from hydroxyalkanoic acids other than 3-hydroxybutanoic acid described above in the "PHA" section of the crosslinked resin particles (B).

[0083] Furthermore, the poly(3-hydroxybutyrate) resin (A) may contain a homopolymer of 3-hydroxybutanoic acid repeating units, which is described as "P3HB" in the above-mentioned crosslinked resin particles (B). In this specification, the "homopolymer of 3-hydroxybutanoic acid repeating units" may be referred to as a "P3HB homopolymer."

[0084] The poly(3-hydroxybutyrate) resin (A) contains 50 mol % or more of 3-hydroxybutanoic acid repeating units, with the repeating unit content being 100 mol %.

[0085] The poly(3-hydroxybutyrate)-based resin (A) in the resin composition contains a copolymer (a-1) of 3-hydroxybutanoic acid units and a hydroxyalkanoic acid other than 3-hydroxybutanoic acid repeating units. The proportion of 3-hydroxybutanoic acid repeating units in the copolymer (a-1) is 76 mol% or less, preferably 50 mol% or more, more preferably 65 mol% or more, and even more preferably 70 mol%. When the proportion of 3-hydroxybutanoic acid repeating units in the copolymer (a-1) is 76 mol% or less, the copolymer (a-1) has lower crystallinity than the copolymer (a-2) and P3HB homopolymer described below. This improves the brittleness of the crosslinked resin particles (B), and imparts high impact resistance and excellent hardness as an elastomer to molded articles made from the resin composition. Furthermore, when the poly(3-hydroxybutyrate)-based resin (A) contains the copolymer (a-1), the molded articles made from the resin composition can be imparted with reduced stickiness (low blocking properties).

[0086] From the viewpoint of imparting low crystallinity to the copolymer (a-1), the other hydroxyalkanoic acid repeating units contained in the copolymer (a-1) are, for example, preferably a 3-hydroxy-3-methylbutanoic acid repeating unit, a 3-hydroxyhexanoic acid repeating unit, a 4-hydroxybutanoic acid repeating unit, a 3-hydroxyoctanoic acid repeating unit, and a 3-hydroxydecanoic acid repeating unit, a 3-hydroxyhexanoic acid repeating unit, or a 4-hydroxybutanoic acid repeating unit, with a 3-hydroxyhexanoic acid repeating unit being more preferred.

[0087] The poly(3-hydroxybutyrate)-based copolymer (A) is preferably at least one selected from the group consisting of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxydecanoate), and more preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0088] In addition to the copolymer (a-1), the poly(3-hydroxybutyrate) resin (A) in the resin composition preferably further comprises at least one resin selected from the group consisting of a copolymer (a-2) of 3-hydroxybutanoic acid repeating units and hydroxyalkanoic acid repeating units other than 3-hydroxybutanoic acid repeating units, and a homopolymer of 3-hydroxybutanoic acid repeating units. The proportion of 3-hydroxybutanoic acid repeating units contained in the copolymer (a-2) is sufficient to be greater than 95 mol% and less than 100 mol%, and preferably 99 mol% or less. Because the proportion of 3-hydroxybutanoic acid repeating units is greater than 95 mol%, the copolymer (a-2) has higher crystallinity than the above-mentioned copolymer (a-1). When the resin composition further comprises at least one selected from the group consisting of the copolymer (a-2) having a proportion of 3-hydroxybutanoic acid repeating units greater than 95 mol% and a P3HB homopolymer, the molded article can be imparted with higher impact resistance, better hardness, and even better anti-stickiness. Furthermore, as will be described later, when the poly(3-hydroxybutyrate)-based resin (A) contains at least one selected from the group consisting of the copolymer (a-2) and a P3HB homopolymer, the processability of the resin composition into a molded article can be improved.

[0089] The poly(3-hydroxybutyrate)-based resin (A) in the resin composition preferably contains a copolymer (a-1) and at least one selected from the group consisting of a copolymer (a-2) and a P3HB homopolymer, each of which has a different proportion of 3-hydroxybutanoic acid repeating units. The copolymer (a-1) is inferior to the copolymer (a-2) and the P3HB homopolymer in processability during production, but has excellent mechanical properties. It is presumed that when the copolymer (a-1) is mixed with at least one selected from the group consisting of a copolymer (a-2) and a P3HB homopolymer, which has higher crystallinity than the copolymer (a-1), the at least one selected from the group consisting of the copolymer (a-2) and the P3HB homopolymer forms fine resin crystal particles in the copolymer (a-1), and the copolymer (a-1) forms tie molecules that connect the resin crystal particles. By using a combination of copolymer (a-1) and at least one selected from the group consisting of copolymer (a-2) and P3HB homopolymer, the mechanical properties of particles and molded articles of the resin composition can be improved, such as impact absorption, abrasion resistance, and heat resistance. Furthermore, by using copolymer (a-1) in combination with at least one selected from the group consisting of copolymer (a-2) and P3HB homopolymer, which have excellent processability during production, the processability of particles and molded articles of the resin composition can be improved.

