Blow-molded article and method for producing same

Abstract

Provided is a blow-molded article having excellent impact resistance. The blow-molded article is obtained by molding a thermoplastic resin composition containing 40 to 99 parts by weight of a thermoplastic resin (A) and 1 to 60 parts by weight of crosslinked resin particles (B) which contain a polyhydroxyalkanoate resin and have a gel percentage of at least 50%. The composition, when injection molded into a parallelopiped shape having a length of 80 mm, a width of 4 mm, and a thickness of 10 mm, demonstrates a Charpy impact strength of at least 5 kJ / m2.

Description

Blow-molded article and method for producing the same

[0001] The present invention relates to a blow molded article and a method for producing the same.

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

[0003] Patent Document 1 describes a biodegradable, environmentally friendly thermoplastic resin composition that contains 100 parts by weight of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and 0.1 to 20 parts by weight of poly(3-hydroxyalkanoate) particles having an average particle size of 300 μm or less. Patent Document 1 also describes that the thermoplastic resin composition can be processed into a molded article by extrusion molding (blow molding) or the like.

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

[0005] The technique of blending poly(3-hydroxyalkanoate) particles into a thermoplastic resin, as described in Patent Document 1, can improve the flexibility of the thermoplastic resin, but does not contribute to improving the impact resistance of the thermoplastic resin. Therefore, the blow-molded article obtained by molding the thermoplastic resin composition described in Patent Document 1 has room for improvement in terms of impact resistance.

[0006] In view of the above-mentioned current situation, an object of the present invention is to provide a blow-molded article having excellent impact resistance.

[0007]

[0006] After extensive research, the present inventors have found that a thermoplastic resin composition obtained by blending crosslinked resin particles composed of a polyhydroxyalkanoate resin and having a specific gel fraction with a thermoplastic resin has improved mechanical strength, such as impact strength. Furthermore, the present inventors have found that a blow-molded article obtained by molding a thermoplastic resin composition obtained by blending the crosslinked resin particles with a thermoplastic resin has excellent impact resistance. Based on the above findings, the present inventors have completed the present invention.

[0008] That is, a blow-molded article according to one embodiment of the present invention is a blow-molded article obtained by molding a thermoplastic resin composition, wherein the thermoplastic resin composition contains 40 to 99 parts by weight of a thermoplastic resin (A) and 1 to 60 parts by weight of crosslinked resin particles (B) [where the total amount of (A) and (B) is 100 parts by weight], the crosslinked resin particles (B) contain a polyhydroxyalkanoate resin and have a gel fraction of 50% or more, and the thermoplastic resin composition has a Charpy impact strength of 5 kJ / m or less as measured by the following methods (1) to (4). ２ The blow-molded article relates to the above-mentioned blow-molded article; (1) The thermoplastic resin composition is dried under conditions of a drying temperature of 80°C and a drying time of 4 hours to sufficiently reduce the moisture content, thereby obtaining a dried composition. (2) The dried composition obtained in step (1) is injection-molded using an injection molding machine and a mold having a rectangular parallelepiped cavity with a closed cavity shape of 80 mm in length, 4 mm in width, and 10 mm in thickness, thereby obtaining a test piece having the same shape as the cavity. (3) The test piece obtained in step (2) is removed from the mold and then aged for 7 days under conditions of 23°C and 50% RH, thereby obtaining an injection-molded article. (4) The injection-molded article obtained in step (3) is V-notched and subjected to a Charpy impact test according to a method in accordance with JIS K 7111, and the Charpy impact strength (unit: kJ / m) of the injection-molded article is measured. ２ Measurements are carried out.

[0009] Furthermore, a method for producing a blow-molded body according to one embodiment of the present invention is a method for producing a blow-molded body according to one embodiment of the present invention, comprising: a parison-forming step of forming a parison from the thermoplastic resin composition; a blowing step of placing the parison formed in the parison-forming step inside a mold and then blowing gas into the parison to expand it; a cooling step of cooling and solidifying the parison expanded in the blowing step to form a blow-molded body; and a removal step of removing the blow-molded body formed in the cooling step from the mold, wherein the thermoplastic resin composition constituting the parison into which the gas is blown in the blowing step is in a molten state.

[0010] The blow molded article according to one embodiment of the present invention has the effect of having excellent impact resistance.

[0011] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. Unless otherwise specified in this specification, "A to B" representing a numerical range means "A or more, B or less." In addition, all documents described in this specification are incorporated herein by reference.

[0012] [1. Blow Molded Article] A blow molded article according to one embodiment of the present invention (hereinafter also referred to as "the present blow molded article") is a blow molded article obtained by molding a thermoplastic resin composition, wherein the thermoplastic resin composition contains 40 to 99 parts by weight of a thermoplastic resin (A) and 1 to 60 parts by weight of crosslinked resin particles (B) [where the total amount of (A) and (B) is 100 parts by weight], the crosslinked resin particles (B) contain a polyhydroxyalkanoate resin and have a gel fraction of 50% or more, and the thermoplastic resin composition has a Charpy impact strength of 5 kJ / m or less as measured by the methods shown in (1) to (4) below. ２ (1) The thermoplastic resin composition is dried under conditions of a drying temperature of 80°C and a drying time of 4 hours to sufficiently reduce the moisture content, thereby obtaining a dried composition. (2) The dried composition obtained in step (1) is injection molded using an injection molding machine and a mold having a rectangular parallelepiped cavity with a length of 80 mm, a width of 4 mm, and a thickness of 10 mm when closed, to obtain a test piece having the same shape as the cavity. (3) The test piece obtained in step (2) is removed from the mold and then cured under conditions of 23°C and 50% RH for 7 days to obtain an injection-molded article. (4) The injection-molded article obtained in step (3) is V-notched and subjected to a Charpy impact test according to a method in accordance with JIS K 7111, and the Charpy impact strength (unit: kJ / m) of the injection-molded article is measured. ２ Measurements are carried out.

[0013] The thermoplastic resin composition constituting the present blow-molded article contains a thermoplastic resin (A), but also contains crosslinked resin particles (B) that contain a polyhydroxyalkanoate resin and have a gel fraction of 50% or more, thereby improving the impact resistance of the thermoplastic resin (A). Thus, the thermoplastic resin composition has excellent impact resistance, and as a result, the present blow-molded article obtained by molding the thermoplastic resin composition also has excellent impact resistance.

[0014] In the following, the term "Charpy impact strength" refers to the Charpy impact strength measured by the methods (1) to (4) above. The Charpy impact strength is the impact strength of an injection-molded article obtained by injection-molding the thermoplastic resin composition into a rectangular parallelepiped shape of a predetermined size. Here, the Charpy impact strength is 5 kJ / m ２ The fact that the Charpy impact strength is 5 kJ / m or more indicates that the thermoplastic resin composition constituting the injection molded article itself has excellent mechanical strength. ２ As described above, the thermoplastic resin composition has excellent mechanical strength and is produced by blow molding, and as a result, the article has excellent impact resistance.

[0015] Each component of the blow molded article will be described in detail below.

[0016] [1-1. Thermoplastic Resin Composition] The thermoplastic resin composition constituting the present blow molded article will be described below. First, the crosslinked resin particles (B) will be described.

[0017] <Crosslinked Resin Particles (B)> The crosslinked resin particles (B) are particles composed of a polyhydroxyalkanoate-based resin as a main resin component. Hereinafter, the polyhydroxyalkanoate-based resin may be abbreviated as "PHA."

[0018] (PHA) "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—]. ２ The repeating units represented by the formula [—CO—O—] may account for 60 mol % or more, 70 mol % or more, 80 mol % or more, or 90 mol % or more of all the monomer repeating units (100 mol %).

[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 (B) 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 (B) 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. When the weight-average molecular weight of the PHA is 50,000 or more, it has the advantage of being able to reduce or avoid the tendency for the crosslinked resin particles (B) to have a low strength. Also / alternatively, when the weight-average molecular weight of the PHA is 50,000 or more, it has the advantage of being able to reduce or avoid the tendency for the PHA to become sticky due to low molecular weight components. On the other hand, a PHA having 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 measuring 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 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 (B) affects the gel fraction of the crosslinked resin particles (B); specifically, the more crosslinked structures there are, the higher the gel fraction. Since the crosslinked resin particles (B) have a certain amount or more of crosslinked structures, they exhibit a high gel fraction, specifically a gel fraction of 50% or more. When the gel fraction of the crosslinked resin particles (B) is 50% or more, the crosslinked resin particles (B) have excellent hardness, heat resistance, and solvent resistance.

[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. The gel fraction value may be 85% or more, or may be 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 the crosslinked resin particles (B), the upper limit of the gel fraction is preferably 99.5% or less, more preferably 99% or less. The upper limit of the gel fraction may 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 (B) is added to chloroform so that the concentration becomes 0.7% by weight, and the resulting mixture is maintained at 60°C for 30 minutes to obtain a chloroform solution; (2) The chloroform solution is then allowed to stand at room temperature for 3 hours, and the chloroform solution is then filtered through a membrane filter having a pore size of 0.45 µm; (3) The gel remaining on the filter is dried, and the weight of the dried gel together with the filter is measured, and the gel fraction is calculated using the following formula: Gel fraction (%) = {(Weight of filter including dried gel - Weight of filter only) / Weight of dried product of crosslinked resin particles (B) used for measurement} x 100.

[0035] (Volume average particle diameter) The volume average particle diameter of the crosslinked resin particles (B) is preferably 0.10 μm to 10.00 μm. This configuration enables the crosslinked resin particles (B) 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. However, melt-kneading the crosslinked resin particles (B) with the thermoplastic resin (A) may cause the original shape of the crosslinked resin particles (B) to be destroyed, resulting in a decrease in the volume average particle diameter.

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

[0037] (Peroxide) The crosslinked structure in the crosslinked resin particles (B) is not particularly limited, but is preferably crosslinked using a peroxide. That is, the 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) constituting the resin particles. As a result, the molecular chains of the resin constituting the resin particles are directly bonded to each other, thereby forming a crosslinked structure.

