Thermoplastic resin composition

Abstract

The present invention addresses the problem of providing a novel thermoplastic resin composition capable of providing a molding with excellent impact resistance. The problem is solved by a thermoplastic resin composition comprising crosslinked resin particles, which contain a biodegradable resin having a glass transition temperature of less than 0° C, a gel fraction of 50% or more, and a volume average particle diameter of 0.05-10.00 μm or a median diameter of 0.05-10.00 μm, and a thermoplastic resin, wherein the thermoplastic resin composition: has a sea-island structure in which the thermoplastic resin forms a sea structure and the crosslinked resin particles form island structures; and satisfies at least one of (1) to (3).　(1) The single particle index for the crosslinked resin particles is 0.30-1.00, (2) the monodispersity of the crosslinked resin particles is 0.20-1.00, and (3) the average degree of aggregation of the crosslinked resin particles is 1.0-5.0.

Description

thermoplastic resin composition

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

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

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

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

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

[0006] One embodiment of the present invention has been made in consideration of the above-mentioned current situation, and its object is to provide a novel thermoplastic resin composition that can provide a molded article having excellent impact resistance.

[0007] As a result of extensive investigations, the present inventors have found that a molded article having excellent impact resistance can be provided by a thermoplastic resin composition having a specific sea-island structure, the thermoplastic resin composition including crosslinked resin particles that contain a biodegradable resin having a glass transition temperature of less than 0°C and that satisfy a specific gel fraction and volume average particle diameter or median diameter, and the thermoplastic resin forming a sea structure and the crosslinked resin particles forming island structures, and thus have completed one embodiment of the present invention.

[0008] That is, a thermoplastic resin composition according to one embodiment of the present invention is a thermoplastic resin composition comprising crosslinked resin particles and a thermoplastic resin, wherein the crosslinked resin particles (i) comprise a biodegradable resin having a glass transition temperature of less than 0°C, (ii) have a gel fraction of 50% or more, and (iii) have a volume average particle diameter of 0.05 μm to 10.00 μm or a median diameter of 0.05 μm to 10.00 μm, and have a sea-island structure in which the thermoplastic resin forms a sea structure and the crosslinked resin particles form island structures, and satisfy at least one of the following (1) to (3): (1) the single particle index of the crosslinked resin particles is 0.30 to 1.00, (2) the monodispersity ratio of the crosslinked resin particles is 0.20 to 1.00, and (3) the average aggregation degree of the crosslinked resin particles is 1.0 to 5.0.

[0009] According to one embodiment of the present invention, it is possible to provide a novel thermoplastic resin composition that can provide a molded article having excellent impact resistance.

[0010] FIG. 1 is a diagram showing the results of transmission electron microscope (TEM) observation of the thermoplastic resin composition obtained in Example 1. FIG. 2 is a diagram showing the results of scanning probe microscope (SPM) analysis of the thermoplastic resin composition obtained in Example 2. FIG. 3 is a diagram showing the results of scanning probe microscope (SPM) analysis of the thermoplastic resin composition obtained in Example 3. FIG. 4 is a diagram showing the results of scanning probe microscope (SPM) analysis of the thermoplastic resin composition obtained in Example 4. FIG. 5 is a diagram showing the results of scanning probe microscope (SPM) analysis of the thermoplastic resin composition obtained in Example 6. FIG. 6 is a diagram showing the results of scanning probe microscope (SPM) analysis of the thermoplastic resin composition obtained in Example 7. FIG. 7 is a diagram showing the results of scanning probe microscope (SPM) analysis of the thermoplastic resin composition obtained in Example 8.

[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 the respective configurations described below, and various modifications are possible within the scope of the claims. Furthermore, embodiments or examples obtained by combining the technical means disclosed in different embodiments or examples are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. All academic literature and patent documents described in this specification are incorporated herein by reference. Furthermore, unless otherwise specified in this specification, "A to B" representing a numerical range means "A or more (including A and greater than A) and B or less (including B and less than B)."

[0012] [1. Thermoplastic Resin Composition] A thermoplastic resin composition according to one embodiment of the present invention is a thermoplastic resin composition comprising crosslinked resin particles and a thermoplastic resin, wherein the crosslinked resin particles (i) comprise a biodegradable resin having a glass transition temperature of less than 0°C, (ii) have a gel fraction of 50% or more, and (iii) have a volume average particle diameter of 0.05 μm to 10.00 μm or a median diameter of 0.05 μm to 10.00 μm, and have a sea-island structure in which the thermoplastic resin forms a sea structure and the crosslinked resin particles form island structures, and satisfy at least one of the following (1) to (3): (1) the single particle index of the crosslinked resin particles is 0.30 to 1.00, (2) the monodispersity ratio of the crosslinked resin particles is 0.20 to 1.00, and (3) the average aggregation degree of the crosslinked resin particles is 1.0 to 5.0.

[0013] In this specification, the "thermoplastic resin composition according to one embodiment of the present invention" may be referred to as the "resin composition".

[0014] The present resin composition has the advantage of being able to provide a molded article having excellent impact resistance. In this specification, the impact resistance of a molded article is defined as "tensile impact strength (kJ / m ２ The tensile impact strength (kJ / m ２ The method for measuring the above will be described in detail in the Examples below.

[0015] [1-1] Crosslinked Resin Particles The crosslinked resin particles contained in the resin composition contain a biodegradable resin having a glass transition temperature of less than 0°C, have a gel fraction of 50% or more, and have a volume average particle size of 0.05 μm to 10.00 μm or a median size of 0.05 μm to 10.00 μm.

[0016] The resin composition contains the crosslinked resin particles, and thus can provide a molded article having excellent impact resistance. In other words, the crosslinked resin particles can function as a modifier or impact improver for a thermoplastic resin.

[0017] <Biodegradable Resin> The crosslinked resin particles contained in the present resin composition contain a biodegradable resin having a glass transition temperature of less than 0° C. Hereinafter, in this specification, the “glass transition temperature” may be referred to as “Tg”.

[0018] The biodegradable resin (including both biodegradable resins with a Tg of less than 0°C and biodegradable resins with a Tg of 0°C or higher) is not particularly limited as long as it is a resin with biodegradability. Examples of biodegradable resins include aliphatic polyesters and aliphatic aromatic polyesters.

[0019] Examples of the aliphatic polyester include (i) polyhydroxyalkanoate resins (hereinafter, also referred to as "PHA"), (ii) polylactic acid (hereinafter, also referred to as "PLA"), (iii) polycaprolactone (hereinafter, also referred to as "PCL"), and (iv) aliphatic polyesters other than PHA, PLA, and PCL.

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

[0022] In this specification, "polyglycolic acid" refers to a group of all monomer repeating units (100 mol%) containing [—CH ２ The term "polyglycolic acid" refers to a resin containing 50 mol % or more of repeating units represented by the formula [—CH—CO—O—]. ２ The repeating units represented by the formula [—CO—O—] may account for 60 mol % or more, 70 mol % or more, 80 mol % or more, or 90 mol % or more of all the monomer repeating units (100 mol %).

[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 has the formula: [—CHR—CH ２ 3-hydroxyalkanoic acid repeating units represented by the formula: —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 units out of all monomer repeating units (100 mol %). The P3HA preferably contains 60 mol % or more, and more preferably 70 mol % or more, of all monomer repeating units (100 mol %).

[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 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. As used herein, "poly(X-co-Y)" refers to a copolymer containing X repeating units and Y repeating units, and is intended to mean a copolymer obtained by copolymerizing a monomer from which the X repeating unit is derived and a monomer from which the Y repeating unit is derived. Furthermore, during the production of P3HA by microorganisms, a small amount (less than 1 mol%) of a monomer may be copolymerized. However, if this does not significantly affect the physical properties of the resulting P3HA, the monomer is considered to be uncopolymerized, and the product will be referred to by a name that does not include that monomer.

[0028] P3HA can be produced by microorganisms. Such microbially produced P3HA is typically composed only of D-form (R-form) 3-hydroxyalkanoic acid repeating units. Among microbially produced P3HAs, P3HB, P3HB3HH, and P3HB4HB are preferred, with P3HB3HH and P3HB4HB being more preferred, due to ease of industrial production.

[0029] It is also preferred that P3HA contains 3-hydroxybutanoic acid (3HB) repeating units. When P3HA contains 3HB repeating units, from the viewpoint of the balance between flexibility and strength, the composition ratio of 3HB repeating units in all monomer repeating units (100 mol%) is preferably 60 mol% to 99 mol%, more preferably 61 mol% to 97 mol%, and even more preferably 62 mol% to 95 mol%. When the composition ratio of 3HB repeating units in P3HA is 60 mol% or more, there is an advantage that the rigidity of the crosslinked resin particles can be further improved. On the other hand, when the composition ratio of 3HB repeating units in P3HA is 99 mol% or less, there is an advantage that the flexibility of the crosslinked resin particles tends to be further improved. The monomer composition ratio of P3HA can be measured by gas chromatography or the like (see, for example, WO 2014 / 020838). As P3HA, two or more types having different composition ratios of 3HB repeating units may be used in combination.

[0030] The microorganism that produces P3HA is not particularly limited as long as it has the ability to produce P3HA. For example, the first P3HB-producing bacterium was Bacillus megaterium, discovered in 1925, and other naturally occurring microorganisms such as Cupriavidus necator (formerly classified as Alcaligenes eutrophus and Ralstonia eutropha) and Alcaligenes latus are known. In these microorganisms, P3HB accumulates intracellularly.

[0031] Known examples of bacteria that produce copolymers of 3HB and other hydroxyalkanoic acids include Aeromonas caviae, which produces P3HB3HH, and Alcaligenes eutrophus, which produces poly(3-hydroxybutyrate-co-4-hydroxybutyrate). In particular, Alcaligenes eutrophus AC32 (FERM BP-6038) (T. Fukui, Y. Doi, J. Bateriol., 179, pp. 4821-4830 (1997)), which has been introduced with genes encoding P3HA synthases, is preferred for increasing P3HB3HH productivity. Microbial cells obtained by culturing such microorganisms under appropriate conditions and allowing P3HA to accumulate within the cells are used. In addition to the above, genetically modified microorganisms into which various P3HA synthesis-related genes have been introduced may be used depending on the P3HA to be produced, or the 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. A PHA with a weight-average molecular weight of 50,000 or more has the advantage of being able to reduce or avoid the tendency for the crosslinked resin particles to become weak. Alternatively, a PHA with a weight-average molecular weight of 50,000 or more has the advantage of being able to reduce or avoid the tendency for the PHA to become sticky due to low molecular weight components. On the other hand, a PHA with a weight-average molecular weight of 3,000,000 or less may have the advantage of being easy to manufacture and / or easy to handle in order to achieve the object of one embodiment of the present invention. The weight-average molecular weight of the PHA is a value obtained by measurement using the PHA before crosslinking treatment.

[0033] The weight-average molecular weight can be measured using gel permeation chromatography (GPC) (Shimadzu Corporation's "High Performance Liquid Chromatograph 20A System"), a polystyrene gel column (Showa Denko K.K.'s "K-G 4A" or "K-806M" or the like), and chloroform as the mobile phase. The weight-average molecular weight can be determined as a polystyrene-equivalent molecular weight using a calibration curve obtained by measuring polystyrenes with known molecular weights using the same measurement method. In this case, the calibration curve can be prepared using polystyrenes with weight-average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. As the column for the GPC, a column appropriate for measuring the molecular weight can be used.

[0034] In this specification, "polylactic acid" refers to a compound having a repeating unit of [-CHCH ３ The term "polylactic acid" refers to a resin containing 50 mol % or more of repeating units represented by the formula [-CHCH ３ The repeating units represented by the formula [—CO—O—] may account for 60 mol % or more, 70 mol % or more, 80 mol % or more, or 90 mol % or more of all the monomer repeating units (100 mol %).

[0035] As the polylactic acid, any conventionally known polylactic acid can be used. The polylactic acid may be crystalline polylactic acid, amorphous polylactic acid, or a mixture of crystalline polylactic acid and amorphous polylactic acid.

[0036] 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.

[0037] Examples of the other monomers include aliphatic hydroxycarboxylic acids other than lactic acid, aliphatic polyhydric alcohols, aliphatic polycarboxylic acids, polyfunctional polysaccharides, and caprolactone.

[0038] The lactic acid raw material for producing polylactic acid is not particularly limited, and can be L-lactic acid, D-lactic acid, DL-lactic acid, or a mixture thereof, or L-lactide, D-lactide, meso-lactide, or a mixture thereof, etc. Lactic acid obtained by microbial fermentation from renewable plant-derived raw materials such as starch can be suitably used.

