Crosslinked resin particles and method for producing the same

Abstract

To provide novel crosslinked resin particles having superior heat resistance and biodegradability.SOLUTION: Provided are crosslinked resin particles which contain a polyhydroxyalkanoate resin, have a gel fraction of 50% or more, have a volume average particle diameter of 0.10 μm to 10.00 μm, and contain peptidoglycan.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to crosslinked resin particles and a method for producing the same. [Background technology]

[0002] 2. Description of the Related Art Conventionally, techniques for adding various modifiers (for example, crosslinked particles) to thermoplastic resins in order to improve the mechanical strength, such as the impact strength, of thermoplastic resins have been known.

[0003] Known examples of crosslinked resin particles include crosslinked resin particles made of resins such as acrylic resins, acrylic silicone resins, and polystyrene (see, for example, Patent Documents 1 and 2).

[0004] Meanwhile, in recent years, from the viewpoint of consideration for the environment during and after the disposal of resin products, there has been active development of biodegradable resins (hereinafter, sometimes referred to as "biodegradable resins"). For example, Patent Document 3 describes crosslinking of poly(3-hydroxyalkanoate), a type of biodegradable resin, by melt-kneading the resin in the presence of an organic peroxide. However, it describes that the crosslinked resin produced by such melt-kneading is used to constitute a film and / or sheet, and there is no description at all about producing small crosslinked resin particles. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-56770 A [Patent Document 2] JP 2003-82191 A [Patent Document 3] International Publication No. 2019 / 022008 Summary of the Invention [Problem to be solved by the invention]

[0006] So far, no biodegradable crosslinked resin particles have been known. Furthermore, the crosslinked resin particles are sometimes required to have heat resistance.

[0007] One embodiment of the present invention has been made in consideration of the above problems, and an object of the invention is to provide novel crosslinked resin particles which are excellent in heat resistance and biodegradable. [Means for solving the problem]

[0008] As a result of extensive investigations aimed at solving the above problems, the present inventors have completed one embodiment of the present invention.

[0009] That is, one embodiment of the present invention includes the following configuration. [1] Crosslinked resin particles containing a polyhydroxyalkanoate resin, having a gel fraction of 50% or more, a volume average particle diameter of 0.10 μm to 10.00 μm, and containing peptidoglycan. [2] The crosslinked resin particles according to [1], wherein the polyhydroxyalkanoate resin is a poly(3-hydroxyalkanoate) resin. [3] The crosslinked resin particles according to [1] or [2], wherein the crosslinked resin particles are crosslinked using a peroxide. [4] The crosslinked resin particles according to [3], wherein the crosslinked resin particles are crosslinked in the presence of the peroxide and a polyfunctional compound. [5] The crosslinked resin particles according to any one of [1] to [4], wherein the crosslinked resin particles are not foamed. [6] The crosslinked resin particles according to any one of [1] to [5], wherein the content of the polyhydroxyalkanoate resin in 100% by weight of the resin component of the crosslinked resin particles is 80% by weight or more. [7] The crosslinked resin particles according to any one of [1] to [6], wherein the gel fraction is 70% to 100%. [8] An aqueous dispersion in which the crosslinked resin particles according to any one of [1] to [7] are dispersed in an aqueous medium. [9] A thermoplastic resin composition comprising a thermoplastic resin and the crosslinked resin particles according to any one of [1] to [7].

[10] The thermoplastic resin composition according to [9], comprising 40 parts by weight to 99 parts by weight of the thermoplastic resin and 1 part by weight to 60 parts by weight of the crosslinked resin particles, where the total amount of the thermoplastic resin and the crosslinked resin particles is 100 parts by weight.

[11] The thermoplastic resin composition according to [9] or

[10] , wherein the thermoplastic resin includes a biodegradable resin.

[12] The thermoplastic resin composition according to

[11] , wherein the biodegradable resin includes a polyester-based resin.

[13] The thermoplastic resin composition according to any one of [9] to

[12] , further comprising a crystal nucleating agent and / or a lubricant.

[14] A molded article obtained by molding the thermoplastic resin composition according to any one of [9] to

[13] .

[15] The molded article according to

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

[16] A modifier for thermoplastic resins, comprising crosslinked resin particles, the crosslinked resin particles comprising a polyhydroxyalkanoate resin, having a gel fraction of 50% or more, a volume average particle diameter of 0.10 μm to 10.00 μm, and comprising peptidoglycan.

[17] A method for producing crosslinked resin particles, comprising: a bacterial cell culture preparation step of preparing a bacterial cell culture solution containing a polyhydroxyalkanoate resin; a dispersion preparation step of removing the bacterial cells from the culture solution to prepare a dispersion containing resin particles containing a polyhydroxyalkanoate resin; an aqueous dispersion preparation step of mixing the dispersion with a peroxide to prepare an aqueous dispersion containing the resin particles and the peroxide; and a crosslinking step of decomposing the peroxide to crosslink the resin particles, wherein the production method does not use a peptidoglycan-degrading enzyme, and the crosslinked resin particles have a gel fraction of 50% or more and a volume average particle diameter of 0.10 μm to 10.00 μm and contain peptidoglycan. Effect of the Invention

[0010] According to one embodiment of the present invention, it is possible to provide novel crosslinked resin particles that are excellent in heat resistance and biodegradability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0012] [1. Technical idea according to one embodiment of the present invention] From the viewpoint of environmental load, the development of biodegradable materials is required. Also, crosslinked resin particles are sometimes required to have heat resistance.

[0013] Meanwhile, polyhydroxyalkanoate resins (hereinafter sometimes referred to as "PHA") are known as biodegradable resins. Polyhydroxyalkanoate resins (particularly poly(3-hydroxyalkanoate) resins) can be produced by microorganisms. For example, a PHA-producing microorganism is cultured to accumulate PHA in the cells, and then the cells in the culture medium are destroyed to separate and remove the cell components, thereby obtaining an aqueous dispersion containing PHA. Here, the aqueous dispersion containing PHA may contain peptidoglycan (hereinafter sometimes referred to as "PG") derived from the cell components. The PG in the aqueous dispersion containing PHA can be decomposed and removed by a peptidoglycan-degrading enzyme (e.g., lysozyme).

[0014] The present inventors have conducted extensive research to provide novel crosslinked resin particles that are excellent in heat resistance and biodegradability. As a result, the present inventors have independently discovered the following novel findings, leading to the completion of one embodiment of the present invention: (i) the discovery that crosslinked resin particles containing peptidoglycan can be obtained by not using a peptidoglycan degrading enzyme when crosslinking resin particles containing PHA to produce the crosslinked resin particles; and (ii) the discovery that crosslinked resin particles containing peptidoglycan are surprisingly excellent in heat resistance.

[0015] [2. Crosslinked resin particles] The crosslinked resin particles according to one embodiment of the present invention contain a polyhydroxyalkanoate resin, have a gel fraction of 50% or more, a volume average particle diameter of 0.10 μm to 10.00 μm, and contain peptidoglycan.

[0016] In this specification, "the crosslinked resin particles according to one embodiment of the present invention" may be referred to as "the present crosslinked resin particles".

[0017] The crosslinked resin particles have the above-mentioned structure, and therefore have the advantages of being excellent in heat resistance and biodegradable. The heat resistance of the crosslinked resin particles can be evaluated, for example, by the amount (%) of aggregates of the crosslinked resin particles generated during or after the production of the crosslinked resin particles. The method for measuring the amount (%) of aggregates of the crosslinked resin particles will be described in detail in the examples below.

[0018] The crosslinked resin particles contain a polyhydroxyalkanoate resin, which is a biodegradable resin, and therefore have the advantage of being biodegradable. Therefore, the crosslinked resin particles are expected to be useful as environmentally friendly crosslinked resin particles that address the problem of plastic waste. The polyhydroxyalkanoate resin has soil decomposition and marine decomposition as biodegradability. Since the crosslinked resin particles contain a polyhydroxyalkanoate resin, the resin composition and molded article containing the crosslinked resin particles can suppress soil pollution and / or marine pollution due to disposal. As a result, one embodiment of the present invention is expected to contribute to the achievement of the Sustainable Development Goals (SDGs), such as Goal 12 "Ensure sustainable consumption and production patterns" and / or Goal 14 "Conserve and sustainably use the oceans and marine resources for sustainable development."

[0019] <Polyhydroxyalkanoate resin> The present crosslinked resin particles contain a polyhydroxyalkanoate resin (hereinafter, sometimes referred to as "PHA").

[0020] "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%).

[0021] There is no particular limitation on the PHA. Examples of PHA include polyglycolic acid, poly(3-hydroxyalkanoate)-based resin (hereinafter sometimes referred to as "P3HA"), poly(4-hydroxyalkanoate)-based resin, and the like. As the PHA, only one type 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 only of a poly(3-hydroxyalkanoate)-based resin).

[0022] In this specification, "polyglycolic acid" refers to a resin containing 50 mol % or more of repeating units represented by [-CH2-CO-O-] out of all monomer repeating units (100 mol %). Polyglycolic acid may contain 60 mol % or more, 70 mol % or more, 80 mol % or more, or 90 mol % or more of repeating units represented by [-CH2-CO-O-] out of all monomer repeating units (100 mol %).

[0023] 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, a copolymer of glycolic acid and caprolactone, etc.).

[0024] Polyglycolic acid can be obtained by known methods such as condensation polymerization of glycolic acid and ring-opening polymerization of glycolide.

[0025] The P3HA is a 3-hydroxyalkanoic acid repeating unit represented by the formula: [-CHR-CH2-CO-O-] (wherein R is C n H 2n+1where 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 unit out of all monomer repeating units (100 mol %). The P3HA preferably contains 60 mol % or more, and more preferably 70 mol % or more of the 3-hydroxyalkanoic acid repeating unit out of all monomer repeating units (100 mol %).

[0026] 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, for example, 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.

[0027] 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. In this specification, "poly(X-co-Y)" refers to a copolymer containing X repeating units and Y repeating units, and is intended to mean a copolymer obtained by copolymerizing a monomer from which the X repeating units are derived and a monomer from which the Y repeating units are derived. In addition, during the production of P3HA by a microorganism, a small amount (about 1 mol% or less) of a monomer may be copolymerized, but if it does not significantly affect the physical properties of the obtained P3HA, the monomer is considered to be not copolymerized, and the product is called by a name that does not include the monomer.

[0028] P3HA can be produced by microorganisms. Such microbially produced P3HA is usually P3HA composed only of D-form (R-form) 3-hydroxyalkanoic acid repeating units. Among the microbially produced P3HA, P3HB, P3HB3HH and P3HB4HB are preferred, and P3HB3HH and P3HB4HB are more preferred, because they are easy to produce industrially.