[0038] When the crosslinked resin particles (B) are crosslinked using a peroxide, the aqueous dispersion containing the crosslinked resin particles (B) may contain substances derived from the peroxide used to introduce the crosslinked structure (such as decomposition products of the peroxide and unreacted peroxide). Alternatively, when the crosslinked resin particles (B) are crosslinked using a peroxide, substances derived from the peroxide used to introduce the crosslinked structure (such as decomposition products of the peroxide and unreacted peroxide) may adhere to the surface of the resulting crosslinked resin particles (B). In other words, when the crosslinked resin particles (B) are crosslinked using a peroxide, the crosslinked resin particles (B) or the present blow-molded article may contain substances derived from the peroxide (such as decomposition products of the peroxide and unreacted peroxide). When the crosslinked resin particles (B) or the present blow-molded article contain substances derived from a peroxide, analysis of the crosslinked resin particles (B) or the blow-molded article reveals that the crosslinked resin particles (B) are crosslinked using a peroxide.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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 in terms of ease of handling and having a decomposition temperature 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 as the peroxide.

[0046] (Polyfunctional Compound) The crosslinked structure in the crosslinked resin particles (B) may be introduced using only peroxide, but it is preferable that it is introduced using both peroxide and polyfunctional compound. That is, it is preferable that the crosslinked resin particles (B) are crosslinked in the presence of peroxide and polyfunctional compound. When both peroxide and polyfunctional compound are used, the gel fraction of the crosslinked resin particles (B) can be increased with a smaller amount of peroxide compared to when only peroxide is used.

[0047] 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.

[0048] 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.

[0049] When a crosslinked structure is formed in the presence of a polyfunctional compound, the resulting crosslinked resin particles (B) usually contain a structure derived from the polyfunctional compound, and in this case, the molecular chains of the resin constituting the resin particles are bonded to each other via the structure derived from the polyfunctional compound.

[0050] (Other Components) The crosslinked resin particles (B) are crosslinked resin particles containing PHA. Therefore, the 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.

[0051] The proportion of PHA in the crosslinked resin particles (B) is not particularly limited. The content of PHA in 100% by weight of the resin component of the crosslinked resin particles (B) may be 50% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more, particularly preferably 95% by weight or more, and may even be 99% by weight or more. The upper limit of the content of PHA in 100% by weight of the resin component of the crosslinked resin particles (B) is not particularly limited, as long as it is 100% by weight or less. Note that the term "resin component of the crosslinked resin particles" 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.).

[0052] 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.

[0053] The crosslinked resin particles (B) are preferably non-expanded and are different from the expanded resin particles disclosed in WO 2007 / 049694 and WO 2019 / 146555. In other words, the crosslinked resin particles (B) preferably contain substantially no air bubbles inside the particles. The phrase "substantially no air bubbles inside the particles" means that the volume of air bubbles (voids) is 10% or less of the 100% volume of the crosslinked resin particles (B).

[0054] When the crosslinked resin particles (B) are not expanded, the apparent density of the crosslinked resin particles (B) is relatively large. The apparent density of the crosslinked resin particles (B) is 0.6 g / cm ３ It is preferable that the density exceeds 0.7 g / cm ３ More preferably, it is 0.9 g / cm or more. ３ The apparent density of the crosslinked resin particles (B) can be determined by the method described in JIS K0061 (Method for measuring density and specific gravity of chemical products) or JIS Z8807 (Method for measuring density and specific gravity of solids).

[0055] The average weight per particle of the crosslinked resin particles (B) is not particularly limited. For example, when the volume average particle diameter of the crosslinked resin particles (B) is 10.00 μm or less, the average weight per particle of the crosslinked resin particles (B) can be much less than 0.1 mg.

[0056] The crosslinked resin particles (B) may be dried. The shape of the crosslinked resin particles (B) after drying can be powder, pellets, crumbs, a film, a sheet, or the like, depending on the drying method.

[0057] <Method for producing crosslinked resin particles (B)> An example of a method for producing the crosslinked resin particles (B) will be specifically described below. The crosslinked resin particles (B) can be produced by crosslinking molecular chains of a resin in an aqueous dispersion containing resin particles before crosslinking treatment in the presence of a peroxide.

[0058] The term "resin particles" refers to particles composed of a resin component that essentially constitutes crosslinked resin particles. When the resin component is composed only of PHA, the resin particles can also be called PHA particles. 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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 organic solvents, 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 removed. Furthermore, as the organic solvent, methanol, ethanol, 1-propanol, 2-propanol, butanol, and acetone are more preferred because they are easily available. Furthermore, as the organic solvent, methanol, ethanol, and acetone are particularly preferred.

[0064] 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.

[0065] In the aqueous dispersion, the volume average particle diameter of the resin particles is preferably within the same range as that of the crosslinked resin particles (B) described above. In the case of PHA 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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 may be any of those described above. The polyfunctional compound may be added in various forms, such as a solid or liquid. Furthermore, the peroxide and any polyfunctional compound may be diluted with a diluent or the like and added to the aqueous dispersion of resin particles in a liquid form. The polyfunctional compound may be added all at once, continuously, or in portions.

[0071] 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.

[0072] The amount of peroxide used can be appropriately set in consideration of the gel fraction of the crosslinked resin particles (B), and is, for example, preferably 0.01 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, even more preferably 0.3 to 5 parts by weight, and particularly preferably 0.5 to 3 parts by weight, per 100 parts by weight of the resin particles.

[0073] According to the production method of crosslinking resin particles in an aqueous dispersion using a peroxide, crosslinking can be easily carried out while maintaining the particle size (volume) before crosslinking to obtain crosslinked resin particles (B). On the other hand, it may be difficult to achieve this in the method of crosslinking a resin by melt-kneading in the presence of a peroxide.

[0074] Furthermore, the production method in which resin particles are crosslinked in an aqueous dispersion using a peroxide has the advantage that it is easy to control the temperature rise caused by the heat generated during the crosslinking reaction, and crosslinked resin particles (B) having a safe and stable crosslinked structure (quality) can be efficiently obtained.

[0075] The amount of the polyfunctional compound used may also be appropriately determined in consideration of the gel fraction of the crosslinked resin particles (B). The amount of the polyfunctional compound used is, for example, preferably 0.01 to 20 parts by weight, more preferably 0.05 to 15 parts by weight, even more preferably 0.1 to 10 parts by weight, still more preferably 0.2 to 5 parts by weight, and particularly preferably 0.3 to 3 parts by weight, per 100 parts by weight of the resin particles.

[0076] 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.

[0077] 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.

[0078] After the crosslinking reaction is completed, the crosslinked resin particles (B) are separated from the aqueous dispersion, and water is removed from the separated crosslinked resin particles (B) to obtain dried crosslinked resin particles (B). The method for separating the crosslinked resin particles (B) from the aqueous dispersion is not particularly limited, and examples thereof include filtration, centrifugation, heat drying, freeze drying, and spray drying. For example, spray drying can be used to obtain dried crosslinked resin particles (B) directly from the aqueous dispersion. Furthermore, by extruding the crosslinked resin particles (B) alone after separation from the aqueous dispersion, residual water can be completely removed, and crosslinked resin particles (B) can be obtained in pellet form. Furthermore, an aggregation step using a coagulant and / or adjusting the pH may be performed.

[0079] In the thermoplastic resin composition constituting the present blow-molded article, the blending amount of the crosslinked resin particles (B) is 1 to 60 parts by weight, based on 100 parts by weight of the total of the thermoplastic resin (A) and the crosslinked resin particles (B). Using the crosslinked resin particles (B) in this range can improve the mechanical strength, such as impact strength, of the thermoplastic resin (A), thereby improving the impact resistance of the present blow-molded article. The content of the crosslinked resin particles (B) in the thermoplastic resin composition constituting the present blow-molded article 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 thermoplastic resin (A) and the crosslinked resin particles (B). The content of the crosslinked resin particles (B) in the thermoplastic resin composition constituting the present blow-molded article 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, per 100 parts by weight of the total of the thermoplastic resin (A) and the crosslinked resin particles (B). The content of the crosslinked resin particles (B) in the thermoplastic resin composition constituting the present blow-molded article 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, per 100 parts by weight of the total of the thermoplastic resin (A) and the crosslinked resin particles (B).

[0080] <Thermoplastic Resin (A)> In the thermoplastic resin composition constituting the blow-molded article, the thermoplastic resin (A) can also be referred to as a matrix resin. The thermoplastic resin (A) is not particularly limited as long as it can be molded into a desired shape by heating to melt it and then cooling and solidifying it. Specific examples of the thermoplastic resin (A) include polyolefin 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 resin, and cyclic polyolefin. As the thermoplastic resin (A), only one type of resin may be used, or two or more types of resins may be used in combination. The thermoplastic resin (A) preferably has a gel fraction of less than 50%. The thermoplastic resin (A) is preferably not crosslinked.

[0081] The thermoplastic resin (A) is particularly preferably a polyester resin, such as an aliphatic polyester (e.g., PHA, PLA, PCL, or an aliphatic polyester having a structure in which an aliphatic diol and an aliphatic dicarboxylic acid are polycondensed) or an aliphatic aromatic polyester.

[0082] Specific embodiments of the aliphatic polyester and the aliphatic aromatic polyester are the same as those described above in the sections (PHA) and (Other Components), and therefore, the descriptions therein are incorporated by reference and will not be described here.

[0083] Since the crosslinked resin particles (B) contain a biodegradable PHA, it is preferable that the thermoplastic resin (A) also contains a biodegradable resin, i.e., a biodegradable resin. This configuration has the advantage of increasing the biodegradability of the entire thermoplastic resin composition and the entire molded product of the thermoplastic resin composition. Therefore, when the thermoplastic resin (A) contains a biodegradable resin, it is expected to be useful as an environmentally friendly thermoplastic resin composition that addresses the problem of plastic waste. Furthermore, when the thermoplastic resin (A) contains a biodegradable resin, the resin composition and its molded product can reduce soil pollution due to disposal. This can contribute to the achievement of Sustainable Development Goals (SDGs), such as Goal 12 "Ensure sustainable consumption and production patterns." Furthermore, when the biodegradable resin contained in the thermoplastic resin (A) is both soil and marine degradable, the resin composition and blow-molded product containing the crosslinked resin particles (B) can reduce marine pollution in addition to reducing soil pollution due to disposal.

[0084] 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 thermoplastic resin (A) also contains a resin produced from a plant-derived raw material, and it is more preferable that the thermoplastic resin (A) is composed only of a resin produced from a plant-derived raw material.

