Thermoplastic resin composition and molded article

Abstract

The present invention addresses the problem of providing a thermoplastic resin composition with which it is possible to produce a molded article having excellent impact resistance, rigidity, and heat resistance in a well-balanced manner. Said problem is solved by a thermoplastic resin composition which comprises a polyhydroxyalkanoate-based resin (A), a polylactic acid (B), and crosslinked resin particles (C), and in which the ratio of the number of particles existing in the polylactic acid (B) with respect to the total number of the crosslinked resin particles (C) is 0-20%.

Description

Thermoplastic resin composition and molded article

[0001] The present invention relates to thermoplastic resin compositions and molded articles.

[0002] In recent years, a technology has been developed that can improve the impact resistance of molded articles made from thermoplastic resin compositions by incorporating crosslinked resin particles into the thermoplastic resin composition.

[0003] For example, Patent Document 1 discloses a thermoplastic resin composition that further contains crosslinked resin particles in addition to a polyhydroxyalkanoate resin and a thermoplastic resin such as polylactic acid, thereby enabling the production of a molded article with improved impact strength. Patent Document 2 also discloses a thermoplastic resin composition that further contains crosslinked resin particles in addition to polylactic acid, which is a thermoplastic resin, thereby enabling the production of a molded article with improved impact strength.

[0004] International Publication No. 2023 / 190185 Brochure International Publication No. 2024 / 090484 Brochure

[0005] However, molded articles produced from thermoplastic resin compositions containing crosslinked resin particles in addition to the thermoplastic resin, as described in Patent Documents 1 and 2, sometimes had insufficient impact strength, such as tensile impact strength. Furthermore, the thermoplastic resin compositions containing crosslinked resin particles in addition to the thermoplastic resin sometimes had insufficient rigidity and / or heat resistance in the molded articles produced.

[0006] One embodiment of the present invention has been made in view of the present circumstances, and its objective is to provide a thermoplastic resin composition that can produce a molded article having a good balance of impact resistance, rigidity, and heat resistance.

[0007] As a result of diligent research to solve the above problems, the present inventors have found that the above problems can be solved if the thermoplastic resin composition comprises a polyhydroxyalkanoate resin, polylactic acid, and crosslinked resin particles, wherein the ratio of the number of crosslinked resin particles present in the polylactic acid to the total number of crosslinked resin particles is a predetermined ratio, and have completed the present invention. That is, the thermoplastic resin composition according to one embodiment of the present invention comprises a polyhydroxyalkanoate resin (A), polylactic acid (B), and crosslinked resin particles (C), wherein the ratio of the number of crosslinked resin particles (C) present in the polylactic acid (B) to the total number of crosslinked resin particles (C) is 0% or more and 20% or less.

[0008] According to one aspect of the present invention, a thermoplastic resin composition can be provided that can be used to manufacture molded articles with a good balance of impact resistance, rigidity, and heat resistance.

[0009] This figure shows the elastic modulus image obtained by performing scanning probe microscopy (SPM) analysis on the cross-section of the molded body manufactured in Example 1. This figure shows the elastic modulus image obtained by performing SPM analysis on the cross-section of the molded body manufactured in Example 2. This figure shows the elastic modulus image obtained by performing SPM analysis on the cross-section of the molded body manufactured in Example 3. This figure shows the elastic modulus image obtained by performing SPM analysis on the cross-section of the molded body manufactured in Example 4. This figure shows the elastic modulus image obtained by performing SPM analysis on the cross-section of the molded body manufactured in Example 5.

[0010] One embodiment of the present invention is described below, but the present invention is not limited thereto. The present invention is not limited to the 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. Moreover, new technical features can be formed by combining the technical means disclosed in each embodiment. All academic and patent documents mentioned herein are incorporated herein by reference.

[0011] [1. Thermoplastic Resin Composition] The thermoplastic resin composition according to one embodiment of the present invention comprises a polyhydroxyalkanoate resin (A), polylactic acid (B), and crosslinked resin particles (C), wherein the ratio of the number of crosslinked resin particles (C) present in the polylactic acid (B) to the total number of crosslinked resin particles (C) is 0% or more and 20% or less. Hereinafter, "glass transition temperature" will also be referred to as "Tg", "thermoplastic resin composition" will also be referred to as "resin composition", "thermoplastic resin composition according to one embodiment of the present invention" will also be referred to as "this resin composition", and "polyhydroxyalkanoate resin" will also be referred to as "PHA".

[0012] This resin composition contains PHA(A). This resin composition also contains polylactic acid(B). Polylactic acid(B) typically exhibits a rapid decrease in storage modulus and softening above its glass transition temperature (approximately 55 to 60°C), meaning it has low heat resistance. Therefore, when obtaining molded articles from a thermoplastic resin composition containing polylactic acid(B), the operating temperature range of the molded article is often narrowed, making practical application difficult. On the other hand, PHA(A) typically has a glass transition temperature below room temperature, and crystallization progresses during the molding process. Therefore, its storage modulus does not rapidly decrease at temperatures above the glass transition temperature of polylactic acid(B). Consequently, by being included in a thermoplastic resin composition containing polylactic acid(B), PHA(A) exhibits the function of increasing the storage modulus of the molded article produced from this thermoplastic resin composition at high temperatures, such as 70°C. Furthermore, this increase in storage modulus at high temperatures means improved heat resistance of the molded article made from the thermoplastic resin composition, thus broadening its operating temperature range. Therefore, by including PHA(A) in this resin composition, the heat resistance of the molded articles produced is suitably improved. In this specification, a molded article produced from a thermoplastic resin composition refers to a molded article obtained by molding a thermoplastic resin composition.

[0013] This resin composition contains polylactic acid (B). Polylactic acid (B) typically has higher rigidity than PHA (A), and when added in an appropriate amount, it facilitates the formation of a morphology in the molded article that allows crosslinked resin particles (C) to efficiently exhibit impact strength. Therefore, polylactic acid (B) has the function of increasing the impact strength and rigidity of molded articles manufactured from thermoplastic resin compositions. Thus, by containing polylactic acid (B), this resin composition exhibits a favorable improvement in the rigidity of the molded articles produced.

[0014] This resin composition contains crosslinked resin particles (C). The crosslinked resin particles (C) have a crosslinked structure, which allows for efficient plastic deformation of the resin phase when an external impact is applied, thus facilitating energy absorption. Therefore, the crosslinked resin particles (C) have the function of increasing the impact strength, expressed as the tensile impact strength, of molded articles manufactured from thermoplastic resin compositions. Thus, by including crosslinked resin particles (C), this resin composition exhibits a favorable improvement in the impact strength of the manufactured molded articles.

[0015] This resin composition has a configuration in which the ratio of the number of crosslinked resin particles (C) present in polylactic acid (B) to the total number of crosslinked resin particles (C) is between 0% and 20%. Hereinafter, "the ratio of the number of crosslinked resin particles (C) present in polylactic acid (B) to the total number of crosslinked resin particles (C)" will also be referred to as "the ratio of crosslinked resin particles (C) present in polylactic acid (B)". Note that a ratio of 0% of crosslinked resin particles (C) present in polylactic acid (B) means that no crosslinked resin particles (C) are present in polylactic acid (B). By having this configuration, this resin composition is expected to produce the following effects.

[0016] First, regarding rigidity, the rigidity of a molded article formed by molding a thermoplastic resin composition containing two or more thermoplastic resins with different rigidities is considered to be largely influenced by the portion composed of the thermoplastic resin with higher rigidity. Furthermore, generally speaking, a molded article produced from a resin composition containing PHA(A) and polylactic acid(B) has higher rigidity in the portion composed of polylactic acid(B) compared to the portion composed of PHA(A). Therefore, if the rigidity of the portion composed of polylactic acid(B) in the molded article can be maintained in a suitably high range, it is considered that the rigidity of the entire molded article can also be maintained in a suitably high range.

[0017] Here, crosslinked resin particles (C) may reduce the rigidity of a portion of a molded article made from a resin composed of multiple resin components (e.g., PHA (A) and polylactic acid (B)) for the following reason: - The total amount of low-rigidity components in the portion of the molded article made from the specific resin component increases. However, since this resin composition has the above-mentioned structure, in this resin composition, crosslinked resin particles (C) are either not present in the polylactic acid (B), or if present, the amount is small. Therefore, in a molded article made from this resin composition, the rigidity of the portion composed of polylactic acid (B) is not reduced by the crosslinked resin particles (C), or if it is reduced, the degree of reduction is mitigated, thus maintaining a suitably high range. Consequently, this resin composition is considered to have the effect of maintaining the rigidity of the entire molded article in a suitably high range.

[0018] Next, regarding the impact strength, when an impact is applied to a molded article manufactured from a thermoplastic resin composition containing two or more thermoplastic resins with different impact strengths, it is considered that the portion composed mainly of the thermoplastic resin with the lower impact strength will break due to the impact. Therefore, it is considered that the impact strength of the molded article is largely influenced by the portion composed of the thermoplastic resin with the lower impact strength. In addition, generally, a molded article manufactured from a resin composition containing PHA(A) and polylactic acid (B) has lower impact strength in the portion composed of PHA(A) compared to the portion composed of polylactic acid (B). Therefore, it is considered that the overall impact strength of the molded article is more favorably improved when the impact strength of the portion composed of PHA(A), rather than the portion composed of polylactic acid (B), is mainly improved.

[0019] As mentioned above, the crosslinked resin particles (C) have the function of increasing the impact strength of the molded article. Furthermore, since this resin composition has the above configuration, in this resin composition, the crosslinked resin particles (C) are either not present in the polylactic acid (B), or if present, the amount is small. Therefore, in this resin composition, all or most of the crosslinked resin particles (C) are present in the PHA (A). Consequently, in the molded article produced from this resin composition, the impact strength is mainly improved in the portion composed of PHA (A), rather than the portion composed of polylactic acid (B). Therefore, it is considered that this resin composition has the effect of more favorably improving the impact strength of the entire molded article produced.

[0020] Based on the above, this resin composition has the effect of producing molded articles with a good balance of impact strength, rigidity, and heat resistance.

[0021] Furthermore, since this resin composition and the molded articles obtained by molding this resin composition contain PHA, which is a biodegradable resin, they have the advantage of being biodegradable. Therefore, they are expected to be useful as thermoplastic resin compositions and molded articles that address the problem of plastic waste and are environmentally friendly. PHA has soil degradability and marine degradability as biodegradable materials. Therefore, this resin composition and the molded articles can be used as thermoplastic resin compositions and molded articles that have soil degradability and marine degradability as biodegradability. In other words, this resin composition and the molded articles can suppress soil pollution and / or marine pollution caused by waste. Therefore, one embodiment of the present invention is expected to contribute to achieving Sustainable Development Goals (SDGs) such as Goal 12 "Ensure sustainable consumption and production patterns" and / or Goal 14 "Conserve and sustainably use the oceans, seas and marine resources for sustainable development".

[0022] The following details the components and physical properties of this resin composition.

[0023] (PHA(A)) "PHA" is a general term for polymers containing hydroxyalkanoic acid as monomer units (monomer repeating units), and is generally biodegradable. PHA is an aliphatic polyester, preferably a polyester that does not contain aromatic rings. In this specification, "PHA" means a polymer that contains 50 mol% or more of hydroxyalkanoic acid repeating units out of the total monomer repeating units (100 mol%). PHA preferably contains 60 mol% or more of hydroxyalkanoic acid repeating units out of the total monomer repeating units (100 mol%), and more preferably 70 mol% or more.

[0024] The PHA(A) in this resin composition is not particularly limited. Examples of PHA(A) include polyglycolic acid, poly(3-hydroxyalkanoate) resins (hereinafter sometimes referred to as "P3HA"), and poly(4-hydroxyalkanoate) resins. One type of PHA(A) may be used alone, or two or more types may be used in combination.

[0025] In this specification, "polyglycolic acid" refers to the [-CH] of the total monomer repeating units (100 mol%). ２ This refers to a resin containing 50 mol% or more of the repeating unit represented by [-CO-O-]. Polyglycolic acid is [-CH ２ The repeating units represented by -CO-O- may be present in an amount of 60 mol% or more, 70 mol% or more, 80 mol% or more, or 90 mol% or more of the total monomer repeating units (100 mol%).

[0026] Polyglycolic acid may be a homopolymer of glycolic acid, or it may be a copolymer of glycolic acid with a monomer other than glycolic acid (for example, a copolymer of glycolic acid and lactic acid, or a copolymer of glycolic acid and caprolactone).