[0029] It is also preferred that P3HA contains a 3-hydroxybutanoic acid (3HB) repeating unit. When P3HA contains a 3HB repeating unit, the composition ratio of the 3HB repeating unit in the total 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%, from the viewpoint of the balance between flexibility and strength. When the composition ratio of the 3HB repeating unit in P3HA is 60 mol% or more, there is an advantage that the rigidity of the crosslinked resin particles can be further improved. On the other hand, when the composition ratio of the 3HB repeating unit in P3HA is 99 mol% or less, there is an advantage that the flexibility of the crosslinked resin particles tends to be further improved. The monomer composition ratio of P3HA can be measured by gas chromatography or the like (for example, see International Publication No. 2014 / 020838). As P3HA, two or more types having different composition ratios of the 3HB repeating unit may be used in combination.

[0030] Microorganisms that produce P3HA are not particularly limited as long as they have the ability to produce P3HA. For example, the first P3HB-producing bacterium was Bacillus megaterium, discovered in 1925, and other natural microorganisms such as Cupriavidus necator (formerly classified as Alcaligenes eutrophus and Ralstonia eutropha) and Alcaligenes latus are also known. In these microorganisms, P3HB accumulates within the bacterial cells.

[0031] Also, as producers of copolymers of 3HB and other hydroxyalkanoic acids, Aeromonas caviae, which produces P3HB3HH, and Alcaligenes eutrophus, which produces poly(3-hydroxybutyrate-co-4-hydroxybutyrate), are known. In particular, in order to increase the productivity of P3HB3HH, Alcaligenes eutrophus AC32 (FERM BP-6038) (T. Fukui, Y. Doi, J. Bateriol., 179, p4821-4830 (1997)) into which genes of P3HA synthase group have been introduced is preferred. Microorganisms that have been cultured under appropriate conditions to accumulate P3HA in 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, and culture conditions, including the type of substrate, may be optimized.

[0032] 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 an advantage that the tendency of the strength of the crosslinked resin particles to decrease can be reduced or avoided. Also / alternatively, when the weight average molecular weight of the PHA is 50,000 or more, it has an advantage that the tendency of the low molecular weight component to become sticky can be reduced or avoided. On the other hand, a PHA having a weight average molecular weight of 3,000,000 or less can have an advantage that the PHA is easy to manufacture and / or that the PHA is 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 the crosslinking treatment.

[0033] The weight average molecular weight can be measured by using gel permeation chromatography (GPC) (Shimadzu Corporation's "High Performance Liquid Chromatograph 20A System"), polystyrene gel (Showa Denko KK's "KG 4A", "K-806M", etc.) as a column, and chloroform as a mobile phase. The weight average molecular weight can be determined as a molecular weight converted into polystyrene using a calibration curve obtained by measuring polystyrene with a known molecular weight by the same measurement method. In this case, the calibration curve can be created using polystyrene 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 may be used.

[0034] <Gel fraction> In this specification, the term "crosslinked resin particles" refers to a resin particle having a crosslinked structure in which the molecular chains of the resin constituting the resin particle are bonded intramolecularly and / or intermolecularly. That is, the present crosslinked resin particles may have a crosslinked structure in which the molecular chains of PHA are bonded together. The amount of crosslinked structures in the crosslinked resin particles affects the gel fraction of the crosslinked resin particles, and specifically, the more crosslinked structures there are, the higher the gel fraction. The present crosslinked resin particles have a certain amount or more of crosslinked structures, and therefore exhibit a high gel fraction, specifically, a gel fraction of 50% or more. Since the present crosslinked resin particles have a gel fraction of 50% or more, the crosslinked resin particles have excellent hardness, heat resistance, and solvent resistance.

[0035] The value of the gel fraction is preferably 60% or more, more preferably 70% or more, even more preferably 75% or more, and particularly preferably 80% or more. It may also be 85% or more, or 90% or more. The upper limit of the gel fraction is not particularly limited, and may be 100% or less. From the viewpoint of production efficiency of crosslinked resin particles, the upper limit of the gel fraction is preferably 99.5% or less, more preferably 99% or less. The upper limit of the gel fraction may also be 98% or less, 97% or less, or 96% or less.

[0036] The gel fraction is a value measured as follows: (1) A dried product of crosslinked resin particles is added to chloroform so as to give a concentration of 0.7% by weight, and the resulting mixture is kept at 60°C for 30 minutes to obtain a chloroform solution; (2) After that, the chloroform solution is allowed to stand at room temperature for 3 hours, and then the chloroform solution is 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. Formula: gel fraction (%)={(weight of filter including dried gel−weight of filter only) / weight of dried crosslinked resin particles used in measurement}×100.

[0037] <Volume average particle size> The crosslinked resin particles have a volume average particle diameter of 0.10 μm to 10.00 μm. This configuration allows the crosslinked resin particles to be suitably used in various applications as described below. From the viewpoint of practical use, 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. Moreover, from the viewpoint of productivity (production of PHA and / or crosslinking treatment, etc.), 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.

[0038] In this specification, the volume average particle diameter (MV) of the crosslinked resin particles is a value obtained by measuring an aqueous dispersion liquid 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 group of k total crosslinked resin particles are d1, d2,...di...dk in ascending order, and the volumes of the individual crosslinked resin particles are V1, V2,...Vi...Vk (here, the volume of the crosslinked resin particles with particle diameter di is Vi).

[0039]

number

[0040] In addition, a general-purpose measuring device can be used as a device for measuring the particle size and volume of the crosslinked resin particles in the aqueous dispersion, and an example of such a device is MicrotracMT3300EXII manufactured by Nikkiso Co., Ltd. In addition, in this specification, the volume average particle size of the uncrosslinked resin particles can be measured by replacing "crosslinked resin particles" with "uncrosslinked resin particles" in the above method.

[0041] <Peptidoglycan> The crosslinked resin particles contain peptidoglycan. In one embodiment of the present invention, resin particles containing PHA can be used as a raw material for the crosslinked resin particles. In one embodiment of the present invention, particulate PHA, which is a raw material for the crosslinked resin particles, may be obtained by microbial production. For example, after culturing a PHA-producing microorganism to accumulate PHA in the cells, the cells in the culture solution are decomposed by enzyme treatment, and then the cell components are separated and removed to obtain an aqueous dispersion containing particulate PHA. The aqueous dispersion thus obtained may contain peptidoglycan derived from the cell components. Therefore, when crosslinked resin particles are produced using the aqueous dispersion thus obtained, the obtained crosslinked resin particles may contain peptidoglycan, for example, on the surface of the crosslinked resin particles. That is, in one embodiment of the present invention, the peptidoglycan contained in the crosslinked resin particles is derived from a microorganism (e.g., a PHA-producing microorganism).

[0042] When the peptidoglycan contained in the crosslinked resin particles is derived from a microorganism, as described above, it is presumed that the peptidoglycan is present on the surface of the crosslinked resin particles. In one embodiment of the present invention, it is preferable that the peptidoglycan is present on the surface of the crosslinked resin particles. In one embodiment of the present invention, the peptidoglycan can form a layer structure on the surface of the crosslinked resin particles. In other words, in one embodiment of the present invention, the crosslinked resin particles include a layer structure consisting of peptidoglycan, i.e., a peptidoglycan layer.

[0043] In addition, when a dry product of uncrosslinked particulate PHA (hereinafter, sometimes referred to as "PHA particles") is obtained from an aqueous dispersion containing particulate PHA and peptidoglycan derived from bacterial components as described above, the dry product may contain PG. When an aqueous dispersion is prepared again using the dry product of uncrosslinked PHA particles containing PG, the aqueous dispersion contains PG. Therefore, when crosslinked resin particles are produced using the aqueous dispersion obtained in this way, the obtained crosslinked resin particles may contain peptidoglycan, for example, on the surface of the crosslinked resin particles. In addition, when an aqueous dispersion is prepared using a dry product of uncrosslinked PHA particles containing PG and a dry product of resin particles of a biodegradable resin other than PHA that does not contain PG (for example, a chemically synthesized biodegradable resin or a plant-derived biodegradable resin), the aqueous dispersion contains PG. Therefore, when crosslinked resin particles are produced using the aqueous dispersion obtained in this way, the obtained crosslinked resin particles may contain a biodegradable resin other than PHA and may contain peptidoglycan on the surface of the crosslinked resin particles.

[0044] <Peroxide> The crosslinked structure in the present crosslinked resin particles is not particularly limited, but is preferably crosslinked using a peroxide. That is, the present crosslinked resin particles 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. This allows the molecular chains of the resin constituting the resin particles to be directly bonded to each other, forming a crosslinked structure.

[0045] When the crosslinked resin particles are crosslinked using a peroxide, the aqueous dispersion containing the crosslinked resin particles may contain substances derived from the peroxide used to introduce the crosslinked structure (such as decomposition products of the peroxide and unreacted peroxide). Alternatively, when the crosslinked resin particles are crosslinked using a peroxide, substances derived from the peroxide used to introduce the crosslinked structure (such as decomposition products of the peroxide and unreacted peroxide) may be attached to the surface of the obtained crosslinked resin particles. That is, when the present crosslinked resin particles are crosslinked using a peroxide, the present crosslinked resin particles may contain substances derived from the peroxide (such as decomposition products of the peroxide and unreacted peroxide). When the present crosslinked resin particles contain substances derived from the peroxide, it is found that the crosslinked resin particles are crosslinked using a peroxide by analyzing the crosslinked resin particles.

[0046] The peroxide may be an organic peroxide or an inorganic peroxide. The peroxide is preferably an organic peroxide because it can increase the gel fraction more efficiently.

[0047] 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 crosslinking temperature and / or crosslinking time in the crosslinking step.

[0048] 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, butylperoxylaurate, 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-hexylperoxyethyl monocarbonate peroxy n-propyl monocarbonate, t-heptyl peroxy n-propyl monocarbonate, t-octyl peroxy n-propyl monocarbonate, 1,1,3,3-tetramethylbutyl peroxy n-propyl monocarbonate, t-butyl peroxy isopropyl monocarbonate, t-pentyl peroxy isopropyl monocarbonate, t-hexyl peroxy isopropyl monocarbonate, t-heptyl peroxy isopropyl monocarbonate, t-octyl peroxy isopropyl monocarbonate, 1,1,3,3-Tetramethylbutylperoxyisopropyl monocarbonate, t-butylperoxyn-butyl monocarbonate, t-pentylperoxyn-butyl monocarbonate, t-hexylperoxyn-butyl monocarbonate, t-heptylperoxyn-butyl monocarbonate, t-octylperoxyn-butyl monocarbonate, 1,1,3,3-tetramethylbutylperoxyn-butyl monocarbonate, t-butylperoxyisobutyl monocarbonate, t-pentylperoxyisobutyl monocarbonate, t -Hexylperoxyisobutylmonocarbonate, t-heptylperoxyisobutylmonocarbonate, t-octylperoxyisobutylmonocarbonate, 1,1,3,3-tetramethylbutylperoxyisobutylmonocarbonate, t-butylperoxysec-butylmonocarbonate, t-pentylperoxysec-butylmonocarbonate, t-hexylperoxysec-butylmonocarbonate, t-heptylperoxysec-butylmonocarbonate, t-octylperoxysec-butylmonocarbonate peroxy 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, cumylperoxy neodecanoate, di-n-propylperoxydicarbonate, diisopropylperoxydicarbonate, di-sec-butylperoxydicarbonate, 1,1,3,3-Tetramethylbutylperoxyneodecanoate, bis(4-t-butylcyclohexyl)peroxydicarbonate, bis(2-ethylhexyl)peroxydicarbonate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxyneoheptanoate, t-hexylperoxypivalate, t-butylperoxypivalate, 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, dibenzoylperoxide, t-butylperoxy-2-ethylhexylcarbonate, t-butylperoxyisopropylcarbonate, 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. The organic peroxides may be used alone or in combination of two or more.