[0085] In the thermoplastic resin composition constituting the blow-molded article, the blending amount of thermoplastic resin (A) is 40 to 99 parts by weight per 100 parts by weight of the total of thermoplastic resin (A) and crosslinked resin particles (B). When the thermoplastic resin (A) is used in this range, the mechanical strength, such as impact strength, of the thermoplastic resin (A) can be improved by the crosslinked resin particles (B), and as a result, the impact resistance of the blow-molded article can also be improved. The content of thermoplastic resin (A) in the thermoplastic resin composition constituting the blow-molded article 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, per 100 parts by weight of the total of thermoplastic resin (A) and crosslinked resin particles (B). The content of the thermoplastic resin (A) in the thermoplastic resin composition constituting the present blow-molded article 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 thermoplastic resin (A) and the crosslinked resin particles (B).

[0086] The case where the thermoplastic resin (A) contains a biodegradable resin will be described. The thermoplastic resin (A) preferably contains 10 to 100% by weight of the biodegradable resin, based on 100% by weight of the thermoplastic resin (A). The thermoplastic resin (A) more preferably contains 30% by weight or more of the biodegradable resin, even more preferably 50% by weight or more, even more preferably 70% by weight or more, and particularly preferably 90% by weight or more, based on 100% by weight of the thermoplastic resin (A). The thermoplastic resin (A) may be composed solely of the biodegradable resin.

[0087] Since the blow-molded article can fully benefit from the impact resistance improving effect of the crosslinked resin particles (B), the biodegradable resin preferably contains a polyester resin, more preferably contains an aliphatic polyester, and particularly preferably contains a PHA and / or polylactic acid. The PHA used as the thermoplastic resin (A) preferably has a gel fraction of less than 50%. The PHA used as the thermoplastic resin (A) preferably does not have a crosslinked structure.

[0088] The case where the thermoplastic resin (A) contains PHA and / or polylactic acid as a biodegradable resin will be described below. The thermoplastic resin (A) preferably contains 10% by weight to 100% by weight of PHA and polylactic acid in total, more preferably 30% by weight or more, even more preferably 50% by weight or more, even more preferably 70% by weight or more, and particularly preferably 90% by weight or more, based on 100% by weight of the thermoplastic resin (A).

[0089] The PHA that can be used as the thermoplastic resin (A) 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 thermoplastic resin (A), P3HA is particularly preferred.

[0090] A case where the crosslinked resin particles (B) contain P3HA and the thermoplastic resin (A) contains P3HA will be described. The P3HA that can be used as the thermoplastic 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 thermoplastic resin (A) may be a resin having the same composition as the P3HA contained in the crosslinked resin particles (B), or may be a resin having a different composition and / or physical properties. The P3HA contained in the thermoplastic 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).

[0091] The case where the P3HA used as the thermoplastic resin (A) contains 3-hydroxybutanoic acid (3HB) repeating units will be described. In this case, from the viewpoint of the balance between flexibility and strength, the composition ratio of 3HB repeating units in the total monomer repeating units (100 mol%) of the P3HA is preferably 80 mol% to 99 mol%, more preferably 82 mol% to 97 mol%. When the composition ratio of 3HB repeating units in the P3HA is 80 mol% or more, the rigidity of the P3HA can be further improved. On the other hand, when the composition ratio of 3HB repeating units in the P3HA is 99 mol% or less, the flexibility of the P3HA tends to be further improved. Two or more types of P3HA having different composition ratios of 3HB repeating units may be used in combination.

[0092] The weight-average molecular weight of the PHA used as the thermoplastic resin (A) 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 blow-molded article. On the other hand, a PHA having 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.

[0093] Polylactic acid usable as the thermoplastic resin (A) 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.

[0094] 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.

[0095] Examples of the other monomers include aliphatic hydroxycarboxylic acids other than lactic acid, aliphatic polyhydric alcohols, aliphatic polycarboxylic acids, and polyfunctional polysaccharides.

[0096] The lactic acid raw material for producing polylactic acid is not particularly limited, and examples thereof include L-lactic acid, D-lactic acid, DL-lactic acid, or a mixture thereof, and L-lactide, D-lactide, meso-lactide, or a mixture thereof. Lactic acid obtained by microbial fermentation from renewable plant-derived raw materials such as starch is preferably used. The method for producing polylactic acid is not particularly limited, and known methods such as dehydration condensation polymerization and ring-opening polymerization can be used.

[0097] The weight-average molecular weight of the polylactic acid (A) used as the thermoplastic resin (A) 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 polylactic acid is 50,000 or more, sufficient rigidity and / or strength can be obtained in the blow-molded article. 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 easy to handle in order to achieve the object of one embodiment of the present invention.

[0098] Regarding the PHA used as the thermoplastic resin (A), other aspects than those described above are the same as those explained in the section (PHA) above, so that the explanation therefor is incorporated by reference and will not be repeated here.

[0099] <Crystal Nucleating Agent> The thermoplastic resin composition may further contain a crystal nucleating agent. In other words, the present blow-molded article may further contain a crystal nucleating agent. When the thermoplastic resin (A) is a crystalline resin, the inclusion of a crystal nucleating agent in the thermoplastic resin composition promotes crystallization during molding, thereby improving molding processability, productivity, and the like. When the thermoplastic resin composition contains a crystal nucleating agent, there is also the advantage that a thermoplastic resin composition and a blow-molded article thereof having excellent heat resistance or mechanical properties can be obtained.

[0100] 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, potassium terephthalate, calcium oxalate, sodium laurate, potassium laurate, and sodium myristate. metal salts of organic carboxylic acids such as aluminum, 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 stearamide, ethylene bislauric acid amide, palmitic acid amide, hydroxystearic acid amide, erucic acid amide, and trimesic acid tris(t-butylamide);Lauric acid ester, palmitic acid ester, oleic acid ester, stearic acid ester, erucic acid ester, 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 bislaurate, ethylene biscaprate, ethylene bisoleate, ethylene bisstearate, ethylene biserucate, ethylene bisisostearate, butylene bisstearate, p-xylylene bisstearyl Examples of suitable crystal nucleating agents include carboxylic acid esters such as phosphate esters; dicarboxylic acid derivatives such as dimethyl adipate, dibutyl adipate, diisodecyl adipate, and dibutyl sebacate; cyclic compounds such as indigo, quinacridone, and quinacridone magenta, each 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; 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.

[0101] The content of the crystal nucleating agent is not particularly limited as long as it can promote the crystallization of the thermoplastic resin (A). The content of the crystal 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 thermoplastic resin (A). When the content of the crystal nucleating agent is within the above range, the effect of the crystal nucleating agent can be obtained while suppressing a decrease in viscosity during molding and a decrease in the physical properties of the blow-molded product.

[0102] <Lubricant> The thermoplastic resin composition may further contain a lubricant. In other words, the present blow-molded article may further contain a lubricant. When the thermoplastic resin composition contains a lubricant, the surface smoothness of the resulting blow-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.

[0103] The content of the lubricant (when multiple lubricants are used, the total content) is not particularly limited as long as it can impart lubricity to the molded article. The content of the lubricant is preferably 0.01 to 20.00 parts by weight, more preferably 0.05 to 10.00 parts by weight, even more preferably 0.10 to 10.00 parts by weight, even more preferably 0.20 to 5.00 parts by weight, and particularly preferably 0.30 to 4.00 parts by weight, per 100 parts by weight of the thermoplastic resin (A). When the content of the lubricant is within the above range, it is possible to obtain the effect of the lubricant while avoiding bleeding out of the lubricant onto the surface of the blow-molded article.

[0104] <Other Components> The thermoplastic resin composition constituting the present blow-molded article may contain other components, such as plasticizers, organic fillers, inorganic fillers, antioxidants, hydrolysis inhibitors, ultraviolet absorbers, colorants such as dyes and pigments, antistatic agents, etc., to the extent that the functions of the resulting molded article are not impaired. In other words, the present blow-molded article may contain other components.

[0105] 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; polyalcohols such as polyethylene glycol, polypropylene glycol, poly(ethylene oxide-propylene oxide) block and / or random copolymers, and polytetramethylene glycol. Examples of suitable plasticizers include polyethylene 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 ester; 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.

[0106] 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.

[0107] 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, and bagasse. Other examples of the natural plant fibers include pulp, cellulose fiber, and regenerated fibers such as rayon, which are processed from plant fibers. Examples of natural animal fibers include wool, silk, cashmere, and mohair.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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, as well as polymeric antistatic agents. These antistatic agents may be used alone or in combination of two or more.

[0114] The thermoplastic resin composition constituting the blow-molded article may 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, its esters, its half esters, 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, etc.), and the like. The resin composition may also contain: ether, brominated 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.);

[0115] 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.

[0116] <Method for producing thermoplastic resin composition> The thermoplastic resin composition constituting the blow-molded article can be produced by a known method. Specifically, a method can be used in which the thermoplastic resin (A), crosslinked resin particles (B), and 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 raw materials (components) in a soluble solvent and then removing the solvent.

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

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

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

[0120] <Melt Flow Rate> The thermoplastic resin composition constituting the present blow-molded article is a thermoplastic resin composition having a melt flow rate (MFR) measured in accordance with ISO 1133 at a temperature of 165°C under a load of 5 kg of preferably 5.0 g / 10 min or less, more preferably 4.8 g / 10 min or less, and even more preferably 4.6 g / 10 min or less.

[0121] In blow molding, a parison is formed from a molten thermoplastic resin composition. Furthermore, when gas is blown into the parison during blow molding, the parison is heated, and the thermoplastic resin composition constituting the parison is in a molten state. Furthermore, in conventional blow molding, when the thermoplastic resin composition constituting the parison is in a molten state, the thermoplastic resin composition may flow, causing changes in the shape of the parison, for example, local wall thickness. In such cases, the moldability of the blow-molded article produced by blow molding may be reduced and thickness deviations may occur due to changes in the shape of the parison, for example, local wall thickness. On the other hand, when the melt flow rate of the thermoplastic resin composition is low, the thermoplastic resin composition in the molten state has low fluidity, making it difficult for the thermoplastic resin composition constituting the parison to flow when in a molten state. Therefore, by ensuring that the melt flow rate of the resin composition constituting the blow-molded article, measured at 165°C under a load of 5 kg in accordance with ISO 1133, is equal to or less than the above-mentioned preferred upper limit of 5.0 g / 10 min, the shape of the parison, for example, local changes in wall thickness, are prevented during production. As a result, the blow-molded article has improved moldability and is suitably prevented from having uneven wall thickness.

[0122] The MFR of the thermoplastic resin composition constituting the present blow molded article is usually 0.01 g / 10 min or more, and preferably 0.05 g / 10 min or more.