[0027] Polyglycolic acid can be obtained by known methods such as the condensation polymerization of glycolic acid and the ring-opening polymerization of glycolide.

[0028] The P3HA is given by the formula: [-CHR-CH ２ 3-hydroxyalkanoic acid repeating unit represented by -CO-O-] (where R is C ｎ H ２ｎ＋１ The PHA(A) contained in this resin composition is a polyhydroxyalkanoate containing an alkyl group represented by , where n is an integer between 1 and 15, as an essential repeating unit. In this specification, "P3HA" refers to a resin containing 50 mol% or more of the 3-hydroxyalkanoic acid repeating unit out of the total monomer repeating units (100 mol%). Because it is highly biodegradable and can be manufactured using renewable biomass resources as raw materials, thus being effective in reducing environmental impact, the PHA(A) contained in this resin composition preferably contains P3HA, and more preferably is P3HA (in other words, composed solely of P3HA).

[0029] The P3HA preferably contains 60 mol% or more of the 3-hydroxyalkanoic acid repeating units out of the total monomer repeating units (100 mol%), and more preferably 70 mol% or more.

[0030] P3HA is not particularly limited and may be a homopolymer containing the aforementioned repeating units or a copolymer containing the aforementioned repeating units. Examples of the copolymer include a copolymer 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, other examples of the copolymer include, for example, a copolymer of 3HB and one or more monomers selected from the group consisting of 4-hydroxybutanoic acid, 4-hydroxypentanoic acid, 4-hydroxyhexanoic acid, 4-hydroxyheptanoic acid, 4-hydroxyoctanoic acid, 4-hydroxynonanoic acid, 4-hydroxydecanoic acid, 4-hydroxyundecanoic acid, 4-hydroxydodecanoic acid, 4-hydroxytridecanoic acid, 4-hydroxytetradecanoic acid, 4-hydroxyhexadecanoic acid, and 4-hydroxyoctadecanoic acid.

[0031] Examples of P3HA include poly(3-hydroxybutyrate) (hereinafter sometimes referred to as "P3HB"), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (hereinafter sometimes referred to as "P3HB3HH"), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate-co-3-hydroxyoctanoate) (hereinafter sometimes referred to as "P3HB3HH3HO"), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (hereinafter sometimes referred to as "P3HB4HB"), and poly(3-hydroxybutyrate-co-3-hydroxypropionate). One type of P3HA may be used, or two or more types may be used in combination. In this specification, "poly(X-co-Y)" refers to a copolymer containing X repeating units and Y repeating units, and is intended to be a copolymer obtained by copolymerizing the monomer from which the X repeating units are derived with the monomer from which the Y repeating units are derived. In addition, during the production of P3HA by microorganisms, trace amounts (approximately 1 mol% or less) of monomers may be copolymerized, but if this does not significantly affect the physical properties of the obtained P3HA, those monomers will be considered not to have been copolymerized, and the product will be referred to by a name that does not include those monomers.

[0032] P3HA can be produced by microorganisms. Such microbially produced P3HA is usually composed only of D-isomer (R-isomer) 3-hydroxyalkanoic acid repeating units. Among microbially produced P3HA, P3HB, P3HB3HH, P3HB3HH3HO, and P3HB4HB are preferred, and P3HB3HH, P3HB3HH3HO, and P3HB4HB are more preferred, due to their ease of industrial production.

[0033] It is also preferable that P3HA contains 3-hydroxybutanoic acid (3HB) repeating units. When P3HA contains 3HB repeating units, from the viewpoint of balancing flexibility and strength, it is preferable that the composition ratio of 3HB repeating units in the total monomer repeating units (100 mol%) of P3HA be 80 mol% or more and 99 mol% or less, and more preferably 82 mol% or more and 98 mol% or less. When the composition ratio of 3HB repeating units in P3HA is 80 mol% or more, the rigidity of P3HA can be further improved. On the other hand, when the composition ratio of 3HB repeating units in P3HA is 99 mol% or less, the flexibility of P3HA tends to be further improved. The monomer composition ratio of P3HA can be measured by gas chromatography or the like (see, for example, International Publication No. 2014 / 020838). Two or more types of P3HA with different composition ratios of 3HB repeating units may be used in combination.

[0034] The microorganisms that produce P3HA are not particularly limited as long as they are capable of producing P3HA. For example, the first P3HB-producing bacterium was Bacillus megaterium, discovered in 1925, and other known natural microorganisms include Cupriavidus necator (formerly classified as Alcaligenes eutrophus, Ralstonia eutropha) and Alcaligenes latus. In these microorganisms, P3HB accumulates within the bacterial cells.

[0035] Furthermore, known microorganisms that produce copolymers of 3HB with other hydroxyalkanoates include Aeromonas caviae, a P3HB3HH-producing microorganism, and Alcaligenes eutrophus, a poly(3-hydroxybutyrate-co-4-hydroxybutyrate)-producing microorganism. In particular, Alcaligenes eutrophus AC32 strain (FERM BP-6038) (T. Fukui, Y. Doi, J. Bacteriol., 179, pp. 4821-4830 (1997)), into which genes for the P3HA synthase group have been introduced to increase the productivity of P3HB3HH, is preferred. Microbial cells that have been cultured under appropriate conditions to accumulate P3HA within their cells are used. In addition to the above, genetically modified microorganisms into which various P3HA synthesis-related genes have been introduced to produce the desired P3HA may be used, or the culture conditions, including the type of substrate, may be optimized.

[0036] The weight-average molecular weight of PHA(A) is not particularly limited. Preferably, the weight-average molecular weight of PHA(A) is 50,000 or more and 3,000,000 or less, more preferably 100,000 or more and 2,000,000 or less, and even more preferably 150,000 or more and 1,500,000 or less. When the weight-average molecular weight of PHA(A) is 50,000 or more, sufficient rigidity and / or strength can be obtained in the resin composition and its molded articles. On the other hand, PHA(A) with a weight-average molecular weight of 3,000,000 or less has the advantage of being easy to manufacture and / or having excellent handling properties.

[0037] In this specification, the measurement of the weight-average molecular weight can be carried out using gel permeation chromatography (GPC) (a "High Performance Liquid Chromatograph 20A System" manufactured by Shimadzu Corporation), using polystyrene gels (such as "K-G 4A" and "K-806M" manufactured by Showa Denko K.K.) for the columns, and using chloroform as the mobile phase. The weight-average molecular weight can be determined as the molecular weight in terms of polystyrene using a calibration curve obtained by measuring polystyrene with known molecular weights by the same measurement method. At this time, the calibration curve can be created using polystyrene with weight-average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. As the column in the GPC, a column appropriate for measuring the molecular weight may be used.

[0038] The gel fraction of PHA (A) is not particularly limited, but it is preferably less than 50%, more preferably 40% or less, still more preferably 30% or less, and may be 20% or less, 10% or less, or even 0% because there are advantages such as good moldability and enhanced modification effects due to the inclusion of crosslinked resin particles (C). The gel fraction of PHA is affected by the amount of the crosslinked structure possessed by the PHA. Specifically, the lower the gel fraction of PHA, the smaller the amount of the crosslinked structure possessed by the PHA. That is, PHA (A) in the present resin composition is preferably PHA with a small amount of crosslinked structure or PHA having no crosslinked structure.

[0039] The gel fraction is measured as follows: (1) Add the dried PHA(A) to chloroform to a concentration of 0.7% by weight, and hold the resulting mixture at 60°C for 30 minutes to obtain a chloroform solution; (2) After that, let the chloroform solution stand at room temperature for 3 hours, and then filter the chloroform solution using a membrane filter with a pore size of 0.45 μm; (3) After filtration, dry the gel remaining on the filter, measure the weight of the filter containing the dried gel, and calculate the gel fraction using the following formula: Formula: Gel fraction (%) = {(Weight of filter containing dried gel - Weight of filter only) / Weight of dried PHA(A) used for measurement} × 100.

[0040] From the viewpoint of suitably improving the heat resistance of molded articles produced from this resin composition, it is preferable that the PHA(A) content in this resin composition be high. Specifically, from the viewpoint of the above, the lower limit of the PHA(A) content is preferably 3 parts by weight or more, more preferably 5 parts by weight or more, even more preferably 10 parts by weight or more, even more preferably 15 parts by weight or more, and particularly preferably 20 parts by weight or more. Furthermore, if the resin composition contains an excessive amount of PHA(A), the rigidity of molded articles produced from this resin composition may decrease. From the viewpoint of preventing or reducing such decrease in rigidity, it is preferable that the PHA(A) content in this resin composition be low. Specifically, from the viewpoint of the above, the upper limit of the PHA(A) content is preferably 90 parts by weight or less, more preferably 85 parts by weight or less, even more preferably 80 parts by weight or less, even more preferably 75 parts by weight or less, and particularly preferably 70 parts by weight or less.

[0041] (Polylactic acid (B)) The polylactic acid (B) in this resin composition is not particularly limited, and conventionally known polylactic acid can be used. In this specification, "polylactic acid" refers to the [-CHCH] of the total monomer repeating units (100 mol%). ３ This refers to a resin containing 50 mol% or more of the repeating unit represented by [-CO-O-]. Polylactic acid is [-CHCH] ３The repeating unit represented by [—CO—O—] may be contained at 60 mol% or more, 70 mol% or more, 80 mol% or more, or 90 mol% or more of all monomer repeating units (100 mol%).

[0042] As the polylactic acid (B) in the present resin composition, it may be a crystalline polylactic acid, an amorphous polylactic acid, or a mixture of a crystalline polylactic acid and an amorphous polylactic acid.

[0043] The polylactic acid (B) in the present resin composition may be a homopolymer of lactic acid or a copolymer of lactic acid and another monomer. Further, it may be a blend of a homopolymer of lactic acid and a copolymer of lactic acid and another monomer.

[0044] Examples of the other monomer include aliphatic hydroxycarboxylic acids other than lactic acid, aliphatic polyhydric alcohols, aliphatic polyvalent carboxylic acids, polyfunctional polysaccharides, and caprolactone.

[0045] The lactic acid raw material for producing the polylactic acid (B) is not particularly limited, and L-lactic acid, D-lactic acid, DL-lactic acid, or a mixture thereof, L-lactide, D-lactide, meso-lactide, or a mixture thereof can be used. Lactic acid obtained by microbial fermentation from renewable raw materials such as starch can be preferably used.

[0046] As a method for producing the polylactic acid (B), known methods such as a dehydration polycondensation method and a ring-opening polymerization method can be applied and are not particularly limited.

[0047] The weight-average molecular weight of polylactic acid (B) in this resin composition is not particularly limited, but is preferably 50,000 or more and 1,000,000 or less, more preferably 70,000 or more and 700,000 or less, and even more preferably 100,000 or more and 400,000 or less. When the weight-average molecular weight of polylactic acid (B) is 50,000 or more, sufficient rigidity and / or strength can be obtained in this resin composition and its molded articles. On the other hand, polylactic acid (B) with a weight-average molecular weight of 1,000,000 or less may have the advantage of being easy to manufacture and / or easy to handle in order to achieve the objectives of one embodiment of the present invention.

[0048] From the viewpoint of suitably improving the rigidity of molded articles produced from this resin composition, a higher content of polylactic acid (B) in this resin composition is preferable. Specifically, from the viewpoint of the above, the lower limit of the polylactic acid (B) content is preferably 10 parts by weight or more, more preferably 15 parts by weight or more, even more preferably 20 parts by weight or more, even more preferably 25 parts by weight or more, and particularly preferably 30 parts by weight or more. Furthermore, if the resin composition contains an excess of polylactic acid (B), the characteristic of PHA(A) that makes it easy to maintain the storage modulus above the glass transition temperature of polylactic acid (B) as described above may not be expressed. For this reason, if the resin composition contains an excess of polylactic acid (B), the storage modulus at high temperatures of the resin composition may decrease, that is, the heat resistance of the molded article produced may decrease. From the viewpoint of preventing or reducing the decrease in the heat resistance of the molded article, a lower content of polylactic acid (B) in this resin composition is preferable. Specifically, from the above viewpoint, the upper limit of the polylactic acid (B) content is preferably 90 parts by weight or less, more preferably 85 parts by weight or less, even more preferably 80 parts by weight or less, even more preferably 75 parts by weight or less, and particularly preferably 70 parts by weight or less.

[0049] (Crosslinked resin particles (C)) The crosslinked resin particles (C) in this resin composition may be any crosslinked resin particles, and the other components are not particularly limited.