[0049] 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, Preferred organic peroxides are t-butyl peroxyisobutyrate, t-hexylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, t-butyl peroxypivalate, t-hexyl peroxypivalate, t-butyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, and 1,1,3,3-tetramethylbutylperoxyneodecanoate, because they can efficiently promote crosslinking of the resin that constitutes the resin particles.

[0050] Since the crosslinking temperature in the crosslinking step 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.

[0051] Particularly preferred organic peroxides exhibiting such a one-hour half-life temperature are t-butylperoxyisopropylmonocarbonate, t-butylperoxy2-ethylhexylmonocarbonate, di-sec-butylperoxydicarbonate, t-butylperoxy2-ethylhexanoate, t-butylperoxyisobutyrate, t-hexylperoxy2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy2-ethylhexanoate, t-butylperoxypivalate, t-hexylperoxypivalate, t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, and 1,1,3,3-tetramethylbutylperoxyneodecanoate.

[0052] 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 crosslinking temperature and / or crosslinking time in the crosslinking step. Among them, 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 crosslinking temperature in the crosslinking step. The inorganic peroxide may be used alone or in combination of two or more. An organic peroxide and an inorganic peroxide may be used in combination.

[0053] <Polyfunctional compounds> The crosslinked structure in the present crosslinked resin particle may be introduced by using only peroxide, but it is preferable that it is introduced by using both peroxide and polyfunctional compound.That is, it is preferable that the present crosslinked resin particle is crosslinked in the presence of peroxide and polyfunctional compound.When using both peroxide and polyfunctional compound, it is possible to increase the gel fraction of the crosslinked resin particle with a smaller amount of peroxide compared to using only peroxide.

[0054] The polyfunctional compound refers to a compound having two or more functional groups (e.g., radical reactive groups) in one 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 a radical generated from a peroxide, and is particularly preferably a compound having two or more radical reactive groups in one 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.

[0055] Such polyfunctional compounds are not particularly limited, but examples thereof include allyl (meth)acrylate, allyl alkyl (meth)acrylates, allyloxy alkyl (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 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 compound is one or more selected from the group consisting of allyl methacrylate and triallyl isocyanurate.

[0056] When a crosslinked structure is formed in the presence of a polyfunctional compound, the resulting crosslinked resin particles may usually contain a structure derived from the polyfunctional compound, in which case the molecular chains of the resin constituting the resin particles are bonded to each other via the structure derived from the polyfunctional compound.

[0057] <Other ingredients, etc.> The present crosslinked resin particles are crosslinked resin particles containing PHA. Therefore, the present crosslinked resin particles 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, ultraviolet absorbers, etc.

[0058] The ratio of PHA in the present crosslinked resin particle is not particularly limited. The content of PHA in 100% by weight of the resin component of the present crosslinked resin particle 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 be 99% by weight or more. The upper limit of the content of PHA in 100% by weight of the resin component of the present crosslinked resin particle is not particularly limited, and may be 100% by weight or less. Note that the "resin component of the crosslinked resin particle" refers to the resin that essentially constitutes the crosslinked resin particle, and does not include the component that crosslinks the molecular chains of the resin (e.g., a structure derived from a polyfunctional compound) and the residue of the component used for crosslinking the molecular chains of the resin (e.g., unreacted peroxide, decomposition product of peroxide, unreacted polyfunctional compound, etc.).

[0059] Examples of the resin other than PHA include aliphatic polyesters other than PHA and aliphatic aromatic polyesters. Examples of the aliphatic polyesters other than PHA include (i) polycaprolactone (PCL), (ii) polylactic acid (PLA), and (iii) aliphatic polyesters having a structure in which an aliphatic diol and an aliphatic dicarboxylic acid are polycondensed. Specific examples of the aliphatic polyesters having a structure in which an aliphatic diol and an aliphatic dicarboxylic acid are polycondensed include polyethylene succinate, polybutylene succinate (hereinafter sometimes referred to as "PBS"), polyhexamethylene succinate, polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polybutylene succinate adipate (hereinafter sometimes referred to as "PBSA"), polyethylene sebacate, polybutylene sebacate, etc. The aliphatic aromatic polyester includes an aliphatic aromatic polyester (both an aliphatic compound and an aromatic compound are used as monomers) obtained by copolymerizing the monomers using both an aliphatic compound and an aromatic compound. 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 present crosslinked resin particles (B), the resins other than PHA may be crosslinked or not crosslinked.

[0060] The present crosslinked resin particles are different from the expanded resin particles disclosed in WO 2007 / 049694 and WO 2019 / 146555, and are preferably not expanded. In other words, the present crosslinked resin particles are preferably substantially free of air bubbles inside the particles. "Substantially free of air bubbles inside the particles" means that the volume of air bubbles (spaces) is 10% or less of the volume of the crosslinked resin particles (100%).

[0061] When the crosslinked resin particles are not expanded, the apparent density of the crosslinked resin particles is relatively large. The apparent density of the crosslinked resin particles 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 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).

[0062] The average weight per particle of the present crosslinked resin particles is not particularly limited. For example, when the volume average particle size of the present crosslinked resin particles is 10.00 μm or less, the average weight per particle of the crosslinked resin particles can be much less than 0.1 mg.

[0063] The crosslinked resin particles may be dried. The shape of the dried particles may be powder, pellets, crumbs, a film, a sheet, or the like, depending on the drying method.

[0064] <Aqueous dispersion> In one embodiment of the present invention, an aqueous dispersion is provided in which the crosslinked resin particles are dispersed in an aqueous medium.

[0065] The aqueous medium contained in the aqueous dispersion may be water alone or may be 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 in water of the organic solvent used.

[0066] 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 them, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, acetonitrile, propionitrile, and the like are preferred because they are easily removed. Moreover, methanol, ethanol, 1-propanol, 2-propanol, butanol, acetone, and the like are more preferred because they are easily available. Furthermore, methanol, ethanol, and acetone are particularly preferred.

[0067] 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.

[0068] The concentration of the crosslinked resin particles in the aqueous dispersion is not particularly limited, and may be, for example, 1% by weight to 60% by weight. The aqueous dispersion may contain a dispersant, which will be described later.

[0069] <Applications of crosslinked resin particles> The crosslinked resin particles according to one embodiment of the present invention are not particularly limited in use, and can be used in applications where conventionally known crosslinked resin particles are used.Specific examples include resin modifiers, rheology adjusters for paints or adhesives, paint pigments, paper coating agents, matting agents, antiblocking agents, cosmetic additives, toner additives, liquid crystal spacers, coating agents, fillers for adhesive tapes, fiber processing agents, medical diagnostic test particles, fillers, aqueous coating films, coated paper, resin tubes, foamed particles, packaging materials, containers, cosmetic containers, antifouling resin compositions, heat seal paper, handle moldings, forks, films, resin films for twist packaging materials, bags, gloves, binding materials, multilayer films, stretched films, fibers, multifilaments, meltblown nonwoven fabrics, masks, pile fabrics, coffee filters, inflation moldings, blow moldings, calendar sheet moldings, injection moldings, laminates, films, sheets, etc.The uses of the crosslinked resin particles are not limited to these.

[0070] [3. Modifiers for thermoplastic resins] One embodiment of the present invention provides a modifier for thermoplastic resins, the modifier comprising crosslinked resin particles, the crosslinked resin particles comprising a polyhydroxyalkanoate resin, a gel fraction of 50% or more, a volume average particle size of 0.10 μm to 10.00 μm, and a peptidoglycan. The modifier for thermoplastic resins according to one embodiment of the present invention can provide a resin composition that can provide, for example, a molded article having excellent impact resistance, by being blended with a thermoplastic resin.

[0071] For each aspect of the thermoplastic resin modifier, the description in the above section [2. Crosslinked resin particles] is incorporated as appropriate.

[0072] [4. Method for producing crosslinked resin particles] A method for producing crosslinked resin particles according to one embodiment of the present invention includes a bacterial cell culture preparation step of preparing a culture solution of bacterial cells containing a polyhydroxyalkanoate resin, a dispersion preparation step of removing the bacterial cells from the culture solution to prepare a dispersion solution containing resin particles containing a polyhydroxyalkanoate resin, an aqueous dispersion preparation step of mixing the dispersion solution and a peroxide to prepare an aqueous dispersion solution containing the resin particles and the peroxide, and a crosslinking step of decomposing the peroxide to crosslink the resin particles, wherein the production method does not use a peptidoglycan degrading enzyme, and the crosslinked resin particles have a gel fraction of 50% or more, a volume average particle diameter of 0.10 μm to 10.00 μm, and contain peptidoglycan.

[0073] In this specification, "a method for producing crosslinked resin particles according to one embodiment of the present invention" may be referred to as "the present production method".

[0074] <Bacteria cell culture solution preparation process> In this specification, "bacteria containing a polyhydroxyalkanoate resin" refers to microorganisms that produce PHA. That is, in one embodiment of the present invention, PHA is produced by a microorganism. The microorganisms used in this production method are not particularly limited as long as they are microorganisms that can produce PHA intracellularly. For example, microorganisms isolated from nature or microorganisms deposited in a depository institution for strains (e.g., IFO, ATCC, etc.), or mutants or transformants that can be prepared from them, etc. can be used. More specifically, for example, bacteria of the genera Cupriavidus, Alcaligenes, Ralstonia, Pseudomonas, Bacillus, Azotobacter, Nocardia, and Aeromonas can be mentioned. Among them, microorganisms belonging to the genus Aeromonas, Alcaligenes, Ralstonia, or Capriavidus are preferred, and strains such as Alcaligenes lipolytica, Alcaligenes latus, Aeromonas caviae, Aeromonas hydrophila, and Capriavidus necator are more preferred, with Capriavidus necator being the most preferred.

[0075] In addition, when a microorganism does not inherently have the ability to produce PHA or produces only a low amount of PHA, a transformant obtained by introducing a target PHA synthase gene and / or a mutant thereof into the microorganism can be used. The PHA synthase gene used to prepare such a transformant is not particularly limited, but the P3HA synthase gene derived from Aeromonas caviae is preferred.