[0123] <Melt Viscosity> The thermoplastic resin composition was melted at a shear rate of 243 sec －１ When the melt viscosity is 8.4 × 10 ３ Pa・s~5.0×10 ４ Pa s, and preferably 8.5 × 10 ３ Pa・s~5.0×10 ４ The thermoplastic resin composition preferably has a shear rate of 365 sec. －１ When the melt viscosity is 6.5 × 10 ３ Pa・s~5.0×10 ４Pa s, and preferably 7.0 × 10 ３ Pa・s~5.0×10 ４ It is more preferable that the viscosity is Pa·s.

[0124] <Charpy impact strength> The thermoplastic resin composition constituting the present blow molded article has a Charpy impact strength of 5 kJ / m or less, as measured by the following methods (1) to (4). ２ or more, preferably 10 kJ / m ２ More preferably, 15 kJ / m ２ That's all. (1) The thermoplastic resin composition is dried under conditions of a drying temperature of 80°C and a drying time of 4 hours to sufficiently reduce the moisture content, thereby obtaining a dried composition. (2) The dried composition obtained in step (1) is injection molded using an injection molding machine and a mold having a rectangular parallelepiped cavity with a closed cavity shape of 80 mm in length, 4 mm in width, and 10 mm in thickness, to obtain a test piece having the same shape as the cavity. (3) The test piece obtained in step (2) is removed from the mold and then cured under conditions of 23°C and 50% RH for 7 days to obtain an injection-molded article. (4) The injection-molded article obtained in step (3) is V-notched and subjected to a Charpy impact test according to a method in accordance with JIS K 7111, and the Charpy impact strength (unit: kJ / m) of the injection-molded article is measured. ２ Measurements are carried out.

[0125] The temperature conditions in step (2), i.e., the cylinder temperature and mold temperature, have almost no effect on the Charpy impact strength of the resulting injection-molded article, unless the temperature is so severe that it significantly deteriorates the thermoplastic resin composition. Therefore, when considering the Charpy impact strength of an injection-molded article, the cylinder temperature and mold temperature during production of the injection-molded article can be ignored. Examples of the cylinder temperature and mold temperature include a cylinder temperature of 120 to 155°C and a mold temperature of 40°C.

[0126] Here, when the thermoplastic resin composition itself has a high mechanical strength, the mechanical strength such as the Charpy impact strength is also improved in an injection molded article made of the thermoplastic resin composition.２ A large value of 5 kJ / m or more means that the thermoplastic resin composition itself has high mechanical strength. When the thermoplastic resin composition itself has high mechanical strength, the mechanical strength such as impact resistance is also improved in a blow molded article obtained by molding the thermoplastic resin composition. Therefore, when the Charpy impact strength of the thermoplastic resin composition constituting the blow molded article is 5 kJ / m or more, ２ With such a large value, the blow molded article has excellent impact resistance.

[0127] [1-2. Blow Molded Article] <Physical Properties of Blow Molded Article> The blow molded article has excellent impact resistance. The excellent impact resistance of the blow molded article can be confirmed by the impact resistance test described in the examples.

[0128] The shape of the blow-molded article is typically a shape with an internal cavity. The specific shape of the blow-molded article can be appropriately set depending on the application and is not particularly limited. The shape of the blow-molded article can be controlled by appropriately adjusting the shape of the mold used in the manufacturing method of the blow-molded article, which will be described later. Examples of the shape of the blow-molded article include a bottle shape. The bottle-shaped article refers to a hollow container having at least a substantially circular or polygonal bottom wall, upright side walls connected to the bottom wall, an opening at the top, and, in some cases, a top wall. The bottle-shaped article is typically used to store liquids and / or solids, and the contents can be added and removed through the opening.

[0129] The thermoplastic resin composition constituting the blow-molded article has high mechanical strength and excellent impact resistance. Therefore, even if the wall thickness is thinner than that of a typical blow-molded article, the blow-molded article is less likely to break when subjected to external impact. Therefore, even if the wall thickness of the thinnest part of the blow-molded article is so thin that a typical blow-molded article cannot be used as a product, the blow-molded article ensures impact resistance and can be suitably used as a product. Based on the above, the wall thickness of the thinnest part of the blow-molded article may be 2 mm or less, preferably 1.6 mm or less, and more preferably 1.2 mm or less. Furthermore, from the viewpoint of ensuring the strength of the blow-molded article, the wall thickness of the thinnest part of the blow-molded article may usually be 0.1 mm or more, preferably 0.3 mm or more, and more preferably 0.5 mm or more.

[0130] In the present blow-molded article, when the melt flow rate of the thermoplastic resin composition constituting the blow-molded article is within the aforementioned preferred range, moldability is further improved and thickness deviation is suitably prevented. In the present blow-molded article, the suitability of preventing thickness deviation specifically means that the ratio of the maximum thickness difference to the average thickness (also referred to as the maximum thickness difference ratio) is a specific value or less, for example, 20% or less, preferably 18% or less, more preferably 15% or less, even more preferably 12% or less, particularly preferably 11% or less, and most preferably 10% or less. Here, the maximum thickness difference refers to the larger of the absolute values ​​of the difference between the maximum thickness (maximum thickness) and the average thickness, and the absolute value of the difference between the minimum thickness (minimum thickness) and the average thickness, calculated by measuring the thickness at multiple locations on the sidewall of the blow-molded article in a cross section perpendicular to the blowing direction and calculating the average thickness. The maximum thickness difference ratio (%) is the value obtained by dividing the maximum thickness difference by the average thickness and multiplying the result by 100.

[0131] In this application, when determining the average thickness and maximum thickness difference ratio of a blow-molded body, the thicknesses of the bottom and top walls of the blow-molded body and the wall portions constituting the opening of the blow-molded body are not taken into consideration. Also, the thicknesses of the corners connecting the side walls to the bottom wall, top wall, or opening, and the thicknesses of the corners of the uneven portions provided on the side walls are not taken into consideration. Furthermore, the thickness of side walls that are formed thicker than the other side walls for the purposes of improving the ease of holding the blow-molded body in the hand, design, productivity, etc. are not taken into consideration.

[0132] <Uses of Blow Molded Article> The uses of the present blow molded article are not particularly limited and can be any general use of blow molded articles. The present blow molded article also has excellent impact resistance and moldability. Furthermore, blow molded articles usually have an internal cavity. Therefore, the present blow molded article can be suitably used in applications that have an internal cavity and require impact resistance and moldability.

[0133] Specific applications of the blow-molded article include, for example, containers, etc. Examples of the containers include packaging containers for liquid daily necessities such as hair washes, hair conditions, cosmetics, detergents, and disinfectants; food packaging containers for liquids such as soft drinks, water, and seasonings; food packaging containers (dessert cups) for solids such as jelly, pudding, and yogurt; packaging containers for other chemicals; and packaging containers for industrial liquids.

[0134] 2. Manufacturing Method of Blow Molded Article A manufacturing method of a blow molded article according to one embodiment of the present invention (hereinafter also referred to as "the manufacturing method") is a method of manufacturing the blow molded article, and includes: a parison-forming step of forming a parison from the thermoplastic resin composition; a blowing step of placing the parison formed in the parison-forming step inside a mold and then blowing gas into the parison to expand it; a cooling step of cooling and solidifying the parison expanded in the blowing step to form a blow molded article; and a removal step of removing the blow molded article formed in the cooling step from the mold, wherein the thermoplastic resin composition constituting the parison into which the gas is blown in the blowing step is in a molten state.

[0135] The present manufacturing method can produce the present blow molded article, i.e., a blow molded article having excellent impact resistance.

[0136] Each step constituting this manufacturing method will be explained below.

[0137] <Parison Forming Step> The parison forming step in this production method is a step of forming a parison from the thermoplastic resin composition. Specifically, the parison forming step is a step of heating the thermoplastic resin composition to a predetermined temperature to form a molten state, and molding the molten thermoplastic resin composition into a predetermined shape to form a parison. In this specification, the term "parison" refers to an intermediate product that expands into the shape of a blow-molded article by blowing gas into a mold in the blowing step described below. The parison includes not only intermediate products in blow molding that are generally called "parisons," but also intermediate products in blow molding that are generally called "preforms."

[0138] The apparatus used in the parison-forming step is not particularly limited as long as it has the function of heating the thermoplastic resin composition to a molten state and is capable of forming a parison from the molten thermoplastic resin composition. Examples of the apparatus used in the parison-forming step include an extruder equipped with a circular die and an injection molding machine equipped with a test tube-shaped mold.

[0139] The thermoplastic resin composition used in the parison forming step is the same as that described above for the thermoplastic resin composition constituting the blow-molded article.

[0140] Furthermore, a low water content in the thermoplastic resin composition can prevent hydrolysis-induced decomposition of the thermoplastic resin during the formation of the parison and the blow-molded article, as well as deterioration in the physical properties of the thermoplastic resin composition and the blow-molded article. Therefore, a low water content in the thermoplastic resin composition constituting the blow-molded article is preferable. Specifically, the water content of the thermoplastic resin composition is preferably 1.5 wt% or less, and more preferably 1.0 wt% or less, based on the total weight of the thermoplastic resin composition. Furthermore, the water content of the thermoplastic resin composition can typically be 0 wt% or more, and preferably 0.01 wt% or more, based on the total weight of the thermoplastic resin composition. The method for controlling the water content of the thermoplastic resin composition is not particularly limited, and examples thereof include the method used in the step of reducing the water content of the thermoplastic resin composition described below.

[0141] The shape of the parison is not particularly limited as long as it can be expanded by blowing gas into the parison during the blowing process. The shape of the parison may be, for example, a cylindrical shape or a test tube shape.

[0142] In this production method, the parison formation step may be, for example, a step of extruding the thermoplastic resin composition in a molten state through an annular die to form a cylindrical parison, and the cylindrical parison may be subjected to the blowing step without being cooled or solidified. This production method having the above-described configuration generally refers to the production method being carried out by a method called "direct blowing." In this specification, the production method in which the thermoplastic resin composition in a molten state is extruded through an annular die to form a cylindrical parison, and the cylindrical parison is subjected to the blowing step without being cooled or solidified, is also referred to as "direct blowing." Here, "direct blowing" generally involves a simple structure of the equipment used, which is advantageous in terms of initial equipment costs. However, it is known that the shape of the parison, for example, the wall thickness, is prone to change locally, which can lead to poor moldability and wall thickness deviation in the blow-molded article produced. On the other hand, in the present production method, when a thermoplastic resin composition having a melt flow rate within the above-mentioned preferred range is used as a raw material, the fluidity of the thermoplastic resin composition in a molten state is low, as described above, and it is possible to preferably prevent changes in the shape of the parison, for example, local changes in wall thickness. Therefore, even when direct blow molding is adopted in the present production method, by using a thermoplastic resin composition having a melt flow rate within the above-mentioned preferred range as a raw material, it is possible to further improve moldability and preferably prevent the occurrence of wall thickness deviations.