[0039] The method for producing polylactic acid is not particularly limited, and known methods such as dehydration condensation polymerization and ring-opening polymerization can be applied.

[0040] The weight-average molecular weight of polylactic acid is not particularly limited, but is preferably 50,000 to 1,000,000, more preferably 70,000 to 700,000, and even more preferably 100,000 to 400,000. When the weight-average molecular weight of polylactic acid is 50,000 or more, the crosslinked resin particles, as well as the crosslinked resin particles and molded articles thereof, can have sufficient rigidity and / or strength. On the other hand, polylactic acid having a weight-average molecular weight of 1,000,000 or less can have the advantage that the polylactic acid is easy to produce and / or easy to handle in order to achieve the object of one embodiment of the present invention.

[0041] "Polycaprolactone" includes, but is not limited to, polymers obtained by ring-opening polymerization of ε-caprolactone. In one embodiment of the present invention, PCL obtained by other manufacturing methods can also be used. An organometallic catalyst can also be used to promote the polymerization of PCL. In this specification, "PCL" also includes copolymers of ε-caprolactone and monomers other than ε-caprolactone (e.g., lactide, glycolic acid, etc.).

[0042] PCL typically has a melting point of 50°C to 65°C, a crystallization temperature of 10°C to 30°C, and a glass transition temperature of -50°C to -60°C.

[0043] The weight-average molecular weight of PCL is preferably 30,000 to 500,000, and more preferably 100,000 to 400,000. When the weight-average molecular weight of PCL is 30,000 or more, the crosslinked resin particles, as well as the crosslinked resin particles and molded articles thereof, can have sufficient rigidity and / or strength. When the weight-average molecular weight of PCL is 500,000 or less, the crosslinked resin particles can be easily processed.

[0044] Commercially available PCL products include, for example, Ingevity's "Capa 6506" (powder, Mw = 130,000), "Capa 6500" (pellet, Mw = 130,000), "Capa 6806" (powder, Mw = 230,000), "Capa 6800" (pellet, Mw = 230,000), and "FB100" (pellet, Mw = 300,000, contains cross-linked PCL).

[0045] Examples of the aliphatic polyester other than PHA include (i) polycaprolactone (PCL), (ii) polylactic acid (PLA), and (iii) aliphatic polyesters having a structure obtained by polycondensation of an aliphatic diol and an aliphatic dicarboxylic acid. Specific examples of the aliphatic polyesters having a structure obtained by polycondensation of an aliphatic diol and an aliphatic dicarboxylic acid include polyethylene succinate, polybutylene succinate (hereinafter also referred to as "PBS"), polyhexamethylene succinate, polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polybutylene succinate adipate (hereinafter also referred to as "PBSA"), polyethylene sebacate, and polybutylene sebacate.

[0046] In this specification, "PBS" refers to an aliphatic polyester copolymer synthesized by an esterification reaction and / or transesterification reaction, and a condensation polymerization reaction, between an aliphatic diol component mainly composed of 1,4-butanediol and an aliphatic dicarboxylic acid component mainly composed of a succinic acid component such as succinic acid and / or a derivative thereof.

[0047] PBS is, for example, [—CO—(CH ２ ) ２ —CO—O—(CH ２ ) ４-O-].

[0048] PBS can be produced from petroleum or non-petroleum-based materials (e.g., plants).

[0049] In this specification, "PBS" also includes a "PBS-based resin" which is a copolymer of the above-mentioned PBS with a monomer other than 1,4-butanediol and succinic acid (for example, L-lactic acid and / or caprolactone).

[0050] Commercially available PBS can also be used, such as "BioPBS FZ71" and "BioPBS FZ91" manufactured by Mitsubishi Chemical Corporation.

[0051] In this specification, "PBSA" refers to an aliphatic polyester copolymer synthesized by an esterification reaction and a condensation polymerization reaction between an aliphatic diol component mainly composed of 1,4-butanediol, an aliphatic dicarboxylic acid component mainly composed of a succinic acid component such as succinic acid and / or a derivative thereof, and adipic acid.

[0052] As long as the effects of one embodiment of the present invention are achieved, the PBSA may contain, in addition to butanediol repeating units, succinic acid repeating units, and adipic acid repeating units, any diol repeating units other than butanediol, any dicarboxylic acid repeating units other than succinic acid and adipic acid, and / or hydroxyalkanoic acid repeating units. Examples of the optional diols include ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol. Examples of the optional dicarboxylic acids include suberic acid, sebacic acid, dodecanoic acid, succinic anhydride, and adipic anhydride.

[0053] In this specification, "PBSA" also includes "PBSA-based resins" which are copolymers of the above-mentioned PBSA with monomers other than 1,4-butanediol, succinic acid, and adipic acid (e.g., lactic acid, terephthalic acid, malic acid, sebacic acid, azelaic acid, etc.) within the range that does not impair biodegradability.

[0054] Commercially available PBSA may also be used, such as "BioPBS FD72" and "BioPBS FD92" manufactured by Mitsubishi Chemical Corporation.

[0055] As the aliphatic polyester, one of the various resins described above may be used alone, or two or more of them may be used in combination. Furthermore, among the various resins described above, one of the resins described above may be used alone, or two or more of them may be used in combination.

[0056] Examples of the aliphatic aromatic polyester include aliphatic aromatic polyesters obtained using both an aliphatic compound and an aromatic compound as monomers (using both an aliphatic compound and an aromatic compound as monomers).

[0057] 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").

[0058] As used herein, "PBAT" refers to a random copolymer of 1,4-butanediol with adipic acid and terephthalic acid.

[0059] The PBAT is not particularly limited, but is preferably a PBAT obtained by reacting (a) a mixture consisting essentially of 35 to 95 mol % of adipic acid or an ester-forming derivative thereof, or a mixture thereof, and 5 to 65 mol % of terephthalic acid or an ester-forming derivative thereof, or a mixture thereof (the sum of the individual mol % is 100 mol %) with (b) a mixture containing butanediol (wherein the molar ratio of (a) to (b) is 0.4:1 to 1.5:1), as described in JP-A-10-508640 and the like.

[0060] In one embodiment of the present invention, in place of the 1,4-butanediol in the production of PBAT, glycol compounds such as ethylene glycol, propylene glycol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, pentaerythritol, bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol may be used. Also, in one embodiment of the present invention, in place of the adipic acid in the production of PBAT, dicarboxylic acids such as oxalic acid, succinic acid, azelaic acid, dodecanedioic acid, malonic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, bis(p-carboxyphenyl)methane, anthracenedicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodiumsulfoisophthalic acid, and 5-tetrabutylphosphonium isophthalic acid may be used.

[0061] Commercially available PBAT may also be used, such as "Ecoflex C1200" manufactured by BASF.

[0062] In this specification, "PBSeT" refers to a random copolymer of 1,4-butanediol with sebacic acid and terephthalic acid. For each embodiment of PBSeT, the above-described embodiments of PBAT can be appropriately applied in which the "adipic acid" and "adipic acid or an ester-forming derivative thereof" moieties are replaced with "sebacic acid" and "sebacic acid or an ester-forming derivative thereof," respectively.

[0063] Commercially available PBSeT may also be used, such as "Ecoflex FS blend C2200" (registered trademark) manufactured by BASF.

[0064] In this specification, "PBAzT" refers to a random copolymer of 1,4-butanediol with azelaic acid and terephthalic acid. For each embodiment of PBAzT, the above-described embodiments of PBAT can be appropriately applied in which the "adipic acid" and "adipic acid or an ester-forming derivative thereof" moieties are replaced with "azelaic acid" and "azelaic acid or an ester-forming derivative thereof," respectively.

[0065] In this specification, "PBST" refers to the above-mentioned PBS into which a terephthalate unit has been introduced. More specifically, "PBST" refers to an aliphatic-aromatic polyester copolymer synthesized by an esterification reaction and a condensation polymerization reaction between an aliphatic dicarboxylic acid component, the main component of which is succinic acid and / or a derivative thereof, and terephthalic acid.

[0066] As used herein, "PBSAT" refers to a copolymer containing, among aliphatic dicarboxylic acid residues, residues of succinic acid, adipic acid, and phthalic acid, preferably in a ratio of 70-90:5-15:5-15 mol %. Therefore, PBSAT can be produced, for example, by esterifying a dicarboxylic acid mixture containing succinic acid, adipic acid, and phthalic acid in the above-mentioned ratios with 1,4-butanediol, an aliphatic glycol, in a molar ratio of 1:1.2-2.0, followed by a condensation polymerization reaction. The reactive groups and reaction conditions used in the reaction can be those used in existing biodegradable resins such as PBS, as appropriate.

[0067] As the aliphatic aromatic polyester, one of the various resins described above may be used alone, or two or more of them may be used in combination. Furthermore, among the various resins described above, one of the resins described above may be used alone, or two or more of them may be used in combination.

[0068] The crosslinked resin particles contain, as a biodegradable resin, at least a biodegradable resin having a glass transition temperature of less than 0° C. This provides the crosslinked resin particles with the advantage of excellent impact strength improvement effect.

[0069] The crosslinked resin particles may further contain a biodegradable resin having a glass transition temperature of 0° C. or higher in addition to the biodegradable resin having a glass transition temperature of less than 0° C. The glass transition temperature of the resin can be easily measured by the method described in the section <Glass Transition Temperature (Tg)> in the Examples section below. In other words, the crosslinked resin particles contain a biodegradable resin having a glass transition temperature of less than 0° C., as determined by the measurement method described below.

[0070] Generally, PHA, PCL, PBS, PBSA, PBAT, PBSeT, PBAzT, PBST, and PBSAT other than polyglycolic acid have a Tg of less than 0°C. PCL generally has a Tg of -50°C to -60°C. PBS generally has a Tg of -30°C to -40°C. PBSA generally has a Tg of -40°C to -50°C. PBAT generally has a Tg of -30°C to -40°C. PBSeT generally has a Tg of -20°C to -40°C. PBAzT generally has a Tg of -20°C to -40°C. PBST generally has a Tg of -20°C to -40°C. PBSAT generally has a Tg of -20°C to -40°C.

[0071] Generally, polyglycolic acid and PLA have a Tg above 0° C. Polyglycolic acid generally has a Tg between 35° C. and 40° C. PLA generally has a Tg between 55° C. and 65° C.

[0072] On the other hand, the glass transition temperature of a resin depends on the structural units that make up the resin. Therefore, for example, polyglycolic acid, which is a copolymer of glycolic acid and caprolactone, may have a Tg of less than 0°C depending on the content of caprolactone. Also, polylactic acid, which is a copolymer of lactic acid and caprolactone, may have a Tg of less than 0°C depending on the content of caprolactone. Such polyglycolic acid and polylactic acid having a glass transition temperature of less than 0°C can also be considered biodegradable resins having a glass transition temperature of less than 0°C.

[0073] For example, the Tg of a copolymer of P3HA with 3HB and a monomer other than 3HB may depend on the type and content of the monomer other than 3HB in the copolymer. For example, P3HB3HH, which contains 10 mol% or more of 3HH repeating units out of 100 mol% of P3HB3HH repeating units, has a Tg of less than 0°C. For example, P3HB4HB, which contains 6 mol% or more of 4HB repeating units out of 100 mol% of P3HB4HB repeating units, has a Tg of less than 0°C.

[0074] As a biodegradable resin having a glass transition temperature of less than 0°C, one of the various resins described above may be used alone, or two or more may be used in combination. Furthermore, among the various resins described above, one of the resins described above may be used alone, or two or more may be used in combination. In relation to this, a biodegradable resin having a glass transition temperature of less than 0°C may be (i) composed solely of one or more aliphatic polyesters, (ii) composed solely of one or more aliphatic-aromatic polyesters, (iii) composed solely of a mixture of one or more aliphatic polyesters and one or more aliphatic-aromatic polyesters, or (iv) composed of a mixture of one or more aliphatic polyesters, one or more aliphatic-aromatic polyesters, and one or more resins other than aliphatic polyesters and aliphatic-aromatic polyesters.

[0075] The biodegradable resin having a glass transition temperature of less than 0°C preferably contains one or more selected from the group consisting of (i) poly(3-hydroxybutyrate-co-4-hydroxybutyrate), (ii) polycaprolactone, (iii) aliphatic polyesters having a structure obtained by polycondensation of an aliphatic diol and an aliphatic dicarboxylic acid, and (v) aliphatic aromatic polyesters, and more preferably is one or more selected from this group (consisting only of one or more selected from this group).