[0076] By culturing the above-mentioned microorganism under appropriate conditions, a culture solution of the cells containing a polyhydroxyalkanoate resin can be prepared (obtained). The method for culturing the microbial cells is not particularly limited, but for example, the method described in JP-A-05-93049 can be used.

[0077] The PHA-containing bacterial cells are preferably inactivated. The inactivation method is not particularly limited, but may be, for example, a method in which a culture solution containing the PHA-containing bacterial cells is heated and stirred at 70°C to 80°C for 8 hours.

[0078] <Dispersion liquid preparation process> In the dispersion preparation step, the bacteria in the culture solution are removed to prepare a dispersion containing resin particles containing PHA. More specifically, in the dispersion preparation step, the bacteria in the culture solution are decomposed by an enzyme treatment, and then the bacterial components are separated and removed.

[0079] The dispersion preparation step preferably includes an enzyme treatment step, an alkali washing step, a surfactant treatment step, a crushing step, and a concentration and purification step.

[0080] (Enzyme treatment process) The present production method preferably includes an enzyme treatment step of treating the bacterial cells with an alkaline protease in the dispersion preparation step. In order to treat the bacterial cells with an alkaline protease in the enzyme treatment step, the alkaline protease may be added to a culture solution of the bacterial cells.

[0081] As used herein, the term "alkaline protease" refers to a protease that has the activity of decomposing proteins in an alkaline environment (for example, in a solution of pH 8.5).

[0082] In addition, in this specification, the term "alkaline protease treatment" refers to a step of adding the alkaline protease to the culture medium and enzymatically treating the bacterial cells.

[0083] In one embodiment of the present invention, the alkaline protease is not particularly limited as long as it has the activity of decomposing proteins in an alkaline environment, and examples thereof include serine-specific proteases (e.g., subtilisin, chymotrypsin, trypsin), cysteine-specific proteases (e.g., papain, bromelain, cathepsin), aspartic acid-specific proteases (e.g., pepsin, cathepsin D, HIV protease), etc. From the viewpoint of economical advantage, serine-specific proteases, particularly subtilisin (e.g., alcalase), are preferred. These may be used alone or in combination of two or more.

[0084] As the alkaline proteolytic enzyme, commercially available products can be used, for example, "Alcalase 2.5L" manufactured by Novozyme; "Protin SD-AY10" and "Protease P "Amano" 3SD" manufactured by Amano Enzyme Inc.; "Multifect PR6L" and "Optimase PR89L" manufactured by Danisco Japan Co., Ltd.; "Sumiteam MP" manufactured by Shin Nippon Chemical Industry Co., Ltd.; "Delborase" manufactured by DSM Japan Inc.; "Bioprase OP", "Bioprase SP-20FG", and "Bioprase SP-4FG" manufactured by Nagase ChemteX Corporation; "Orientase 22BF" manufactured by HBI Inc.; and "Aroase XA-10" manufactured by Yakult Pharmaceutical Co., Ltd.

[0085] In one embodiment of the present invention, the optimal pH of the alkaline protease is not particularly limited as long as the alkaline protease has activity in an alkaline environment, and is, for example, 8.0 to 14.0, preferably 8.0 to 12.0, more preferably 8.0 to 10.0, and even more preferably 8.0 to 9.0.

[0086] In one embodiment of the present invention, the optimum temperature of the alkaline protease is not particularly limited, but from the viewpoint of not requiring excessive heating and being able to prevent thermal changes (thermal decomposition) of PHA, it is preferably 60° C. or less, more preferably 50° C. or less. The lower limit of the optimum temperature is not particularly limited, but from the viewpoint of not requiring excessive cooling operations and being economical, it is preferably room temperature (e.g., 25° C.) or higher.

[0087] (Alkaline cleaning process) In the dispersion preparation step, the present production method preferably includes an alkali washing step in which an aqueous alkaline solution is added to the aqueous dispersion to adjust the pH of the aqueous dispersion. In the alkali washing step, an aqueous alkaline solution is preferably added to adjust the pH of the aqueous dispersion to 10.0 to 12.0. This step dissolves impurities derived from the bacterial cells, allowing a more pure PHA to be separated from the bacterial cells.

[0088] In one embodiment of the present invention, the pH of the aqueous dispersion in the alkaline washing step is not particularly limited as long as it is adjusted to an alkaline region, but it is preferable to adjust the pH of the aqueous dispersion in consideration of the optimal pH of the alkaline protease. In the alkaline washing step, for example, the pH of the aqueous dispersion is preferably adjusted to 10.0 to 12.0, more preferably 10.2 to 11.8, and even more preferably 10.4 to 11.6. If the pH is within the above range, impurities derived from the bacterial cells can be sufficiently dissolved without excessively reducing the molecular weight of the PHA.

[0089] In one embodiment of the present invention, the reaction time (in other words, the time for adjusting and maintaining the pH at 10.0 to 12.0) is, for example, preferably 1 hour to 12 hours, more preferably 1 hour to 6 hours. If the reaction time is within the above range, impurities derived from the bacterial cells can be sufficiently dissolved without excessively reducing the molecular weight of the PHA.

[0090] In one embodiment of the present invention, the reaction temperature (in other words, the temperature at which the pH is adjusted to and maintained at 10.0 to 12.0) is preferably 60° C. or lower, and more preferably 50° C. or lower. There is no particular limitation on the lower limit of the reaction temperature, but from the viewpoint of not requiring excessive cooling operations and being economical, it is preferably room temperature (e.g., 25° C.) or higher.

[0091] (Surfactant treatment process) The present production method preferably includes a surfactant treatment step in which the bacterial cells in the aqueous dispersion are treated with a surfactant in the dispersion preparation step. By treating the bacterial cells with a surfactant in the surfactant treatment step, impurities contained in the bacterial cells, particularly cell membranes, can be efficiently treated, and more impurities derived from the bacterial cells can be removed, allowing a higher purity PHA to be separated from the bacterial cells.

[0092] In one embodiment of the present invention, the surfactant is not particularly limited, but examples thereof include anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. Among these, anionic surfactants are preferred from the viewpoint of high cell membrane removal ability. These surfactants may be used alone or in combination of two or more.

[0093] Examples of anionic surfactants include alkyl sulfates, alkylbenzene sulfonates, alkyl sulfate esters, alkenyl sulfate esters, alkyl ether sulfate esters, alkenyl ether sulfate esters, α-olefin sulfonates, α-sulfo fatty acid salts, esters of α-sulfo fatty acid salts, alkyl ether carboxylates, alkenyl ether carboxylates, amino acid surfactants, and N-acyl amino acid surfactants. Among these, alkyl sulfate esters are preferred, and sodium dodecyl sulfate (SDS) is particularly preferred from the viewpoint of high cell membrane removal ability and low cost. These may be used alone or in combination of two or more.

[0094] In the dispersion preparation step, the amount of the surfactant to be added is not particularly limited and is, for example, 0.1 to 10.0% by weight, and preferably 0.3 to 5.0% by weight, relative to 100% by weight of the resin particles in the culture liquid.

[0095] The volume average particle diameter of the resin particles in the dispersion obtained in the dispersion preparation process is preferably within the same range as the volume average particle diameter of the crosslinked resin particles described above. When the resin particles produced by PHA-producing microorganisms are used as a raw material, the volume average particle diameter of the resin particles can usually be within the above range. Therefore, when the resin particles produced by PHA-producing microorganisms are used as a raw material, an aqueous dispersion of resin particles having a desired volume average particle diameter can be obtained without carrying out a special process for adjusting the particle diameter.

[0096] The concentration of the resin particles in the dispersion obtained in the dispersion preparation step is not particularly limited and can be set appropriately, but may be, for example, about 1% by weight to 70% by weight, and preferably about 5% by weight to 50% by weight.

[0097] Conventionally, a peptidoglycan decomposing enzyme has sometimes been used in the preparation process of resin particles (e.g., in the enzyme treatment step). In this case, the obtained resin particles do not contain peptidoglycan. Through intensive research, the present inventor independently obtained the novel finding that when a peptidoglycan decomposing enzyme is not used throughout the entire production method (e.g., in the enzyme treatment step), the obtained crosslinked resin particles contain peptidoglycan, and thus, surprisingly, crosslinked resin particles having excellent heat resistance can be obtained. In other words, in the present production method, a peptidoglycan decomposing enzyme is not used throughout the entire production method.

[0098] (Crushing process) In the dispersion preparation process, the present production method preferably further includes a disruption process for disrupting the bacterial components in the culture solution. The disruption process has the advantage that the bacterial cells decomposed by the enzyme can be easily removed. The specific embodiment of the disruption process is not particularly limited, and examples thereof include a method of applying a certain shear force to the culture solution of the bacterial cells using a homogenizer, ultrasonic treatment, pump transfer, etc.

[0099] In the course of intensive research, the present inventors also discovered that when an aqueous dispersion of resin particles before crosslinking contains peptidoglycan, the resin particles before crosslinking surprisingly have excellent aggregation stability against physical forces during the production process of the aqueous dispersion.

[0100] (Concentration and purification process) The present production method may further include a concentration and purification process step in which the resin particles in the dispersion liquid are concentrated and purified in the dispersion liquid preparation process. The concentration and purification process step is, for example, a step of centrifuging the dispersion liquid obtained in the dispersion liquid preparation process and removing the supernatant to obtain a dispersion liquid in which the resin particles containing PHA are concentrated. That is, it is a step of removing impurities from the resin particles of PHA separated from the bacterial cells, concentrating and purifying the resin particles in the dispersion liquid. The concentration and purification process step can also be said to be a centrifugation process.

[0101] In the concentration and purification steps, the method for centrifuging the dispersion is not particularly limited, and any known method can be used.

[0102] In the concentration and purification process, it is preferable to repeat the steps of centrifuging the dispersion, removing the supernatant, adding a solution to the sediment, centrifuging again, and removing the supernatant. This operation allows a dispersion in which the resin particles are more concentrated and purified to be obtained. Here, the solution added after removing the supernatant is preferably an alkaline aqueous solution adjusted to the same pH as the dispersion.

[0103] In the concentration and purification process, the solvent constituting the dispersion ("solvent" is also referred to as "aqueous medium") is not particularly limited, and may be water or a mixed solvent of water and an organic solvent. In the mixed solvent, the concentration of the organic solvent is not particularly limited as long as it is equal to or lower than the solubility of the organic solvent used in water. In addition, the organic solvent is not particularly limited, and examples thereof include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, iso-butanol, 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, and piperidine. Among them, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, iso-butanol, acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, acetonitrile, propionitrile, etc. are preferred because they are easily removed. Also, methanol, ethanol, 1-propanol, 2-propanol, butanol, acetone, etc. are more preferred because they are easily available. Furthermore, methanol, ethanol, and acetone are particularly preferred.

[0104] The water content in the aqueous medium in the dispersion is preferably 5% by weight or more, more preferably 10% by weight or more, even more preferably 30% by weight or more, and particularly preferably 50% by weight or more.