[0090] In the poly(3-hydroxybutyrate)-based resin (A), from the viewpoints of the processability and mechanical properties described above, when the total of the copolymers (a-1) and (a-2) is taken as 100% by weight, the proportion of the copolymer (a-1) is preferably 65% ​​by weight or less, more preferably 40% by weight or less, and even more preferably 35% by weight or less. Furthermore, when the total of the copolymers (a-1) and (a-2) is taken as 100% by weight, the proportion of the copolymer (a-1) is preferably 10% by weight or more, more preferably 15% by weight or more.

[0091] In the poly(3-hydroxybutyrate)-based resin (A), from the viewpoints of the processability and mechanical properties described above, when the total of the copolymers (a-1) and (a-2) is taken as 100% by weight, the proportion of the copolymer (a-2) is preferably 35% by weight or more, more preferably 60% by weight or more, and even more preferably 65% ​​by weight or more. When the total of the copolymers (a-1) and (a-2) is taken as 100% by weight, the proportion of the copolymer (a-2) is preferably 90% by weight or less, more preferably 85% by weight or less.

[0092] When the poly(3-hydroxybutyrate)-based resin (A) contains a homopolymer of a 3-hydroxybutanoic acid repeating unit, part or all of the copolymer (a-2) contained in the poly(3-hydroxybutyrate)-based resin (A) may be replaced with the homopolymer.

[0093] The weight-average molecular weight (Mw) of the copolymer (a-1) is preferably 200,000 to 2,500,000, more preferably 250,000 to 2,300,000, and even more preferably 300,000 to 2,000,000, from the viewpoints of the processability, mechanical properties, and stickiness described above. On the other hand, the weight-average molecular weight of the copolymer (a-2) is preferably 200,000 to 1,000,000, more preferably 220,000 to 800,000, and even more preferably 250,000 to 600,000, from the viewpoints of the processability and mechanical properties described above.

[0094] The weight average molecular weight of the P3HB homopolymer is preferably 200,000 to 1,000,000, more preferably 220,000 to 800,000, and even more preferably 250,000 to 600,000, from the viewpoint of the processability and mechanical properties described above.

[0095] The weight-average molecular weight of the poly(3-hydroxybutyrate) resin or poly(3-hydroxybutyrate) resin component can be measured in terms of polystyrene using gel permeation chromatography (HPLC GPC system manufactured by Shimadzu Corporation) using a chloroform solution. As the column for the gel permeation chromatography, a column appropriate for measuring the weight-average molecular weight may be used.

[0096] The melting point of the poly(3-hydroxybutyrate) copolymer (A) is preferably 120 to 170°C, more preferably 130 to 160°C, from the viewpoints of moldability, strength and resistance to stickiness of the particles of the resin composition.

[0097] The method for producing the poly(3-hydroxybutyrate)-based resin (A) is not particularly limited, and may be a production method using chemical synthesis or a production method using a microorganism. Among these, a production method using a microorganism is preferred. The above-mentioned method for producing PHA using a microorganism can be applied to the production method using a microorganism.

[0098] The method for obtaining a blend of the copolymer (a-1) and the copolymer (a-2) in the poly(3-hydroxybutyrate)-based resin (A), and / or a P3HB homopolymer, is not particularly limited, and may be a method for obtaining a blend by microbial production or a method for obtaining a blend by chemical synthesis. Alternatively, the blend may be obtained by melt-kneading two or more resins using an extruder, kneader, Banbury mixer, roll, or the like, or by dissolving two or more resins in a solvent, mixing, and drying the mixture.

[0099] The crosslinked resin particles (B) contain a biodegradable PHA, and the poly(3-hydroxybutyrate)-based resin (A) is also biodegradable. This offers the advantage of high biodegradability for the entire thermoplastic resin composition and for molded articles made from the thermoplastic resin composition as a whole. Therefore, one embodiment of the present invention is expected to address the problem of plastic waste and be useful as an environmentally friendly thermoplastic resin composition. Furthermore, because the poly(3-hydroxybutyrate)-based resin (A) contains a biodegradable resin, the resin composition and molded articles made from it can prevent soil and / or marine pollution caused by waste disposal. This 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."

[0100] Furthermore, when the crosslinked resin particles (B) contain a resin produced from a plant-derived raw material, from the viewpoint of resource circulation, it is preferable that the poly(3-hydroxybutyrate)-based resin (A) also contains a resin produced from a plant-derived raw material, and it is more preferable that the poly(3-hydroxybutyrate)-based resin (A) is composed only of a resin produced from a plant-derived raw material.