[0076] The crosslinked resin particles preferably contain 60% by weight or more of a biodegradable resin, more preferably 70% by weight or more, even more preferably 80% by weight or more, and particularly preferably 90% by weight or more, based on 100% by weight of the resin component of the crosslinked resin particles. The crosslinked resin particles may contain 100% by weight of a biodegradable resin, based on 100% by weight of the resin component of the crosslinked resin particles. In other words, the resin component of the crosslinked resin particles may be composed solely of a biodegradable resin.

[0077] The crosslinked resin particles may contain 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, even more preferably 80% by weight or more, and particularly preferably 90% by weight or more of a biodegradable resin having a glass transition temperature of less than 0°C, based on 100% by weight of the resin component of the crosslinked resin particles. A biodegradable resin having a glass transition temperature of less than 0°C is preferably contained in an amount of 50% by weight or more, since it has an excellent impact strength improving effect. Furthermore, a biodegradable resin having a glass transition temperature of less than 0°C is preferably contained in an amount of 70% by weight or more, since it has an even more excellent impact strength improving effect. The crosslinked resin particles may contain 100% by weight of a biodegradable resin having a glass transition temperature of less than 0°C, based on 100% by weight of the resin component of the crosslinked resin particles. In other words, the resin component of the crosslinked resin particles may be composed solely of a biodegradable resin having a glass transition temperature of less than 0°C. The term "resin component of the crosslinked resin particles" refers to the resin that essentially constitutes the crosslinked resin particles, and does not include components that crosslink the molecular chains of the resin (e.g., structures derived from polyfunctional compounds) or residues of components used to crosslink the molecular chains of the resin (e.g., unreacted peroxides, decomposition products of peroxides, unreacted polyfunctional compounds, etc.).

[0078] In one embodiment of the present invention, the biodegradable resin having a glass transition temperature of less than 0° C. may be a composition excluding crosslinked resin particles containing 50% by weight or more of P3HB3HH, a composition excluding crosslinked resin particles containing 60% by weight or more, a composition excluding crosslinked resin particles containing 70% by weight or more, a composition excluding crosslinked resin particles containing 80% by weight or more, or a composition excluding crosslinked resin particles containing 90% by weight or more. In one embodiment of the present invention, the crosslinked resin particles may be free of P3HB3HH. In other words, in one embodiment of the present invention, the crosslinked resin particles may be a composition excluding crosslinked resin particles containing P3HB3HH.

[0079] In one embodiment of the present invention, the biodegradable resin having a glass transition temperature of less than 0° C. may be a composition excluding crosslinked resin particles containing 50% by weight or more of P3HA, a composition excluding crosslinked resin particles containing 60% by weight or more, a composition excluding crosslinked resin particles containing 70% by weight or more, a composition excluding crosslinked resin particles containing 80% by weight or more, or a composition excluding crosslinked resin particles containing 90% by weight or more. The crosslinked resin particles in one embodiment of the present invention may be free of P3HA; in other words, in one embodiment of the present invention, the crosslinked resin particles may be a composition excluding crosslinked resin particles containing P3HA.

[0080] In one embodiment of the present invention, the biodegradable resin having a glass transition temperature of less than 0° C. may be a composition excluding crosslinked resin particles containing 50% by weight or more of PHA, a composition excluding crosslinked resin particles containing 60% by weight or more, a composition excluding crosslinked resin particles containing 70% by weight or more, a composition excluding crosslinked resin particles containing 80% by weight or more, or a composition excluding crosslinked resin particles containing 90% by weight or more. The crosslinked resin particles in one embodiment of the present invention may be free of PHA; in other words, in one embodiment of the present invention, the crosslinked resin particles may be a composition excluding crosslinked resin particles containing PHA.

[0081] <Gel Fraction> In this specification, the term "crosslinked resin particles" refers to particles having a crosslinked structure in which molecular chains of the resin constituting the resin particles are bonded intramolecularly and / or intermolecularly. That is, the crosslinked resin particles may have a crosslinked structure in which molecular chains of a biodegradable resin having a glass transition temperature of less than 0°C are bonded together. The amount of crosslinked structures in the crosslinked resin particles affects the gel fraction of the crosslinked resin particles; specifically, the more crosslinked structures there are, the higher the gel fraction. Since the crosslinked resin particles have a certain amount or more of crosslinked structures, they exhibit a high gel fraction, specifically a gel fraction of 50% or more. When the gel fraction of the crosslinked resin particles is 50% or more, the crosslinked resin particles have excellent hardness, heat resistance, and solvent resistance.

[0082] The gel fraction value is preferably 60% or more, more preferably 70% or more, even more preferably 75% or more, and particularly preferably 80% or more. It may also be 85% or more, or 90% or more. The upper limit of the gel fraction is not particularly limited, and may be 100% or less. From the viewpoint of production efficiency of crosslinked resin particles, the upper limit of the gel fraction is preferably 99.5% or less, more preferably 99% or less. The upper limit of the gel fraction may also be 98% or less, 97% or less, or 96% or less.

[0083] The gel fraction is a value measured as follows: (1) A dried product of crosslinked resin particles is added to chloroform so that the concentration becomes 0.7% by weight, and the resulting mixture is kept at 60°C for 30 minutes to obtain a chloroform solution; (2) The chloroform solution is then left to stand at room temperature for 3 hours, and then the chloroform solution is filtered through a membrane filter with a pore size of 0.45 µm; (3) The gel remaining on the filter is dried, and the weight of the dried gel together with the filter is measured, and the gel fraction is calculated using the following formula: Gel fraction (%) = {(Weight of filter including dried gel - Weight of filter only) / Weight of dried product of crosslinked resin particles used for measurement} x 100.

[0084] <Volume Average Particle Diameter> The volume average particle diameter of the crosslinked resin particles is preferably 0.05 μm to 10.00 μm. This configuration allows the crosslinked resin particles to be suitably used in various applications, as described below. From the viewpoint of practical use opportunities, the lower limit of the volume average particle diameter is more preferably 0.10 μm or more, more preferably 0.15 μm or more, and even more preferably 0.20 μm or more. Furthermore, from the viewpoint of productivity (such as the production and / or crosslinking treatment of biodegradable resins having a glass transition temperature of less than 0°C), 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.

[0085] In this specification, the volume average particle diameter (MV) of the crosslinked resin particles is a value obtained by measuring an aqueous dispersion in which the crosslinked resin particles are dispersed in an aqueous medium. More specifically, the volume average particle diameter (MV) of the crosslinked resin particles is a value calculated by the following formula (1), i.e., formula (2), when the particle diameters of the individual crosslinked resin particles contained in a population of k crosslinked resin particles in total are denoted as d1, d2, ..., di... dk in ascending order, and the volumes of these individual crosslinked resin particles are denoted as V1, V2, ..., Vi... Vk (where Vi is the volume of the crosslinked resin particle with particle diameter di):

[0086] A general-purpose measuring device can be used to measure the particle size and volume of crosslinked resin particles in an aqueous dispersion, and an example of such a device is Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd. In this specification, the volume average particle size of uncrosslinked resin particles can be measured by replacing "crosslinked resin particles" with "uncrosslinked resin particles" in the above method.

[0087] <Median diameter (D50)> The median diameter of the crosslinked resin particles is preferably 0.05 μm to 10.00 μm. This configuration enables the crosslinked resin particles to be suitably used in various applications, as described below. From the viewpoint of practical use opportunities, the lower limit of the median diameter is more preferably 0.10 μm or more, more preferably 0.15 μm or more, and even more preferably 0.20 μm or more. Furthermore, from the viewpoint of productivity (such as production and / or crosslinking treatment of the biodegradable resin (A)), the upper limit of the median diameter is more preferably 8.00 μm or less, and even more preferably 5.00 μm or less.

[0088] The median diameter is a value obtained by measurement using a dispersion liquid in which crosslinked resin particles are dispersed in an aqueous solvent. A general-purpose measuring device can be used as the measuring device, and an example of such a device is MicrotracMT3300EXII manufactured by Nikkiso Co., Ltd. More specifically, the particle diameter at which the larger and smaller sides are equal (50%) in the cumulative particle diameter distribution obtained by measurement is defined as the "median diameter (D50)".

[0089] <Peroxide> The crosslinked structure in the crosslinked resin particles is not particularly limited, but is preferably crosslinked using a peroxide. That is, the 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 constituting the resin particles (for example, a biodegradable resin having a glass transition temperature of less than 0°C). As a result, molecular chains of the resin constituting the resin particles are directly bonded to each other, thereby forming a crosslinked structure.

[0090] When the crosslinked resin particles are crosslinked using a peroxide, the aqueous dispersion containing the crosslinked resin particles may contain substances derived from the peroxide used to introduce the crosslinked structure (such as decomposition products of the peroxide and unreacted peroxide). Alternatively, when the crosslinked resin particles are crosslinked using a peroxide, substances derived from the peroxide used to introduce the crosslinked structure (such as decomposition products of the peroxide and unreacted peroxide) may adhere to the surface of the resulting crosslinked resin particles. In other words, when the crosslinked resin particles are crosslinked using a peroxide, the crosslinked resin particles or the present resin composition may contain substances derived from the peroxide (such as decomposition products of the peroxide and unreacted peroxide). When the crosslinked resin particles or the present resin composition contain substances derived from a peroxide, analysis of the crosslinked resin particles or the resin composition reveals that the crosslinked resin particles are crosslinked using a peroxide.

[0091] The peroxide may be an organic peroxide or an inorganic peroxide, but is preferably an organic peroxide because it can increase the gel fraction more efficiently.

[0092] As the organic peroxide, it is preferable to use at least one selected from the group consisting of diacyl peroxides, alkyl peroxy esters, dialkyl peroxides, hydroperoxides, peroxyketals, peroxycarbonates, and peroxydicarbonates, taking into consideration the heating temperature and / or time during the crosslinking treatment.

[0093] Specific examples of such organic peroxides include butyl peroxy neododecanoate, octanoyl peroxide, dilauroyl peroxide, succinic peroxide, a mixture of toluoyl peroxide and benzoyl peroxide, benzoyl peroxide, bis(butylperoxy)trimethylcyclohexane, butyl peroxylaurate, dimethyldi(benzoylperoxy)hexane, bis(butylperoxy)methylcyclohexane, bis(butylperoxy)cyclohexane, and butylperoxybenzo ester, butyl bis(butylperoxy)valerate, dicumyl peroxide, di-t-hexyl peroxide, t-butylperoxy 2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxypivalate, t-hexylperoxypivalate, t-butylperoxymethyl monocarbonate, t-pentylperoxymethyl monocarbonate, t-hexylperoxymethyl monocarbonate, t-heptylperoxymethyl monocarbonate, t-octylperoxymethyl monocarbonate, 1 , 1,3,3-tetramethylbutylperoxymethyl monocarbonate, t-butylperoxyethyl monocarbonate, t-pentylperoxyethyl monocarbonate, t-hexylperoxyethyl monocarbonate, t-heptylperoxyethyl monocarbonate, t-octylperoxyethyl monocarbonate, 1,1,3,3-tetramethylbutylperoxyethyl monocarbonate, t-butylperoxy n-propyl monocarbonate, t-pentylperoxy n-propyl monocarbonate, t-hexylperoxy peroxy isopropyl monocarbonate, t-heptylperoxy isopropyl monocarbonate, t-octylperoxy isopropyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy isopropyl monocarbonate, t-butylperoxy isopropyl monocarbonate, t-pentylperoxy isopropyl monocarbonate, t-hexylperoxy isopropyl monocarbonate, t-heptylperoxy isopropyl monocarbonate, t-octylperoxy isopropyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy isopropyl monocarbonate, t-butylperoxy n-butyl monocarbonate, t-pentylperoxy n-butyl monocarbonate, t-hexylperoxy n-butyl monocarbonate, t-heptylperoxy n-butyl monocarbonate, t-octylperoxy n-butyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy n-butyl monocarbonate, t-butylperoxy isobutyl monocarbonate, t-pentylperoxy isobutyl monocarbonate, t -Hexylperoxy isobutyl monocarbonate, t-heptylperoxy isobutyl monocarbonate, t-octylperoxy isobutyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy isobutyl monocarbonate, t-butylperoxy sec-butyl monocarbonate, t-pentylperoxy sec-butyl monocarbonate, t-hexylperoxy sec-butyl monocarbonate, t-heptylperoxy sec-butyl monocarbonate, t-octylperoxy sec-butyl monocarbonate t-butylperoxy t-butyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy sec-butyl monocarbonate, t-butylperoxy t-butyl monocarbonate, t-pentylperoxy t-butyl monocarbonate, t-hexylperoxy t-butyl monocarbonate, t-heptylperoxy t-butyl monocarbonate, t-octylperoxy t-butyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy t-butyl monocarbonate, t-butylperoxy 2-ethylhexyl monocarbonate, t-pentylperoxy 2-ethylhexyl monocarbonate ethylhexyl monocarbonate, t-hexylperoxy 2-ethylhexyl monocarbonate, t-heptylperoxy 2-ethylhexyl monocarbonate, t-octylperoxy 2-ethylhexyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexyl monocarbonate, diisobutyl peroxide, cumyl peroxy neodecanoate, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, bis(4-t-butylcyclohexyl) peroxydicarbonate, bis(2-ethylhexyl) peroxydicarbonate, t-hexyl peroxyneodecanoate, t-butyl peroxyneodecanoate, t-butyl peroxyneoheptanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, di(3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, disuccinic acid peroxide, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy) Examples of organic peroxides include hexane, t-hexylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, dibenzoyl peroxide, t-butylperoxy-2-ethylhexyl carbonate, t-butylperoxyisopropyl carbonate, 1,6-bis(t-butylperoxycarbonyloxy)hexane, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxyacetate, t-butylperoxybenzoate, t-amylperoxy-3,5,5-trimethylhexanoate, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, and 2,2-di-t-butylperoxybutane. One organic peroxide may be used alone, or two or more organic peroxides may be used in combination.