[0105] <Aqueous dispersion preparation process> In the aqueous dispersion preparation step, the dispersion obtained in the aqueous dispersion preparation step is mixed with a peroxide. Through this operation, an aqueous dispersion containing resin particles containing a polyhydroxyalkanoate resin and a peroxide can be obtained.

[0106] In the aqueous dispersion preparation step, the peroxide may be any of the above-mentioned peroxides. In the aqueous dispersion preparation step, the peroxide may be in various forms, such as a solid or liquid form. In addition, in the aqueous dispersion preparation step, the peroxide may be in a liquid form diluted with a diluent or the like.

[0107] In the aqueous dispersion preparation step, the method of mixing the dispersion and the peroxide can be, for example, a method of adding the peroxide to the dispersion. When the aqueous dispersion preparation step is a step of adding the peroxide to the dispersion, the total amount of the peroxide to be used may be added to the dispersion all at once, or may be added continuously or in portions.

[0108] The amount of peroxide used in the present production method (for example, the step of adding the peroxide) is 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, relative to 100 parts by weight of the uncrosslinked resin particles.

[0109] According to a manufacturing method in which resin particles are crosslinked in an aqueous dispersion using a peroxide, crosslinking can be promoted while maintaining the particle size (volume) before crosslinking, and crosslinked resin particles can be easily obtained. On the other hand, in a method in which a resin is crosslinked by melt kneading in the presence of a peroxide, this can be difficult to achieve.

[0110] In addition, the manufacturing method in which resin particles are crosslinked in an aqueous dispersion using a peroxide makes it easy to control the temperature increase caused by the heat generated during the crosslinking reaction, and is advantageous in efficiently obtaining crosslinked resin particles having a safe and stable crosslinked structure (quality).

[0111] The present production method preferably further includes an addition step of adding a polyfunctional compound to the dispersion and / or aqueous dispersion. In other words, the aqueous dispersion preparation step in the present production method preferably further includes an addition step of adding a polyfunctional compound to the dispersion and / or aqueous dispersion. The polyfunctional compound may be any of those described above. In the addition step, the polyfunctional compound may be added in various forms such as solid and liquid. In addition, in the addition step, a liquid diluted with a diluent or the like may be added. In addition, in the addition step, the total amount of the polyfunctional compound used may be added to the dispersion and / or aqueous dispersion all at once, or may be added continuously or in portions.

[0112] In the aqueous dispersion preparation process, the timing of performing the addition process of adding a polyfunctional compound (in other words, the timing of adding the polyfunctional compound to the dispersion and / or aqueous dispersion) is not particularly limited. For example, the dispersion, the peroxide, and the polyfunctional compound may be mixed at the same time. Alternatively, the polyfunctional compound may be added to the dispersion, and then the obtained dispersion and the peroxide may be mixed. Alternatively, the dispersion and the peroxide may be mixed, and then the polyfunctional compound may be added to the obtained aqueous dispersion.

[0113] In the present production method, the amount of the polyfunctional compound used is 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, even more preferably 0.2 to 5 parts by weight, and particularly preferably 0.3 to 3 parts by weight, relative to 100 parts by weight of the uncrosslinked resin particles.

[0114] <Impregnation process> The present manufacturing method preferably includes an impregnation step of impregnating the resin particles with a peroxide after the preparation step and before the crosslinking step. When a polyfunctional compound is used in the preparation step, the impregnation step is preferably a step in which the resin particles can be impregnated with the polyfunctional compound in addition to the peroxide, and more preferably a step in which the peroxide and the polyfunctional compound can be impregnated. In the impregnation step, the peroxide and / or the polyfunctional compound are preferably at least partially impregnated into the resin particles, and more preferably completely impregnated.

[0115] An example of the impregnation step is a step of setting (heating) the temperature of the aqueous dispersion to a predetermined temperature (impregnation temperature) while a peroxide and, optionally, a polyfunctional compound are being added to an aqueous dispersion precursor containing resin particles, and / or after the peroxide and, optionally, a polyfunctional compound are being added, and further, optionally, maintaining the temperature of the aqueous dispersion at the predetermined temperature (impregnation temperature) for a predetermined time (impregnation time).

[0116] In the impregnation step, the set temperature (heating temperature) of the aqueous dispersion, i.e., the impregnation temperature, is not particularly limited. The impregnation temperature may be, for example, (i) 0°C or higher and lower than a temperature suitable for decomposing the peroxide used in the crosslinking step described later, (ii) 0°C or higher and lower than 80°C, or (iii) 0°C or higher and lower than 60°C.

[0117] In the impregnation step, the time for which the aqueous dispersion is held at the impregnation temperature, i.e., the impregnation time, is not particularly limited. The impregnation time may be, for example, 1 minute to 5 hours, 10 minutes to 3 hours, or 30 minutes to 1 hour.

[0118] In the impregnation step, the aqueous dispersion is maintained at the impregnation temperature and for the impregnation time described above, whereby the resin particles can be impregnated with the peroxide and, if used, the polyfunctional compound.

[0119] <Crosslinking process> This manufacturing method includes a crosslinking step of decomposing the peroxide and crosslinking the resin particles. As described above, the decomposition of the peroxide generates radicals, and the radicals directly bond the molecular chains of the resin constituting the resin particles, that is, a crosslinked structure can be formed. It can be said that the resin particles are crosslinked as long as the peroxide is decomposed. Therefore, the crosslinking step is not particularly limited as long as it can decompose the peroxide.

[0120] The crosslinking step may be, for example, a step of heating the aqueous dispersion obtained in the preparation step or the aqueous dispersion obtained through the preparation step and the impregnation step to a temperature suitable for decomposition of peroxide (hereinafter, also referred to as the "crosslinking temperature"). Alternatively, the crosslinking step may be a step of mixing the aqueous dispersion obtained in the preparation step or the aqueous dispersion obtained through the preparation step and the impregnation step with a substance that promotes decomposition of peroxide (for example, an acid, an alkali, a reducing agent, etc.).

[0121] The aqueous dispersion obtained in the preparation step, and the aqueous dispersion obtained through the preparation step and the impregnation step, may each independently be an aqueous dispersion such as the following: (i) an aqueous dispersion comprising resin particles impregnated with peroxide and, optionally, peroxide that is not impregnated into the resin particles; (ii) an aqueous dispersion containing resin particles partially impregnated with peroxide and peroxide that is not impregnated into the resin particles; (iii) an aqueous dispersion containing resin particles not impregnated with peroxide and peroxide not impregnated into the resin particles; (iv) an aqueous dispersion containing resin particles partially impregnated with peroxide, resin particles not impregnated with peroxide, and peroxide not impregnated into the resin particles; or (v) An aqueous dispersion containing resin particles impregnated with peroxide and resin particles partially impregnated with peroxide and / or resin particles not impregnated with peroxide and peroxide not impregnated into the resin particles.

[0122] The crosslinking temperature is preferably within a range of about 25°C above and 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 crosslinking temperature is preferably 30°C to 140°C, more preferably 50°C to 135°C, and even more preferably 60°C to 130°C. According to this configuration, it is possible to crosslink the uncrosslinked resin particles at a temperature lower than the melting temperature of the resin component constituting the uncrosslinked resin particles, so that deterioration of the uncrosslinked resin particles due to heat can be avoided. The melting temperature of PHA is, for example, 50°C to 210°C.

[0123] In the crosslinking step, the aqueous dispersion is preferably maintained at the above-mentioned crosslinking temperature for a predetermined time (crosslinking time). The crosslinking time is not particularly limited, but is preferably 1 minute to 15 hours, and more preferably 1 hour to 10 hours. This configuration allows the crosslinking reaction using the peroxide to proceed sufficiently.

[0124] In the crosslinking step, the pH of the aqueous dispersion is preferably 4 to 13, more preferably 7 to 12. When the pH of the aqueous dispersion is within the above range, there is an advantage that the dispersibility of the crosslinked resin particles in the aqueous dispersion is good.

[0125] In the crosslinking step, the pressure in the reactor is preferably less than 1 MPa in gauge pressure, more preferably less than 0.8 MPa, even more preferably less than 0.6 MPa, and particularly preferably less than 0.2 MPa. The pressure in the reactor is preferably 0 MPa or more in gauge pressure. When the pressure in the reactor is within the above range, the reaction can be carried out under mild conditions, which has the advantage of increasing the options for reaction vessels.

[0126] In the crosslinking step, it is sufficient that at least a portion of the resin particles is crosslinked. In the crosslinking step, it is preferable that the resin particles are crosslinked to such an extent that crosslinked resin particles having a desired gel fraction (for example, 50% or more) are obtained.

[0127] After the crosslinking reaction is completed, the crosslinked resin particles are separated from the aqueous dispersion, and water is removed from the separated crosslinked resin particles to obtain dried crosslinked resin particles. The method for separating the crosslinked resin particles from the aqueous dispersion is not particularly limited, and for example, filtration, centrifugation, heat drying, freeze drying, spray drying, etc. can be used. For example, spray drying can be used to obtain dried crosslinked resin particles directly from the aqueous dispersion. In addition, by extruding the crosslinked resin particles alone after separation from the aqueous dispersion, the crosslinked resin particles can be obtained in the form of pellets while completely removing the remaining moisture. In addition, an aggregation process using a coagulant and / or adjusting the pH may be performed.

[0128] The aqueous dispersion itself after the crosslinking reaction, the aqueous dispersion obtained by concentrating the aqueous dispersion after the crosslinking reaction to increase the concentration of the crosslinked resin particles, or the aqueous dispersion obtained by diluting the aqueous dispersion after the crosslinking reaction by adding an aqueous medium also constitute one aspect of the present invention. In addition, (i) an aqueous dispersion with an adjusted pH, and / or (ii) an aqueous dispersion to which other additives such as a dispersant, an antioxidant, a hydrolysis inhibitor, an antiblocking agent, a crystal nucleating agent, or an ultraviolet absorber have been added also constitute one aspect of the present invention.

[0129] [5. Thermoplastic resin composition] A thermoplastic resin composition according to one embodiment of the present invention contains a thermoplastic resin and the crosslinked resin particles described above in the section [2. Crosslinked resin particles].

[0130] In this specification, "the thermoplastic resin composition according to one embodiment of the present invention" may be referred to as "the present resin composition".

[0131] Since the present resin composition has the above-mentioned constitution, it can fully enjoy the effect of improving mechanical strength such as impact strength by the crosslinked resin particles, and as a result, the present resin composition has an advantage that it can provide a resin composition capable of providing a molded article having excellent impact resistance.

[0132] A molded article can be obtained by molding the thermoplastic resin composition by a known method.