[0050] In this specification, "crosslinked resin particle" means a resin particle having a crosslinked structure in which the molecular chains of the resin constituting the resin particle are bonded together, for example, intramolecularly and / or intermolecularly. That is, a crosslinked resin particle (C) may have a crosslinked structure in which the molecular chains of the resin constituting it are bonded together.

[0051] The resin constituting the crosslinked resin particles (C) preferably includes a biodegradable resin. In other words, the crosslinked resin particles (C) preferably include a biodegradable resin.

[0052] Examples of the biodegradable resins include aliphatic polyesters and aliphatic aromatic polyesters.

[0053] Examples of aliphatic polyesters include (i) polyhydroxyalkanoate resins (sometimes referred to as "PHA"), (ii) polylactic acid (sometimes referred to as "PLA"), (iii) polycaprolactone (sometimes referred to as "PCL"), and (iv) aliphatic polyesters other than PHA, PLA, and PCL.

[0054] Aliphatic polyesters other than PHA, PLA, and PCL include aliphatic polyesters having a structure formed by the polycondensation of aliphatic diols and aliphatic dicarboxylic acids. Specific examples of aliphatic polyesters having a structure formed by the polycondensation of aliphatic diols and aliphatic dicarboxylic acids include polyethylene succinate, polybutylene succinate (sometimes referred to as "PBS"), polyhexamethylene succinate, polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polybutylene succinate adipate (sometimes referred to as "PBSA"), polyethylene sebacate, polybutylene sebacate, and the like.

[0055] Examples of the aliphatic aromatic polyesters include polybutylene adipate terephthalate (sometimes referred to as "PBAT"), polybutylene sebacate terephthalate (sometimes referred to as "PBSeT"), polybutylene azelate terephthalate (sometimes referred to as "PBazT"), polybutylene succinate terephthalate (sometimes referred to as "PBST"), and polybutylene succinate adipate terephthalate (sometimes referred to as "PBSAT").

[0056] The crosslinked resin particles (C) may contain one of the above-mentioned biodegradable resins alone, or two or more, regardless of the glass transition temperature of the resin. Preferably, the crosslinked resin particles (C) contain a biodegradable resin having a crosslinked structure, regardless of the glass transition temperature of the resin. In this specification, "X having a crosslinked structure" refers to X having a structure in which the molecular chains of two or more X molecules are bonded together, for example, intramolecularly and / or intermolecularly.

[0057] In one embodiment of the present invention, the crosslinked resin particles (C) preferably contain a resin that has higher compatibility with PHA (A) than with polylactic acid (B). In this case, the proportion of crosslinked resin particles (C) present in the polylactic acid (B) can be suitably controlled to 0% or more and 20% or less during the production of the resin composition, and as a result, the resin composition can be suitably produced. The resin with high compatibility with PHA (A) is not particularly limited, and for example, PHA can be mentioned. Therefore, in one embodiment of the present invention, the crosslinked resin particles (C) preferably contain PHA, and more preferably contain PHA having a crosslinked structure.

[0058] With respect to the PHA contained in the crosslinked resin particles (C), aspects other than those shown below are the same as those described in the section (PHA (A)) above, so we will refer to that description and omit further explanation here.

[0059] The PHA contained in the crosslinked resin particles (C) is preferably P3HA. The crosslinked resin particles (C) preferably contain P3HA, and more preferably contain P3HA having a crosslinked structure.

[0060] The P3HA contained in the crosslinked resin particles (C) preferably contains 3-hydroxybutanoic acid (3HB) repeating units. When the P3HA in the crosslinked resin particles (C) contains 3HB repeating units, from the viewpoint of balancing flexibility and strength, the composition ratio of 3HB repeating units in the total monomer repeating units (100 mol%) is preferably 60 mol% or more and 99 mol% or less, more preferably 61 mol% or more and 97 mol% or less, and even more preferably 62 mol% or more and 95 mol% or less. When the composition ratio of 3HB repeating units in the P3HA of the crosslinked resin particles (C) is 60 mol% or more, there is an advantage that the rigidity of the crosslinked resin particles (C) may be further improved. On the other hand, when the composition ratio of 3HB repeating units in the P3HA of the crosslinked resin particles (C) is 99 mol% or less, there is an advantage that the flexibility of the crosslinked resin particles (C) tends to be further improved. The monomer composition ratio of P3HA in the crosslinked resin particles (C) can be measured by gas chromatography or the like, similar to the monomer composition ratio of P3HA in PHA (A) (see, for example, International Publication No. 2014 / 020838). Two or more types of P3HA with different composition ratios of 3HB repeating units may be used in combination as the P3HA in the crosslinked resin particles (C).

[0061] The weight-average molecular weight of the resin contained in the crosslinked resin particles (C) is not particularly limited. Preferably, the weight-average molecular weight of the resin contained in the crosslinked resin particles (C) is 50,000 or more and 3,000,000 or less, preferably 100,000 or more and 2,000,000 or less, and more preferably 150,000 or more and 1,500,000 or less. When the weight-average molecular weight of the resin contained in the crosslinked resin particles (C) is 50,000 or more, there is an advantage that the tendency for the strength of the crosslinked resin particles (C) to decrease can be reduced or avoided. Alternatively, when the weight-average molecular weight of the resin contained in the crosslinked resin particles (C) is 50,000 or more, there is an advantage that the tendency for the crosslinked resin particles (C) to become sticky due to low molecular weight components can be reduced or avoided. On the other hand, if the weight-average molecular weight of the resin contained in the crosslinked resin particles (C) is 3,000,000 or less, it may have the advantage that the resin is easy to manufacture and / or that it is easy to handle in order to achieve the objective of one embodiment of the present invention. The numerical value of the weight-average molecular weight of the resin contained in the crosslinked resin particles (C) is a value obtained by measuring using the resin before the crosslinking treatment (for example, using resin particles before the crosslinking treatment (uncrosslinked resin particles)).

[0062] The resin content in the crosslinked resin particles (C) is not particularly limited. The resin content in the crosslinked resin particles (C) is preferably 50% by weight or more, more preferably 60% by weight or more, more preferably 70% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more, based on 100% by weight of the total amount of the crosslinked resin particles (C). The resin content in the crosslinked resin particles (C) may be 100% by weight, 99% by weight or less, or 95% by weight or less, based on 100% by weight of the total amount of the crosslinked resin particles (C). The resin content in the crosslinked resin particles (C) is preferably 50% by weight or more, more preferably 60% by weight or more, more preferably 70% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more, even more preferably 95% by weight or more, particularly preferably 99% by weight or more, and may also be 100% by weight.

[0063] Here, "resin components of crosslinked resin particles (C)" refers to the resin that substantially constitutes the crosslinked resin particles (C), and does not include components that crosslink the molecular chains of the resin or residues of components used for crosslinking the molecular chains of the resin. Examples of components that crosslink the molecular chains of the resin include structures derived from the polyfunctional compounds described later. Examples of residues of components used for crosslinking the molecular chains of the resin include unreacted peroxides, decomposition products of peroxides, and unreacted polyfunctional compounds derived from the peroxides and polyfunctional compounds described later. Note that the crosslinked resin particles (C) may contain the aforementioned components that crosslink the molecular chains of the resin and residues of components used for crosslinking the molecular chains of the resin.

[0064] From the viewpoint of easily improving the impact strength of molded articles produced from this resin composition, it is preferable that the crosslinked resin particles (C) include a 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 (glass transition temperature) section of the [Examples] section later. In other words, it is preferable that the crosslinked resin particles (C) include a biodegradable resin having a glass transition temperature of less than 0°C, as determined by the measurement method described later.

[0065] The crosslinked resin particles (C) may contain one type of resin, or two or more types of resins. The crosslinked resin particles (C) may, for example, contain only a biodegradable resin having a glass transition temperature of less than 0°C, in other words, may consist only of a biodegradable resin having a glass transition temperature of less than 0°C. The crosslinked resin particles (C) may, for example, contain only resins other than biodegradable resins having a glass transition temperature of less than 0°C, in other words, may consist only of resins other than biodegradable resins having a glass transition temperature of less than 0°C. Alternatively, the crosslinked resin particles (C) may contain a biodegradable resin having a glass transition temperature of less than 0°C and a resin other than a biodegradable resin having a glass transition temperature of less than 0°C. Examples of "resins other than biodegradable resins having a glass transition temperature of less than 0°C" include biodegradable resins having a glass transition temperature of 0°C or higher, and resins other than biodegradable resins.

[0066] 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 or higher and -60°C or lower. PBS generally has a Tg of -30°C or higher and -40°C or lower. PBSA generally has a Tg of -40°C or higher and -50°C or lower. PBAT generally has a Tg of -30°C or higher and -40°C or lower. PBSeT generally has a Tg of -20°C or higher and -40°C or lower. PBAZT generally has a Tg of -20°C or higher and -40°C or lower. PBST generally has a Tg of -20°C or higher and -40°C or lower. PBSAT generally has a Tg of -20°C or higher and -40°C or lower.

[0067] Generally, polyglycolic acid and PLA have a Tg of 0°C or higher. Polyglycolic acid generally has a Tg of 35°C or higher and 40°C or lower. PLA generally has a Tg of 55°C or higher and 65°C or lower.

[0068] On the other hand, the glass transition temperature of a resin depends on the constituent units of 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 caprolactone content. Similarly, polylactic acid, which is a copolymer of lactic acid and caprolactone, may also have a Tg of less than 0°C depending on the caprolactone content. Such polyglycolic acid and polylactic acid with a glass transition temperature of less than 0°C can also be considered biodegradable resins with a glass transition temperature of less than 0°C.

[0069] For example, the Tg of a copolymer of P3HA with 3HB and monomers other than 3HB may depend on the type of monomer other than 3HB in the copolymer and the content ratio of that monomer. For example, P3HB3HH in which 10 mol% or more of the total repeating units of P3HB3HH are 3HH repeating units is 10 mol% or more, has a Tg of less than 0°C. For example, P3HB4HB in which 6 mol% or more of the total repeating units of P3HB4HB are 4HB repeating units is 100 mol% or more, has a Tg of less than 0°C.

[0070] The crosslinked resin particles (C) may consist of one of the above-mentioned resin types alone, or a combination of two or more resins, as a biodegradable resin with a glass transition temperature of less than 0°C. Furthermore, each of the above-mentioned resin types may consist only of resins with the same composition of constituent units, or it may consist of a combination of two or more resins with different compositions of constituent units.

[0071] The crosslinked resin particles (C) are a biodegradable resin having a glass transition temperature of less than 0°C, and it is more preferable that (i) they contain PHA having a glass transition temperature of less than 0°C, (ii) they contain PHA having a glass transition temperature of less than 0°C and a crosslinked structure, (iii) they contain P3HA having a glass transition temperature of less than 0°C, and (iv) they contain P3HA having a glass transition temperature of less than 0°C and a crosslinked structure. The crosslinked resin particles (C) (the resin component of the crosslinked resin particles (C)) may consist only of PHA having a glass transition temperature of less than 0°C, or may consist only of P3HA having a glass transition temperature of less than 0°C.

[0072] Examples of resins other than biodegradable resins include polyolefin resins, acrylic resins, AS resins, polyamides, polyacetals, polycarbonates, modified polyphenylene ethers, non-biodegradable polyester resins, and cyclic polyolefins.

[0073] The content of resins other than biodegradable resins with a glass transition temperature of less than 0°C in the crosslinked resin particles (C) is not particularly limited, as long as it does not impair the effects of the present invention. The content of resins other than biodegradable resins with a glass transition temperature of less than 0°C in the crosslinked resin particles (C) is preferably 80% by weight or less, and more preferably 50% by weight or less, of 100% by weight of the resin component of the crosslinked resin particles (C). The content of resins other than biodegradable resins with a glass transition temperature of less than 0°C in the crosslinked resin particles (C) may be 0% by weight of 100% by weight of the resin component of the crosslinked resin particles (C). In other words, the crosslinked resin particles (C) may be crosslinked resin particles that do not contain resins other than biodegradable resins with a glass transition temperature of 0°C or higher. The content of resins other than biodegradable resins with a glass transition temperature of 0°C or higher in the crosslinked resin particles (C) can be measured by known methods.

[0074] <Peroxide> The cross-linked structure of the resin contained in the cross-linked resin particles (C) is not particularly limited, but it is preferable that it is cross-linked using a peroxide. That is, it is preferable that the cross-linked resin particles (C) contain a resin that has been cross-linked using a peroxide. When a peroxide is used, radicals generated by the decomposition of the peroxide act on the resin molecules that make up the resin particles. As a result, the molecular chains of the resin that make up the resin particles can be directly bonded together, for example, intramolecularly and / or intermolecularly, thereby forming a cross-linked structure.