[0094] Among these, t-butylperoxyisopropyl monocarbonate, t-pentylperoxyisopropyl monocarbonate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy2-ethylhexyl monocarbonate, t-pentylperoxy2-ethylhexyl monocarbonate, t-hexylperoxy2-ethylhexyl monocarbonate, t-amylperoxyisopropyl monocarbonate, di-t-hexyl peroxide, t-butylperoxy2-ethylhexanoate Peroxymethylbutylperoxyisobutyrate, t-hexylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, t-butylperoxypivalate, t-hexylperoxypivalate, t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, and 1,1,3,3-tetramethylbutylperoxyneodecanoate are preferred organic peroxides because they can efficiently promote crosslinking of the resin that constitutes the resin particles.

[0095] Since the heating temperature during the crosslinking treatment can be set low, the peroxide is preferably a compound exhibiting a one-hour half-life temperature of 200° C. or less, more preferably a compound exhibiting a one-hour half-life temperature of 170° C. or less, and even more preferably a compound exhibiting a one-hour half-life temperature of 140° C. or less. The lower limit of the one-hour half-life temperature of the peroxide may be 50° C. or more, 60° C. or more, or 70° C. or more.

[0096] Particularly preferred organic peroxides exhibiting such a one-hour half-life temperature include t-butylperoxyisopropyl monocarbonate, t-butylperoxy 2-ethylhexyl monocarbonate, di-sec-butylperoxydicarbonate, t-butylperoxy 2-ethylhexanoate, t-butylperoxyisobutyrate, t-hexylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, t-butylperoxypivalate, t-hexylperoxypivalate, t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, and 1,1,3,3-tetramethylbutylperoxyneodecanoate.

[0097] The case where the peroxide is an inorganic peroxide will be described. Examples of the inorganic peroxide include hydrogen peroxide, potassium peroxide, calcium peroxide, sodium peroxide, magnesium peroxide, potassium persulfate, sodium persulfate, and ammonium persulfate, taking into consideration the heating temperature and / or time during the crosslinking treatment. Among these, hydrogen peroxide, potassium persulfate, sodium persulfate, and ammonium persulfate are preferred because they are easy to handle and have decomposition temperatures suitable for the heating temperature during the crosslinking treatment. The inorganic peroxide may be used alone or in combination of two or more. Furthermore, an organic peroxide and an inorganic peroxide may be used in combination.

[0098] <Multifunctional Compound> The crosslinked structure in the crosslinked resin particles may be introduced using only a peroxide, but it is preferable that it is introduced using both a peroxide and a multifunctional compound. That is, it is preferable that the crosslinked resin particles are crosslinked in the presence of a peroxide and a multifunctional compound. When both a peroxide and a multifunctional compound are used, the gel fraction of the crosslinked resin particles can be increased with a smaller amount of peroxide than when only a peroxide is used.

[0099] The polyfunctional compound refers to a compound having two or more functional groups (e.g., radical reactive groups) per molecule that can crosslink the resin that constitutes the resin particles (e.g., a biodegradable resin with a glass transition temperature of less than 0°C). The polyfunctional compound is not particularly limited, but is preferably a compound that is reactive with radicals generated from peroxides, and is particularly preferably a compound having two or more radical reactive groups per molecule. The radical reactive group is preferably at least one selected from the group consisting of a vinyl group, an allyl group, an acryloyl group, and a methacryloyl group.

[0100] Such polyfunctional compounds are not particularly limited, but examples thereof include allyl (meth)acrylate, allyl alkyl (meth)acrylates, allyloxyalkyl (meth)acrylates, polyfunctional (meth)acrylates having two or more (meth)acrylic groups such as ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol (meth)acrylate, divinylbenzene, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene. Preferably, the polyfunctional compound is one or more selected from the group consisting of allyl methacrylate, triallyl isocyanurate, butanediol di(meth)acrylate, and divinylbenzene, and more preferably, the polyfunctional compound is one or more selected from the group consisting of allyl methacrylate and triallyl isocyanurate.

[0101] When a crosslinked structure is formed in the presence of a polyfunctional compound, the resulting crosslinked resin particles usually contain a structure derived from the polyfunctional compound, in which case the molecular chains of the resin constituting the resin particles are bonded to each other via the structure derived from the polyfunctional compound.

[0102] <Other Components> The crosslinked resin particles may be composed solely of a biodegradable resin having a crosslinked structure and a glass transition temperature of less than 0° C., or may further contain a component other than the biodegradable resin having a crosslinked structure and a glass transition temperature of less than 0° C. Examples of components other than the biodegradable resin having a crosslinked structure and a glass transition temperature of less than 0° C. include the above-mentioned biodegradable resins having a glass transition temperature of 0° C. or higher, resins other than biodegradable resins, antioxidants, hydrolysis inhibitors, antiblocking agents, crystal nucleating agents, and ultraviolet absorbers.

[0103] The resins other than biodegradable resins having a glass transition temperature of less than 0° C. include the above-mentioned biodegradable resins having a glass transition temperature of 0° C. or higher, and resins other than biodegradable resins. These resins other than biodegradable resins having a glass transition temperature of less than 0° C. may be used alone or in combination of two or more. In the crosslinked resin particles, the resins other than biodegradable resins having a glass transition temperature of less than 0° C. may be crosslinked or not crosslinked.

[0104] The crosslinked resin particles are preferably non-expanded and are different from the expanded resin particles disclosed in WO 2007 / 049694 and WO 2019 / 146555. In other words, the crosslinked resin particles preferably contain substantially no air bubbles inside the particles. The phrase "substantially no air bubbles inside the particles" means that the volume of air bubbles (voids) is 10% or less of the 100% volume of the crosslinked resin particles.

[0105] 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).

[0106] The average weight per particle of the crosslinked resin particles is not particularly limited. For example, when the volume average particle size of the crosslinked resin particles is 10.00 μm or less, or when the median diameter of the 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. Here, a single crosslinked resin particle refers to a single particle (primary particle) that is not aggregated.

[0107] The shape of the crosslinked resin particles is not particularly limited. Examples of the shape of the crosslinked resin particles include spherical, elliptical, and rod-like shapes. The crosslinked resin particles do not all need to have a uniform shape, and various shapes may be present.

[0108] The crosslinked resin particles may be dried, and the shape of the dried particles may be powder, pellets, crumbs, a film, a sheet, or the like, depending on the drying method.

[0109] <Method for producing crosslinked resin particles> An example of a method for producing the crosslinked resin particles will be specifically described. The crosslinked resin particles can be produced by crosslinking resin molecular chains in an aqueous dispersion containing resin particles before crosslinking treatment in the presence of a peroxide. The term "resin particles" refers to particles composed of a resin component that essentially constitutes the crosslinked resin particles. When the resin component is composed solely of a biodegradable resin having a glass transition temperature of less than 0°C, the resin particles can also be referred to as biodegradable resin particles having a glass transition temperature of less than 0°C. To efficiently crosslink the resin molecular chains, it is preferable to heat the aqueous dispersion of resin particles containing a peroxide to a temperature suitable for decomposing the peroxide.

[0110] More specifically, the method for producing the crosslinked resin particles preferably includes the steps of: (1) preparing an aqueous dispersion of resin particles in which pre-crosslinked resin particles (e.g., PHA particles) are dispersed in water; (2) adding a peroxide to the aqueous dispersion of resin particles to impregnate the resin particles with the peroxide; and (3) heating the aqueous dispersion of resin particles impregnated with the peroxide to a heating temperature to crosslink the resin molecular chains (e.g., PHA molecular chains). Furthermore, the method more preferably includes the step of maintaining the heating temperature after all the peroxide has been added.

[0111] In step (1), for example, the aqueous dispersion of PHA particles may be an aqueous dispersion obtained by culturing a PHA-producing microorganism to accumulate PHA in the cells, disrupting the cells in the culture solution, and then separating and removing the cell components, or an aqueous dispersion obtained by concentrating or diluting the aqueous dispersion. According to such a method, the process from producing PHA particles by culturing a PHA-producing microorganism to crosslinking treatment can be carried out without separating the PHA particles from water.

[0112] Alternatively, the aqueous dispersion of resin particles (for example, PHA particles) can be prepared by dispersing dried resin particles (for example, PHA particles) in water.

[0113] The aqueous medium contained in the aqueous dispersion may be water alone or a mixed solvent of water and a water-compatible organic solvent. In the mixed solvent, the concentration of the water-compatible organic solvent is not particularly limited as long as it is equal to or lower than the solubility of the organic solvent in water.

[0114] The organic solvent is not particularly limited, but examples thereof include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, pentanol, hexanol, and heptanol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; nitriles such as acetonitrile and propionitrile; amides such as dimethylformamide and acetamide; dimethyl sulfoxide; pyridine; piperidine; and the like. Among these, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, acetonitrile, and propionitrile are preferred because they are easily removable. Furthermore, methanol, ethanol, 1-propanol, 2-propanol, butanol, and acetone are more preferred because they are easily available. Furthermore, methanol, ethanol, and acetone are particularly preferred.

[0115] 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.

[0116] In the aqueous dispersion, the volume average particle size or median size of the resin particles is preferably within the same range as that of the crosslinked resin particles. In the case of PHA particles produced by a PHA-producing microorganism, the volume average particle size or median size can usually be within the above range, so that an aqueous dispersion of PHA particles having a desired volume average particle size or median size can be obtained without performing a special step for adjusting the particle size.

[0117] The concentration of the resin particles in the aqueous dispersion is not particularly limited and can be set appropriately, but may be, for example, about 1 to 70% by weight, and preferably about 5 to 50% by weight.

[0118] The aqueous dispersion of resin particles preferably contains a dispersant to improve the dispersibility of the resin particles and promote the crosslinking reaction uniformly. Examples of the dispersant include anionic surfactants such as dioctyl sodium sulfosuccinate, sodium dodecyl sulfate, sodium lauryl sulfate, and sodium oleate; cationic surfactants such as lauryl trimethylammonium chloride; nonionic surfactants such as glycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene polyoxypropylene glycol; and water-soluble polymers such as polyvinyl alcohol, ethylene-modified polyvinyl alcohol, polyvinylpyrrolidone, methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, polyacrylic acid, sodium polyacrylate, potassium polyacrylate, polymethacrylic acid, and sodium polymethacrylate. These dispersants may be used alone or in combination of two or more.

[0119] When a dispersant is used, the content (addition amount) of the dispersant in the aqueous dispersion is not particularly limited. The content of the dispersant in the aqueous dispersion may be, for example, 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, and particularly preferably 0.5 to 3 parts by weight, relative to 100 parts by weight of the resin particles.

[0120] In step (2), a peroxide is added to the aqueous dispersion of resin particles obtained in step (1) to impregnate the resin particles with the peroxide. The peroxides described above can be used. Peroxides in various forms, such as solid and liquid, can be added. Alternatively, a diluted peroxide solution diluted with a diluent or the like can be added. The peroxide can be added all at once, continuously, or in portions.

[0121] When a peroxide and a polyfunctional compound are used in combination, it is preferable to add the polyfunctional compound to the aqueous dispersion of resin particles in step (2). The polyfunctional compound may be any of the polyfunctional compounds described above. The polyfunctional compound may be in various forms, such as a solid or liquid. Alternatively, the polyfunctional compound may be diluted with a diluent or the like to form a liquid polyfunctional compound. The polyfunctional compound may be added all at once, continuously, or in portions.