[0133] The content of the crosslinked resin particles in the resin composition is not particularly limited. The content of the crosslinked resin particles in the resin composition may be 0.1 parts by weight or more, 0.3 parts by weight or more, 0.5 parts by weight or more, 1 part by weight or more, 5 parts by weight or more, 7 parts by weight or more, 10 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 and the crosslinked resin particles. The content of the crosslinked resin particles in the resin composition is preferably 60 parts by weight or less, more preferably 55 parts by weight or less, even more preferably 53 parts by weight or less, and particularly preferably 50 parts by weight or less, based on 100 parts by weight of the total of the thermoplastic resin and the crosslinked resin particles. The content of the crosslinked resin particles in the present resin composition may be 45 parts by weight or less, 40 parts by weight or less, 30 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, 12 parts by weight or less, or 10 parts by weight or less, based on 100 parts by weight of the total of the thermoplastic resin and the crosslinked resin particles.

[0134] <Thermoplastic resin> In the present resin composition, the thermoplastic resin can be said to be a matrix resin. The thermoplastic resin is not particularly limited as long as it is a resin that can be molded into a desired shape by melting it by heating and then cooling and solidifying it. Specific examples of the thermoplastic resin include polyolefin resins such as polyethylene and polypropylene, acrylic resins such as polyvinyl chloride, polystyrene, polyvinyl acetate, polyurethane, polytetrafluoroethylene, and polymethyl methacrylic acid, AS resins, polyamides, polyacetals, polycarbonates, modified polyphenylene ethers, polyester resins, and cyclic polyolefins. These thermoplastic resins may be used alone or in combination of two or more. The thermoplastic resin preferably has a gel fraction of less than 50%. The thermoplastic resin is preferably not crosslinked.

[0135] As the thermoplastic resin, polyester-based resins are particularly preferred, such as aliphatic polyesters (e.g., PHA, PLA, PCL, and aliphatic polyesters having a structure in which an aliphatic diol and an aliphatic dicarboxylic acid are polycondensed, etc.) and aliphatic aromatic polyesters.

[0136] Specific embodiments of the aliphatic polyester and the aliphatic aromatic polyester are the same as those described in the sections <Polyhydroxyalkanoate resin> and <Other components> of [2. Crosslinked resin particles] above, so the descriptions therein are incorporated by reference and will not be described here.

[0137] Since the crosslinked resin particles contain a biodegradable PHA, it is preferable that the thermoplastic resin also contains a biodegradable resin, i.e., a biodegradable resin. This configuration has the advantage that the biodegradability of the entire thermoplastic resin composition and the entire molded product of the thermoplastic resin composition can be improved.

[0138] Furthermore, when the crosslinked resin particles contain a resin produced from a plant-derived raw material, from the viewpoint of resource circulation, it is preferable that the thermoplastic resin also contains a resin produced from a plant-derived raw material, and it is more preferable that the thermoplastic resin is composed only of a resin produced from a plant-derived raw material.

[0139] The case where the thermoplastic resin contains a biodegradable resin will be described. The thermoplastic resin preferably contains 10% by weight to 100% by weight of the biodegradable resin in 100% by weight of the thermoplastic resin. The thermoplastic resin more preferably contains 30% by weight or more of the biodegradable resin in 100% by weight of the thermoplastic resin, more preferably contains 50% by weight or more, even more preferably contains 70% by weight or more, and particularly preferably contains 90% by weight or more. The thermoplastic resin may be composed of only the biodegradable resin.

[0140] Since the thermoplastic resin composition and its molded article can enjoy the impact resistance improving effect of the crosslinked resin particles, the biodegradable resin contained in the thermoplastic resin preferably contains a polyester resin, more preferably contains an aliphatic polyester, and particularly preferably contains PHA and / or polylactic acid. The PHA used as the thermoplastic resin preferably has a gel fraction of less than 50%. The PHA used as the thermoplastic resin preferably does not have a crosslinked structure.

[0141] The case where the thermoplastic resin contains PHA and / or polylactic acid as a biodegradable resin will be described below. The thermoplastic resin 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.

[0142] The PHA that can be used as the thermoplastic resin is not particularly limited, and examples thereof include polyglycolic acid, P3HA, poly(4-hydroxyalkanoate) 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, P3HA is particularly preferred.

[0143] A case where the crosslinked resin particles contain P3HA and the thermoplastic resin contains P3HA will be described. The P3HA that can be used as the thermoplastic resin is the same as the P3HA related to the crosslinked resin particles, and the various P3HAs described above can be used. The P3HA contained in the thermoplastic resin may be a resin with the same composition as the P3HA contained in the crosslinked resin particles, or may be a resin with a different composition and / or physical properties. The P3HA contained in the thermoplastic resin is preferably a resin with a different composition and / or physical properties from the P3HA contained in the crosslinked resin particles, and more preferably a resin that is harder than the P3HA contained in the crosslinked resin particles.

[0144] The case where the P3HA used as the thermoplastic resin 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 the 3HB repeating units in the total monomer repeating units of P3HA (100 mol%) is preferably 80 mol% to 99 mol%, and more preferably 82 mol% to 97 mol%. When the composition ratio of the 3HB repeating units in P3HA is 80 mol% or more, the rigidity of P3HA can be improved. On the other hand, when the composition ratio of the 3HB repeating units in P3HA is 99 mol% or less, the flexibility of P3HA tends to be improved. As P3HA, two or more types having different composition ratios of the 3HB repeating units may be used in combination.

[0145] The weight average molecular weight of the PHA used as the thermoplastic resin 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 present resin composition and its molded article. On the other hand, a PHA having a weight average molecular weight of 3,000,000 or less may have the advantage that the PHA is easy to manufacture and / or easy to handle in order to achieve the object of one embodiment of the present invention.

[0146] Polylactic acid usable as the thermoplastic resin may be any conventionally known polylactic acid. The polylactic acid may be crystalline polylactic acid, amorphous polylactic acid, or a mixture of crystalline polylactic acid and amorphous polylactic acid.

[0147] 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.

[0148] Examples of the other monomers include aliphatic hydroxycarboxylic acids other than lactic acid, aliphatic polyhydric alcohols, aliphatic polycarboxylic acids, and polyfunctional polysaccharides.

[0149] The lactic acid raw material for producing polylactic acid is not particularly limited, and L-lactic acid, D-lactic acid, DL-lactic acid, or a mixture thereof, or L-lactide, D-lactide, meso-lactide, or a mixture thereof, etc. Lactic acid obtained by microbial fermentation from renewable raw materials derived from plants such as starch can be suitably used.

[0150] 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.

[0151] The weight average molecular weight of the polylactic acid used as the thermoplastic resin is not particularly limited, but is preferably 50,000 to 1,000,000, more preferably 70,000 to 700,000, and even more preferably 100,000 to 400,000. When the weight average molecular weight of the polylactic acid is 50,000 or more, sufficient rigidity and / or strength can be obtained in the present resin composition and its 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.

[0152] Regarding the PHA used as the thermoplastic resin, other aspects than those described above are the same as those explained in the section [2. Crosslinked resin particles] above, so the explanation therefor is incorporated by reference and will not be repeated here.

[0153] The content of the thermoplastic resin in the resin composition is not particularly limited. The content of the thermoplastic resin in the resin composition is preferably 40 parts by weight to 99.9 parts by weight, more preferably 40 parts by weight to 99.7 parts by weight, more preferably 40 parts by weight to 99.5 parts by weight, more preferably 40 parts by weight to 99 parts by weight, and even more preferably 40 parts by weight to 95 parts by weight, in the total of 100 parts by weight of the thermoplastic resin and the crosslinked resin particles. According to this configuration, the thermoplastic resin composition can provide a molded product having excellent impact resistance. The content of the thermoplastic resin in the resin composition may be 45 parts by weight to 93 parts by weight, 47 parts by weight to 90 parts by weight, 50 parts by weight to 80 parts by weight, 50 parts by weight to 75 parts by weight, or 50 parts by weight to 70 parts by weight, in the total of 100 parts by weight of the thermoplastic resin and the crosslinked resin particles. The content of the thermoplastic resin in the present resin composition may be 55 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, 80 parts by weight or more, 85 parts by weight or more, 88 parts by weight or more, or 90 parts by weight or more, based on 100 parts by weight of the total of the thermoplastic resin and the crosslinked resin particles.

[0154] <Nucleating agent> The present resin composition may further contain a crystal nucleating agent. When the thermoplastic resin composition contains a crystal nucleating agent, crystallization during molding is promoted in the case where the thermoplastic resin is a crystalline resin, and molding processability, productivity, etc. can be improved. When the present resin composition contains a crystal nucleating agent, it also has the advantage that a thermoplastic resin composition and a molded article thereof having excellent heat resistance or mechanical properties can be obtained.

[0155] The crystal nucleating agent is not particularly limited, and conventionally known ones can be used. The crystal nucleating agent can be, for example, 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 phosphate; sugar alcohol compounds derived from natural products such as erythritol, pentaerythritol, galactitol, mannitol, and arabitol; polysaccharides such as chitin and chitosan; polyols such as aliphatic alcohols (polyols), polyvinyl alcohol, and polyethylene oxide; sodium benzoate, potassium benzoate, lithium benzoate, calcium benzoate, magnesium benzoate, barium benzoate, lithium terephthalate, sodium terephthalate, and terephthalic acid salts. metal salts of organic carboxylic acids such as potassium phosphate, calcium oxalate, sodium laurate, potassium laurate, sodium myristate, potassium myristate, calcium myristate, sodium octacosanoate, calcium octacosanoate, sodium stearate, potassium stearate, lithium stearate, calcium stearate, magnesium stearate, barium stearate, sodium montanate, calcium montanate, sodium toluate, sodium salicylate, potassium salicylate, zinc salicylate, aluminum dibenzoate, potassium dibenzoate, lithium dibenzoate, sodium β-naphthalate, and sodium cyclohexanecarboxylate; organic sulfonates such as sodium p-toluenesulfonate and sodium sulfoisophthalate;Carboxylic acid amides such as ethylene stearic acid amide, ethylene bislauric acid amide, palmitic acid amide, hydroxystearic acid amide, erucic acid amide, and trimesic acid tris(t-butylamide), lauric acid esters, palmitic acid esters, oleic acid esters, stearic acid esters, erucic acid esters, N-oleyl palmitic acid ester, N-oleyl oleic acid ester, N-oleyl stearate ester, N-stearyl oleic acid ester, N-stearyl stearate ester, N-stearyl erucic acid ester, methylene bisstearate ester, ethylene bislauric acid ester, ethylene biscapric acid ester, ethylene bisoleic acid ester, ethylene bisstearic acid ester, ethylene biserucic acid ester, ethylene Examples of the nucleating agent include carboxylic acid esters such as butylene bisisostearate, butylene bisstearate, and p-xylylene bisstearate; dicarboxylic acid derivatives such as dimethyl adipate, dibutyl adipate, diisodecyl adipate, and dibutyl sebacate; cyclic compounds having a functional group C=O and one or more functional groups selected from the group consisting of NH, S, and O in the molecule, such as indigo, quinacridone, and quinacridone magenta; sorbitol derivatives such as bisbenzylidene sorbitol and bis(p-methylbenzylidene) sorbitol; compounds containing a nitrogen-containing heteroaromatic nucleus such as pyridine, triazine, and imidazole; phosphoric acid 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.