[0143] In this manufacturing method, for example, the parison-forming step may be a step of forming a test-tube-shaped parison from the thermoplastic resin composition by injection molding. This manufacturing method having the above-described configuration generally means that the manufacturing method is carried out by a method called "injection blow molding." In this specification, the manufacturing method in which the parison-forming step is a step of forming a test-tube-shaped parison from the thermoplastic resin composition by injection molding is also referred to as "injection blow molding." By employing injection blow molding, this manufacturing method can achieve higher dimensional accuracy and more effectively prevent thickness deviation.

[0144] When injection blow molding is used in this production method, a method (hot parison method) may be used in which the test-tube parison is subjected to the blowing process while maintaining a predetermined temperature (heat) without being completely cooled and solidified. Alternatively, a method (cold parison method) may be used in this production method in which the test-tube parison is subjected to the blowing process after being completely cooled and solidified. When the cold parison method is used, the test-tube parison may be reheated to melt the thermoplastic resin composition constituting the parison before blowing gas into the test-tube parison in the blowing process. When the cold parison method is used, the method for cooling and solidifying the test-tube parison is not particularly limited, and may include, for example, cooling in a mold and / or allowing it to cool naturally.

[0145] In addition to the direct blowing and injection blowing methods, the present manufacturing method can also employ a method generally called "stretch blowing," a method generally called "multilayer blowing," a method generally called "three-dimensional blowing," and the like.

[0146] The stretch-blowing is a method of stretching the parison before and / or simultaneously with the gas blowing in the injection-blowing process. By employing the stretch-blowing method, this production method can produce blow-molded articles with improved strength, transparency, gas barrier properties, etc.

[0147] The multi-layer blow molding is a method in which the parison formation step is a step of forming a multi-layered parison by co-extrusion of multiple materials. By adopting the multi-layer blow molding, this manufacturing method can produce a blow-molded article having a multi-layer structure.

[0148] The three-dimensional blowing is a method in which a cylindrical parison formed by the direct blowing is guided along a complex mold shape using computer control or the like, and subjected to a blowing process. By employing the three-dimensional blowing, this manufacturing method can produce high-quality products with complex shapes including curved portions and / or bellows, such as hoses for coolers and heaters.

[0149] In the parison-forming step, the temperature of the thermoplastic resin composition forming the parison (hereinafter referred to as the "parison-forming temperature") is not particularly limited as long as it is a temperature at which the thermoplastic resin composition is in a molten state. The parison-forming temperature is preferably 150°C or higher, more preferably 155°C or higher, and even more preferably 160°C or higher. The injection temperature is preferably 250°C or lower, more preferably 230°C or lower, and even more preferably 210°C or lower.

[0150] When the present production method employs a method using injection molding to form a parison, such as the injection blow molding method, pressure is applied to the thermoplastic resin composition in the parison formation step, and the thermoplastic resin composition is injected into a mold. The mold that can be used in the parison formation step has a closed cavity with the same shape as the resulting parison, i.e., a test tube shape. The pressure applied to the thermoplastic resin composition (hereinafter also referred to as the "parison formation injection pressure") is not particularly limited, as long as it is possible to inject the thermoplastic resin composition into the mold and form a parison. The parison formation injection pressure is preferably 10 MPa or more, more preferably 20 MPa or more, and even more preferably 30 MPa or more. The parison formation injection pressure is preferably 200 MPa or less, more preferably 150 MPa or less, and even more preferably 120 MPa or less.

[0151] <Blowing Step> In the blowing step of this production method, the parison formed in the parison-forming step is placed inside a mold, and then gas is blown into the parison to expand it, and the thermoplastic resin composition constituting the parison into which the gas is blown is in a molten state. In the blowing step, the parison expands and comes into contact with the inner wall of the mold. Thereafter, in the cooling step described below, the parison is cooled and solidified, forming a blow-molded article having a shape that conforms to the inner wall of the mold. The gas is not particularly limited as long as it does not adversely affect the thermoplastic resin composition constituting the parison, and for example, air can be used.

[0152] In the blowing step, the temperature of the parison into which the gas is blown (hereinafter referred to as the "blow temperature") is not particularly limited as long as it is a temperature at which the thermoplastic resin composition constituting the parison is in a molten state. Specifically, the blow temperature is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher. The blow temperature is preferably 250°C or lower, more preferably 230°C or lower, and even more preferably 210°C or lower.

[0153] In the blowing step, the flow rate of the gas blown into the parison can be adjusted appropriately depending on the shape and size of the desired blow-molded article, as well as the composition of the thermoplastic resin composition that is the raw material.

[0154] The shape of the mold used in the blowing step, particularly the shape of the inner wall, may be changed to match the shape of the intended blow-molded article. The material of the mold is not particularly limited as long as it does not break and / or deform under the temperature and pressure applied during the blowing step. Examples of the mold material include steel having a predetermined durability and heat resistance.

[0155] <Cooling Step> The cooling step in this production method is a step of cooling and solidifying the parison expanded in the blowing step to form a blow-molded article.

[0156] The method for cooling and solidifying the expanded parison in the cooling step (hereinafter also referred to as the "cooling method") may be any known method and is not particularly limited. Examples of the cooling method include adjusting the temperature of the mold used in the blowing step to a temperature lower than the blowing temperature. The temperature of the mold used in the blowing step is not particularly limited as long as it can cool and solidify the expanded parison to form a blow-molded article. A lower temperature of the mold used in the blowing step is preferable because it can suitably cool and solidify the expanded parison and suitably form a blow-molded article. From the viewpoint of suitably forming the blow-molded article, the temperature of the mold used in the blowing step is preferably 130°C or lower, more preferably 120°C or lower, and even more preferably 110°C or lower. Furthermore, from the viewpoint of the cost required to control the temperature of the mold used in the blowing step, the temperature of the mold used in the blowing step is preferably 10°C or higher, more preferably 20°C or higher, and even more preferably 30°C or higher.

[0157] The cooling time in the cooling step is not particularly limited as long as the expanded parison can be cooled and solidified to form a blow-molded article. The cooling time refers to the time from when the parison expands in the blowing step and contacts the inner wall of the mold to when the cooled and solidified thermoplastic resin composition is removed from the mold, i.e., until the start of the removal step. The cooling time is not particularly limited and can be appropriately adjusted depending on the shape of the blow-molded article to be produced and the composition of the thermoplastic resin composition used, such as the type of thermoplastic resin (A).

[0158] In the cooling step, it is preferable to maintain the temperature of the mold used in the blowing step at a low temperature throughout the cooling step by using cooling water, hot water, etc. This allows the thermoplastic resin composition in the mold to be more suitably cooled and solidified.

[0159] <Removal Step> The removal step in this manufacturing method is a step of removing the blow molded article formed in the cooling step from the inside of the mold. In the removal step, the method for removing the formed blow molded article from the mold is not particularly limited, and any known method can be used.

[0160] <Thermoplastic resin composition preparation step> The present production method may include a thermoplastic resin composition preparation step of preparing a thermoplastic resin composition as a raw material. The thermoplastic resin composition preparation step may employ the above-described method for producing the thermoplastic resin composition constituting the present blow-molded article.

[0161] <Step of Reducing the Moisture Content of the Thermoplastic Resin Composition> The present production method may include a step of reducing the moisture content of the thermoplastic resin composition prior to the parison formation step. The method for reducing the moisture content of the thermoplastic resin composition may be any known moisture-reducing method, i.e., any known drying method, and is not particularly limited. For example, a method for reducing the moisture content of the thermoplastic resin composition may be used, such as drying at a predetermined temperature for a predetermined drying time. The drying temperature and drying time may be adjusted appropriately depending on the moisture content of the thermoplastic resin composition to be subjected to the step of reducing the moisture content of the thermoplastic resin composition, i.e., the thermoplastic resin composition before drying. The drying temperature is, for example, 40°C to 120°C, preferably 50°C to 110°C, and more preferably 60°C to 100°C. The drying time is, for example, 10 minutes to 50 hours, preferably 20 minutes to 40 hours, and more preferably 30 minutes to 30 hours.

[0162] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0163] That is, one embodiment of the present invention includes the following inventions: <1> A blow-molded article obtained by molding a thermoplastic resin composition, wherein the thermoplastic resin composition contains 40 to 99 parts by weight of a thermoplastic resin (A) and 1 to 60 parts by weight of crosslinked resin particles (B) (where the total amount of (A) and (B) is 100 parts by weight), the crosslinked resin particles (B) contain a polyhydroxyalkanoate resin and have a gel fraction of 50% or more, and the thermoplastic resin composition has a Charpy impact strength of 5 kJ / m or less as measured by the following methods (1) to (4). ２ (1) The thermoplastic resin composition is dried under conditions of a drying temperature of 80°C and a drying time of 4 hours to sufficiently reduce the moisture content, thereby obtaining a dried composition. (2) The dried composition obtained in step (1) is injection molded using an injection molding machine and a mold having a rectangular parallelepiped cavity with a length of 80 mm, a width of 4 mm, and a thickness of 10 mm when closed, to obtain a test piece having the same shape as the cavity. (3) The test piece obtained in step (2) is removed from the mold and then cured under conditions of 23°C and 50% RH for 7 days to obtain an injection-molded article. (4) The injection-molded article obtained in step (3) is V-notched and subjected to a Charpy impact test according to a method in accordance with JIS K 7111, and the Charpy impact strength (unit: kJ / m) of the injection-molded article is measured. ２The measurement is carried out. <2> The blow-molded article according to <1>, wherein the thermoplastic resin composition has a melt flow rate of 5.0 g / 10 min or less, measured in accordance with ISO 1133 at 165°C under a load of 5 kg. <3> The blow-molded article according to <1> or <2>, wherein the polyhydroxyalkanoate resin is a poly(3-hydroxyalkanoate) resin. <4> The blow-molded article according to any one of <1> to <3>, wherein the crosslinked resin particles (B) have a volume average particle diameter of 0.10 μm to 10.00 μm or less. <5> The blow-molded article according to any one of <1> to <4>, wherein the crosslinked resin particles (B) are crosslinked using a peroxide. <6> The blow-molded article according to any one of <1> to <5>, wherein the crosslinked resin particles (B) are further crosslinked in the presence of a polyfunctional compound. <7> The blow-molded article according to any one of <1> to <6>, wherein the crosslinked resin particles (B) are not foamed. <8> The blow-molded article according to any one of <1> to <7>, wherein the proportion of the polyhydroxyalkanoate-based resin in the crosslinked resin particles (B) is 80% by weight or more. <9> The blow-molded article according to any one of <1> to <8>, wherein the thermoplastic resin (A) contains a biodegradable resin. <10> The blow-molded article according to <9>, wherein the biodegradable resin is a polyester-based resin. <11> The blow-molded article according to any one of <1> to <10>, wherein the thermoplastic resin composition further contains a crystal nucleating agent and / or a lubricant. <12> A method for producing the blow-molded article according to any one of <1> to <11>, comprising: a parison-forming step of forming a parison from the thermoplastic resin composition; a blowing step of placing the parison formed in the parison-forming step inside a mold and then blowing gas into the parison to expand it; a cooling step of cooling and solidifying the parison expanded in the blowing step to form a blow-molded article; and a removal step of removing the blow-molded article formed in the cooling step from the mold, wherein the thermoplastic resin composition constituting the parison into which the gas is blown in the blowing step is in a molten state.<13> The method for producing a blow-molded article according to <12>, further comprising a step of reducing the moisture content of the thermoplastic resin composition before the parison-forming step. <14> The method for producing a blow-molded article according to <12> or <13>, wherein the parison-forming step is a step of extruding the thermoplastic resin composition in a molten state through an annular die to form a cylindrical parison, and the cylindrical parison is subjected to the blowing step without being cooled or solidified. <15> The method for producing a blow-molded article according to <12> or <13>, wherein the parison-forming step is a step of forming a test-tube-shaped parison from the thermoplastic resin composition by injection molding.