[0122] In step (2), the resin particles are impregnated with the peroxide and the optional polyfunctional compound by, for example, setting the temperature of the aqueous dispersion to, for example, 0°C or higher but lower than a temperature suitable for decomposing the peroxide employed in the subsequent step (3) after or while adding the peroxide and the optional polyfunctional compound to the aqueous dispersion of the resin particles, and maintaining the temperature for, for example, about 1 minute to 5 hours while stirring the aqueous dispersion. Specifically, the temperature of the aqueous dispersion during impregnation may be about 10°C to 60°C.

[0123] The amount of peroxide used can be appropriately set in consideration of the gel fraction of the crosslinked resin particles, and is, for example, preferably 0.01 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, even more preferably 0.3 to 5 parts by weight, and particularly preferably 0.5 to 3 parts by weight, per 100 parts by weight of the resin particles.

[0124] In the production method of crosslinking resin particles in an aqueous dispersion using a peroxide, crosslinking can be easily carried out while maintaining the particle size (volume) before crosslinking, thereby obtaining crosslinked resin particles. On the other hand, in the method of crosslinking a resin by melt-kneading in the presence of a peroxide, this can be difficult to achieve.

[0125] Furthermore, the manufacturing method of crosslinking resin particles in an aqueous dispersion using a peroxide has the advantage that it is easy to control the temperature rise caused by the heat generated during the crosslinking reaction, and crosslinked resin particles having a stable crosslinked structure (quality) can be obtained safely and efficiently.

[0126] The amount of the polyfunctional compound used may also be appropriately determined in consideration of the gel fraction of the crosslinked resin particles. The amount of the polyfunctional compound used is, for example, preferably 0.01 to 20 parts by weight, more preferably 0.05 to 15 parts by weight, even more preferably 0.1 to 10 parts by weight, still more preferably 0.2 to 5 parts by weight, and particularly preferably 0.3 to 3 parts by weight, relative to 100 parts by weight of the resin particles.

[0127] In step (3), the aqueous dispersion of resin particles impregnated with peroxide is heated to a temperature suitable for decomposing the peroxide. The heating temperature is preferably within a range of approximately 25°C above or below the one-hour half-life temperature of the peroxide (one-hour half-life temperature -25°C to one-hour half-life temperature +25°C). Specifically, the heating temperature is preferably 30°C to 140°C, more preferably 50°C to 135°C, and even more preferably 60°C to 130°C. This method allows the resin (e.g., PHA) to be crosslinked at a temperature lower than its melting point, thereby avoiding resin degradation due to heating during the crosslinking process. The melting point of PHA is, for example, 50°C to 210°C.

[0128] In the subsequent step (4), it is preferable to maintain the heating temperature. This allows the crosslinking reaction using the peroxide to proceed sufficiently. The time for maintaining the heating temperature is not particularly limited, but is preferably 1 minute to 15 hours, and more preferably 1 hour to 10 hours.

[0129] After the crosslinking reaction is complete, the crosslinked resin particles are separated from the aqueous dispersion, and water is removed from the separated crosslinked resin particles to obtain dried crosslinked resin particles. The method for separating the crosslinked resin particles from the aqueous dispersion is not particularly limited, and examples thereof include filtration, centrifugation, heat drying, freeze drying, and spray drying. For example, spray drying can be used to obtain dried crosslinked resin particles directly from the aqueous dispersion. Furthermore, by extruding the crosslinked resin particles alone after separation from the aqueous dispersion, residual water can be completely removed, and crosslinked resin particles can be obtained in pellet form. Furthermore, an aggregation step using a coagulant and / or pH adjustment may be performed.

[0130] 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 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. According to this configuration, the thermoplastic resin composition can provide a molded product having excellent impact resistance.

[0131] [1-2] Thermoplastic Resin The present resin composition contains a thermoplastic resin. In the present resin composition, the thermoplastic resin can also be called a matrix resin. The thermoplastic resin is not particularly limited as long as it can be molded into a desired shape by melting it when heated and then solidifying it by cooling.

[0132] Specific examples of thermoplastic resins include polyolefin resins such as polyethylene and polypropylene; polyvinyl chloride; polystyrene; polyvinyl acetate; polyurethane; polytetrafluoroethylene; acrylic resins such as polymethyl methacrylic acid; AS resin; polyamide; polyacetal; polycarbonate; modified polyphenylene ether; polyester resin; and cyclic polyolefin. 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.

[0133] The thermoplastic resin is particularly preferably a polyester resin, such as an aliphatic polyester (e.g., PHA, PLA, PCL, or an aliphatic polyester having a structure obtained by polycondensation of an aliphatic diol and an aliphatic dicarboxylic acid) or an aliphatic aromatic polyester.

[0134] Specific embodiments of the aliphatic polyester and the aliphatic aromatic polyester are the same as those described in the section <Biodegradable resin> in the section [1-1] Crosslinked resin particles, and therefore, the description therein is incorporated by reference and will not be repeated here.

[0135] Since the crosslinked resin particles contain a biodegradable resin, it is preferable that the thermoplastic resin also contains a biodegradable resin. This configuration has the advantage of increasing the biodegradability of the entire thermoplastic resin composition and the entire molded product of the thermoplastic resin composition. Therefore, it is expected to be useful as an environmentally friendly thermoplastic resin composition that addresses the problem of plastic waste. Furthermore, because this resin composition is biodegradable, the resin composition and molded product can reduce soil pollution due to disposal. This can contribute to the achievement of Sustainable Development Goals (SDGs), such as Goal 12 "Ensure sustainable consumption and production patterns." Furthermore, if the biodegradable resin is both soil and marine degradable, the resin composition and molded product can reduce marine pollution in addition to reducing soil pollution due to disposal.

[0136] The biodegradable resin contained in the thermoplastic resin may be a biodegradable resin having a glass transition temperature of less than 0°C, a biodegradable resin having a glass transition temperature of 0°C or higher, or a mixture of a biodegradable resin having a glass transition temperature of less than 0°C and a biodegradable resin having a glass transition temperature of 0°C or higher. Since the effects of incorporating crosslinked resin particles (e.g., impact resistance improvement effect) can be more fully enjoyed, it is preferable that the biodegradable resin contained in the thermoplastic resin contains a biodegradable resin having a glass transition temperature of 0°C or higher. The biodegradable resin contained in the thermoplastic resin preferably contains 50% by weight or more of a biodegradable resin having a glass transition temperature of 0°C or higher, more preferably 60% by weight or more, even more preferably 70% by weight or more, and particularly preferably 80% by weight or more, based on 100% by weight of the biodegradable resin. The biodegradable resin may be composed solely of a biodegradable resin having a glass transition temperature of 0°C or higher.

[0137] 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.

[0138] The case where the thermoplastic resin contains a biodegradable resin will be described below. The thermoplastic resin preferably contains 10% to 100% by weight of the biodegradable resin relative to 100% by weight of the thermoplastic resin. The thermoplastic resin more preferably contains 30% or more by weight of the biodegradable resin relative to 100% by weight of the thermoplastic resin, more preferably 50% or more by weight, even more preferably 70% or more by weight, and particularly preferably 90% or more by weight. The thermoplastic resin may be composed solely of the biodegradable resin.

[0139] Since the thermoplastic resin composition and its molded article can largely benefit from the impact resistance improving effect of the crosslinked resin particles, the biodegradable resin contained in the thermoplastic resin preferably contains a polyester-based resin, more preferably contains an aliphatic polyester, and particularly preferably contains PHA and / or polylactic acid. The PHA and / or polylactic acid used as the thermoplastic resin preferably has a gel fraction of less than 50%. The PHA and / or polylactic acid used as the thermoplastic resin preferably does not have a crosslinked structure.

[0140] 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.

[0141] There are no particular limitations on the PHA that can be used as the thermoplastic resin, and examples thereof include polyglycolic acid, P3HA, and poly(4-hydroxyalkanoate)-based resins. Only one type of PHA may be used, or two or more types may be used in combination. P3HA is particularly preferred as the PHA used as the thermoplastic resin.

[0142] 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 having the same composition as the P3HA contained in the crosslinked resin particles, or may be a resin having a different composition and / or physical properties. The P3HA contained in the thermoplastic resin is preferably a resin having a different composition and / or physical properties from the P3HA contained in the crosslinked resin particles, and is more preferably a resin that is harder than the P3HA contained in the crosslinked resin particles.

[0143] 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 3HB repeating units in all monomer repeating units (100 mol%) of the P3HA is preferably 80 mol% to 99 mol%, more preferably 82 mol% to 97 mol%. When the composition ratio of 3HB repeating units in the P3HA is 80 mol% or more, the rigidity of the P3HA can be further improved. On the other hand, when the composition ratio of 3HB repeating units in the P3HA is 99 mol% or less, the flexibility of the P3HA tends to be further improved. Two or more types of P3HA having different composition ratios of 3HB repeating units may be used in combination.

[0144] 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 resin composition and molded articles thereof. On the other hand, a PHA having a weight-average molecular weight of 3,000,000 or less can have the advantage of being easy to manufacture and / or easy to handle in order to achieve the object of one embodiment of the present invention.

[0145] Regarding the PHA and polylactic acid used as the thermoplastic resin, aspects other than those described above are the same as those explained in the section <Biodegradable Resin> in the section [1-1] Crosslinked Resin Particles above, and therefore, the explanation therefor is omitted here by citing that description.

[0146] 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 to 99.9 parts by weight, more preferably 40 to 99.7 parts by weight, more preferably 40 to 99.5 parts by weight, even more preferably 40 to 99 parts by weight, and even more preferably 40 to 95 parts by weight, per 100 parts by weight of the total of the thermoplastic resin and the crosslinked resin particles. According to this configuration, the thermoplastic resin composition can provide a molded article with excellent impact resistance. The content of the thermoplastic resin in the resin composition may be 45 to 93 parts by weight, 47 to 90 parts by weight, 50 to 80 parts by weight, 50 to 75 parts by weight, or 50 to 70 parts by weight, per 100 parts by weight of the total of 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.

[0147] [1-3] Sea-island structure The resin composition has a sea-island structure in which the thermoplastic resin forms a sea structure and the crosslinked resin particles form island structures. The sea-island structure refers to a structure in which island structures exist in the form of particles in a sea structure.

[0148] The average particle size of the island structure is preferably 0.05 μm to 10.0 μm, more preferably 0.07 μm to 9.0 μm, and even more preferably 0.10 μm to 8.0 μm.

[0149] It is preferable that the average particle size of the island structure is within the range of 0.05 μm to 10.0 μm, since excellent impact resistance can be achieved.

[0150] The average particle size of the island structures in the sea-island structure can be calculated, for example, by cutting the resin composition to form a cross section or a flake, then obtaining an enlarged image of the cross section or a plane of the flake using a microscope, and measuring the particle size of the island structures in the enlarged image. More specifically, in the Examples described below, in order to calculate the "single particle index, monodispersity ratio, and average aggregation degree of crosslinked resin particles in a thermoplastic resin composition," an enlarged image obtained by (Method 1) or (Method 2) is used to calculate the particle sizes of 30 or more particles (island structures) in a visual field where 30 or more particles (island structures) are present, and the number average is used as the average particle size. In this case, for particles with a distorted shape, the maximum length observed may be used as the length of the particle, and this may be used to calculate the average particle size.

[0151] The crosslinked resin particles may exist in the resin composition in the form of primary particles or secondary particles formed by aggregation of multiple crosslinked resin particles. When the crosslinked resin particles exist in the form of primary particles, in other words, when the crosslinked resin particles exist independently without aggregation, the primary particles, and when the crosslinked resin particles exist in the form of secondary particles formed by aggregation, the secondary particles each form a particulate island structure. The more the crosslinked resin particles are dispersed as primary particles without aggregation, the higher the dispersibility of the crosslinked resin particles. High dispersibility of the crosslinked resin particles enhances the impact energy absorption effect due to the uniform distribution of crosslinked resin particles that can function as an impact resistance modifier. Therefore, a molded product with excellent impact resistance can be provided.

[0152] In this specification, primary particles are considered to be "aggregated" (i.e., secondary particles) if they are in contact with each other even partially.

[0153] The shape of the particulate island structures is not particularly limited. Examples of the shape of the island structures include spherical, elliptical, rod-like, and irregular shapes. Furthermore, the island structures do not all need to be uniform in shape, and various shapes may be present. Furthermore, the shape of the primary particles of the crosslinked resin particles that form the island structures, or the shape of each of the crosslinked resin particles contained in the secondary particles that form the island structures and are formed by agglomeration of multiple crosslinked resin particles, is also not particularly limited. Examples of the shape of the crosslinked resin particles include spherical, elliptical, and rod-like shapes. Furthermore, the individual crosslinked resin particles do not all need to be uniform in shape, and various shapes may be present.