[0101] The content of the poly(3-hydroxybutyrate)-based resin (A) in the resin composition is preferably 40 to 99 parts by weight, based on 100 parts by weight of the total of the poly(3-hydroxybutyrate)-based resin (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 poly(3-hydroxybutyrate)-based resin (A) in the resin composition may be 40 to 95 parts by weight, 45 to 93 parts by weight, 47 to 90 parts by weight, 50 to 80 parts by weight, 50 to 85 parts by weight, 50 to 75 parts by weight, or 50 to 70 parts by weight, based on 100 parts by weight of the total of the poly(3-hydroxybutyrate)-based resin (A) and the crosslinked resin particles (B). The content of the poly(3-hydroxybutyrate)-based resin (A) in the present resin composition may be 55 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, 80 parts by weight or more, 85 parts by weight or more, 88 parts by weight or more, or 90 parts by weight or more, based on 100 parts by weight of the total of the poly(3-hydroxybutyrate)-based resin (A) and the crosslinked resin particles (B).

[0102] <Other Biodegradable Resins> This section describes the case where the present resin composition contains a biodegradable resin other than the poly(3-hydroxybutyrate)-based resin (A) as the matrix resin (hereinafter, sometimes referred to as the "other biodegradable resin"). Because the present resin composition and its molded article can benefit greatly from the impact resistance improvement effect of the crosslinked resin particles (B), the present resin composition preferably contains a polyester-based resin as the other biodegradable resin, more preferably an aliphatic polyester, and particularly preferably a PHA and / or polylactic acid. Like the poly(3-hydroxybutyrate)-based resin (A), the other biodegradable resin preferably has a gel fraction of less than 50%. Furthermore, the PHA used as the other biodegradable resin preferably does not have a crosslinked structure.

[0103] The PHA that can be used as the other biodegradable resin is not particularly limited, and examples thereof include polyglycolic acid, P3HA, poly(4-hydroxyalkanoate)-based resins, etc. As the PHA, only one type may be used, or two or more types may be used in combination. As the PHA used as the other biodegradable resin, P3HA is particularly preferred.

[0104] A case where the crosslinked resin particles (B) contain P3HA will be described. The P3HA that can be used as the poly(3-hydroxybutyrate)-based resin (A) is the same as the P3HA related to the crosslinked resin particles (B), and the various P3HAs described above can be used. The P3HA contained in the crosslinked resin particles (B) may be a resin having the same composition as the P3HA contained in the poly(3-hydroxybutyrate)-based resin (A), or may be a resin having a different composition and / or physical properties. The P3HA contained in the poly(3-hydroxybutyrate)-based resin (A) is preferably a resin having a different composition and / or physical properties from the P3HA contained in the crosslinked resin particles (B), and is more preferably a resin that is harder than the P3HA contained in the crosslinked resin particles (B).

[0105] The weight-average molecular weight of the PHA used as the other biodegradable resin contained in the resin composition is not particularly limited, but is preferably 50,000 to 3,000,000, more preferably 100,000 to 2,000,000, and even more preferably 150,000 to 1,500,000. When the weight-average molecular weight of the PHA is 50,000 or more, sufficient rigidity and / or strength can be obtained in the resin composition and molded articles thereof. On the other hand, a PHA having a weight-average molecular weight of 3,000,000 or less can have the advantage of being easy to manufacture and / or easy to handle in order to achieve the object of one embodiment of the present invention.

[0106] The polylactic acid that can be used as the other biodegradable resin contained in the resin composition may be any conventionally known polylactic acid, and may be crystalline polylactic acid, amorphous polylactic acid, or a mixture of crystalline polylactic acid and amorphous polylactic acid.

[0107] The polylactic acid may be a homopolymer of lactic acid, a copolymer of lactic acid and other monomers, or a blend of a homopolymer of lactic acid and a copolymer of lactic acid and other monomers.

[0108] Examples of the other monomers include aliphatic hydroxycarboxylic acids other than lactic acid, aliphatic polyhydric alcohols, aliphatic polycarboxylic acids, and polyfunctional polysaccharides.

[0109] The lactic acid raw material for producing polylactic acid is not particularly limited, and can be L-lactic acid, D-lactic acid, DL-lactic acid, or a mixture thereof, or L-lactide, D-lactide, meso-lactide, or a mixture thereof, etc. Lactic acid obtained by microbial fermentation from renewable plant-derived raw materials such as starch can be suitably used.

[0110] The method for producing polylactic acid is not particularly limited, and known methods such as dehydration condensation polymerization and ring-opening polymerization can be applied.

[0111] The weight-average molecular weight of the polylactic acid used as the other biodegradable resin contained in the resin composition is not particularly limited, but is preferably 50,000 to 1,000,000, more preferably 70,000 to 700,000, and even more preferably 100,000 to 400,000. When the weight-average molecular weight of the polylactic acid is 50,000 or more, the resin composition and its molded article can obtain sufficient rigidity and / or strength. On the other hand, polylactic acid having a weight-average molecular weight of 1,000,000 or less can have the advantage that the polylactic acid is easy to produce and / or can be easily handled to achieve the object of one embodiment of the present invention.

[0112] Regarding the PHA used as another biodegradable resin contained in this resin composition, aspects other than those described above are the same as those explained in the (PHA) section above, so that the explanation therefor is incorporated by reference and will not be repeated here.