[0156] The content of the crystal nucleating agent is not particularly limited as long as it can promote the crystallization of the thermoplastic resin. The content of the crystal nucleating agent is preferably 0.05 parts by weight to 12.00 parts by weight, more preferably 0.10 parts by weight to 10.00 parts by weight, and even more preferably 0.50 parts by weight to 8.00 parts by weight, relative to 100 parts by weight of the thermoplastic resin. 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 the decrease in viscosity during molding and the physical properties of the molded product.

[0157] <Lubricant> The resin composition may further contain a lubricant. When the thermoplastic resin composition contains a lubricant, the surface smoothness of the obtained molded article can be improved. The lubricant is not particularly limited. Examples of the lubricant include, but are not limited to, fatty acid metal salts such as magnesium stearate and calcium stearate; fatty acid amides such as behenic acid amide, stearic acid amide, erucic acid amide, oleic acid amide, methylene bisstearic acid amide, and ethylene bisstearic acid amide; polyethylene wax, oxidized polyester wax, glycerin mono fatty 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. The lubricant may be used alone or in combination of two or more.

[0158] The content of the lubricant (when a plurality of lubricants are used, the total content thereof) is not particularly limited as long as it can impart lubricity to the molded body. 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, relative to 100 parts by weight of the thermoplastic resin. When the content of the lubricant is within the above range, it is possible to obtain the effect as a lubricant while avoiding the bleeding out of the lubricant onto the surface of the molded body.

[0159] <Other ingredients> The present resin composition may contain other components, such as organic fillers, inorganic fillers, antioxidants, hydrolysis inhibitors, ultraviolet absorbers, colorants such as dyes and pigments, and antistatic agents, to the extent that the functionality of the resulting molded article is not impaired.

[0160] 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 vegetable 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.

[0161] The plant-derived natural fibers are not particularly limited. Examples of the plant-derived natural fibers include kenaf fiber, abaca fiber, bamboo fiber, jute fiber, hemp fiber, linen fiber, henequen (sisal), ramie fiber, hemp, cotton, banana fiber, coconut fiber, palm, paper mulberry, mitsumata, bagasse, etc. In addition, regenerated fibers such as pulp, cellulose fiber, and rayon processed from plant fibers are also included. Examples of the animal-derived natural fibers include wool, silk, cashmere, and mohair.

[0162] 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 obtained 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, white clay, clay, talc, calcium carbonate, manganese carbonate, magnesium carbonate, barium sulfate, silver powder, etc. These inorganic fillers may be surface-treated to increase dispersibility in the resin composition. In addition, these inorganic fillers may be used alone or in combination of two or more.

[0163] 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.

[0164] 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.

[0165] The ultraviolet absorbing agent is not particularly limited. Examples of the ultraviolet absorbing agent include benzophenone compounds, benzotriazole compounds, triazine compounds, salicylic acid compounds, cyanoacrylate compounds, and nickel complex compounds. These ultraviolet absorbing agents may be used alone or in combination of two or more.

[0166] The coloring agent such as the pigment or dye is not particularly limited. Examples of the coloring agent include inorganic coloring agents 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 coloring agents may be used alone or in combination of two or more.

[0167] The antistatic agent is not particularly limited. Examples of the antistatic agent include low molecular weight antistatic agents such as fatty acid ester compounds, aliphatic ethanolamine compounds, and aliphatic ethanolamide compounds, and polymeric antistatic agents. These antistatic agents may be used alone or in combination of two or more.

[0168] The resin composition may further contain, as additives, catalyst deactivators (hindered phenol compounds, thioether compounds, vitamin compounds, triazole compounds, polyamine compounds, hydrazine derivative compounds, phosphorus compounds, etc.), 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 ... It may also contain: aliphatic compounds such as carboxylic acid, carboxylic acid di ...

[0169] 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 set by a person skilled in the art.

[0170] <Method of producing thermoplastic resin composition> The resin composition can be produced by a known method. Specifically, a method of melt-kneading a thermoplastic resin, crosslinked resin particles, and optional components such as a crystal nucleating agent, a lubricant, and other components using an extruder, a kneader, a Banbury mixer, a kneading roll, or the like can be mentioned. When melt-kneading, it is preferable to mix while paying attention to the decrease in molecular weight due to thermal decomposition. In addition, the thermoplastic resin composition can also be produced by dissolving all the raw materials (components) in a soluble solvent and then removing the solvent.

[0171] When producing a thermoplastic resin composition by melt kneading, each component may be individually charged 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, after mixing an aqueous dispersion of a thermoplastic resin with an aqueous dispersion of crosslinked resin particles, the resulting mixture may be dried in a dryer to obtain a mixed powder, and the mixed powder may be charged into an extruder, etc.

[0172] 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 cylinder shape, an elliptical cylinder shape, a sphere shape, a cube shape, a rectangular prism shape, or the like.

[0173] The resin temperature during melt kneading cannot be generally defined because it depends on the melting point and melt viscosity of the resin used, etc. The resin temperature is preferably 140°C to 250°C, more preferably 150°C to 230°C, and even more preferably 160°C to 210°C, from the viewpoint of uniformly dispersing the crosslinked resin particles in the thermoplastic resin while avoiding thermal decomposition of the thermoplastic resin.

[0174] <Method of manufacturing molded body> In one embodiment of the present invention, a molded article is provided by molding the resin composition. The molding method of the thermoplastic resin composition is not particularly limited, and a commonly used molding method can be applied. Specific examples of the molding method include inflation film molding, extrusion blow molding, injection blow molding, extrusion molding, calendar molding, vacuum molding, injection molding, and the like. The molded article formed by molding the thermoplastic resin composition can also be said to be a molded article containing the thermoplastic resin composition.

[0175] By carrying out the above-mentioned molding method using the present resin composition, a molded product having excellent impact resistance can be provided with good productivity. Specifically, by carrying out the above-mentioned molding method using the present resin composition, a film molded product, a sheet molded product, a blow molded product, an extrusion molded product, a vacuum molded product, or an injection molded product can be produced. In this specification, the term "film molded product" refers to a product conforming to JIS20108:2012, specifically a thin film having a thickness of less than 0.25 mm. In this specification, the term "sheet molded product" refers to a product conforming to JIS20108:2012, specifically a thin plate having a thickness of 0.25 mm or more.

[0176] Molded articles containing the present resin composition can be suitably used in fields such as agriculture, fisheries, forestry, horticulture, medicine, sanitary products, the food industry, clothing, non-clothing, packaging, automobiles, building materials, and others. EXAMPLES

[0177] The following examples are provided to more specifically illustrate one embodiment of the present invention, but the present invention is not limited to these examples.

[0178] [Measurement and evaluation methods] (Weight average molecular weight) The resin to be measured was added to chloroform, and the resulting mixture was heated in a hot water bath at 60°C for 30 minutes. The resulting mixture (chloroform solution) was filtered through a disposable PTFE filter with a 0.45 μm pore size. The filtrate was then subjected to GPC measurement under the following conditions to determine the weight average molecular weight. GPC measurement device: Shimadzu High Performance Liquid Chromatograph 20A System Column: Showa Denko KG 4A (1 column), K-806M (2 columns) Sample concentration: 1mg / ml Free solution: Chloroform solution Free liquid flow rate: 1.0ml / min Sample injection volume: 100 μL Analysis time: 30 minutes Standard sample: standard polystyrene.

[0179] (Volume average particle size) The volume average particle diameter of the crosslinked resin particles was measured using the aqueous dispersion of the crosslinked resin particles as a sample. As a measuring device, MicrotracMT3300EXII manufactured by Nikkiso Co., Ltd. was used. Specifically, the particle diameter and volume of each of the crosslinked resin particles (B) or the uncrosslinked resin particles in the aqueous dispersion of the crosslinked resin particles (B) or the uncrosslinked resin particles were measured using the above device, and the volume average particle diameter was calculated based on the above formula (1), i.e., formula (2), from the results obtained by the measurement.

[0180] (Gel fraction) The dried crosslinked or uncrosslinked resin particles were added to chloroform to a concentration of 0.7% by weight, and the mixture was kept at 60°C for 30 minutes to obtain a chloroform solution. After that, the mixture was left to stand at room temperature for 3 hours, and then the chloroform solution was filtered through a membrane filter with a pore size of 0.45 μm. The inside of the container and the filter were thoroughly washed with chloroform several times while filtering to prevent loss. 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 dry gel−weight of filter only) / weight of crosslinked resin particles or uncrosslinked resin particles used in measurement)×100 (%).

[0181] (Heat resistance of crosslinked resin particles) After the reaction (crosslinking step) at a high temperature exceeding 100°C as described below is completed, the particles adhering to the stirrer, baffle, and wall surfaces aggregated into lumps (=aggregates) were removed and dried in an oven, after which the weight was measured and the ratio to the total amount of resin particles charged (100 parts by weight) was taken as the amount of aggregates generated. Products with an amount of aggregates of 10% or less were judged to have excellent heat resistance and were rated as "A." Products with an amount of aggregates of 10% or more were judged to have poor heat resistance and were rated as "B."

[0182] [Raw material for cross-linked resin particles] (1) Uncrosslinked resin particles The uncrosslinked resin particles obtained in Comparative Example 1 and Examples 1 and 2 below. (2) Peroxides t-Butylperoxy-2-ethylhexyl monocarbonate: "Perbutyl (registered trademark) E" manufactured by Nippon Oil & Fats Co., Ltd., 1-hour half-life temperature: 119°C (3) Polyfunctional compound Triallyl isocyanurate [Method of manufacturing uncrosslinked resin particles] <Comparative Example 1> (Bacteria culture solution preparation process) Ralstonia eutropha described in International Publication No. WO2019 / 142717 was cultured by the method described in paragraphs

[0041] to

[0048] of the same document to obtain a cell culture solution containing cells containing P3HA. The composition ratio of the repeating units of P3HA was (3-hydroxybutyrate) / (3-hydroxyhexanoate)=89 / 11 (mol / mol).

[0183] (inactivation) The obtained bacterial culture solution was heated and stirred at an internal temperature of 70° C. for 8 hours for sterilization.

[0184] (Dispersion liquid preparation process) (Enzyme treatment process) The sterilized bacterial culture was adjusted to pH 7.0±0.2 by adding 10% sulfuric acid to obtain a solution. Next, lysozyme (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a peptidoglycan decomposition enzyme to the obtained solution at 0.07% relative to 100% by weight of the resin solid content in the solution, and the obtained solution was kept at 50°C for 2 hours. Then, an alkaline protease, Alcalase (manufactured by Novozyme), was added to the solution at 0.4% relative to 100% by weight of the resin solid content in the solution. Next, 30% sodium hydroxide was added to the solution to adjust the pH of the solution to 9.0. After adjusting to pH 9.0, the solution was kept at 50°C and pH 9.0 for 2 hours.