[0154] Furthermore, the present resin composition preferably satisfies at least one of the following (1) to (3).

[0155] (1) the crosslinked resin particles have a monoparticle index of 0.30 to 1.00; (2) the crosslinked resin particles have a monodispersity of 0.20 to 1.00; and (3) the crosslinked resin particles have an average aggregation degree of 1.0 to 5.0.

[0156] The above (1) to (3) are all indicators showing the dispersibility of the crosslinked resin particles in the present resin composition. By satisfying at least one, more preferably two, and even more preferably all of the indicators (1) to (3), there is an advantage that the molded article obtained by molding the present resin composition will have excellent impact resistance.

[0157] Here, in this specification, the term "single particle index" refers to the probability of primary particles existing as single particles without aggregation relative to the total number of particles (island structures) present in the resin composition (the sum of the number of secondary particles of the crosslinked resin particles and the number of primary particles existing as single particles without aggregation). For example, if the resin composition contains a total of three particles: a single particle consisting of one primary particle, one secondary particle formed by the aggregation of 10 primary particles, and one secondary particle formed by the aggregation of 20 primary particles, the "single particle index" is 1 / 3 = 0.33. In the resin composition, the single particle index of the crosslinked resin particles is 0.30 to 1.00, more preferably 0.40 to 1.00, and even more preferably 0.50 to 1.00. A single particle index of 0.30 or higher indicates that the crosslinked resin particles are more efficiently and uniformly dispersed, which has the advantage of providing a molded product with superior impact resistance for the same number of primary particles. The upper limit of the single particle index is 1.00.

[0158] As used herein, the term "monodispersity ratio" refers to the ratio of the number of primary particles present as single particles without aggregation to the total number of primary particles present in the resin composition (the sum of the number of primary particles contained in the secondary particles, which are aggregates, and the number of primary particles present as single particles without aggregation). In the above example, the "monodispersity ratio" is 1 / (1 + 10 + 20) = 0.032. In the resin composition, the monodispersity ratio of the crosslinked resin particles is 0.20 to 1.00, more preferably 0.30 to 1.00, and even more preferably 0.40 to 1.00. A monodispersity ratio of 0.20 or higher means that the crosslinked resin particles are more efficiently and uniformly dispersed, which has the advantage of providing a molded product with superior impact resistance for the same number of primary particles. The upper limit of the monodispersity ratio is 1.00.

[0159] As used herein, the term "average aggregation degree" refers to the average aggregation state of the crosslinked resin particles, calculated by dividing the total number of primary particles present in the resin composition (the sum of the number of primary particles contained in the secondary particles, which are aggregates, and the number of primary particles present as single particles without aggregation) by the total number of particles (island structures) present in the resin composition (the sum of the number of secondary particles of the crosslinked resin particles and the number of primary particles present as single particles without aggregation). In the above example, the "average aggregation degree" is (3 1 / 3) = 10.3. In the resin composition, the average aggregation degree of the crosslinked resin particles is 1.0 to 5.0, more preferably 1.0 to 3.0, and even more preferably 1.0 to 2.0. An average aggregation degree of 5.0 or less means that the crosslinked resin particles are more efficiently and uniformly dispersed, which has the advantage of providing a molded product with superior impact resistance for the same number of primary particles. The lower limit of the monodispersity ratio is 1.0.

[0160] The "single particle index," "monodispersity ratio," and "average degree of aggregation" can be calculated, for example, by cutting the resin composition to form a cross section or a thin section, obtaining an enlarged image of the cross section or an enlarged image of the surface of the thin section using a microscope, and then counting the number of particles (island structures), the total number of primary particles, the number of primary particles that exist as single particles without aggregation, and the number of secondary particles within a field of view where 30 or more particles (island structures) exist in the resin composition. Specific calculation methods will be described in detail in the Examples below.

[0161] In calculating the "single particle index," "monodispersity ratio," and "average degree of aggregation," as well as the average particle size of the island structure, only the cross-sectional surface of the resin composition is observed, or a thin slice thinner than the size of the primary particle is cut out, and an enlarged image of the cross-sectional surface or an enlarged image of the surface in the plane direction of the thin slice is observed, so that multiple layers of particles existing in the thickness direction of the observed area do not appear overlapping (particles existing deep below the observed surface are not visible). However, depending on where the cross-linked resin particles are cut when forming the cross-section or cutting out the thin slice, the particle size may be observed to be smaller than the actual particle size of the cross-linked resin particles.

[0162] [1-4] Other Components Included in the Resin Composition <Crystal Nucleating Agent> The resin composition may further contain a crystal nucleating agent. When the thermoplastic resin is a crystalline resin, the inclusion of a crystal nucleating agent in the thermoplastic resin composition promotes crystallization during molding, thereby improving molding processability, productivity, and the like. When the resin composition contains a crystal nucleating agent, there is also the advantage that a thermoplastic resin composition and a molded article thereof having excellent heat resistance or mechanical properties can be obtained.

[0163] The crystal nucleating agent is not particularly limited, and conventionally known ones can be used. Examples of the crystal nucleating agent include inorganic substances such as talc, kaolinite, montmorillonite, mica, synthetic mica, clay, zeolite, silica, carbon black, graphite, boron nitride, zinc oxide, titanium oxide, tin oxide, calcium carbonate, magnesium carbonate, aluminum oxide, neodymium oxide, barium sulfate, sodium chloride, and metal phosphates; sugar alcohol compounds derived from natural products such as erythritol, pentaerythritol, galactitol, mannitol, and arabitol; polysaccharides such as chitin and chitosan; polyols such as aliphatic alcohols (polyols), polyvinyl alcohol, and polyethylene oxide; sodium benzoate, potassium benzoate, lithium benzoate, calcium benzoate, magnesium benzoate, barium benzoate, lithium terephthalate, sodium terephthalate, and terephthalic acid salts. metal salts of organic carboxylic acids such as potassium phosphate, calcium oxalate, sodium laurate, potassium laurate, sodium myristate, potassium myristate, calcium myristate, sodium octacosanoate, calcium octacosanoate, sodium stearate, potassium stearate, lithium stearate, calcium stearate, magnesium stearate, barium stearate, sodium montanate, calcium montanate, sodium toluate, sodium salicylate, potassium salicylate, zinc salicylate, aluminum dibenzoate, potassium dibenzoate, lithium dibenzoate, sodium β-naphthalate, and sodium cyclohexanecarboxylate; organic sulfonates such as sodium p-toluenesulfonate and sodium sulfoisophthalate;Carboxylic acid amides such as ethylene stearic acid amide, ethylene bislauric acid amide, palmitic acid amide, hydroxystearic acid amide, erucic acid amide, and trimesic acid tris(t-butylamide), lauric acid esters, palmitic acid esters, oleic acid esters, stearic acid esters, erucic acid esters, N-oleyl palmitic acid ester, N-oleyl oleic acid ester, N-oleyl stearate, N-stearyl oleic acid ester, N-stearyl stearate, N-stearyl erucic acid ester, methylene bisstearate, ethylene bislauric acid ester, ethylene biscapric acid ester, ethylene bisoleic acid ester, ethylene bisstearate, ethylene biserucic acid ester, ethylene Examples of suitable crystal nucleating agents include carboxylic acid esters such as butylene bisisostearate, butylene bisstearate, and p-xylylene bisstearate; dicarboxylic acid derivatives such as dimethyl adipate, dibutyl adipate, diisodecyl adipate, and dibutyl sebacate; cyclic compounds having a functional group C═O and one or more functional groups selected from the group consisting of NH, S, and O in the molecule, such as indigo, quinacridone, and quinacridone magenta; sorbitol derivatives such as bisbenzylidene sorbitol and bis(p-methylbenzylidene)sorbitol; compounds containing a nitrogen-containing heteroaromatic nucleus, such as pyridine, triazine, and imidazole; phosphate ester compounds, bisamides of higher fatty acids, and metal salts of higher fatty acids; branched polylactic acid; and low-molecular-weight poly(3-hydroxybutyrate). These crystal nucleating agents may be used alone or in combination of two or more.

[0164] The content of the nucleating agent is not particularly limited as long as it can promote the crystallization of the thermoplastic resin. The content of the nucleating agent is preferably 0.05 to 12.00 parts by weight, more preferably 0.10 to 10.00 parts by weight, and even more preferably 0.50 to 8.00 parts by weight, per 100 parts by weight of the thermoplastic resin. When the content of the nucleating agent is within the above range, the effect of the nucleating agent can be obtained while suppressing a decrease in viscosity during molding and in the physical properties of the molded product.

[0165] <Lubricant> The resin composition may further contain a lubricant. When the thermoplastic resin composition contains a lubricant, the surface smoothness of the obtained molded article can be improved. The lubricant is not particularly limited. Examples of the lubricant include, but are not limited to, fatty acid metal salts such as magnesium stearate and calcium stearate; fatty acid amides such as behenic acid amide, stearic acid amide, erucic acid amide, oleic acid amide, methylenebisstearic acid amide, and ethylenebisstearic acid amide; polyethylene wax, oxidized polyester wax, glycerin monofatty acid esters such as glycerin monostearate, glycerin monobehenate, and glycerin monolaurate; organic acid monoglycerides such as succinic acid saturated fatty acid monoglycerides; sorbitan fatty acid esters such as sorbitan behenate, sorbitan stearate, and sorbitan laurate; polyglycerin fatty acid esters such as diglycerin stearate, diglycerin laurate, tetraglycerin stearate, tetraglycerin laurate, decaglycerin stearate, and decaglycerin laurate; and higher alcohol fatty acid esters such as stearyl stearate. Lubricants may be used alone or in combination of two or more.

[0166] The content of the lubricant (when multiple lubricants are used, the total content) is not particularly limited as long as it can impart lubricity to the molded 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 of the lubricant while avoiding bleeding out of the lubricant onto the surface of the molded body.

[0167] <Other Components> The present resin composition may contain other components such as plasticizers; organic fillers; inorganic fillers; antioxidants; hydrolysis inhibitors; ultraviolet absorbers; colorants such as dyes and pigments; and antistatic agents, to the extent that the functionality of the resulting molded article is not impaired.

[0168] The plasticizer is not particularly limited. Examples of the plasticizer include polyester-based plasticizers such as polypropylene glycol sebacate ester; aliphatic dibasic acid ester-based plasticizers such as di-1-butyl adipate, di-n-butyl sebacate, and di-2-ethylhexyl azelate; glycerin-based plasticizers such as glycerin diacetomonolaurate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate; polycarboxylic acid ester-based plasticizers such as tri-2-ethylhexyl acetylcitrate and tributyl acetylcitrate; polyolefin plasticizers such as polyethylene glycol, polypropylene glycol, poly(ethylene oxide-propylene oxide) block and / or random copolymers, and polytetramethylene glycol. alkylene glycol-based plasticizers; phosphate ester-based plasticizers such as diphenyl-2-ethylhexyl phosphate and diphenyloctyl phosphate; epoxy-based plasticizers such as epoxidized soybean oil and epoxidized linseed oil fatty acid butyl esters; and castor oil-based plasticizers such as castor oil fatty acid esters, methyl ricinoleate, ethyl ricinoleate, isopropyl ricinoleate, butyl ricinoleate, ethylene glycol monoricylate, propylene glycol monoricylate, trimethylolpropane monoricylate, sorbitan monoricylate, castor oil fatty acid polyethylene glycol esters, castor oil ethylene oxide adducts, castor oil-based polyols, castor oil-based toluene, and castor oil-based diols. These plasticizers may be used alone or in combination of two or more.

[0169] The organic filler is not particularly limited. Examples of the organic filler include fillers made of naturally-derived materials such as wood-based materials (e.g., wood chips, wood flour, sawdust, etc.), rice husks, rice flour, starch, corn starch, rice straw, wheat straw, and natural rubber; organic fibers such as natural plant fibers, natural animal fibers, and synthetic fibers; and fillers made of synthetic resin materials such as polyester, polyacrylic, polyamide, nylon, polyethylene, polyolefin, polyvinyl alcohol, polyvinyl chloride, polyurethane, polyacetal, aramid, PBO (poly-p-phenylene benzobisoxazole), polyphenylene sulfide, acetyl cellulose, polybenzazole, polyarylate, polyvinyl acetate, and synthetic rubber.