[0113] <Other Resin Components> The resin composition may contain other resin components in addition to the poly(3-hydroxybutyrate)-based resin (A), provided that the effects of the present invention are not impaired. The other resin components are not particularly limited as long as they are resins that can be molded into a desired shape by melting them when heated and then cooling and solidifying them. Specific examples include polyolefin-based resins such as polyethylene and polypropylene, acrylic resins such as polyvinyl chloride, polystyrene, polyvinyl acetate, polyurethane, polytetrafluoroethylene, and polymethyl methacrylate, AS resin, polyamide, polyacetal, polycarbonate, modified polyphenylene ether, polyester-based resins, and cyclic polyolefins. These other resin components may be used alone or in combination of two or more.

[0114] <Crystal Nucleating Agent> The present resin composition may further contain a crystal nucleating agent. When the thermoplastic resin composition contains a crystal nucleating agent, crystallization during molding is promoted in the case where the thermoplastic resin is a crystalline resin, and molding processability, productivity, etc. can be improved.

[0115] When the present resin composition contains a crystal nucleating agent, there is an advantage that a thermoplastic resin composition and a molded article thereof having excellent heat resistance or mechanical properties can be obtained.

[0116] 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.

[0117] The content of the nucleating agent is not particularly limited as long as it can promote the crystallization of the thermoplastic resin composition. 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 poly(3-hydroxybutyrate) resin (A) and the crosslinked resin particles (B) combined. 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.

[0118] <Lubricant> The resin composition may further contain a lubricant. When the thermoplastic resin composition contains a lubricant, the surface smoothness of the resulting 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.

[0119] The content of the lubricant (when multiple lubricants are used, the total content thereof) 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 poly(3-hydroxybutyrate) resin (A) and the crosslinked resin particles (B) combined. 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.

[0120] <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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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, ultrafine amorphous silica, etc.), 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 resin composition. These inorganic fillers may be used alone or in combination of two or more.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] <Method for producing thermoplastic resin composition> The resin composition can be produced by a known method. Specific examples include a method in which the poly(3-hydroxybutyrate) resin (A) and crosslinked resin particles (B), as well as optional components such as a crystal nucleating agent, a lubricant, and other components, are melt-kneaded using an extruder, kneader, Banbury mixer, kneading roll, or the like. When melt-kneading, it is preferable to mix the components while taking care to avoid a decrease in molecular weight due to thermal decomposition. Alternatively, the thermoplastic resin composition can be produced by dissolving all of the raw materials (components) in a soluble solvent and then removing the solvent.

[0133] When producing a thermoplastic resin composition by melt-kneading, each component may be charged separately into an extruder, etc., or the components may be mixed in advance and the resulting mixture may be charged into an extruder, etc. For example, an aqueous dispersion of a thermoplastic resin and an aqueous dispersion of crosslinked resin particles 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.

[0134] 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.

[0135] 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 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 in the thermoplastic resin while avoiding thermal decomposition of the thermoplastic resin.

[0136] <Method for producing molded article> In one embodiment of the present invention, a molded article is provided, which is obtained by molding the present resin composition. The method for molding the thermoplastic 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. A molded article obtained by molding a thermoplastic resin composition can also be said to be a molded article containing a thermoplastic resin composition.

[0137] By carrying out the above-described molding method using the resin composition, molded articles having excellent impact resistance, specifically, film molded articles, sheet molded articles, blow molded articles, extrusion molded articles, vacuum molded articles, or injection molded articles, can be produced with good productivity. In this specification, the term "film molded article" refers to a product conforming to JIS 20108:2012, specifically a thin film having a thickness of less than 0.25 mm. In this specification, the term "sheet molded article" refers to a product conforming to JIS 20108:2012, specifically a thin plate having a thickness of 0.25 mm or more.

[0138] Molded articles containing the resin composition 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.