[0185] (Alkaline cleaning process) The pH of the solution after the enzyme treatment was adjusted to 10.5 by adding 30% sodium hydroxide. After adjusting to pH 10.5, the solution was kept at 50° C. and pH 10.5 for 3 hours.

[0186] (Surfactant treatment process) Next, sodium dodecyl sulfate (SDS manufactured by Kao Corporation) was added to the solution so that the concentration was 0.6 to 10% relative to 100% by weight of the resin solid content in the solution. Then, 30% sodium hydroxide was added to the solution to adjust the pH of the solution to pH 11.0. After adjusting the pH to 11.0, the solution was kept at 40°C and pH 11.0 for 1 hour.

[0187] (Crushing process) After the surfactant treatment step, the solution was subjected to shearing for a certain period of time using a homogenizer MARKII 2.5 manufactured by Primix Corporation to disrupt the cells.

[0188] (Concentration and purification process) The solution after the crushing process was centrifuged (6900 rpm, 15 minutes), and the supernatant was removed. The residue after the removal of the supernatant was added with an aqueous sodium hydroxide solution (pH 11.0) in the same amount as the removed supernatant to redisperse the resin particles, and a slurry was obtained. The slurry was then centrifuged (6900 rpm, 15 minutes), and the supernatant was removed. The residue after the removal of the supernatant was added with an aqueous sodium hydroxide solution (pH 11.0) in the same amount as the removed supernatant to redisperse the resin particles, and a slurry was obtained. This process was repeated two more times (three times in total). Then, the residue after the removal of the supernatant was added with an aqueous sodium hydroxide solution (pH 11.0) in an amount such that the concentration of the resin particles was 23±2% by weight, and the resin particles were redispersed to obtain an aqueous dispersion containing P3HA resin particles.

[0189] (Dispersant added) 1.0 phr (1 part by weight per 100 parts by weight of resin particle solids) of ethylene oxide / propylene oxide copolymer nonionic dispersant (polyethylene oxide molecular weight 8000, polypropylene oxide molecular weight 2000, product name Pronon 208) was added to the resin particle aqueous dispersion obtained above and mixed.

[0190] Using the resin particles of P3HA in the aqueous dispersion as a sample, the weight average molecular weight of P3HA was measured by the above-mentioned method and found to be 500,000 to 1.5 million.

[0191] (Aqueous dispersion preparation process) In an autoclave equipped with a stirrer, baffle, nitrogen inlet, nitrogen outlet, and thermometer, an aqueous dispersion in which uncrosslinked resin particles are dispersed in water (100 parts by weight in terms of solid content), 200 parts by weight of deionized water, 2 parts by weight of peroxide, 2 parts by weight of sodium dioctyl sulfosuccinate, and 0.5 parts by weight of a polyfunctional compound were added to prepare an aqueous dispersion. Then, stirring of the aqueous dispersion obtained was started at room temperature, and the atmosphere in the autoclave was replaced with nitrogen.

[0192] (Impregnation process) Thereafter, the content of the autoclave (aqueous dispersion) was stirred for 1 hour at 50° C. Through this operation, the peroxide and the polyfunctional compound were impregnated into the interior of the uncrosslinked resin particles.

[0193] (Crosslinking process) Thereafter, the aqueous dispersion was heated to 119° C. After reaching 119° C., the aqueous dispersion was maintained at 119° C. for 3 hours. This operation reacted the peroxide to obtain an aqueous dispersion in which crosslinked resin particles were dispersed in water.

[0194] After the reaction was completed, the particles adhering to the stirrer, baffle, and wall surface were aggregated and formed into lumps (=aggregates), which were taken out and dried in an oven. The weight of the aggregates was measured, and the ratio of the amount of aggregates to the amount of resin particles charged (100 parts by weight) was taken as the amount of aggregates generated. The heat resistance was then evaluated by the method described above. The volume average particle size and gel fraction of the obtained crosslinked resin particles were also measured by the method described above. The results are shown in Table 1.

[0195] After removing the aggregates, the pH of the aqueous dispersion was adjusted, and the mixture was dried in an oven to obtain solidified crosslinked resin particles.

[0196] <Reference example 1> (Preparation of bacterial culture solution) Ralstonia eutropha described in International Publication No. WO2019 / 142717 was cultured by the method described in paragraphs

[0041] to

[0048] of the same document to obtain a cell culture solution containing cells containing P3HA. The composition ratio of the repeating units of P3HA was (3-hydroxybutyrate) / (3-hydroxyhexanoate)=72 / 28 (mol / mol).

[0197] Thereafter, an attempt was made to carry out the same operations as in Comparative Example 1. As a result, a large number of particle aggregates were generated during the crushing and the subsequent centrifugation operations, and therefore it was not possible to carry out the subsequent operations.

[0198] <Example 1> (Preparation of bacterial culture solution) Ralstonia eutropha described in International Publication No. WO2019 / 142717 was cultured by the method described in paragraphs

[0041] to

[0048] of the same document to obtain a cell culture solution containing cells containing P3HA. The composition ratio of the repeating units of P3HA was (3-hydroxybutyrate) / (3-hydroxyhexanoate)=72 / 28 (mol / mol).

[0199] Crosslinked resin particles were produced by the same procedure as in Comparative Example 1, except that the treatment with lysozyme enzyme, which is a peptidoglycan degrading enzyme, was not carried out, and a dispersant (Pronon 208) was not added. In the production process, after the crosslinking step, the amount of aggregates generated was measured by the above-mentioned method, and the heat resistance was evaluated. In addition, the volume average particle size and gel fraction of the obtained crosslinked resin particles were measured by the above-mentioned method. The results are shown in Table 1.

[0200] <Example 2> (Preparation of bacterial culture solution) Ralstonia eutropha described in International Publication No. WO2019 / 142717 was cultured by the method described in paragraphs

[0041] to

[0048] of the same document to obtain a cell culture solution containing cells containing P3HA. The composition ratio of the repeating units of P3HA was (3-hydroxybutyrate) / (3-hydroxyhexanoate)=89 / 11 (mol / mol).

[0201] Crosslinked resin particles were produced in the same manner as in Comparative Example 1, except that the treatment with lysozyme, a peptidoglycan degrading enzyme, was not carried out. In the production process, after the crosslinking step, the amount of aggregates generated was measured by the above-mentioned method, and the heat resistance was evaluated. In addition, the volume average particle size and gel fraction of the obtained crosslinked resin particles were measured by the above-mentioned method. The results are shown in Table 1.

[0202] [Table 1]

[0203] Compared with Comparative Example 1 in which a peptidoglycan-degrading enzyme treatment was performed, in Examples 1 and 2 in which a peptidoglycan-degrading enzyme treatment was not performed, the amount of aggregates generated after the completion of the reaction at a high temperature exceeding 100° C. was small, indicating excellent heat resistance. Furthermore, in Reference Example 1, since peptidoglycan was removed by the peptidoglycan-degrading enzyme, aggregates were generated due to inability to withstand shearing during the crushing treatment step, etc., whereas in Example 1 in which a peptidoglycan-degrading enzyme treatment was not performed, an aqueous dispersion of uncrosslinked resin particles was obtained without generating aggregates, despite the use of P3HA having the same structure as in Reference Example 1, indicating that the aggregation stability against physical forces is also improved. [Industrial Applicability]

[0204] According to one embodiment of the present invention, there is provided a method for producing crosslinked resin particles that can provide crosslinked resin particles having biodegradability and excellent impact resistance and heat resistance. Therefore, one embodiment of the present invention can be suitably used as a modifier for thermoplastic resins, a spacer, an antiblocking agent, a matting agent, etc.

Claims

1. Contains polyhydroxyalkanoate resin, The gel fraction is 50% or more, and the volume average particle size is 0.10 μm to 10.00 μm, Cross-linked resin particles comprising peptidoglycan.

2. 2. The crosslinked resin particles according to claim 1, wherein the polyhydroxyalkanoate-based resin is a poly(3-hydroxyalkanoate)-based resin.

3. 2. The crosslinked resin particles of claim 1, wherein the crosslinked resin particles are crosslinked using a peroxide.

4. 4. The crosslinked resin particles according to claim 3, wherein the crosslinked resin particles are crosslinked in the presence of the peroxide and a polyfunctional compound.

5. 2. The crosslinked resin particles of claim 1, wherein the crosslinked resin particles are non-foamed.

6. 2. The crosslinked resin particles according to claim 1, wherein the content of said polyhydroxyalkanoate resin in 100% by weight of the resin component of said crosslinked resin particles is 80% by weight or more.

7. 2. The crosslinked resin particles according to claim 1, wherein the gel fraction is from 70% to 100%.

8. 8. An aqueous dispersion in which the crosslinked resin particles according to claim 1 are dispersed in an aqueous medium.

9. Thermoplastic resin, and A thermoplastic resin composition comprising the crosslinked resin particles according to any one of claims 1 to 7.

10. The thermoplastic resin composition comprises 10. The thermoplastic resin composition according to claim 9, comprising: 40 to 99 parts by weight of the thermoplastic resin; and 1 to 60 parts by weight of the crosslinked resin particles, the total amount of the thermoplastic resin and the crosslinked resin particles being 100 parts by weight.

11. The thermoplastic resin composition according to claim 9 , wherein the thermoplastic resin comprises a biodegradable resin.

12. The thermoplastic resin composition according to claim 11 , wherein the biodegradable resin comprises a polyester-based resin.

13. The thermoplastic resin composition according to claim 9, further comprising a crystal nucleating agent and / or a lubricant.

14. A molded article obtained by molding the thermoplastic resin composition according to claim 9.

15. The molded article according to claim 14, wherein the molded article is a film molded article, a sheet molded article, a blow molded article, an extrusion molded article, a vacuum molded article, or an injection molded article.

16. Contains crosslinked resin particles, The crosslinked resin particles contain a polyhydroxyalkanoate resin, The gel fraction is 50% or more, and the volume average particle size is 0.10 μm to 10.00 μm, A modifier for thermoplastic resins, comprising peptidoglycan.

17. A method for producing crosslinked resin particles, comprising the steps of: a bacterial cell culture preparation step of preparing a bacterial cell culture solution containing a polyhydroxyalkanoate resin; a dispersion liquid preparation step of removing the bacterial cells from the culture liquid to prepare a dispersion liquid containing resin particles containing a polyhydroxyalkanoate-based resin; an aqueous dispersion preparation step of mixing the dispersion and a peroxide to prepare an aqueous dispersion containing the resin particles and the peroxide; a crosslinking step of decomposing the peroxide and crosslinking the resin particles, In the above-mentioned production method, no peptidoglycan degrading enzyme is used, The crosslinked resin particles have a gel fraction of 50% or more, a volume average particle diameter of 0.10 μm to 10.00 μm, and contain peptidoglycan.

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