[0164] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0165] [Measurement and Evaluation Methods] <Volume Average Particle Diameter> The volume average particle diameter of the crosslinked resin particles produced in Production Example 1 was measured in the state of a resin particle slurry. A Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd. was used as the measuring device.

[0166] <Gel Fraction> The gel fraction of the crosslinked resin particles produced in Production Examples 1 and 2 was measured in a dry state. Specifically, the dried crosslinked resin particles were added to chloroform to a concentration of 0.7 wt % and dissolved at 60°C for 30 minutes to obtain a chloroform solution. The chloroform solution was then allowed to stand at room temperature for 3 hours and then filtered using a membrane filter with a pore size of 0.45 μm. Prior to the filtration, the weight of the filter alone was measured. During the filtration, the inside of the container and the filter were thoroughly washed with chloroform multiple times during filtration to prevent loss. After the filtration, the gel remaining on the filter was dried and the weight of the filter was measured, and the gel fraction was calculated using the following formula. Formula: Gel fraction = (weight of filter including dried gel - weight of filter only) / weight of crosslinked resin particles used for measurement x 100 (%) <Melt flow rate (MFR)> Using the thermoplastic resin compositions described in Production Examples 3 to 14, the melt flow rate (MFR) of each thermoplastic resin composition was measured by the following method.

[0167] The thermoplastic resin composition was dried at a drying temperature of 80°C for 4 hours to sufficiently reduce its moisture content. The thermoplastic resin composition from which the moisture content had been sufficiently reduced was subjected to MFR measurement in accordance with ISO-1133 using an MFR tester (Yasuda Seiki Seisakusho: No. 120-LABOT) at a measurement temperature of 165°C and a load of 5 kg. Subsequently, the MFR measurement was performed twice using the same method as described above. In other words, the MFR measurement was performed three times using the conditions and method described above. The average of the MFR measurements (unit: g / 10 min) obtained in each of the three MFR measurements was then calculated. The calculated average value was used as the melt flow rate (unit: g / 10 min) of the thermoplastic resin composition measured at a temperature of 165°C and a load of 5 kg in accordance with ISO 1133.

[0168] <Charpy Impact Strength> Using the thermoplastic resin compositions described in Production Examples 3 to 14, the Charpy impact strength of the thermoplastic resin compositions was measured by the following methods (1') to (4'). (1') The thermoplastic resin composition was dried at a drying temperature of 80°C for 4 hours to sufficiently reduce its moisture content, yielding a dried composition. (2') The dried composition obtained in step (1') was injection-molded using a 15MT injection molding machine (Si-15III manufactured by Toyo Machinery & Metal Co., Ltd.) and a mold having a rectangular parallelepiped cavity with a closed cavity shape of 80 mm in length, 4 mm in width, and 10 mm in thickness, at a cylinder temperature of 120 to 155°C and a mold temperature of 40°C, to obtain a test piece having the same shape as the cavity. (3') The test piece obtained in step (2') was removed from the mold and aged for 7 days at 23°C and 50% RH to obtain an injection-molded article. (4') The injection molded article obtained in step (3') is V-notched and subjected to a Charpy impact test in accordance with JIS K 7111, and the Charpy impact strength of the injection molded article is measured (unit: kJ / m). ２ Measurements were carried out.

[0169] <Melt Viscosity> Using a capillary rheometer (manufacturer: Toyo Seiki Seisaku-sho, Ltd., product name: Capillograph 1D), the thermoplastic resin compositions described in Production Examples 3 to 5 were extruded from an orifice connected to the end of the barrel of the capillary rheometer under the following conditions:

[0170] (Conditions) Barrel set temperature: 165°C Barrel radius (D): 0.4775 cm Orifice radius (d): 0.05 cm Orifice capillary length (l): 1 cm Shear rate: 243 sec －１ , or 365 seconds －１ Next, the shear rate is 243 sec －１ The volume flow rate (Q) when the thermoplastic resin composition was extruded from the orifice and the load (F) when the molten thermoplastic resin composition was extruded were measured. －１The volumetric flow rate (Q) when the thermoplastic resin composition was extruded from the orifice and the load (F) when the molten thermoplastic resin composition was extruded were measured. Using the measured volumetric flow rate (Q) and load (F), as well as the barrel radius (D), the orifice radius (d), and the orifice capillary length (l), the shear rate was calculated based on the following (Equation 1): －１ The apparent melt viscosity (η) and shear rate of 365 sec －１ The apparent melt viscosity (η) (unit: Pa·s) was calculated. <Parison Shape Retention> For parisons 1 to 12 formed in Examples 1 to 8 and Comparative Examples 1 to 4, whether or not drawdown could be confirmed was determined by the method described below, and if drawdown was confirmed, the magnitude of the drawdown was confirmed. Note that "drawdown" refers to the parison being deformed by its own weight from the time of formation until just before gas is blown into it, resulting in a drooping state. Hereinafter, this drooping state is referred to as the occurrence of "necking," and the length of the drooping portion is referred to as the "length of the necking portion." After forming the parison, the presence or absence of necking was visually confirmed, and if necking did not occur, it was evaluated as having no drawdown, and if necking did occur, it was evaluated as having drawdown.

[0171] Furthermore, when drawdown occurred, if the length of the necking portion was less than 20% of the total length of the parison, the drawdown was judged to be small, and if the length of the necking portion was 20% or more of the total length of the parison, the drawdown was judged to be large. If drawdown did not occur or if the drawdown was small, the parison shape retention was judged to be "good," and if drawdown was large, the parison shape retention was judged to be "poor."

[0172] <Impact Resistance> The impact resistance of blow molded articles 1 to 8 produced in Examples 1 to 8 and comparative blow molded articles 1 to 4 produced in Comparative Examples 1 to 4 was evaluated using the method described below. Specifically, water at 23°C was poured into the blow molded article, and the cavity inside the blow molded article was filled with the water. The blow molded article with the cavity filled with water was then allowed to gravity drop from a height of 1.0 m onto the floor in an environment of 23°C. If cracks occurred in the blow molded article after gravity dropping, the impact resistance of the blow molded article was judged to be poor. On the other hand, if no cracks occurred in the blow molded article after gravity dropping, the impact resistance of the blow molded article was judged to be good.

[0173] [Compounds Used] The compounds used in the following Production Examples, Examples, and Comparative Examples are shown below. In the following, the terms "thermoplastic resin (A)," "plasticizer," "crystal nucleating agent," "lubricant A," "lubricant B," "uncrosslinked resin particles," "peroxide," and "polyfunctional compound" refer to the compounds shown below unless otherwise specified. Thermoplastic resin (A) (A-1): Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (Kaneka Biodegradable Polymer PHBH (registered trademark) manufactured by Kaneka Corporation), a copolymer having a monomer ratio of (3-hydroxybutyrate) / (3-hydroxyhexanoate)=94.4 / 5.6 (mol / mol), weight average molecular weight Mw: 530,000 (A-2): PLA: Luminy (registered trademark) LX975 manufactured by Total Corbion PLA Corporation (A-3): PBSA: FD92PB manufactured by Mitsubishi Chemical Corporation Nucleating agent: Pentaerythritol (Neuraizer P manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) Lubricant A: Behenic acid amide (BNT22H manufactured by Nippon Fine Chemical Industry Co., Ltd.) Lubricant B: Erucic acid amide (Neutron S manufactured by Nippon Fine Chemical Industry Co., Ltd.) Uncrosslinked resin particles: a copolymer of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) having a monomer ratio of (3-hydroxybutyrate) / (3-hydroxyhexanoate)=72 / 28 (mol / mol) (hereinafter also referred to as "PHA-1"), weight average molecular weight Mw: 500,000 to 1,500,000; Peroxide: di-sec-butyl peroxydicarbonate ("Luperox 225" manufactured by Arkema Yoshitomi Co., Ltd., 1-hour half-life temperature: 69°C); Polyfunctional compound: triallyl isocyanurate. [Production Example 1: Preparation of crosslinked resin particles] A mixed dispersion was obtained by adding an aqueous dispersion (100 parts by weight in terms of solid content) of PHA-1 dispersed in water, 200 parts by weight of deionized water, 2 parts by weight of peroxide, 1 part by weight of sodium dioctyl sulfosuccinate, and 0.5 parts by weight of a polyfunctional compound to a glass vessel equipped with a stirrer, a baffle, a nitrogen inlet / outlet port, and a thermometer. Subsequently, the mixed dispersion was stirred at room temperature, and the atmosphere inside the glass vessel was replaced with nitrogen at the same time as the stirring was started.