[0075] If the crosslinked resin particles (C) contain a resin crosslinked using a peroxide, the aqueous dispersion containing the crosslinked resin particles (C) may contain substances derived from the peroxide used to introduce the crosslinked structure (such as decomposition products of the peroxide and unreacted peroxide). Alternatively, if the crosslinked resin particles (C) contain a resin crosslinked using a peroxide, substances derived from the peroxide used to introduce the crosslinked structure may be adhering to the surface of the obtained crosslinked resin particles (C). In other words, if the crosslinked resin particles (C) contain a resin crosslinked using a peroxide, the crosslinked resin particles (C) may contain substances derived from the peroxide. To put it another way, if the crosslinked resin particles (C) contain substances derived from the peroxide, then the crosslinked resin particles (C) can be said to be crosslinked resin particles containing a resin crosslinked using a peroxide. Therefore, by analyzing the presence or content of substances derived from the peroxide in the crosslinked resin particles (C), it is possible to determine whether or not the crosslinked resin particles (C) contain a resin crosslinked using a peroxide (i.e., whether they are crosslinked resin particles or uncrosslinked resin particles).

[0076] The peroxide may be an organic peroxide or an inorganic peroxide. Organic peroxides are preferred because they can more efficiently increase the gel fraction.

[0077] As the organic peroxide, it is preferable to use at least one selected from the group consisting of diacyl peroxide, alkyl peroxyester, dialkyl peroxide, hydroperoxide, peroxyketal, peroxycarbonate, and peroxydicarbonate, taking into consideration the heating temperature and / or time during the crosslinking treatment.

[0078] Examples of such organic peroxides include butyl peroxyneododecanoate, octanoyl peroxide, dilauroyl peroxide, succinic peroxide, a mixture of toluyl peroxide and benzoyl peroxide, benzoyl peroxide, bis(butyl peroxy)trimethylcyclohexane, butyl peroxylaurate, dimethyldi(benzoyl peroxy)hexane, bis(butyl peroxy)methylcyclohexane, bis(butyl peroxy)cyclohexane, and butyl peroxybenzo Eth, butylbis(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-tetramethylbutyl peroxymethyl monocarbonate, t-butyl peroxyethyl monocarbonate, t-pentyl peroxyethyl monocarbonate, t-hexyl peroxyethyl monocarbonate, t-heptyl peroxyethyl monocarbonate, t-octyl peroxyethyl monocarbonate, 1,1,3,3-tetramethylbutyl peroxyethyl monocarbonate, t-butyl peroxyn-propyl monocarbonate, t-pentyl peroxyn-propyl monocarbonate, t-hexyl peroxy Xy n-propyl monocarbonate, t-heptyl peroxy n-propyl monocarbonate, t-octyl peroxy n-propyl monocarbonate, 1,1,3,3-tetramethylbutyl peroxy n-propyl monocarbonate, t-butyl peroxyisopropyl monocarbonate, t-pentyl peroxyisopropyl monocarbonate, t-hexyl peroxyisopropyl monocarbonate, t-heptyl peroxyisopropyl monocarbonate, t-octyl peroxyisopropyl monocarbonate, 1,1,3,3-Tetramethylbutyl peroxyisopropyl monocarbonate, t-butyl peroxyn-butyl monocarbonate, t-pentyl peroxyn-butyl monocarbonate, t-hexyl peroxyn-butyl monocarbonate, t-heptyl peroxyn-butyl monocarbonate, t-octyl peroxyn-butyl monocarbonate, 1,1,3,3-tetramethylbutyl peroxyn-butyl monocarbonate, t-butyl peroxyisobutyl monocarbonate, t-pentyl peroxyisobutyl monocarbonate, t -Hexyl peroxyisobutyl monocarbonate, t-heptyl peroxyisobutyl monocarbonate, t-octyl peroxyisobutyl monocarbonate, 1,1,3,3-tetramethylbutyl peroxyisobutyl monocarbonate, t-butyl peroxysec-butyl monocarbonate, t-pentyl peroxysec-butyl monocarbonate, t-hexyl peroxysec-butyl monocarbonate, t-heptyl peroxysec-butyl monocarbonate, t-octyl peroxysec-butyl monocarbonate T, 1,1,3,3-tetramethylbutylperoxysec-butyl monocarbonate, t-butylperoxyt-butyl monocarbonate, t-pentylperoxyt-butyl monocarbonate, t-hexylperoxyt-butyl monocarbonate, t-heptylperoxyt-butyl monocarbonate, t-octylperoxyt-butyl monocarbonate, 1,1,3,3-tetramethylbutylperoxyt-butyl monocarbonate, t-butylperoxy2-ethylhexyl monocarbonate, t-pentylperoxy2-ethylhexyl Tylhexyl monocarbonate, t-hexyl peroxy 2-ethylhexyl monocarbonate, t-heptyl peroxy 2-ethylhexyl monocarbonate, t-octyl peroxy 2-ethylhexyl monocarbonate, 1,1,3,3-tetramethylbutyl peroxy 2-ethylhexyl monocarbonate, diisobutyl peroxide, cumyl peroxyneodecanoate, 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-tetramethylbutyl peroxy-2-ethylhexanoate, disuccinate peroxide, 2,5-dimethyl-2,5-bis(2-ethylhexanoyl peroxy) Examples include xane, t-hexyl peroxy-2-ethylhexanoate, di(4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butyl peroxy-2-ethylhexyl carbonate, t-butyl peroxyisopropyl carbonate, 1,6-bis(t-butyl peroxycarbonyloxy)hexane, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxyacetate, t-butyl peroxybenzoate, t-amyl peroxy, 3,5,5-trimethylhexanoate, 2,2-bis(4,4-di-t-butyl peroxycyclohexyl)propane, and 2,2-di-t-butyl peroxybutane. Organic peroxides may be used individually or in combination of two or more.

[0079] Among these, the following organic peroxides are preferred because they can efficiently promote the crosslinking of the resin constituting the crosslinked resin particles (C): t-butyl peroxyisopropyl monocarbonate, t-pentyl peroxyisopropyl monocarbonate, t-hexyl peroxyisopropyl monocarbonate, t-butyl peroxy 2-ethylhexyl monocarbonate, t-pentyl peroxy 2-ethylhexyl monocarbonate, t-hexyl peroxy 2-ethylhexyl monocarbonate, t-amyl peroxyisopropyl monocarbonate, di-t-hexyl peroxide, t -Butyl peroxy 2-ethylhexanoate, t-butyl peroxyisobutyrate, t-hexyl peroxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxy 2-ethylhexanoate, t-butyl peroxypivalate, t-hexyl peroxypivalate, t-butyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, and 1,1,3,3-tetramethylbutyl peroxyneodecanoate.

[0080] The peroxide is preferably a compound exhibiting a 1-hour half-life temperature of 200°C or less, more preferably 170°C or less, and even more preferably 140°C or less, so that the heating temperature during the crosslinking treatment can be set low. The lower limit of the 1-hour half-life temperature of the peroxide may be 50°C or higher, 60°C or higher, or 70°C or higher.

[0081] Among organic peroxides exhibiting such a 1-hour half-life temperature, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy 2-ethylhexyl monocarbonate, di-sec-butyl peroxydicarbonate, t-butyl peroxy 2-ethylhexanoate, t-butyl peroxyisobutyrate, t-hexyl peroxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxy 2-ethylhexanoate, t-butyl peroxypivalate, t-hexyl peroxypivalate, t-butyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, and 1,1,3,3-tetramethylbutyl peroxyneodecanoate are particularly preferred.

[0082] The case where the peroxide is an inorganic peroxide will be described. Examples of such inorganic peroxides 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 process. Among these, hydrogen peroxide, potassium persulfate, sodium persulfate, and ammonium persulfate are preferred in terms of ease of handling and having a decomposition temperature suitable for the heating temperature during the crosslinking process. One type of inorganic peroxide may be used alone, or two or more types may be used in combination. Furthermore, an organic peroxide and an inorganic peroxide may be used in combination.

[0083] <Polyfunctional Compounds> The crosslinked structure of the resin contained in the crosslinked resin particles (C) may be introduced using only peroxides, but it is preferable that it be introduced using both peroxides and polyfunctional compounds. That is, it is preferable that the crosslinked resin particles (C) contain resin that has been crosslinked in the presence of peroxides and polyfunctional compounds. When both peroxides and polyfunctional compounds are used, it becomes possible to increase the gel fraction of the crosslinked resin particles with a smaller amount of peroxide compared to when only peroxides are used.

[0084] In this specification, "polyfunctional compound" refers to a compound having two or more functional groups (e.g., radical-reactive groups) in one molecule that can bond to the resin constituting the resin particles. While polyfunctional compounds are not particularly limited, compounds that react with radicals generated from peroxides are preferred, and compounds having two or more radical-reactive groups in one molecule are particularly preferred. As radical-reactive groups, at least one selected from the group consisting of vinyl groups, allyl groups, acryloyl groups, and methacryloyl groups is preferred.

[0085] Such polyfunctional compounds are not particularly limited, but examples include allyl (meth)acrylate; allylalkyl (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; and divinylbenzene, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, etc. Preferably, one or more selected from the group consisting of allyl methacrylate, triallyl isocyanurate, butanediol di(meth)acrylate, and divinylbenzene, and particularly preferably one or more selected from the group consisting of allyl methacrylate and triallyl isocyanurate.

[0086] When a crosslinked structure is formed in the presence of a polyfunctional compound, the resulting crosslinked resin particles (C) may typically contain structures derived from the polyfunctional compound. In this case, the molecular chains of the resin constituting the resin particles are bonded together via structures derived from the polyfunctional compound.

[0087] <Other Components, etc.> The crosslinked resin particles (C) may further contain components other than the resin component. Examples of components other than the resin component include surfactants, proteins, antioxidants, hydrolysis inhibitors, blocking inhibitors, crystal nucleating agents, lubricants, and ultraviolet absorbers. The content of components other than the resin component is not particularly limited, as long as it does not impair the effects of the present invention. The content of components other than the resin component may be, for example, 5% by weight or less, and preferably 2% by weight or less, relative to the total weight of the crosslinked resin particles (C). Alternatively, the content of components other than the resin component may be 0% by weight relative to the total weight of the crosslinked resin particles (C), meaning that the crosslinked resin particles (C) may be crosslinked resin particles that do not contain components other than the resin component. The content of components other than the resin component can be measured by known methods.

[0088] The surfactant is not particularly limited and can be any conventionally known surfactant. Examples of the surfactant include cationic surfactants, anionic surfactants, and nonionic surfactants. Examples of cationic surfactants include lauryltrimethylammonium chloride. Examples of anionic surfactants include sodium dioctyl sulfosuccinate, sodium dodecyl sulfate, sodium lauryl sulfate, and sodium oleate. Examples of nonionic surfactants include glycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene polyoxypropylene glycol.

[0089] The aforementioned protein may be a protein derived from a PHA-producing microorganism that can be obtained when PHA, which is a raw material for cross-linked resin particles (C), is obtained using a PHA-producing microorganism. Therefore, when cross-linked resin particles (C) are obtained using PHA produced by a PHA-producing microorganism as a raw material, the resulting cross-linked resin particles (C) may contain a protein derived from the PHA-producing microorganism.

[0090] <Gel Fraction> The amount of cross-linked structure in the resin contained in the cross-linked resin particles (C) affects the gel fraction of the cross-linked resin particles (C). In other words, the amount of cross-linked structure in the resin contained in the cross-linked resin particles (C) can be evaluated by the gel fraction of the cross-linked resin particles (C). Specifically, the more cross-linked structure the resin contained in the cross-linked resin particles (C) has, the higher the gel fraction of the cross-linked resin particles (C). Since the cross-linked resin particles (C) contain a certain amount or more of resin with a cross-linked structure, they exhibit a high gel fraction, preferably 50% or more. When the gel fraction of the cross-linked resin particles (C) is 50% or more, the cross-linked resin particles (C) have excellent hardness, heat resistance, and solvent resistance.

[0091] The gel fraction of the crosslinked resin particles (C) is preferably 50% or more, more preferably 60% or more, even more preferably 70% or more, even more preferably 75% or more, and particularly preferably 80% or more. The gel fraction of the crosslinked resin particles (C) may also be 85% or more, or 90% or more. There is no particular upper limit to the gel fraction of the crosslinked resin particles (C), and it may be 100% or less. From the viewpoint of production efficiency of the crosslinked resin particles (C), the upper limit of the gel fraction of the crosslinked resin particles (C) is preferably 99.5% or less, and more preferably 99% or less. Furthermore, the upper limit of the gel fraction of the crosslinked resin particles (C) may also be 98% or less, 97% or less, or 96% or less.