[0139] <Summary> One embodiment of the present invention may include the following configuration: [1] A polymer composition comprising a poly(3-hydroxybutyrate)-based resin (A) and crosslinked resin particles (B), wherein the poly(3-hydroxybutyrate)-based resin (A) comprises at least one selected from the group consisting of a copolymer (a-2) and a homopolymer, and a copolymer (a-1), wherein the copolymer (a-1) comprises a 3-hydroxybutanoic acid repeating unit and a hydroxyalkanoic acid repeating unit other than the 3-hydroxybutanoic acid repeating unit, the proportion of the 3-hydroxybutanoic acid repeating unit contained in the copolymer (a-1) being 76 mol % or less, and the copolymer (a-2) comprises a 3-hydroxybutanoic acid repeating unit and a hydroxyalkanoic acid repeating unit other than the 3-hydroxybutanoic acid repeating unit, [2] The thermoplastic resin composition according to [1], wherein the proportion of 3-hydroxybutanoic acid repeating units in the copolymer (a-2) is greater than 95 mol %, the homopolymer is a homopolymer of 3-hydroxybutanoic acid repeating units, and when the total of the copolymer (a-1), the copolymer (a-2), and the homopolymer in the poly(3-hydroxybutyrate) resin (A) is taken as 100 wt %, the proportion of the copolymer (a-1) is 65 wt % or less and the total proportion of the copolymer (a-2) and the homopolymer is 35 wt % or more, and the crosslinked resin particles (B) contain a polyhydroxyalkanoate resin and have a gel fraction of 50% or more. [3] The thermoplastic resin composition according to [1] or [2], wherein the other hydroxyalkanoic acid repeating unit contained in the copolymer (a-1) is a 3-hydroxyhexanoic acid repeating unit. [4] The thermoplastic resin composition according to any one of [1] to [3], wherein the other hydroxyalkanoic acid repeating unit contained in the copolymer (a-2) is a 3-hydroxyhexanoic acid repeating unit. [5] The thermoplastic resin composition according to any one of [1] to [4], wherein the crosslinked resin particles (B) are contained in an amount of 1 part by weight or more and 60 parts by weight or less per 100 parts by weight of the total amount of the poly(3-hydroxybutyrate) resin (A) and the crosslinked resin particles (B).[6] The thermoplastic resin composition according to any one of [1] to [5], wherein the crosslinked resin particles (B) have a volume average particle diameter of 0.1 μm to 10.0 μm. [7] The thermoplastic resin composition according to any one of [1] to [6], wherein the crosslinked resin particles (B) are crosslinked using a peroxide. [8] The thermoplastic resin composition according to [7], wherein the crosslinked resin particles (B) are crosslinked in the presence of the peroxide and a polyfunctional compound. [9] The thermoplastic resin composition according to any one of [1] to [8], wherein the proportion of the polyhydroxyalkanoate resin in 100% by weight of the crosslinked resin particles (B) is 80% by weight or more.

[10] A molded article comprising the thermoplastic resin composition according to any one of [1] to [9].

[11] The molded article according to

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

[12] A shock absorber comprising the molded article according to

[10] or

[11] .

[13] A structure comprising the shock absorber according to

[12] .

[14] The structure according to

[13] , which is artificial turf or pavement.

[0140] A molded article containing the resin composition can be used as an impact absorber, and the impact absorber can be preferably contained in a structure as a particulate impact absorber. The impact absorber is particularly suitable for use in structures laid on courts, roads, etc. for the purpose of absorbing impacts during walking and sports such as tennis and track and field. The structure containing the impact absorber may or may not be fixed to the ground of a facility, a road, etc. Suitable examples of the structure include structures such as artificial turf and pavement.

[0141] EXAMPLES The following examples will be used to more specifically explain one embodiment of the present invention, but the present invention is not limited to these examples in any way.

[0142] [1] Measurement Conditions 1-1. Weight-Average Molecular Weight The resin to be measured was added to chloroform, and the resulting mixture was heated in a 60°C hot water bath 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 Apparatus: Shimadzu High-Performance Liquid Chromatograph 20A System Columns: Showa Denko K-G 4A (1 column), K-806M (2 columns) 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.

[0143] 1-2. Measurement of Monomer Composition Ratio of Copolymer (P3HB3HH) The monomer composition ratio of P3HB3HH was determined as follows. Approximately 20 mg of P3HB3HH was added to 1 mL of a concentrated sulfuric acid (98%)-methanol mixture (15:85) and 1 mL of chloroform, and the resulting mixture was sealed. The resulting mixture was heated at 100°C for 140 minutes to obtain a methyl ester solution containing P3HB3HH decomposition products. After cooling the methyl ester solution, 0.5 mL of deionized water was added to the methyl ester solution and mixed thoroughly. The resulting mixture was then allowed to stand until the aqueous and organic layers separated. The organic layer was then separated, and the monomer repeat unit composition of the P3HB3HH decomposition products in the separated organic layer was analyzed by capillary gas chromatography. The ratio of 3-hydroxyhexanoic acid repeat units in P3HB3HH was calculated from the peak areas obtained. Furthermore, the ratio of 3-hydroxybutanoic acid repeating units was calculated by subtracting the ratio of 3-hydroxyhexanoic acid repeating units from 100 mol %.

[0144] 1-3. Volume-average particle diameter The volume-average particle diameter of the crosslinked resin particles (B) was measured using an aqueous dispersion of the crosslinked resin particles (B) as a sample. A Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd. was used as the measuring device. Specifically, the particle diameter and volume of each crosslinked resin particle in the aqueous dispersion of the crosslinked resin particles were measured using the above-mentioned 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] 1-4. Gel Fraction Dried crosslinked resin particles (B) were added to chloroform to a concentration of 0.7 wt % and maintained 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 its weight was measured 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 (B) used in measurement} × 100 (%).

[0146] 1-5. Hardness Evaluation Method 1-5-1. Durometer Hardness Pellets of the thermoplastic resin composition were filled between two polyimide films, and then press-molded using a hot press under conditions of a temperature of 165°C, a pressure of 5 MPa, and a time of 5 minutes to form a sample into a plate shape with a thickness of 10 mm. Test pieces were prepared by cutting out the sample. The durometer hardness of the test pieces was evaluated using a Type A durometer in accordance with JIS K7215.