[0170] The natural plant fibers are not particularly limited. Examples of the natural plant fibers include kenaf fiber, abaca fiber, bamboo fiber, jute fiber, hemp fiber, linen fiber, henequen (sisal), ramie fiber, hemp, cotton, banana fiber, coconut fiber, palm, paper mulberry, Mitsumata, bagasse, etc. Other examples include regenerated fibers such as pulp, cellulose fiber, and rayon processed from plant fibers. Examples of natural animal fibers include wool, silk, cashmere, and mohair.

[0171] The inorganic filler is not particularly limited. Examples of the inorganic filler include silica-based inorganic fillers (e.g., quartz, fumed silica, silicic anhydride, fused silica, crystalline silica, amorphous silica, fillers formed by condensing alkoxysilanes, ultrafine amorphous silica, etc.), alumina, zircon, iron oxide, zinc oxide, titanium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, glass, silicone rubber, silicone resin, titanium oxide, carbon fiber, mica, graphite, carbon black, ferrite, graphite, diatomaceous earth, clay, clay, talc, calcium carbonate, manganese carbonate, magnesium carbonate, barium sulfate, and silver powder. These inorganic fillers may be surface-treated to improve dispersibility in the resin composition. These inorganic fillers may be used alone or in combination of two or more.

[0172] 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.

[0173] 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.

[0174] The ultraviolet absorber is not particularly limited. Examples of the ultraviolet absorber include benzophenone compounds, benzotriazole compounds, triazine compounds, salicylic acid compounds, cyanoacrylate compounds, and nickel complex salt compounds. These ultraviolet absorbers may be used alone or in combination of two or more.

[0175] The colorants such as pigments and dyes are not particularly limited. Examples of colorants include inorganic colorants such as titanium oxide, calcium carbonate, chromium oxide, cuprous oxide, calcium silicate, iron oxide, carbon black, graphite, titanium yellow, and cobalt blue; soluble azo pigments such as lake red, lithol red, and brilliant carmine; insoluble azo pigments such as dinitrile orange and fast yellow; phthalocyanine pigments such as monochlorophthalocyanine blue, polychlorophthalocyanine blue, and polybromophthalocyanine green; condensed polycyclic pigments such as indigo blue, perylene red, isoindolinone yellow, and quinacridone red; and dyes such as oracet yellow. These colorants may be used alone or in combination of two or more.

[0176] 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.

[0177] The resin composition may further contain any of the following additives: catalyst deactivators (hindered phenol compounds, thioether compounds, vitamin compounds, triazole compounds, polyamine compounds, hydrazine derivative compounds, phosphorus compounds, etc.), mold release agents (montanic acid and its salts, esters thereof, half esters thereof, stearyl alcohol, stearamide, polyethylene wax, etc.), color inhibitors (phosphites, hypophosphites, etc.), silane coupling agents (epoxy silane coupling agents, amino silane coupling agents, (meth)acrylic silane coupling agents, isocyanate silane coupling agents, etc.), flame retardants (red phosphorus, phosphate esters, brominated polystyrene, brominated polyphenylene ether, brominated polyisocyanate, methyl methyl silane ... The composition may also contain: polycarbonate, aluminum hydroxide, magnesium hydroxide, melamine and cyanuric acid or salts thereof, silicon compounds, etc.), conductive agents (carbon black, etc.), sliding property improvers (graphite, fluororesin, etc.), epoxy compounds (glycidyl ether compounds, glycidyl ester compounds, polymer compounds grafted or copolymerized with a glycidyl compound, etc.), acid anhydride compounds (maleic anhydride, succinic anhydride, polymer compounds grafted or copolymerized with an acid anhydride, etc.), carbodiimide compounds (N,N'-di-2,6-diisopropylphenylcarbodiimide, 2,6,2',6'-tetraisopropyldiphenylcarbodiimide, polycarbodiimide, etc.), etc.

[0178] The content of each of the other components described above is not particularly limited as long as the effect of one embodiment of the present invention is exhibited, and can be appropriately determined by a person skilled in the art.

[0179] [1-5] Method for Producing Thermoplastic Resin Composition The resin composition can be produced by a known method. Specifically, a method can be used in which a thermoplastic resin, crosslinked resin particles, and optional components such as a crystal nucleating agent, a lubricant, and other components are melt-kneaded using an extruder, kneader, Banbury mixer, kneading roll, or the like. When melt-kneading, it is preferable to mix the components while taking care to avoid a decrease in molecular weight due to thermal decomposition. Alternatively, the thermoplastic resin composition can be produced by dissolving all raw materials (components) in a soluble solvent and then removing the solvent.

[0180] When producing a thermoplastic resin composition by melt-kneading, each component may be charged separately into an extruder, etc., or the components may be mixed in advance and the resulting mixture may be charged into an extruder, etc. For example, an aqueous dispersion of a thermoplastic resin and an aqueous dispersion of crosslinked resin particles may be mixed, and then the resulting mixture may be dried in a dryer to obtain a mixed powder, which may then be charged into an extruder, etc.

[0181] When the thermoplastic resin, crosslinked resin particles, and optional components are melt-kneaded using an extruder, the resulting thermoplastic resin composition may be extruded from the extruder in the form of a strand and then cut, thereby processing the thermoplastic resin composition into particle shapes such as a bar shape, a cylindrical shape, an elliptical cylindrical shape, a sphere shape, a cube shape, or a rectangular parallelepiped shape.

[0182] 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.

[0183] [2. Molded Article] In one embodiment of the present invention, a molded article is provided, which is obtained by molding the present resin composition. The method for molding the thermoplastic resin composition is not particularly limited, and commonly used molding methods can be applied. Specific molding methods include inflation film molding, extrusion blow molding, injection blow molding, extrusion molding, calendar molding, vacuum molding, and injection molding. A molded article obtained by molding a thermoplastic resin composition can also be said to be a molded article containing a thermoplastic resin composition.

[0184] By carrying out the above-described molding method using the resin composition, molded articles having excellent impact resistance, specifically, sheet molded articles, film molded articles, blow molded articles, extrusion molded articles, vacuum molded articles, or injection molded articles, can be produced with good productivity. In this specification, the term "film molded article" refers to a product conforming to JIS 20108:2012, specifically, a thin film having a thickness of less than 0.25 mm. In this specification, the term "sheet molded article" refers to a product conforming to JIS 20108:2012, specifically, a thin plate having a thickness of 0.25 mm or more.

[0185] Molded articles containing the resin composition can be suitably used in agriculture, fisheries, forestry, horticulture, medicine, hygiene products, the food industry, clothing, non-clothing, packaging, automobiles, building materials, and other fields.

[0186] <Summary> One embodiment of the present invention includes the following configuration.

[0187] [1] A thermoplastic resin composition comprising crosslinked resin particles and a thermoplastic resin, wherein the crosslinked resin particles (i) comprise a biodegradable resin having a glass transition temperature of less than 0°C, (ii) have a gel fraction of 50% or more, and (iii) have a volume average particle diameter of 0.05 μm to 10.00 μm or a median diameter of 0.05 μm to 10.00 μm, and have a sea-island structure in which the thermoplastic resin forms a sea structure and the crosslinked resin particles form island structures, and the thermoplastic resin composition satisfies at least one of the following (1) to (3): (1) the single particle index of the crosslinked resin particles is 0.30 to 1.00, (2) the monodispersity ratio of the crosslinked resin particles is 0.20 to 1.00, and (3) the average aggregation degree of the crosslinked resin particles is 1.0 to 5.0.

[0188] [2] The thermoplastic resin composition according to [1], comprising 40 to 99 parts by weight of the thermoplastic resin and 1 to 60 parts by weight of the crosslinked resin particles (wherein the total amount of the thermoplastic resin and the crosslinked resin particles is 100 parts by weight).

[0189] [3] The thermoplastic resin composition according to [1] or [2], wherein the biodegradable resin is a polyhydroxyalkanoate-based resin.

[0190] [4] The thermoplastic resin composition according to [3], wherein the polyhydroxyalkanoate resin is a poly(3-hydroxyalkanoate) resin.

[0191] [5] The thermoplastic resin composition according to any one of [1] to [4], wherein the crosslinked resin particles are crosslinked using a peroxide.

[0192] [6] The thermoplastic resin composition according to [5], wherein the crosslinked resin particles are crosslinked in the presence of the peroxide and a polyfunctional compound.

[0193] [7] The thermoplastic resin composition according to any one of [1] to [6], wherein the crosslinked resin particles are not foamed.

[0194] [8] The thermoplastic resin composition according to any one of [1] to [7], further comprising a crystal nucleating agent and / or a lubricant.

[0195] [9] A molded article obtained by molding the thermoplastic resin composition according to any one of [1] to [8].

[0196]

[10] The molded article according to [9], which is a sheet molded article, a film molded article, a blow molded article, an extrusion molded article, a vacuum molded article, or an injection molded article.

[0197] EXAMPLES The following examples will be used to more specifically explain one embodiment of the present invention, but the present invention is not limited to these examples in any way.

[0198] [Measurement Method] <Weight-Average Molecular Weight> The resin to be measured was added to chloroform, and the resulting mixture was heated in a hot water bath at 60°C for 30 minutes. The resulting mixture (chloroform solution) was filtered through a disposable PTFE filter with a 0.45 μm pore size. The resulting filtrate was then subjected to GPC measurement under the following conditions to determine the weight-average molecular weight. GPC measurement device: High-performance liquid chromatograph 20A system manufactured by Shimadzu Corporation Columns: K-G 4A (1 column), K-806M (2 columns) manufactured by Showa Denko K.K. Sample concentration: 1 mg / ml Free solution: chloroform solution Free solution flow rate: 1.0 ml / min Sample injection volume: 100 μL Analysis time: 30 minutes Standard sample: standard polystyrene.

[0199] <Volume average particle diameter> The volume average particle diameter of the crosslinked resin particles or the uncrosslinked resin particles was measured using an aqueous dispersion of the crosslinked resin particles or the uncrosslinked resin particles as a sample. A Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd. was used as the measuring device. Specifically, the particle diameter and volume of each crosslinked resin particle in the aqueous dispersion of the crosslinked resin particles were measured using the above-mentioned device, and the volume average particle diameter was calculated from the measurement results based on the above-mentioned formula (1), i.e., formula (2).

[0200] <Median diameter (D50)> The median diameter of the crosslinked resin particles was measured using an aqueous dispersion of crosslinked resin particles as a sample. The measuring device used was a Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd. More specifically, the particle diameter at which the larger and smaller sides of the cumulative particle diameter distribution obtained by the measurement were equal (50%) was defined as the "median diameter (D50)."

[0201] <Gel Fraction> A dried product of crosslinked resin particles (B) or uncrosslinked resin particles was added to chloroform to a concentration of 0.7 wt % and maintained at 60°C for 30 minutes to obtain a chloroform solution. After allowing to stand at room temperature for 3 hours, the chloroform solution was filtered through a membrane filter with a pore size of 0.45 μm. Losses were prevented by pouring chloroform over the inside of the container and the filter multiple times while thoroughly washing. The gel remaining on the filter was dried and weighed together with the filter, and the gel fraction was calculated using the following formula: Gel fraction = (weight of filter including dried gel - weight of filter only) / weight of crosslinked resin particles (B) or uncrosslinked resin particles used in measurement × 100 (%).

[0202] <Tensile impact strength> A molded article having a thickness of 500 μm, prepared by the method described below, was cured for 7 days under conditions of 23° C. and 50% RH, and then punched out into a test specimen in the shape of JIS K 71603. A tensile impact test was performed on the test specimen according to the method in accordance with JIS K 7160 A.

[0203] <Glass Transition Temperature (Tg)> The temperature determined by measurement using the following method (differential scanning calorimetry (DSC)) was taken as the glass transition temperature of the resin: (1) 2 mg to 3 mg of resin was packed into an aluminum pan; (2) the aluminum pan was placed in a differential scanning calorimeter, and the temperature of the analyzer was raised from −80° C. to 180° C. at a rate of 10° C. / min under a nitrogen stream to completely melt the resin; (3) thereafter, the temperature of the analyzer was lowered from 180° C. to −80° C. at a rate of 10° C. / min; (4) the temperature of the analyzer was again raised from −80° C. to 180° C. at a rate of 10° C. / min; (5) for the DSC curve obtained in (4), the intermediate temperature between the temperature at which a shift (change) from the baseline started and the temperature at which it ended was taken as the glass transition temperature (Tg) of the resin.