[0092] The gel fraction of the cross-linked resin particles (C) is measured as follows: (1') The dried cross-linked resin particles (C) are added to chloroform to a concentration of 0.7% by weight, and the resulting mixture is held at 60°C for 30 minutes to obtain a chloroform solution; (2') After that, the chloroform solution is left to stand at room temperature for 3 hours, and then filtered using a membrane filter with a pore size of 0.45 μm; (3') After filtration, the gel remaining on the filter is dried, and the weight of the filter containing the dried gel is measured, and the gel fraction is calculated using the following formula: Formula: Gel fraction (%) = {(Weight of filter containing dried gel - Weight of filter only) / Weight of dried cross-linked resin particles used for measurement} × 100.

[0093] <Volume-average particle diameter> The volume-average particle diameter of the crosslinked resin particles (C) is preferably 0.10 μm or more and 10.00 μm or less. From the viewpoint of practical use, the lower limit of the volume-average particle diameter is more preferably 0.15 μm or more, more preferably 0.20 μm or more, even more preferably 0.30 μm or more, and particularly preferably 0.50 μm or more. Furthermore, from the viewpoint of productivity (production of biodegradable resins with a glass transition temperature of less than 0°C and / or crosslinking treatment, etc.), the upper limit of the volume-average particle diameter is more preferably 8.00 μm or less, and even more preferably 5.00 μm or less.

[0094] In this specification, the volume-average particle diameter (MV) of a cross-linked resin particle (C) is a value obtained by measuring using an aqueous dispersion in which the cross-linked resin particle (C) is dispersed in an aqueous medium. More specifically, the volume-average particle diameter (MV) of a cross-linked resin particle (C) is a value calculated by the following equation (1), i.e., equation (2), when, for a group of k cross-linked resin particles (C) in total, the particle diameters of the individual cross-linked resin particles (C) included in the group are denoted as d1, d2, ... di ... dk in ascending order, and the volumes of these individual cross-linked resin particles (C) are denoted as V1, V2, ... Vi ... Vk (where Vi is the volume of a cross-linked resin particle (C) with particle diameter di).

[0095] Furthermore, a general-purpose measuring device can be used as the measuring device for the volume-average particle diameter of the cross-linked resin particles (C) in the aqueous dispersion (in other words, the particle diameter and volume of the cross-linked resin particles (C)). An example of such a device is the MicrotracMT3300EXII manufactured by Nikkiso Co., Ltd. In addition, in this specification, the volume-average particle diameter of uncrosslinked resin particles can be measured by replacing "cross-linked resin particles (C)" with "uncrosslinked resin particles" in the above method.

[0096] The crosslinked resin particles (C) are different from the foamed resin particles as disclosed in International Publication No. 2007 / 049694 and International Publication No. 2019 / 146555, and are preferably non-foamed. In other words, the crosslinked resin particles (C) preferably substantially do not contain air bubbles inside the particles. "Substantially do not contain air bubbles inside the particles" means that the volume of air bubbles (space) is 10% or less in 100% of the volume of the crosslinked resin particles (C).

[0097] When the crosslinked resin particles (C) are not foamed, the apparent density of the crosslinked resin particles (C) shows a relatively large value. The apparent density of the crosslinked resin particles (C) is preferably more than 0.6 g / cm ３ and more preferably 0.7 g / cm ３ or more, and even more preferably 0.9 g / cm ３ or more. The apparent density of the crosslinked resin particles (C) can be determined by the method described in JIS K0061 (Methods for Measuring the Density and Specific Gravity of Chemical Products) or JIS Z8807 (Methods for Measuring the Density and Specific Gravity of Solids).

[0098] The average weight per particle of the crosslinked resin particles (C) is not particularly limited. For example, when the volume average particle diameter of the crosslinked resin particles is 10.00 μm or less, the average weight per particle of the crosslinked resin particles can be a value far lower than 0.1 mg.

[0099] The crosslinked resin particles (C) may be dried. The shape after drying can be in the form of powder, pellet, crumb, film, sheet, etc. depending on the drying method, but is not particularly limited.

[0100] From the viewpoint of suitably improving the impact strength of molded articles manufactured from this resin composition, it is preferable that the content of crosslinked resin particles (C) in this resin composition be high. Specifically, from the above viewpoint, the lower limit of the content of crosslinked resin particles (C) is preferably 5 parts by weight or more, more preferably 7 parts by weight or more, even more preferably 10 parts by weight or more, even more preferably 15 parts by weight or more, and particularly preferably 20 parts by weight or more. Furthermore, if the resin composition contains an excessive amount of crosslinked resin particles (C), the rigidity of molded articles manufactured from this resin composition may decrease. From the viewpoint of preventing or reducing such decrease in rigidity, it is preferable that the content of crosslinked resin particles (C) in this resin composition be low. Specifically, from the above viewpoint, the upper limit of the content of crosslinked resin particles (C) is preferably 50 parts by weight or less, more preferably 45 parts by weight or less, even more preferably 40 parts by weight or less, even more preferably 35 parts by weight or less, and particularly preferably 30 parts by weight or less.

[0101] From the viewpoint of more favorably improving the impact strength of a molded article formed from this resin composition and maintaining the rigidity of the molded article within a suitably high range, it is preferable that the proportion of crosslinked resin particles (C) present in polylactic acid (B) in this resin composition is small. From the above viewpoint, the upper limit of the proportion of crosslinked resin particles (C) present in polylactic acid (B) in this resin composition is 20% or less, preferably 15% or less, more preferably 10% or less, and even more preferably 8% or less. The lower limit of the proportion of crosslinked resin particles (C) present in polylactic acid (B) is 0%. In other words, in this resin composition, crosslinked resin particles (C) may not be present in polylactic acid (B). In this resin composition, the proportion of crosslinked resin particles (C) present in polylactic acid (B) may be 0.5% or more, or 1% or more.

[0102] The method for measuring and calculating the proportion of crosslinked resin particles (C) present in the polylactic acid (B) is not particularly limited, and known methods can be used. The proportion of crosslinked resin particles (C) present in the polylactic acid (B) in a resin composition is reflected with approximately the same accuracy in the proportion of crosslinked resin particles (C) present in the polylactic acid (B) in a molded article obtained by molding the resin composition. Therefore, the proportion of crosslinked resin particles (C) present in the polylactic acid (B) can be measured and calculated using a molded article obtained by molding the resin composition as a sample, and the obtained result can be considered as the proportion of crosslinked resin particles (C) present in the polylactic acid (B) in the resin composition.

[0103] Therefore, as a method for measuring and calculating the proportion of crosslinked resin particles (C) present in polylactic acid (B), for example, a method including the following steps (a) to (e), such as the method described in the examples, can be cited. Step (a): A step of molding the resin composition by any method to obtain a molded body. Step (b): A step of cutting the molded body obtained in step (a) by any method to prepare a cross-section of the molded body. Step (c): A step of performing scanning probe microscopy (SPM) analysis on the cross-section prepared in step (b) to obtain an elastic modulus image, which is a magnified image of the cross-section. Step (d): A step of measuring the total number of crosslinked resin particles (C) and the number of crosslinked resin particles (C) present in polylactic acid (B) in the elastic modulus image obtained in step (c) by any method. Step (e): A step of calculating the proportion of crosslinked resin particles (C) present in the polylactic acid (B) based on the following formula (3), using the total number of crosslinked resin particles (C) and the number of crosslinked resin particles (C) present in polylactic acid (B) measured in step (d). The percentage of cross-linked resin particles (C) present in polylactic acid (B) = (number of cross-linked resin particles (C) present in polylactic acid (B) / total number of cross-linked resin particles (C)) × 100 (3).

[0104] (Content ratio of each component) In this resin composition, the content ratio of each component (i.e., PHA(A), polylactic acid(B), and crosslinked resin particles(C)) is not particularly limited when the total amount of PHA(A), polylactic acid(B), and crosslinked resin particles(C) is set to 100% by weight. However, it is preferable that the content of PHA(A) is 2% by weight or more and 72% by weight or less, the content of polylactic acid(B) is 5% by weight or more and 90% by weight or less, and the content of crosslinked resin particles(C) is 2% by weight or more and 44% by weight or less.

[0105] That is, a thermoplastic resin composition according to a preferred embodiment of the present invention can also be expressed as follows: a thermoplastic resin composition comprising: 2% by weight or more and 72% by weight or less of a polyhydroxyalkanoate resin (A); 5% by weight or more and 90% by weight or less of polylactic acid (B); and 2% by weight or more and 44% by weight or less of crosslinked resin particles (C) [provided that the total amount of (A) to (C) is 100% by weight], wherein the ratio of the number of crosslinked resin particles (C) present in the polylactic acid (B) to the total number of crosslinked resin particles (C) is 0% or more and 20% or less.

[0106] In this resin composition, the content ratio of each component (where the total amount of (A) to (C) is 100% by weight) is preferably such that PHA (A) is 2% by weight or more and 64% by weight or less, polylactic acid (B) is 14% by weight or more and 87% by weight or less, and the content of crosslinked resin particles (C) is 3% by weight or more and 40% by weight or less; it is even more preferably such that PHA (A) is 3% by weight or more and 56% by weight or less, polylactic acid (B) is 22% by weight or more and 85% by weight or less, and the content of crosslinked resin particles (C) is 4% by weight or more and 37% by weight or less; and it is even more preferably such that PHA (A) is 3% by weight or more and 50% by weight or less, polylactic acid (B) is 30% by weight or more and 80% by weight or less, and the content of crosslinked resin particles (C) is 7% by weight or more and 34% by weight or less.

[0107] (Nurturing agent, lubricant) This resin composition may further contain a nucleating agent and / or a lubricant.

[0108] <Crystal Nucleating Agent> When the resin component contained in this resin composition is a crystalline resin, the inclusion of a crystal nucleating agent in this resin composition promotes crystallization during molding, which has the advantage of improving moldability, productivity, etc. When this resin composition contains a crystal nucleating agent, the resin composition and its molded article also have the advantage of having excellent heat resistance and / or mechanical properties. The resin component contained in this resin composition is, for example, PHA (A), polylactic acid (B), and other resins described later, as well as the resin contained in crosslinked resin particles (C).

[0109] The nucleating agent is not particularly limited and conventionally known substances can be used. Examples of the 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; aliphatic alcohols (polyols), polyvinyl alcohol, polyethylene oxide, and other polyols; sodium benzoate, potassium benzoate, lithium benzoate, calcium benzoate, magnesium benzoate, barium benzoate, lithium terephthalate, sodium terephthalate, and terephthalate. Organic carboxylic acid metal salts such as potassium oxalate, 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 montanaate, calcium montanaate, sodium toluylate, sodium salicylate, potassium salicylate, zinc salicylate, aluminum dibenzoate, potassium dibenzoate, lithium dibenzoate, sodium β-naphthalate, sodium cyclohexanecarboxylate, etc.; organic sulfonates such as sodium p-toluenesulfonate and sodium sulfisophthalate;Carboxylate amides such as ethylenebisstearamide, ethylenebislauamide, palmitamide, hydroxystearamide, erucamide, tris(t-butylamide) trimesinate, lauric acid esters, palmitic acid esters, oleic acid esters, stearic acid esters, erucic acid esters, N-oleyl palmitate, N-oleyl oleate, N-oleyl stearate, N-stearyl oleate, N-stearyl stearate, N-stearyl erucate, methylenebisstearate, ethylenebislaurate, ethylenebiscaprate, ethylenebisoleate, ethylenebisstearate, ethylenebiserucate, ethylene Examples include carboxylic acid esters such as lenbisisostearate, butylenebisstearate, and p-xylylenebisstearate; 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 their molecule, such as indigo, quinacridone, and quinacridone magenta; sorbitol derivatives such as bisbenzylidene sorbitol and bis(p-methylbenzylidene) sorbitol; compounds containing nitrogen-containing heteroaromatic nuclei 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 nucleating agents may be used individually or in combination of two or more.