[0147] 1-5-2. Qualitative Evaluation of Hardness (Flexibility) Pellets of the thermoplastic resin composition were pinched with fingers and pressed, and the hardness (flexibility) was qualitatively evaluated based on the feel. Qualitative evaluation of hardness (flexibility) was performed by selecting approximately oval pellets with a minor axis of 2 mm to 2.5 mm, a major axis of 2.8 to 3.0 mm, and a height of 1.0 to 1.5 mm. The evaluation criteria for hardness (flexibility) are as follows: <Evaluation Criteria> Good: The pellet can be felt to deform when pressure is applied with a finger, and the pellet can be felt to return to its original shape due to its elasticity as the pressure is released. Poor (hard): The pellet cannot be felt to elastically deform when pressure is applied with a finger. Poor (soft): The pellet can be felt to deform when pressure is applied with a finger, but the pellet cannot be felt to return to its original shape due to its elasticity as the pressure is released.

[0148] 1-6. Evaluation of Stickiness The stickiness of the thermoplastic resin composition pellets was qualitatively evaluated by touch. The stickiness was evaluated by placing 100 to 200 pellets of the thermoplastic resin composition in the palm of the hand after leaving them for 48 hours at a temperature of 20°C to 25°C and a humidity of 40 to 60% and then squeezing them several times. The stickiness of the pellet surface felt by the hand after squeezing them and the presence or absence of blocking between the pellets were observed to qualitatively evaluate the stickiness. The evaluation was performed by five people, and the most common rating was adopted. In the case of multiple ratings with the same number, the lowest rating was adopted. The evaluation criteria for stickiness are as follows: <Evaluation Criteria> Good: No stickiness on the pellet surface and no blocking between the pellets. Poor: Stickiness was felt on the pellet surface and the pellets were blocking between the pellets.

[0149] 1-7. Impact Absorption of Structure (Artificial Turf) 1-7-1. DIN 18032 Impact Absorption Test The impact absorption of the structure of the artificial turf sample using the impact-absorbency-imparting particles was evaluated using the DIN 18032 impact absorption test.

[0150] A 1 m x 1 m artificial turf (turf height: 65 mm, pile type: polyethylene, pile shape: straight, diamond-shaped yarn / width 1 mm, pile thickness: 14,400 dtex, base fabric: PP plain weave fabric) was laid on concrete, and pellets of a thermoplastic resin composition (i.e., impact-absorbing particles) were filled between the piles to create an artificial turf sample (structure) with a pellet-filled layer (3 mm thick). The impact attenuation rate (FR%) of the artificial turf sample structure was evaluated using an impact attenuation tester conforming to DIN 18032. The impact attenuation rate (FR%) was evaluated by dropping a 20 kg weight onto the artificial turf sample from a height of 55 mm.

[0151] 1-7-2. Impact absorption test of structure (pavement) A primer (polyoxypropylene glycol (Mw = 1000) / methylene bisphenyl isocyanate addition polymer: terminal isocyanate group content 16%) was applied to a pavement with a basis weight of 300 g / m. ２A primer layer was formed by applying the mixture of 100 parts by weight of the thermoplastic resin composition pellets and 100 parts by weight of a binder (polyoxypropylene glycol (Mw=1000) / methylene bisphenyl isocyanate addition polymer: terminal isocyanate group content 9%) to a thickness of 30 mm onto the primer layer to form an elastic layer, thereby preparing a pavement sample (structure).

[0152] Next, the tester repeatedly walked barefoot on the same spot on the pavement sample structure, and qualitatively evaluated the shock absorption according to the following evaluation criteria: <Evaluation criteria> Good: The structure absorbed the shock, and the knee joints felt less shock when walking compared to walking on asphalt. Poor (hard): There was no difference from walking on asphalt, and the knee joints felt shock when walking. Poor (soft): The structure absorbed the shock, and the knee joints felt less shock when walking compared to walking on asphalt, but no repulsive force was felt and the feet were not released properly, making it difficult to walk.

[0153] [2] Evaluation of Thermoplastic Resin Compositions 2-1. Poly(3-hydroxybutyrate)-Based Resin (A) (Production Example 1) P3HB3HH-28: Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate): The repeating unit composition was (3-hydroxybutyrate) / (3-hydroxyhexanoate)=72 / 28 (mol / mol), and the weight-average molecular weight was 600,000.

[0154] P3HB3HH-28 in Production Example 1 was produced in accordance with the method described in Example 9 of WO 2019 / 142845.

[0155] (Production Example 2) P3HB3HH-3: Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate): The repeating unit composition was (3-hydroxybutyrate) / (3-hydroxyhexanoate)=96 / 3 (mol / mol), and the weight average molecular weight was 700,000.

[0156] P3HB3HH-3 in Production Example 2 was produced in accordance with the method described in Example 2 of WO 2019 / 142845.

[0157] (Production Example 3) P3HB3HH-6: Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate): The repeating unit composition was (3-hydroxybutyrate) / (3-hydroxyhexanoate)=94 / 6 (mol / mol), and the weight average molecular weight was 600,000.