[0174] Thereafter, the mixed dispersion after the nitrogen substitution was further stirred at room temperature for 1 hour, thereby allowing the peroxide and the polyfunctional compound to be impregnated into the uncrosslinked resin particles, i.e., PHA-1, in the mixed dispersion, and then the temperature of the mixed dispersion was raised to 75° C. After the temperature of the mixed dispersion reached 75° C., the crosslinking reaction of PHA-1 due to decomposition of the peroxide was allowed to proceed over 3.5 hours, thereby obtaining an aqueous dispersion B in which crosslinked resin particles were dispersed in water.

[0175] The pH of the obtained aqueous dispersion B was adjusted to 3.5 to 4.0 by adding an acid or alkali. The aqueous dispersion B after pH adjustment was heated in an oven at 55°C for 15 hours and dried to prepare solidified crosslinked resin particles. Hereinafter, the crosslinked resin particles prepared in Production Example 1 are referred to as "crosslinked resin particles (B-1)." The volume average particle diameter and gel fraction of the crosslinked resin particles (B-1) were measured by the methods described above. As a result, the crosslinked resin particles (B-1) had a volume average particle diameter of 1.70 μm and a gel fraction of 95%.

[0176] [Production Example 2] Aqueous dispersion B was prepared by the same method as that used to prepare aqueous dispersion B in Production Example 1. This aqueous dispersion B was an aqueous dispersion of crosslinked resin particles (B-1), and had a solids concentration of 20% by weight. The prepared aqueous dispersion B and an aqueous dispersion of silica particles (Snowtex ZL manufactured by Nissan Chemical Industries, Ltd., solids concentration: 40% by weight) in which silica particles were dispersed in water were mixed so that the ratio of aqueous dispersion B / aqueous dispersion of silica particles was 90.9 / 9.1% by weight in terms of solids, thereby obtaining a mixed solution. The pH of the obtained mixed solution was adjusted to 3.5 to 4.0. The mixed solution after pH adjustment was spray-dried using an OD-50 spray dryer manufactured by Okawara Kakoki Co., Ltd. under conditions of a hot air temperature of 150°C, an exhaust air temperature of 70°C, and a disk rotation speed of 10,000 rpm, thereby preparing crosslinked resin particles containing silica particles. Hereinafter, the crosslinked resin particles prepared in Production Example 2 will be referred to as crosslinked resin particles (B-2). The volume average particle diameter and gel fraction of the crosslinked resin particles (B-2) were measured by the methods described above. As a result, the crosslinked resin particles (B-2) had a volume average particle diameter of 1.6 μm and a gel fraction of 96%.

[0177] [Production Example 3: Preparation of Thermoplastic Resin Composition] 70 parts by weight of thermoplastic resin (A-1), 30 parts by weight of the crosslinked resin particles (B-1) prepared in Production Example 1, 1 part by weight of a crystal nucleating agent, 0.5 parts by weight of lubricant A, and 0.5 parts by weight of lubricant B were mixed to obtain mixture 1. The obtained mixture 1 was kneaded in a twin-screw extruder (KZW15TWIN-45WG manufactured by Technovel Co., Ltd.) with the barrel temperature heated to 140 to 165°C at a screw rotation speed of 80 rpm to obtain kneaded product 1. The obtained kneaded product 1 is referred to as thermoplastic resin composition 1.

[0178] [Production Example 4: Preparation of thermoplastic resin composition] A kneaded material 2 was obtained in the same manner as in Production Example 3, except that the amount of thermoplastic resin (A-1) used was changed to 50 parts by weight, and the amount of crosslinked resin particles (B-1) used was changed to 50 parts by weight. The obtained kneaded material 2 is referred to as thermoplastic resin composition 2.

[0179] [Production Example 5: Preparation of thermoplastic resin composition] A kneaded material 3 was obtained in the same manner as in Production Example 3, except that the amount of thermoplastic resin (A-1) used was changed to 100 parts by weight and the crosslinked resin particles (B-1) were not used. The obtained kneaded material 3 is referred to as thermoplastic resin composition 3.

[0180] [Production Example 6: Preparation of Thermoplastic Resin Composition] 89 parts by weight of thermoplastic resin (A-2) and 11 parts by weight of the crosslinked resin particles (B-2) prepared in Production Example 2 were mixed to obtain Mixture 4. The obtained Mixture 4 was melt-kneaded in a twin-screw extruder (Shibaura Machine Co., Ltd. TEM-26SS) heated to a barrel temperature of 155°C at a screw rotation speed of 100 rpm to obtain a melt-kneaded product. The obtained melt-kneaded product was dried in a dehumidifying dryer at 50°C for 12 hours to sufficiently reduce the moisture content, thereby obtaining a thermoplastic resin composition. The obtained thermoplastic resin composition is designated Thermoplastic Resin Composition 4.

[0181] [Production Example 7: Preparation of thermoplastic resin composition] 67 parts by weight of thermoplastic resin (A-2) and 33 parts by weight of crosslinked resin particles (B-2) were mixed to obtain mixture 5. A thermoplastic resin composition was obtained in the same manner as in Production Example 6, except that mixture 5 was used instead of mixture 4. The obtained thermoplastic resin composition is designated as thermoplastic resin composition 5.

[0182] [Production Example 8: Preparation of thermoplastic resin composition] 33.5 parts by weight of thermoplastic resin (A-1), 33.5 parts by weight of thermoplastic resin (A-2), 33 parts by weight of crosslinked resin particles (B-2), 1 part by weight of a crystal nucleating agent, and 0.5 parts by weight of lubricant A were mixed to obtain mixture 6. A thermoplastic resin composition was obtained in the same manner as in Production Example 6, except that mixture 6 was used instead of mixture 4. The obtained thermoplastic resin composition is designated thermoplastic resin composition 6.

[0183] [Production Example 9: Preparation of thermoplastic resin composition] 20.1 parts by weight of thermoplastic resin (A-1), 46.9 parts by weight of thermoplastic resin (A-2), 33 parts by weight of crosslinked resin particles (B-2), 1 part by weight of a crystal nucleating agent, and 0.5 parts by weight of lubricant A were mixed to obtain mixture 7. A thermoplastic resin composition was obtained in the same manner as in Production Example 6, except that mixture 7 was used instead of mixture 4. The obtained thermoplastic resin composition is designated thermoplastic resin composition 7.

[0184] [Production Example 10: Preparation of thermoplastic resin composition] 89 parts by weight of thermoplastic resin (A-3) and 11 parts by weight of crosslinked resin particles (B-2) were mixed to obtain mixture 8. A thermoplastic resin composition was obtained in the same manner as in Production Example 6, except that mixture 8 was used instead of mixture 4. The obtained thermoplastic resin composition is designated as thermoplastic resin composition 8.

[0185] [Production Example 11: Preparation of thermoplastic resin composition] 67 parts by weight of thermoplastic resin (A-3) and 33 parts by weight of crosslinked resin particles (B-2) were mixed to obtain mixture 9. A thermoplastic resin composition was obtained in the same manner as in Production Example 6, except that mixture 9 was used instead of mixture 4. The obtained thermoplastic resin composition is designated as thermoplastic resin composition 9.

[0186] [Production Example 12: Preparation of thermoplastic resin composition] A thermoplastic resin composition was obtained in the same manner as in Production Example 6, except that 100 parts by weight of thermoplastic resin (A-2) was used instead of mixture 4. The obtained thermoplastic resin composition is designated as thermoplastic resin composition 10.

[0187] [Production Example 13: Preparation of thermoplastic resin composition] 50 parts by weight of thermoplastic resin (A-1), 50 parts by weight of thermoplastic resin (A-2), 1 part by weight of a crystal nucleating agent, and 0.5 parts by weight of lubricant A were mixed to obtain mixture 11. A thermoplastic resin composition was obtained in the same manner as in Production Example 6, except that mixture 11 was used instead of mixture 4. The obtained thermoplastic resin composition is designated as thermoplastic resin composition 11.

[0188] [Production Example 14: Preparation of thermoplastic resin composition] 30 parts by weight of thermoplastic resin (A-1), 70 parts by weight of thermoplastic resin (A-2), 1 part by weight of a crystal nucleating agent, and 0.5 parts by weight of lubricant A were mixed to obtain mixture 12. A thermoplastic resin composition was obtained in the same manner as in Production Example 6, except that mixture 12 was used instead of mixture 4. The obtained thermoplastic resin composition is designated as thermoplastic resin composition 12.

[0189] [Example 1: Production of blow-molded article] Thermoplastic resin composition 1 obtained in Production Example 3 was dried under conditions of a drying temperature of 80°C and a drying time of 4 hours to sufficiently reduce its moisture content. Hereinafter, the thermoplastic resin composition whose moisture content has been sufficiently reduced is also referred to as a "dried composition."

[0190] The obtained dry composition was extruded through an annular die using a direct blow molding machine MSE-40E manufactured by Tahara Corporation at an extruder temperature of 160°C to form a cylindrical parison 1. Here, the extruder temperature refers to the "parison formation temperature" mentioned above. Subsequently, the cylindrical parison 1 was placed inside a mold whose temperature was controlled at 40°C without being cooled or solidified, and air was blown into the interior to expand it (direct blowing was performed). Therefore, the "blow temperature" in Example 1 was maintained at 160°C. The shape and size of the mold was a cylindrical bottle with a height of 150 mm, a diameter of 60 mm, a cap diameter of 30 mm, and a cap height of 20 mm. The expanded parison was molded along the shape of the inner wall of the mold and simultaneously cooled and solidified to form a blow-molded article 1. Finally, the blow-molded article 1 was removed from the mold, and a blow-molded article 1 was produced.

[0191] Example 2: Production of blow-molded body A parison 2 was formed in the same manner as in Example 1, except that the thermoplastic resin composition 2 prepared in Production Example 4 was used instead of the thermoplastic resin composition 1, and a blow-molded body 2 was produced using the parison 2.

[0192] Comparative Example 1: Production of comparative blow-molded article A parison 3 was formed in the same manner as in Example 1, except that the thermoplastic resin composition 3 prepared in Production Example 5 was used instead of the thermoplastic resin composition 1, and a comparative blow-molded article 1 was produced using the parison 3.

[0193] Example 3: Production of blow-molded article A parison 4 was formed in the same manner as in Example 1, except that the thermoplastic resin composition 4 prepared in Production Example 6 was used instead of the thermoplastic resin composition 1, and a blow-molded article 3 was produced using the parison 4.