[0204] <Single particle index, monodispersity ratio, and average aggregation degree of crosslinked resin particles in thermoplastic resin composition> (Method 1) For the thermoplastic resin composition pellets prepared by the method described below, a magnified image of the surface in the plane direction of the thin section was obtained. Specifically, using an FC6 manufactured by Leica Microsystems, ultrathin sections were prepared on the cross-sections of the thermoplastic resin composition pellets (cross-sections perpendicular to the extrusion direction of the pellets) under frozen conditions using an ultramicrotome. The prepared ultrathin sections were observed with a transmission electron microscope (TEM) H-7650 manufactured by Hitachi High-Technologies at a magnification of 40,000 times under observation conditions of an accelerating voltage of 100 kV. RuO was used for staining. ４ was used. More than 30 particles (island structures) were present within the obtained field of view of 6.2 μm × 4.1 μm. Within the field of view, the number of particles (island structures), the total number of primary particles, the number of primary particles that existed as single particles without aggregation, and the number of secondary particles were counted, and the single particle index, monodispersity ratio, and average aggregation degree were calculated using each number. Note that the areas seen with dark contrast in the TEM image are particles (island structures).

[0205] (Method 2) Enlarged cross-sectional images were obtained for the thermoplastic resin composition pellets prepared by the method described below. Specifically, a Leica Microsystems FC7 ultramicrotome was used to prepare cross-sectional cross sections (cross sections perpendicular to the extrusion direction of the pellets) of the thermoplastic resin composition pellets under frozen conditions. Mechanical property analysis was performed on the prepared cross sections using a scanning probe microscope (SPM) using a Bruker AXS Dimension Icon under the following conditions. Scanning probe microscope (SPM) analysis conditions: Mode: PeakForceQMN; Measurement area: 20 μm × 20 μm; Data count: 512 × 512; Probe: R-TESPA300. More than 30 particles (island structures) were present within the obtained 20 μm × 20 μm field of view. Within the field of view, the number of particles (island structures), the total number of primary particles, the number of primary particles that existed as single particles without aggregation, and the number of secondary particles were counted, and the single particle index, monodispersity ratio, and average aggregation degree were calculated using each number. The calculation of the single particle index, monodispersity ratio, and average aggregation degree utilized the elastic modulus image. Particles (island structures) are dark contrast areas that are circular, elliptical, etc., and other shapes that are clearly different from particles, such as linear or streaky, are noise generated during measurement or foreign matter, and are not particles.

[0206] [Production Examples 1 to 7: Production of Crosslinked Resin Particles] <Raw Materials for Crosslinked Resin Particles> (Uncrosslinked Resin Particles) PCL: Capa 6800 manufactured by Ingevity Corporation PHA-1: Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), repeating unit composition: (3-hydroxybutyrate) / (3-hydroxyhexanoate)=72 / 28 (mol / mol), weight average molecular weight Mw: 500,000 to 1,500,000 PHA-2: Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), repeating unit composition: (3-hydroxybutyrate) / (3-hydroxyhexanoate)=75 / 25 (mol / mol), weight average molecular weight Mw: 600,000 to 1,500,000 PHA-3: (poly(3-hydroxybutyrate-co-4-hydroxybutyrate), repeating unit composition: (3-hydroxybutyrate) / (4-hydroxybutyrate)=65 / 35 (mol / mol), weight average molecular weight Mw: 400,000 to 1,500,000)} PBAT: Ecoflex (registered trademark) F blend C1200 manufactured by BASF PLC PBSA: FD92 manufactured by Mitsubishi Chemical Corporation The weight average molecular weight of each resin was measured by the method described above.

[0207] (Peroxide) Di-sec-butyl peroxydicarbonate ("Luperox 225" manufactured by Arkema Yoshitomi Co., Ltd., 1-hour half-life temperature: 69°C).

[0208] (Polyfunctional compounds) CA-1: allyl methacrylate CA-2: triallyl isocyanurate.

[0209] <Production of Crosslinked Resin Particles> (Production Examples 1, 5 to 7) Crosslinked resin particles of Production Examples 1 and 5 to 7 were produced using the types of raw materials shown in Table 1 in the amounts shown in Table 1 according to the procedure described below.

[0210] A water dispersion (100 parts by weight of solids) of uncrosslinked resin particles dispersed in water, 200 parts by weight of deionized water, a predetermined amount of peroxide, 2 parts by weight of sodium dioctyl sulfosuccinate, and a predetermined amount of polyfunctional compound were added to a reaction vessel equipped with a stirrer, baffle, nitrogen inlet / outlet, and thermometer to prepare a water dispersion. Stirring of the resulting water dispersion was started at room temperature, and simultaneously, the atmosphere in the reaction vessel was replaced with nitrogen. The water dispersion in the reaction vessel was then stirred at room temperature for about 1 hour, allowing the peroxide and polyfunctional compound to be impregnated into the interior of the uncrosslinked resin particles.

[0211] Thereafter, the aqueous dispersion was heated to a reaction temperature under the crosslinking conditions shown in Table 1. After the reaction temperature was reached, the reaction was continued at the reaction temperature for the reaction time and heating temperature under the crosslinking conditions shown in Table 1, thereby obtaining an aqueous dispersion in which crosslinked resin particles were dispersed in water.

[0212] After adjusting the pH of the aqueous dispersion, the dispersion was dried in an oven to obtain solidified crosslinked resin particles.

[0213] (Production Examples 2 to 4) Crosslinked resin particles of Production Examples 2 to 4 were produced by the same procedure as in Production Example 1, except that the types of raw materials shown in Table 1 were used in the amounts shown in Table 1, the amount of deionized water used was changed from 200 parts by weight to 220 parts by weight, and the amount of dioctyl sodium sulfosuccinate used was changed from 2 parts by weight to 0.95 parts by weight.

[0214] <Measurement of Volume Average Particle Diameter or Median Diameter, and Gel Fraction> The volume average particle diameter or median diameter, and gel fraction of the crosslinked resin particles obtained in each Production Example were measured by the above-mentioned methods. The results are shown in Table 1.

[0215] Examples 1 to 8: Production of thermoplastic resin compositions Raw materials for thermoplastic resin compositions (Thermoplastic resins) PHBH (poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)): manufactured by Kaneka Corporation, Kaneka Biodegradable Polymer PHBH (registered trademark), repeating unit composition: (3-hydroxybutyrate) / (3-hydroxyhexanoate)=94.4 / 5.6 (mol / mol), weight average molecular weight Mw: 530,000, Tg: 3°C PLA (polylactic acid): manufactured by NatureWorks Inc. 2003D (crosslinked resin particles) Crosslinked resin particles prepared in Production Examples 1 to 4 (Crystal nucleating agent) Pentaerythritol: manufactured by Nippon Synthetic Chemical Industry Co., Ltd. Neuizer P (lubricant) Behenamide: manufactured by Nippon Fine Chemical Co., Ltd. BNT22H.

[0216] <Production of Thermoplastic Resin Composition> (Examples 1, 6 to 8) The thermoplastic resin, crosslinked resin particles, crystal nucleating agent, and lubricant listed in Table 2 were mixed in the amounts listed in Table 2 to obtain a mixture. The obtained mixture was melt-kneaded for 180 seconds in a small twin-screw kneader (Xplore MC5 manufactured by DSM) with the barrel temperature heated to 175°C and a screw rotation speed of 100 rpm to obtain a strand-shaped melt-kneaded product (mixture). The obtained melt-kneaded product was dried in a dryer at 80°C for 4 hours to sufficiently reduce the moisture content, thereby obtaining the thermoplastic resin compositions of Examples 1, 6 to 8. The obtained thermoplastic resin composition was then press-molded at 165°C to produce a molded product with a thickness of 500 μm.

[0217] (Examples 2, 3, and 5) For each Example, a mixture was obtained by mixing the thermoplastic resin, crosslinked resin particles, crystal nucleating agent, and lubricant shown in Table 2 in the amounts shown in Table 2. The same operation as in Example 1 was carried out on the obtained mixture, except that the screw rotation speed in melt-kneading was changed from 100 rpm and 180 seconds to 120 rpm and 150 seconds, to obtain thermoplastic resin compositions of Examples 2, 3, and 5, and the same operation as in Example 1 was carried out to prepare molded bodies.

[0218] <Measurement of tensile impact strength, single particle index, monodispersity ratio, and average degree of aggregation> The tensile impact strength was measured by the above-mentioned method for the molded products of Examples 1, 2, 3, and 5 to 8. The results are shown in Table 2.

[0219] The strand-like melt-kneaded product was cut using a pelletizer to obtain pellets of the thermoplastic resin composition. The single particle index, monodispersity, and average aggregation degree of the obtained pellet-like thermoplastic resin composition were calculated using the above-mentioned (Method 1) for the thermoplastic resin composition obtained in Example 1, and the above-mentioned (Method 2) for the thermoplastic resin compositions obtained in Examples 2, 3, and 5 to 8. The results are shown in Table 2.

[0220] Comparative Example 1 A molded body was prepared and its tensile impact strength was measured in the same manner as in Examples 1 to 3 and 5 to 8, except that no crosslinked resin particles were added and the thermoplastic resin, nucleating agent, and lubricant shown in Table 2 were mixed in the amounts shown in Table 2.

[0221] Example 4 For Example 4, the thermoplastic resin and crosslinked resin particles listed in Table 2 were mixed in the amounts listed in Table 2 to obtain a mixture. The obtained mixture was melt-kneaded for 150 seconds in a small twin-screw kneader (Xplore MC5 manufactured by DSM) with the barrel temperature heated to 175°C and a screw rotation speed of 120 rpm to obtain a strand-shaped melt-kneaded product (mixture). The obtained melt-kneaded product was dried in a dryer at 90°C for 2 hours to sufficiently reduce the moisture content, thereby obtaining the thermoplastic resin composition of Example 4. Furthermore, the obtained thermoplastic resin composition was press-molded at 170°C to produce a molded product with a thickness of 500 μm.

[0222] The tensile impact strength of the molded article of Example 4 was measured by the above-mentioned method. The results are shown in Table 2.

[0223] The strand-like melt-kneaded product was cut using a pelletizer to obtain pellets of a thermoplastic resin composition. The single particle index, monodispersity ratio, and average degree of aggregation of the obtained pellet-like thermoplastic resin composition were calculated using the above-mentioned (Method 2). The results are shown in Table 2.

[0224] As shown in Table 2, the thermoplastic resin compositions of Examples 1 to 8, which have an island-sea structure satisfying the specified single particle index, monodispersity rate, and average aggregation degree, have high tensile impact strength and excellent impact resistance. On the other hand, the thermoplastic resin composition of Comparative Example 1, which does not have a sea-island structure, has poor impact resistance.

[0225] According to one embodiment of the present invention, a novel thermoplastic resin composition capable of providing a molded article having excellent impact resistance can be provided, and therefore, this embodiment of the present invention can be suitably used in fields such as agriculture, fisheries, forestry, horticulture, medicine, hygiene products, the food industry, clothing, non-clothing, packaging, automobiles, building materials, and the like.

Claims

1. A thermoplastic resin composition comprising crosslinked resin particles and a thermoplastic resin, wherein the crosslinked resin particles (i) comprise a biodegradable resin having a glass transition temperature of less than 0°C, (ii) have a gel fraction of 50% or more, and (iii) have a volume average particle diameter of 0.05 μm to 10.00 μm or a median diameter of 0.05 μm to 10.00 μm, and have a sea-island structure in which the thermoplastic resin forms a sea structure and the crosslinked resin particles form an island structure, and the thermoplastic resin composition satisfies at least any one of the following (1) to (3): (1) the single particle index of the crosslinked resin particles is 0.30 to 1.00, (2) the monodispersity ratio of the crosslinked resin particles is 0.20 to 1.00, and (3) the average aggregation degree of the crosslinked resin particles is 1.0 to 5.

0.

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

3. The thermoplastic resin composition according to claim 1, wherein the biodegradable resin is a polyhydroxyalkanoate resin.

4. The thermoplastic resin composition according to claim 3, wherein the polyhydroxyalkanoate resin is a poly(3-hydroxyalkanoate) resin.

5. The thermoplastic resin composition according to claim 1, wherein the crosslinked resin particles are crosslinked using a peroxide.

6. The thermoplastic resin composition according to claim 5, wherein the crosslinked resin particles are crosslinked in the presence of the peroxide and a polyfunctional compound.

7. The thermoplastic resin composition according to claim 1, wherein the crosslinked resin particles are not expanded.

8. The thermoplastic resin composition according to claim 1, further comprising a crystal nucleating agent and / or a lubricant.

9. A molded article obtained by molding the thermoplastic resin composition according to any one of claims 1 to 8.

10. The molded product according to claim 9, which is a sheet molded product, a film molded product, a blow molded product, an extrusion molded product, a vacuum molded product, or an injection molded product.

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