[0158] P3HB3HH-6 in Production Example 3 was produced in accordance with the method described in WO 2008 / 010296.

[0159] The weight average molecular weight and monomer composition ratio of each resin component were measured by the methods described above.

[0160] 2-2. Crosslinked Resin Particles (B) The crosslinked resin particles (B) used were crosslinked resin particles produced from the crosslinked resin particle raw material described below according to the following procedure.

[0161] 2-2-1. Raw materials for crosslinked resin particles: Uncrosslinked polyhydroxyalkanoate resin: P3HB3HH-28 of Production Example 1; Di-sec-butyl peroxydicarbonate ("Luperox (registered trademark) 225" manufactured by Arkema Yoshitomi Co., Ltd., 1-hour half-life temperature: 69°C); Multifunctional compound: triallyl isocyanurate.

[0162] 2-2-2. Manufacturing Method of Crosslinked Resin Particles (B) Crosslinked resin particles (B) of Manufacturing Example 4 were manufactured according to the procedure described below. An autoclave equipped with a stirrer, baffles, a nitrogen inlet / outlet, and a thermometer was charged with an aqueous dispersion (100 parts by weight of solids) of P3HB3HH-28 as a polyhydroxyalkanoate resin, 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 to prepare an aqueous dispersion. Stirring of the resulting aqueous dispersion was initiated at room temperature, and 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 P3HB3HH-28.

[0163] Thereafter, the aqueous dispersion was heated to 75° C., which was the reaction temperature for the crosslinking conditions. After the reaction temperature was reached, the mixture was reacted at the reaction temperature for 3.5 hours to obtain an aqueous dispersion in which the crosslinked resin particles (B) were dispersed in water.

[0164] After adjusting the pH of the aqueous dispersion, the dispersion was dried in an oven to obtain solidified crosslinked resin particles (B).

[0165] The volume average particle size and gel fraction of the resulting crosslinked resin particles (B) were measured by the above-mentioned methods, and the volume average particle size was 1.70 μm and the gel fraction was 95%.

[0166] 2-3. Raw materials for thermoplastic resin composition 2-3-1. Poly(3-hydroxybutyrate) resin (A) P3HB3HH-28 of Production Example 1 (copolymer (a-1)) P3HB3HH-3 of Production Example 2 (copolymer (a-2)) P3HB3HH-6 of Production Example 3 (neither copolymer (a-1) nor copolymer (a-2))

[0167] 2-3-2. Crosslinked resin particles (B) Crosslinked resin particles (B) of Production Example 4 2-3-3. Plasticizer Glycerin diacetomonolaurate (BIOCIZER, manufactured by Riken Vitamin Co., Ltd.) 2-3-4. Lubricant Behenic acid amide: BNT22H, manufactured by Nippon Fine Chemical Co., Ltd.

[0168] 2-4. Method for Producing Thermoplastic Resin Composition (Example 1) A blend of 35 parts by weight of P3HB3HH-3, 35 parts by weight of P3HB3HH-28, and 0.5 parts by weight of the additive behenic acid amide was mixed with 30 parts by weight of crosslinked resin particles (B) and further blended to obtain a resin mixture. The resulting resin composition was extruded into a φ26 mm co-rotating twin-screw extruder with a cylinder temperature set to 150°C and a die temperature set to 145°C. The extruded thermoplastic resin composition was passed through a water tank filled with hot water at 40°C to solidify the strands, which were then cut using a pelletizer to obtain pellets (impact-absorbing particles) of the thermoplastic resin composition of Example 1.

[0169] (Examples 2 to 4, Comparative Examples 1 to 3, 5) Pellets of the thermoplastic resin compositions of Examples 2 to 4 and Comparative Examples 1 to 3, 5 were prepared in the same manner as in Example 1, except that the compositions were changed according to the descriptions in Table 1.

[0170] Comparative Example 4 Pellets were prepared in the same manner as in Example 1, except that the resin (A) was entirely changed to polybutylene succinate (manufactured by PTT MCC Biochem, BioPBS (registered trademark) FZ91PM).

[0171] From the pellets of the thermoplastic resin composition of Examples 1 to 4 and Comparative Examples 1 to 5, pellets with a roughly elliptical shape, with a minor axis in the range of 2 mm to 2.5 mm, a major axis in the range of 2.8 to 3.0 mm, and a height in the range of 1.0 to 1.5 mm, were selected, and qualitative evaluations of stickiness and hardness (flexibility) were performed. Furthermore, from each of the pellets of the thermoplastic resin composition of Examples 1 to 4 and Comparative Examples 1 to 5, test specimens for durometer hardness evaluation, artificial turf samples, and pavement samples were prepared, and DIN 18032 impact absorption and qualitative evaluations of impact absorption were performed. The results are shown in Table 1.