[0110] The content of the nucleating agent in this resin composition (or the total amount if the resin composition contains multiple types of nucleating agents) is not particularly limited as long as it promotes the crystallization of the resin component. Preferably, the content of the nucleating agent in this resin composition is 0.05 parts by weight or more and 12.00 parts by weight or less, more preferably 0.10 parts by weight or more and 10.00 parts by weight or less, and even more preferably 0.50 parts by weight or more and 8.00 parts by weight or less, per 100 parts by weight of the resin component. 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 and physical properties of the molded product during molding.

[0111] <Lubricant> When this resin composition contains a lubricant, the surface smoothness of the resulting molded article may be improved. The lubricant is not particularly limited. Examples of lubricants include, but are not limited to, fatty acid metal salts such as magnesium stearate and calcium stearate; fatty acid amides such as behenamide, stearamide, erucamide, oleamide, methylenebisstearate, and ethylenebisstearate; glycerin monofatty acid esters such as polyethylene wax, oxidized polyester wax, glycerin monostearate, glycerin monobehenate, and glycerin monolaurate; organic acid monoglycerides such as succinic acid saturated fatty acid monoglyceride; sorbitan fatty acid esters such as sorbitan behenate, sorbitan stearate, and sorbitan laurate; polyglycerin fatty acid esters such as diglycerin stearate, diglycerin laurate, tetraglycerin stearate, tetraglycerin laurate, decaglycerin stearate, and decaglycerin laurate; and higher alcohol fatty acid esters such as stearyl stearate. The lubricant may be used alone or in combination of two or more types.

[0112] The lubricant content in this resin composition (or the total content if the resin composition contains multiple types of lubricants) is not particularly limited as long as it imparts lubricity to the molded article. Preferably, the lubricant content in this resin composition is 0.01 parts by weight or more and 20.00 parts by weight or less, more preferably 0.05 parts by weight or more and 10.00 parts by weight or less, even more preferably 0.10 parts by weight or more and 10.00 parts by weight or less, even more preferably 0.20 parts by weight or more and 5.00 parts by weight or less, and particularly preferably 0.30 parts by weight or more and 4.00 parts by weight or less, per 100 parts by weight of the resin component. When the lubricant content is within the above range, the lubricant effect can be obtained while avoiding the bleed-out of the lubricant to the surface of the molded article.

[0113] <Additives> In addition to the PHA(A), polylactic acid(B), crosslinked resin particles(C), and optionally included nucleating agents and lubricants, the resin composition may further contain, to the extent that it does not impair the effects of the present invention, additives such as the following: resins other than the PHA(A) and polylactic acid(B); plasticizers; organic fillers; inorganic fillers; antioxidants; hydrolysis inhibitors; ultraviolet absorbers; colorants such as dyes and pigments; antistatic agents, etc.

[0114] Hereinafter, resins other than PHA(A) and polylactic acid(B) will be referred to as "other resins." These other resins are not particularly limited and include, for example, polyolefin resins, acrylic resins, AS resins, polyamides, polyacetals, polycarbonates, modified polyphenylene ethers, polyester resins other than PHA and polylactic acid, and cyclic polyolefins.

[0115] Examples of the polyolefin resin include polyethylene and polypropylene. Examples of the acrylic resin include polyvinyl chloride, polystyrene, polyvinyl acetate, polyurethane, polytetrafluoroethylene, and polymethylmethacrylic acid.

[0116] The aforementioned other resins may be of one type only, or two or more types may be used in combination. Preferably, the gel fraction of the aforementioned other resins is less than 50%. Preferably, the aforementioned other resins are not crosslinked.

[0117] The plasticizer is not particularly limited. Examples of the plasticizer include polyester-based plasticizers such as polypropylene glycol sebacate; aliphatic dibasic acid ester plasticizers such as di-1-butyl adipate, di-n-butyl sebacate and di-2-ethylhexyl azelaate; glycerin-based plasticizers such as glycerin diacetomonolaurate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate; polycarboxylic acid ester plasticizers such as tri-2-ethylhexyl acetylcitrate and tributyl acetylcitrate; and poly(ethylene oxide / propylene oxide) block and / or random copolymers, poly(ethylene oxide / propylene oxide) block and / or random copolymers, polytetramethylene glycol, etc. Examples of plasticizers include lucylene 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 ricinoleates, ethyl ricinoleates, isopropyl ricinoleates, butyl ricinoleates, ethylene glycol monolicylate, propylene glycol monolicylate, trimethylolpropane monolicylate, sorbitan monolicylate, castor oil fatty acid polyethylene glycol ester, castor oil ethylene oxide adduct, castor oil-based polyols, castor oil-based toluene, or castor oil-based diols. These plasticizers may be used individually or in combination of two or more.

[0118] The organic filler is not particularly limited. Examples of the organic filler include fillers made from naturally derived materials such as wood-based materials (e.g., wood chips, wood powder, sawdust, etc.), rice husks, rice flour, starch, corn starch, rice straw, wheat straw, and natural rubber; organic fibers such as plant-derived natural fibers, animal-derived natural fibers, and synthetic fibers; and synthetic resins made from materials such as polyester, polyacrylic, polyamide, nylon, polyethylene, polyolefin, polyvinyl alcohol, polyvinyl chloride, polyurethane, polyacetal, aramid, PBO (poly-p-phenylenebenzobisoxazole), polyphenylene sulfide, acetylcellulose, polybenzazole, polyarylate, polyvinyl acetate, and synthetic rubber.

[0119] The aforementioned plant-derived natural fibers are not particularly limited. Examples of such plant-derived natural fibers include kenaf fiber, abaca fiber, bamboo fiber, jute fiber, hemp fiber, linen fiber, heneken (sisal), ramie fiber, hemp, cotton, banana fiber, coconut fiber, palm, paper mulberry, mitsumata, bagasse, etc. Also, regenerated fibers such as pulp, cellulose fiber, and rayon processed from plant fibers are also included. Examples of animal-derived natural fibers include wool, silk, cashmere, mohair, etc.

[0120] The inorganic filler is not particularly limited. Examples of the inorganic filler include silica-based inorganic fillers (e.g., quartz, fumed silica, anhydrous silicic acid, fused silica, crystalline silica, amorphous silica, fillers formed by condensing alkoxysilane, ultrafine amorphous silica, etc.), alumina, zircon, iron oxide, zinc oxide, titanium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, glass, silicone rubber, silicone resin, titanium oxide, carbon fiber, mica, graphite, carbon black, ferrite, graphite, diatomaceous earth, white clay, clay, talc, calcium carbonate, manganese carbonate, magnesium carbonate, barium sulfate, silver powder, etc. These inorganic fillers may be surface-treated to improve their dispersibility in the resin composition. Furthermore, these inorganic fillers may be used individually or in combination of two or more types.

[0121] The antioxidant is not particularly limited. Examples of the antioxidant include phenolic antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and the like. These antioxidants may be used individually or in combination of two or more.

[0122] The hydrolysis inhibitor is not particularly limited. Examples of hydrolysis inhibitors include carbodiimide compounds, epoxy compounds, isocyanate compounds, oxazoline compounds, and the like. These hydrolysis inhibitors may be used individually or in combination of two or more.

[0123] The ultraviolet absorber is not particularly limited. Examples of ultraviolet absorbers include benzophenone compounds, benzotriazole compounds, triazine compounds, salicylic acid compounds, cyanoacrylate compounds, nickel complex salt compounds, and the like. These ultraviolet absorbers may be used individually or in combination of two or more.

[0124] The aforementioned colorants, such as pigments and dyes, are not particularly limited. Examples of colorants include inorganic colorants such as titanium dioxide, 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, lysole red, and brilliant carmine; insoluble azo pigments such as dinitrian 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 oraset yellow. These colorants may be used individually or in combination of two or more.

[0125] The antistatic agent is not particularly limited. Examples of the antistatic agent include low molecular weight antistatic agents such as fatty acid ester compounds, aliphatic ethanolamine compounds, and aliphatic ethanolamide compounds, as well as high molecular weight antistatic agents. These antistatic agents may be used individually or in combination of two or more.

[0126] Furthermore, this resin composition contains the following additives: catalyst deactivators (hindered phenol compounds, thioether compounds, vitamin compounds, triazole compounds, polyhydric amine compounds, hydrazine derivative compounds, phosphorus compounds, etc.), mold release agents (montanic acid and its salts, its esters, its half-esters, stearyl alcohol, stearamide, and polyethylene wax, etc.), color inhibitors (phosphates, hypophosphates, etc.), silane coupling agents (epoxysilane coupling agents, aminosilane coupling agents, (meth)acrylicsilane coupling agents, isocyanate silane coupling agents, etc.), and flame retardants (red phosphorus, phosphate esters, brominated polystyrene, brominated polyphenylene ether). It may also contain brominated polycarbonate, aluminum hydroxide, magnesium hydroxide, melamine and cyanuric acid or its salts, silicon compounds, etc.), conductive agents (carbon black, etc.), lubrication modifiers (graphite, fluororesin, etc.), epoxy compounds (glycidyl ether compounds, glycidyl ester compounds, polymer compounds grafted or copolymerized with glycidyl compounds, etc.), acid anhydride compounds (maleic anhydride, succinic anhydride, polymer compounds grafted or copolymerized with acid anhydrides, etc.), carbodiimide compounds (N,N'-di-2,6-diisopropylphenylcarbodiimide, 2,6,2',6'-tetraisopropyldiphenylcarbodiimide, polycarbodiimide, etc.), etc.

[0127] The content of each additive described above is not particularly limited as long as it achieves the effect of the embodiment of the present invention, and can be appropriately determined by those skilled in the art.

[0128] (Marine biodegradability) Furthermore, since this resin composition contains PHA, which is a marine biodegradable resin, it may have excellent marine biodegradability. In other words, this composition may be a marine biodegradable composition.

[0129] In this specification, the marine biodegradability of a resin composition is evaluated by the degree of biodegradation after 30 days in seawater in a biochemical oxygen demand test (hereinafter sometimes referred to as "30-day biodegradation"). Specifically, a resin composition with a 30-day biodegradation of 40% or more can be evaluated as a resin composition with excellent marine biodegradability, i.e., a marine biodegradable composition.

[0130] From the viewpoint of reducing environmental impact, this composition is preferably a marine biodegradable composition, in other words, it is preferable that the degree of biodegradation after 30 days is 40% or more. From the viewpoint of further enhancing the effect of reducing environmental impact, the higher the degree of biodegradation of this resin composition after 30 days, the better. Specifically, it is preferable that it is 50% or more, more preferably 60% or more, even more preferably 70% or more, even more preferably 80% or more, and particularly preferable that it is 86% or more.

[0131] (Method for producing the resin composition) A known method can be used to produce the resin composition, and is not particularly limited. For example, a method for producing the resin composition can be a method of preparing the raw materials for the resin composition, such as PHA (A), polylactic acid (B), and crosslinked resin particles (C), as well as optionally the crystal nucleating agent, optionally the lubricant, and optionally the additive, and mixing the raw materials.

[0132] The method for preparing PHA(A) is not particularly limited, and known methods can be used, for example, the method listed in the section on (PHA(A)) above. The method for preparing polylactic acid(B) is not particularly limited, and known methods can be used, for example, the method listed in the section on (Polylactic acid(B)) above. The method for preparing crosslinked resin particles(C) is not particularly limited, and known methods can be used, for example, the method shown in the section on <Method for preparing crosslinked resin particles(C)> below can be used. The method for preparing the nucleating agent, the lubricant and the additive is not particularly limited, and known methods can be used.

[0133] The method for mixing the raw materials is not particularly limited, and known methods can be used. For example, the method described in the section on "Mixing Method" below can be used.

[0134] <Method for preparing cross-linked resin particles (C)> A specific example of a method for preparing cross-linked resin particles (C) is shown below. Hereinafter, this specific example of a method for preparing cross-linked resin particles (C) will be referred to as the "method for preparing cross-linked resin particles".

[0135] The aforementioned method for preparing crosslinked resin particles involves crosslinking the molecular chains of the resin in an aqueous dispersion containing resin particles before crosslinking treatment, in the presence of a peroxide.

[0136] Furthermore, "resin particles" refers to particles composed of resin components that substantially constitute the crosslinked resin particles (C). If the resin components consist only of the resin contained in the crosslinked resin particles (C), then the resin particles can also be said to be particles made of the resin contained in the crosslinked resin particles (C). In order to efficiently crosslink the molecular chains of the resin and efficiently prepare the crosslinked resin particles (C), it is preferable to heat the aqueous dispersion of resin particles containing peroxide to a temperature suitable for the decomposition of peroxide.