[0194] Example 4: Production of blow-molded article A parison 5 was formed in the same manner as in Example 3, except that the thermoplastic resin composition 5 prepared in Production Example 7 was used instead of the thermoplastic resin composition 4, and a blow-molded article 4 was produced using the parison 5.

[0195] Example 5: Production of blow-molded article A parison 6 was formed in the same manner as in Example 3, except that the thermoplastic resin composition 6 prepared in Production Example 8 was used instead of the thermoplastic resin composition 4, and a blow-molded article 5 was produced using the parison 6.

[0196] Example 6: Production of blow-molded article A parison 7 was formed in the same manner as in Example 3, except that the thermoplastic resin composition 7 prepared in Production Example 9 was used instead of the thermoplastic resin composition 4, and a blow-molded article 6 was produced using the parison 7.

[0197] Example 7: Production of blow-molded article A parison 8 was formed in the same manner as in Example 1, except that the thermoplastic resin composition 8 prepared in Production Example 10 was used instead of the thermoplastic resin composition 1, and a blow-molded article 7 was produced using the parison 8.

[0198] Example 8: Production of blow-molded article A parison 9 was formed in the same manner as in Example 7, except that the thermoplastic resin composition 9 prepared in Production Example 11 was used instead of the thermoplastic resin composition 8, and a blow-molded article 8 was produced using the parison 9.

[0199] Comparative Example 2: Production of Comparative Blow Molded Article A parison 10 was formed in the same manner as in Example 3, except that the thermoplastic resin composition 10 prepared in Production Example 12 was used instead of the thermoplastic resin composition 1, and a comparative blow molded article 2 was produced using the parison 10.

[0200] Comparative Example 3: Production of Comparative Blow Molded Article A parison 11 was formed in the same manner as in Example 3, except that the thermoplastic resin composition 11 prepared in Production Example 13 was used instead of the thermoplastic resin composition 1, and a comparative blow molded article 3 was produced using the parison 11.

[0201] Comparative Example 4: Production of Comparative Blow Molded Article A parison 12 was formed in the same manner as in Example 3, except that the thermoplastic resin composition 12 prepared in Production Example 14 was used instead of the thermoplastic resin composition 1, and a comparative blow molded article 4 was produced using the parison 12.

[0202] [Results] The compositions of thermoplastic resin compositions 1 to 12 used in Examples 1 to 8 and Comparative Examples 1 to 4 and produced in Production Examples 3 to 14 are shown in Table 1 below. The physical properties of thermoplastic resin compositions 1 to 12 used in Examples 1 to 8 and Comparative Examples 1 to 4, and parisons 1 to 12, blow molded articles 1 to 8, and comparative blow molded articles 1 to 4 produced in Examples 1 to 8 and Comparative Examples 1 to 4, were measured and evaluated by the above-mentioned measurement and evaluation methods, and the results are shown in Table 2 below. As shown in Production Examples 1 to 4, 6 to 11, Examples 1 to 8, and Table 1, the thermoplastic resin compositions used to produce blow molded articles 1 to 8 in Examples 1 to 8 and constituting these blow molded articles are thermoplastic resin compositions 1, 2, and 4 to 9. Thermoplastic resin compositions 1, 2, and 4 to 9 satisfy the following requirements: - Comprise 40 to 99 parts by weight of thermoplastic resin (A) and 1 to 60 parts by weight of crosslinked resin particles (B) [where the total amount of (A) and (B) is 100 parts by weight]. - The crosslinked resin particles (B) contain a polyhydroxyalkanoate resin and have a gel fraction of 50% or more. - A Charpy impact strength of 5 kJ / m ２Thus, blow molded articles 1 to 8 correspond to the present blow molded article. The manufacturing methods for the blow molded articles in Examples 1 to 8 also correspond to the present manufacturing method.

[0203] On the other hand, in Production Examples 5 and 12 to 14, and Comparative Examples 1 to 4, as well as in Table 1, the thermoplastic resin compositions used to produce comparative blow molded articles 1 to 4 and constituting these blow molded articles are thermoplastic resin compositions 3 and 10 to 12. Thermoplastic resin compositions 3 and 10 to 12 do not contain crosslinked resin particles (B) and have a Charpy impact strength of 5 kJ / m ２ Therefore, comparative blow molded articles 1 to 4 do not fall under the category of the blow molded article of the present invention. Furthermore, the manufacturing methods for the blow molded articles in Comparative Examples 1 to 4 do not fall under the category of the manufacturing method of the present invention.

[0204] As shown in Table 2, the blow molded bodies 1 to 8 were found to have excellent impact resistance, with the results of the impact resistance test being "good." On the other hand, the comparative blow molded bodies 1 to 4 were found to have poor impact resistance, with the results of the impact resistance test being "poor."

[0205] As shown in Table 2, the thermoplastic resin compositions described in Examples 1 and 2 have a melt flow rate of 5.0 g / 10 min or less, measured at a temperature of 165°C and a load of 5 kg according to ISO 1133. The melt viscosity of the thermoplastic resin compositions described in Examples 1 and 2 is particularly high at a shear rate of 365 sec. －１When the melt flow rate is larger than 5.0 g / 10 min, the melt viscosity is higher than that of the thermoplastic resin composition described in Comparative Example 1. Furthermore, parisons 1 and 2 have "good" shape retention. Therefore, parisons 1 and 2 are composed of thermoplastic resin compositions with high melt viscosity and have high shape retention. Therefore, blow-molded articles 1 and 2 produced using parisons 1 and 2 have excellent moldability and are prevented from having uneven thickness. On the other hand, in Comparative Example 1, thermoplastic resin composition 3 has a melt flow rate of more than 5.0 g / 10 min, and parison 3 is composed of a thermoplastic resin composition with a low melt viscosity and has poor shape retention. Therefore, comparative blow-molded article 1 produced using parison 3 has poor moldability and is prone to uneven thickness. Furthermore, in Comparative Examples 2 and 4, thermoplastic resin compositions 10 and 12 have melt flow rates of more than 5.0 g / 10 min, and parisons 10 and 12 have poor shape retention. Therefore, it was found that the comparative blow-molded bodies 2 and 4, which were produced using the parisons 10 and 12, also had poor moldability and were prone to thickness deviation.

[0206] From the above, it was found that by using a thermoplastic resin composition having a melt flow rate of 5.0 g / 10 min or less as a raw material in the blow-molded article, not only excellent impact resistance but also excellent moldability is achieved and thickness deviation is prevented. Also, it was found that by using a thermoplastic resin composition having a melt flow rate of 5.0 g / 10 min or less as a raw material in the production method, it is possible to produce a blow-molded article having excellent impact resistance, which prevents thickness deviation due to excellent moldability.

[0207] The blow-molded article has excellent impact resistance. Therefore, the blow-molded article and the manufacturing method can be used to manufacture products using blow-molded articles with excellent impact resistance. Examples of such products include containers.

Claims

1. A blow molded article obtained by molding a thermoplastic resin composition, the thermoplastic resin composition comprising 40 to 99 parts by weight of a thermoplastic resin (A) and 1 to 60 parts by weight of crosslinked resin particles (B) (wherein the total amount of (A) and (B) is 100 parts by weight), the crosslinked resin particles (B) comprising a polyhydroxyalkanoate resin and having a gel fraction of 50% or more, the thermoplastic resin composition having a Charpy impact strength of 5 kJ / m or less as measured by the methods shown in (1) to (4) below. ２ or more; (1) The thermoplastic resin composition is dried under conditions of drying temperature: 80°C, drying time: 4 hours, and the moisture content is sufficiently reduced to obtain a dried composition. (2) The dried composition obtained in step (1) is injection molded using an injection molding machine and a mold having a closed cavity shape of a rectangular parallelepiped with a length of 80 mm, a width of 4 mm, and a thickness of 10 mm, to obtain a test piece having the same shape as the cavity. (3) The test piece obtained in step (2) is removed from the mold and then cured under conditions of 23°C and 50% RH for 7 days to obtain an injection molded article. (4) The injection molded article obtained in step (3) is V-notched and subjected to a Charpy impact test according to a method conforming to JIS K 7111, and the Charpy impact strength of the injection molded article (unit: kJ / m) is measured. ２ Measurements are carried out.

2. The blow molded article according to claim 1, wherein the thermoplastic resin composition has a melt flow rate of 5.0 g / 10 min or less, measured in accordance with ISO 1133 at a temperature of 165° C. and a load of 5 kg.

3. The blow molded article according to claim 1, wherein the polyhydroxyalkanoate resin is a poly(3-hydroxyalkanoate) resin.

4. The blow molded article according to claim 1, wherein the crosslinked resin particles (B) have a volume average particle size of 0.10 μm to 10.00 μm.

5. The blow molded article according to claim 1, wherein the crosslinked resin particles (B) are crosslinked using a peroxide.

6. The blow molded article according to claim 1, wherein the crosslinked resin particles (B) are further crosslinked in the presence of a polyfunctional compound.

7. The blow molded article according to claim 1, wherein the crosslinked resin particles (B) are not expanded.

8. The blow molded article according to claim 1, wherein the proportion of said polyhydroxyalkanoate resin in said crosslinked resin particles (B) is 80% by weight or more.

9. The blow molded article according to claim 1, wherein the thermoplastic resin (A) comprises a biodegradable resin.

10. The blow molded article according to claim 9, wherein the biodegradable resin is a polyester-based resin.

11. The blow molded article according to claim 1, wherein the thermoplastic resin composition further comprises a crystal nucleating agent and / or a lubricant.

12. A method for producing a blow molded product according to any one of claims 1 to 11, comprising: a parison forming step of forming a parison from the thermoplastic resin composition; a blowing step of placing the parison formed in the parison forming step inside a mold and then blowing gas into the parison to expand it; a cooling step of cooling and solidifying the parison expanded in the blowing step to form a blow molded product; and a removal step of removing the blow molded product formed in the cooling step from the mold, wherein the thermoplastic resin composition constituting the parison into which the gas is blown in the blowing step is in a molten state.

13. The method for producing a blow molded article according to claim 12, further comprising a step of reducing the moisture content of the thermoplastic resin composition prior to the parison formation step.

14. The method for producing a blow molded article according to claim 12, wherein the parison formation step is a step of extruding the thermoplastic resin composition in a molten state through an annular die to form a cylindrical parison, and the cylindrical parison is subjected to the blowing step without being cooled or solidified.

15. The method for producing a blow molded article according to claim 12, wherein the parison forming step is a step of forming a test tube-shaped parison from the thermoplastic resin composition by injection molding.

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