[0172]

[0173] The following can be seen from Table 1: From Examples 1 to 4, impact absorbency imparting particles using poly(3-hydroxybutyrate)-based resin (A) containing copolymer (a-1) in which the proportion of 3-hydroxybutanoic acid repeating units is 76 mol % or less (the content of 3-hydroxyhexanoic acid repeating units is 24 mol % or more) and crosslinked resin particles (B) have good hardness, excellent impact absorption properties, are not sticky, and are less likely to cause blocking (adhesion) between pellets.

[0174] On the other hand, Comparative Example 1 shows that when crosslinked resin particles (B) are not used, impact absorption is insufficient. Furthermore, Comparative Example 2 shows that when a plasticizer is used instead of crosslinked resin particles (B), the product feels sticky and pellets are likely to adhere to each other. Furthermore, Comparative Examples 3 and 4 show that when a poly(3-hydroxybutyrate)-based resin (A) that does not contain copolymer (a-1) in which the proportion of 3-hydroxybutanoic acid repeating units is 76 mol % or less (the content of 3-hydroxyhexanoic acid repeating units is 24 mol % or more) is used, the product is hard and the impact absorption is insufficient compared to the Examples.

[0175] From Comparative Example 5, when the proportion of copolymer (a-1) in the resin component is greater than 65% by weight and the proportion of copolymer (a-2) is less than 35% by weight, the shoe is soft and sticky, and while it has sufficient shock absorption, it does not feel resilient and is difficult to walk in.

[0176] Furthermore, in the qualitative evaluation of shock absorption, the structures of Examples 1 to 4 not only cushioned the impact when landing, but also provided a moderate repulsive force when the foot left the structure, and no resistance due to stickiness was felt when the foot left the structure.

[0177] According to one embodiment of the present invention, a novel thermoplastic resin composition capable of providing a molded article having excellent impact resistance 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, sports and leisure facilities, paving materials for road surfaces and the like, structural materials for artificial turf and the like, and other fields.

Claims

1. A polymer comprising a poly(3-hydroxybutyrate)-based resin (A) and crosslinked resin particles (B), wherein the poly(3-hydroxybutyrate)-based resin (A) comprises at least one selected from the group consisting of a copolymer (a-2) and a homopolymer, and a copolymer (a-1), wherein the copolymer (a-1) comprises a 3-hydroxybutanoic acid repeating unit and a hydroxyalkanoic acid repeating unit other than the 3-hydroxybutanoic acid repeating unit, wherein the proportion of the 3-hydroxybutanoic acid repeating unit contained in the copolymer (a-1) is 76 mol % or less, the copolymer (a-2) comprises a 3-hydroxybutanoic acid repeating unit and a hydroxyalkanoic acid repeating unit other than the 3-hydroxybutanoic acid repeating unit, wherein the proportion of the 3-hydroxybutanoic acid repeating unit contained in the copolymer (a-2) is greater than 95 mol %, and the homopolymer is a homopolymer of a 3-hydroxybutanoic acid repeating unit, In the poly(3-hydroxybutyrate)-based resin (A), when the total of the copolymer (a-1), the copolymer (a-2), and the homopolymer is taken as 100% by weight, a ratio of the copolymer (a-1) is 65% by weight or less and a ratio of the total of the copolymer (a-2) and the homopolymer is 35% by weight or more; and the crosslinked resin particles (B) contain a polyhydroxyalkanoate-based resin and have a gel fraction of 50% or more.

2. The thermoplastic resin composition according to claim 1, wherein the proportion of 3-hydroxybutanoic acid repeating units contained in said copolymer (a-2) is 99 mol % or less.

3. The thermoplastic resin composition according to claim 1, wherein the other hydroxyalkanoic acid repeating unit contained in the copolymer (a-1) is a 3-hydroxyhexanoic acid repeating unit.

4. The thermoplastic resin composition according to claim 1, wherein the other hydroxyalkanoic acid repeating unit contained in the copolymer (a-2) is a 3-hydroxyhexanoic acid repeating unit.

5. The thermoplastic resin composition according to claim 1, comprising 1 part by weight or more and 60 parts by weight or less of the crosslinked resin particles (B) per 100 parts by weight of the total amount of the poly(3-hydroxybutyrate) resin (A) and the crosslinked resin particles (B).

6. The thermoplastic resin composition according to claim 1, wherein the crosslinked resin particles (B) have a volume average particle size of 0.1 μm to 10.0 μm.

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

8. The thermoplastic resin composition according to claim 7, wherein the crosslinked resin particles (B) are crosslinked in the presence of the peroxide and a polyfunctional compound.

9. The thermoplastic resin composition according to any one of claims 1 to 8, wherein the proportion of the polyhydroxyalkanoate resin in 100% by weight of the crosslinked resin particles (B) is 80% by weight or more.

10. A molded article comprising the thermoplastic resin composition according to claim 9.

11. The molded article according to claim 10, which is a sheet molded article, a film molded article, a blow molded article, an extrusion molded article, a vacuum molded article, or an injection molded article.

12. A shock absorbing material comprising the molded article according to claim 10.

13. A structure comprising the impact absorbing material according to claim 12.

14. The structure of claim 13, which is an artificial turf or pavement.

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