[0137] More specifically, the method for preparing crosslinked resin particles preferably includes the steps of: (1) preparing an aqueous dispersion of resin particles in which the resin particles before crosslinking treatment are dispersed in water; (2) adding peroxide to the aqueous dispersion of resin particles to impregnate the resin particles with peroxide; and (3) heating the aqueous dispersion of resin particles impregnated with peroxide to a heating temperature to crosslink the molecular chains of the resin. Furthermore, it is more preferable to include the step of maintaining the heating temperature after all the peroxide has been added (4).

[0138] In step (1), consider the case where, for example, PHA is used as the resin contained in the crosslinked resin particles (C), and a water dispersion of particles made of PHA, i.e., PHA particles, is prepared. In this case, the water dispersion of PHA particles may be a water dispersion obtained by culturing PHA-producing microorganisms to accumulate PHA in the cells, then destroying the cells in the culture medium and separating and removing the cell components, or a water dispersion obtained by concentrating or diluting the said water dispersion. With this method, the process from producing PHA particles by culturing PHA-producing microorganisms to the crosslinking treatment can be carried out without separating the PHA particles from the water.

[0139] Furthermore, an aqueous dispersion of resin particles can also be prepared by dispersing dried resin particles in water.

[0140] The aqueous medium contained in the aqueous dispersion may be water alone, or it may be a mixed solvent of water and a water-miscible organic solvent. In this mixed solvent, the concentration of the water-miscible organic solvent is not particularly limited, as long as it is less than or equal to the solubility of the organic solvent used in water.

[0141] The aforementioned organic solvent is not particularly limited and includes, for example, 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 the organic solvents listed above, 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 easy to remove. Furthermore, among the organic solvents listed above, methanol, ethanol, 1-propanol, 2-propanol, butanol, and acetone are more preferred because they are readily available. Moreover, among the organic solvents listed above, methanol, ethanol, and acetone are particularly preferred.

[0142] The water content in the total aqueous medium (100% by weight) constituting the aqueous dispersion is preferably 5% by weight or more and 100% by weight or less. 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 95% by weight or more.

[0143] In the aqueous dispersion, it is preferable that the volume-average particle diameter of the resin particles is within the same range as the volume-average particle diameter of the cross-linked resin particles (C) described above. In the case of PHA particles produced by PHA-producing microorganisms, their volume-average particle diameter is usually within the above range, so an aqueous dispersion of PHA particles having a desirable volume-average particle diameter can be obtained without performing any special steps to adjust the particle size.

[0144] The concentration of the resin particles in the aqueous dispersion is not particularly limited and can be set as appropriate, but for example, it may be about 1% by weight or more and 70% by weight or less, and preferably about 5% by weight or more and 50% by weight or less.

[0145] The aqueous dispersion of the resin particles preferably contains a dispersant to enhance the dispersibility of the resin particles and allow the crosslinking reaction to proceed uniformly. Examples of the dispersant include anionic surfactants such as sodium dioctyl 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, methylcellulose, ethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, polyacrylic acid, sodium polyacrylate, potassium polyacrylate, polymethacrylic acid, and polysodium polymethacrylate. One type of dispersant may be used, or two or more types may be used in combination.

[0146] When using the aforementioned dispersant, the amount of the dispersant in the aqueous dispersion is not particularly limited. The amount of the dispersant in the aqueous dispersion may be, for example, 0.1 parts by weight or more and 10 parts by weight or less, preferably 0.5 parts by weight or more and 5 parts by weight or less, and particularly preferably 0.5 parts by weight or more and 3 parts by weight or less, per 100 parts by weight of the resin particles.

[0147] In step (2), a peroxide is added to the aqueous dispersion of resin particles obtained in step (1) to impregnate the resin particles with the peroxide. The peroxide can be any of the types described above. The peroxide can be added in various forms, such as solid or liquid. Alternatively, the peroxide may be added in liquid form diluted with a diluent or the like. The peroxide may be added all at once, continuously, or in stages.

[0148] The peroxide and the polyfunctional compound may be used in combination, in which case it is preferable to add the polyfunctional compound to the aqueous dispersion of resin particles in step (2). The polyfunctional compound can be one of those described above. The polyfunctional compound can be added in various forms, such as solid or liquid. The polyfunctional compound may also be added in liquid form diluted with a diluent or the like. The polyfunctional compound may be added all at once, continuously, or in portions.

[0149] In step (2), a method for impregnating the resin particles with the peroxide and any of the polyfunctional compounds is to add these compounds to an aqueous dispersion of the resin particles, or while adding them, set the temperature of the aqueous dispersion to, for example, 0°C or higher and below a temperature suitable for the decomposition of the peroxide to be used in the next step (3), and maintain the temperature of the aqueous dispersion while stirring it for, for example, 1 minute or more and 5 hours or less. Specifically, the temperature of the aqueous dispersion during impregnation may be 0°C or higher and 80°C or lower.

[0150] The amount of peroxide used can be appropriately set considering the gel fraction of the crosslinked resin particles (C). The amount of peroxide used is preferably 0.01 parts by weight or more and 10 parts by weight or less, more preferably 0.1 parts by weight or more and 8 parts by weight or less, even more preferably 0.3 parts by weight or more and 5 parts by weight or less, and particularly preferably 0.5 parts by weight or more and 3 parts by weight or less, per 100 parts by weight of the resin particles.

[0151] According to the manufacturing method in which the resin particles are crosslinked in an aqueous dispersion using the peroxide, it is easy to obtain crosslinked resin particles (C) by proceeding with crosslinking while maintaining the particle size (volume) before crosslinking. On the other hand, it can be difficult to achieve this in the method of crosslinking the resin by melt-kneading in the presence of the peroxide.

[0152] Furthermore, the manufacturing method of crosslinking the resin particles in an aqueous dispersion using the peroxide has the advantage of making it easier to control the temperature rise due to the heat generated during the crosslinking reaction, and efficiently obtaining crosslinked resin particles (C) having a safe and stable crosslinked structure (quality).

[0153] Furthermore, the amount of the polyfunctional compound used may be appropriately set considering the gel fraction of the crosslinked resin particles (C). The amount of the polyfunctional compound used is preferably 0.01 parts by weight or more and 20 parts by weight or less per 100 parts by weight of the resin particles, more preferably 0.05 parts by weight or more and 15 parts by weight or less, even more preferably 0.1 parts by weight or more and 10 parts by weight or less, even more preferably 0.2 parts by weight or more and 5 parts by weight or less, and particularly preferably 0.3 parts by weight or more and 3 parts by weight or less.

[0154] In step (3), the aqueous dispersion of resin particles impregnated with the peroxide is heated to a temperature suitable for the decomposition of the peroxide. The heating temperature is preferably within a range of approximately ±25°C from the 1-hour half-life temperature of the peroxide (1-hour half-life temperature - 25°C or higher, and 1-hour half-life temperature + 25°C or lower). Specifically, the heating temperature is preferably 30°C or higher and 140°C or lower, more preferably 50°C or higher and 135°C, and even more preferably 60°C or higher and 130°C or lower. This method makes it possible to crosslink the resin at a temperature lower than the melting temperature of the resin contained in the crosslinked resin particles (C), thus avoiding deterioration of the resin due to heating during the crosslinking process. For example, the melting temperature of PHA, which is one example of the resin contained in the crosslinked resin particles (C), is 50°C or higher and 210°C or lower.

[0155] 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 or more and 15 hours or less, and more preferably 1 hour or more and 10 hours or less.

[0156] After the crosslinking reaction is completed, the crosslinked resin particles (C) can be separated from the aqueous dispersion, and dried crosslinked resin particles (C) can be obtained by removing water from the separated crosslinked resin particles (C). The method for separating the crosslinked resin particles (C) from the aqueous dispersion is not particularly limited, and for example, filtration, centrifugation, heat drying, freeze-drying, spray drying, etc. can be used. For example, by using spray drying, dried crosslinked resin particles (C) can be obtained directly from the aqueous dispersion. Alternatively, the crosslinked resin particles (C) can be obtained in pellet form while completely removing any remaining moisture by extruding the crosslinked resin particles (C) individually after separation from the aqueous dispersion. Alternatively, the crosslinked resin particles (C) can be obtained from the aqueous dispersion by performing a coagulation process using a coagulant and / or pH adjustment.

[0157] <Mixing Method> A specific example of a method for mixing the raw materials is described below. Hereinafter, this specific example of a method for mixing the raw materials will also be simply referred to as the "mixing method."

[0158] The mixing method described above is, for example, a method of mixing the raw materials using an extruder, kneader, Banbury mixer, kneading rolls, etc. In the mixing method described above, each component constituting the raw materials may be melt-kneaded using the apparatus described above. The components described above are PHA (A), polylactic acid (B), and crosslinked resin particles (C), and optionally the crystal nucleating agent, optionally the lubricant, and optionally the additive. When melt-kneading each component in the mixing method described above, it is preferable to mix them while paying attention to the decrease in molecular weight due to thermal decomposition. Alternatively, the resin composition can also be produced by dissolving all the raw materials (components) in a soluble solvent and then removing the solvent.

[0159] Furthermore, one embodiment of the mixing method is to simultaneously mix all of the PHA (A), polylactic acid (B), and crosslinked resin particles (C), as well as optionally the crystal nucleating agent, optionally the lubricant, and optionally the additive. Another embodiment of the mixing method is to divide the aforementioned raw materials into several groups before finally producing the resin composition, mix the raw materials in each group in separate processes, and finally mix all the raw materials. As specific examples of the aforementioned alternative embodiments, the following embodiments (i) to (iii) can be cited: (i) an embodiment in which PHA (A) and polylactic acid (B) are first melt-mixed, and then cross-linked resin particles (C) are added and further melt-mixed; (ii) an embodiment in which PHA (A) and cross-linked resin particles (C) are first melt-mixed, and then polylactic acid (B) is added and further melt-mixed; (iii) an embodiment in which polylactic acid (B) and cross-linked resin particles (C) are first melt-mixed, and then PHA (A) is added and further melt-mixed. A person skilled in the art can suitably select any of the embodiments (i) to (iii) above to produce the resin composition, taking into consideration the shape and heat resistance and other properties of each raw material of the resin composition to be manufactured, as well as the compatibility of each raw material with respect to each other. Each of the above raw materials includes, in addition to PHA (A), polylactic acid (B), and crosslinked resin particles (C), the nucleating agent, the lubricant, and the additive, if used.

[0160] Furthermore, in any of the embodiments (i) to (iii) above, at least one of the nucleating agent, the lubricant, and the additive may be melt-mixed together during at least one melt-mixing process. In addition, after mixing PHA (A), polylactic acid (B), and crosslinked resin particles (C) in any of the embodiments (i) to (iii) above, the mixture obtained as a result of the mixing may be melt-mixed with at least one of the nucleating agent, the lubricant, and the additive.

[0161] When producing the resin composition by melt kneading, each of the components may be individually fed into an extruder or the like, or a mixture obtained by pre-mixing the components may be fed into an extruder or the like. For example, an aqueous dispersion of PHA (A) and polylactic acid (B) may be mixed with an aqueous dispersion of crosslinked resin particles (C), and the resulting mixture may be dried in a dryer to obtain a mixed powder, which may then be fed into an extruder or the like.

[0162] When the resin composition is melt-kneaded using an extruder, the resulting resin composition may be processed into particle shapes such as bars, cylinders, elliptical cylinders, spheres, cubes, or rectangular parallelepipeds by extruding it from the extruder in a strand shape and then cutting it.

[0163] The resin temperature during melt mixing cannot be specified in general terms, as it depends on the melting point and melt viscosity of the resin used. From the viewpoint of uniformly dispersing the crosslinked resin particles (C) in the thermoplastic resin while avoiding thermal decomposition of the thermoplastic resin used, 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. The resin used refers to the resin in the PHA (A), polylactic acid (B), and crosslinked resin particles (C), as well as other resins optionally used as additives. The thermoplastic resin used refers to the PHA (A) and polylactic acid (B), as well as other resins optionally used as additives.

[0164] In the method for producing this resin composition, the amount of each component used determines the content of each component in the resulting resin composition. In other words, in the method for producing this resin composition, the amount of each component used should be adjusted as appropriate, taking into consideration the desired content of each component in the resin composition to be produced.

[0165] From the viewpoint of suitably controlling the proportion of crosslinked resin particles (C) present in the polylactic acid (B) in the resulting thermoplastic resin composition to a range of 0% to 20%, the method for producing this resin composition preferably satisfies the following requirements: Requirement; A resin with high compatibility with PHA (A) is used as the resin constituting the crosslinked resin particles (C).

[0166] The present resin composition may have a structure in which the crosslinked resin particles (C) are contained in at least a PHA(A) phase and a polylactic acid (B) phase, and the PHA(A) phase and the polylactic acid (B) phase. When the above requirements are met, the compatibility between the crosslinked resin particles (C) and PHA(A) is higher than the compatibility between the crosslinked resin particles (C) and the polylactic acid (B) and the other resins. Therefore, when the present resin composition is manufactured by mixing the resin components and the crosslinked resin particles (C), the crosslinked resin particles (C) are preferentially contained in the PHA(A) phase. As a result, the amount of crosslinked resin particles (C) contained in the polylactic acid (B) phase decreases while the amount contained in the PHA(A) phase decreases. Therefore, in this case, the proportion of crosslinked resin particles (C) present in the polylactic acid (B) in the thermoplastic resin composition produced can be reduced and suitably controlled to a range of 0% to 20%.

[0167] Regarding the above requirements, an example of a resin with high compatibility with PHA(A) is PHA.

[0168] [2. Molded Article] A molded article according to one embodiment of the present invention is obtained by molding the resin composition. Hereinafter, a molded article according to one embodiment of the present invention will also be referred to as "the molded article".

[0169] Because this molded product is made by molding this resin composition, it exhibits excellent and well-balanced properties of impact resistance, rigidity, and heat resistance. Furthermore, due to its superior heat resistance, this molded product has a wide operating temperature range and can be applied to a wide range of products.

[0170] A molded article according to another embodiment of the present invention comprises a polyhydroxyalkanoate resin (A), polylactic acid (B), and crosslinked resin particles (C), wherein the ratio of the number of crosslinked resin particles (C) present in the polylactic acid (B) to the total number of crosslinked resin particles (C) is 0% or more and 20% or less. Hereinafter, the molded article according to another embodiment of the present invention will also be referred to as "the other molded article."

[0171] Another molded article, by having the above configuration, exhibits the effect of having a well-balanced and excellent impact resistance, rigidity, and heat resistance for the same reasons as the aforementioned resin composition exhibits the above effect. Furthermore, because this other molded article also has excellent heat resistance, it has the effect of having a wide operating temperature range and being applicable to a wide range of products.

[0172] Another molded article may be manufactured by molding a resin composition. Another molded article may be a molded article corresponding to the present molded article, that is, a molded article made by molding the resin composition. Therefore, another molded article may contain the same components as the components of the aforementioned resin composition.

[0173] The molding method for the resin composition used to provide this molded article and the molding method for the resin composition used to manufacture another molded article are not particularly limited, and commonly used molding methods can be applied. Specific examples of such molding methods include inflation film molding, extrusion blow molding, injection blow molding, extrusion molding, calendering, vacuum forming, injection molding, and press molding. This molded article can also be described as a molded article containing this resin composition.

[0174] The form of this molded body and other molded bodies are not particularly limited. These molded bodies and other molded bodies may be, for example, film molded bodies, sheet molded bodies, blow molded bodies, extruded bodies, vacuum molded bodies, or injection molded bodies. In this specification, "film molded body" refers to a thin film with a thickness of less than 0.25 mm, in accordance with JIS 20108:2012. In this specification, "sheet molded body" refers to a thin plate with a thickness of 0.25 mm or more, in accordance with JIS 20108:2012.

[0175] This molded body and other molded bodies can be suitably used in agriculture, fisheries, forestry, industry, horticulture, medicine, hygiene products, food industry, clothing, non-clothing products, packaging, automobiles, building materials, and other fields.

[0176] [3. Others] One embodiment of the present invention may include the following configurations.

[0177] [1] A thermoplastic resin composition comprising a polyhydroxyalkanoate resin (A), polylactic acid (B), and crosslinked resin particles (C), wherein the ratio of the number of crosslinked resin particles (C) present in the polylactic acid (B) to the total number of crosslinked resin particles (C) is 0% or more and 20% or less.

[0178] [2] The thermoplastic resin composition according to [1], wherein the crosslinked resin particles (C) have a gel fraction of 50% or more. [3] The thermoplastic resin composition according to [1] or [2], wherein the crosslinked resin particles (C) include a biodegradable resin having a glass transition temperature of less than 0°C.

[0179] [4] The thermoplastic resin composition according to [1] or [2], wherein the crosslinked resin particles (C) contain a polyhydroxyalkanoate resin.

[0180] [5] The thermoplastic resin composition according to [4], wherein the polyhydroxyalkanoate resin contained in the crosslinked resin particles (C) is a poly(3-hydroxyalkanoate) resin.

[0181] [6] The thermoplastic resin composition according to any one of [1] to [5], wherein the crosslinked resin particles (C) are crosslinked using a peroxide.

[0182] [7] The thermoplastic resin composition according to [6], wherein the crosslinked resin particles (C) are crosslinked in the presence of the peroxide and the polyfunctional compound.

[0183] [8] The thermoplastic resin composition according to any one of [1] to [7], wherein the crosslinked resin particles (C) are not foamed.

[0184] [9] A thermoplastic resin composition according to any one of [1] to [8], further comprising a nucleating agent and / or a lubricant.

[0185]

[10] A thermoplastic resin composition according to any one of [1] to [9], which is a marine biodegradable composition.

[0186]

[11] A thermoplastic resin composition according to any one of [1] to

[10] , wherein the degree of biodegradation after 30 days in seawater in a biochemical oxygen demand test is 40% or more.

[0187]

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

[11] , comprising: 2% by weight or more and 72% by weight or less of the polyhydroxyalkanoate resin (A); 5% by weight or more and 90% by weight of the polylactic acid (B); and 2% by weight or more and 44% by weight or less of the crosslinked resin particles (C) [provided that the total amount of the polyhydroxyalkanoate resin (A), the polylactic acid (B), and the crosslinked resin particles (C) is 100% by weight].

[0188] A molded article obtained by molding a thermoplastic resin composition described in any one of [1] to

[12] .

[0189]

[14] The molded article according to

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

[0190]

[15] A molded article comprising a polyhydroxyalkanoate resin (A), polylactic acid (B), and crosslinked resin particles (C), wherein the ratio of the number of crosslinked resin particles (C) present in the polylactic acid (B) to the total number of crosslinked resin particles (C) is 0% or more and 20% or less.

[0191]

[16] The molded article according to

[15] , wherein the crosslinked resin particles (C) have a gel fraction of 50% or more.

[0192] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to these examples.

[0193] [Measurement Method and Evaluation Method] (Weight-Average Molecular Weight) The resin to be measured was added to chloroform, and the resulting mixture was heated in a 60°C hot water bath for 30 minutes. The resulting mixture (chloroform solution) was filtered using a PTFE disposable filter with a pore size of 0.45 μm. Then, the weight-average molecular weight was determined by GPC measurement using the obtained filtrate under the following conditions. GPC measuring instrument: Shimadzu High Performance Liquid Chromatograph 20A system Column: Showa Denko K-G 4A (1 column), K-806M (2 columns) Sample concentration: 1 mg / ml Free solution: Chloroform solution Free solution flow rate: 1.0 ml / min Sample injection volume: 100 μL Analysis time: 30 minutes Standard sample: Standard polystyrene.

[0194] (Volume-average particle diameter) The volume-average particle diameter of the cross-linked resin particles (C) was measured using an aqueous dispersion of the cross-linked resin particles (C) obtained in Production Example 1 as a sample. A MicrotracMT3300EXII manufactured by Nikkiso Co., Ltd. was used as the measuring device. Specifically, the particle diameter and volume of each cross-linked resin particle (C) in the aqueous dispersion of the cross-linked resin particles (C) were measured using the above device, and the volume-average particle diameter was calculated from the results obtained based on the above-mentioned formula (1), i.e., formula (2).

[0195] (Gel fraction) The aqueous dispersion of cross-linked resin particles (C) obtained in Production Example 1 was dried at a drying temperature of 55°C for 24 hours to obtain a dried product of cross-linked resin particles (C). The gel fraction of the cross-linked resin particles (C) was measured using the obtained dried product of cross-linked resin particles (C). Specifically, the dried product of cross-linked resin particles (C) was added to chloroform to a concentration of 0.7% by weight, and the resulting mixture was held at 60°C for 30 minutes to obtain a chloroform solution. After that, the chloroform solution was allowed to stand at room temperature for 3 hours, and then the chloroform solution after standing was filtered using a membrane filter with a pore size of 0.45 μm. Before filtration, the weight of the filter alone was measured. During filtration, chloroform was poured over the inside of the container and the filter multiple times to thoroughly wash it and prevent loss. After filtration, the gel remaining on the filter was dried, and the weight of the filter containing the dried gel was measured. The gel fraction was calculated using the following formula. Formula: Gel fraction = {(Weight of filter containing dry gel - Weight of filter only) / Weight of cross-linked resin particles used for measurement} × 100 (%).

[0196] (Glass transition temperature (Tg)) The temperature determined by the following method (differential scanning calorimetry (DSC method)) was defined as the glass transition temperature (Tg) of the resin (uncrosslinked resin particles): (1) 2 mg to 3 mg of resin was packed into an aluminum pan; (2) The aluminum pan was subjected to a differential scanning calorimetry analyzer, and the analyzer temperature was increased from -80°C to 180°C at a rate of 10°C / min under a nitrogen atmosphere to completely melt the resin; (3) After that, the analyzer temperature was decreased from 180°C to -80°C at a rate of 10°C / min; (4) The analyzer temperature was again increased from -80°C to 180°C at a rate of 10°C / min; (5) For the DSC curve obtained in (4), the temperature midway between the temperature at which the shift (change) from the baseline began and the temperature at which it ended was defined as the glass transition temperature (Tg) of the resin (uncrosslinked resin particles).

[0197] (Tensile Impact Strength) The thermoplastic resin compositions produced in Examples 1 to 20 and Comparative Examples 1 to 9 were press-molded under the following press temperature conditions to obtain sheet molded articles with a thickness of 500 μm. Subsequently, the obtained 500 μm thick sheet molded articles were cured for 7 days under conditions of 23°C and 50% RH, and then punched out into the shape of JIS K 7160 Type 3 to prepare test specimens. Tensile impact tests were performed on the prepared test specimens according to the method in accordance with JIS K 7160 Method A, and the tensile impact strength was measured. In Examples 1 to 20 and Comparative Examples 1 to 3, 5, 7 and 9, the press molding was carried out under the condition of a press temperature of 155°C. In Comparative Examples 4, 6 and 8, the press molding was carried out under the condition of a press temperature of 165°C.

[0198] (Tensile Properties) The thermoplastic resin compositions produced in Examples 1 to 20 and Comparative Examples 1 to 9 were press-molded under the same conditions as the press temperature conditions described in the (Tensile Impact Strength) section above to obtain sheet molded articles with a thickness of 200 μm. The obtained sheet molded articles with a thickness of 200 μm were cured for 7 days under conditions of 23°C and 50% RH, and then the tensile properties were measured using a tensile testing machine (Shimadzu Corporation: EZ-LX 1kN) in accordance with the method in accordance with JIS K 7133, at a test speed of 100 mm / min. Specifically, the tensile properties were measured as follows: modulus of elasticity (MPa), stress at fracture (N / mm²). ２Measurements of ) and elongation at break (%) were performed.

[0199] (Storage modulus at 70°C) The thermoplastic resin compositions produced in Examples 1 to 20 and Comparative Examples 1 to 9 were press-molded under the same conditions as the press temperature conditions described in the (Tensile Impact Strength) section above to obtain sheet molded articles with a thickness of 500 μm. The obtained sheet molded articles with a thickness of 500 μm were cured for one week under conditions of 23°C and 50% RH. After curing, the storage modulus of the sheet molded articles was measured using a DVA-200 manufactured by IT Measurement Control Co., Ltd. under the following conditions. Based on the measurement results, the value of the storage modulus at 70°C (unit: MPa) was obtained. <Conditions> ・Measurement mode: Tensile ・Gripping distance: 20 mm ・Test piece width: 5 mm ・Measurement temperature: -40°C to +150°C ・Heating rate: 5°C / min ・Measurement frequency: 1 Hz.

[0200] (Percentage of crosslinked resin particles (C) present in polylactic acid (B)) The thermoplastic resin compositions produced in Examples 1 to 5 were press-molded at 155°C to obtain sheet molded articles with a thickness of 500 μm. Magnified cross-sectional images of the obtained 500 μm thick sheet molded articles were obtained using the method shown below. Specifically, the sheet molded articles were subjected to ultramicrotome analysis under freezing conditions using a Leica Microsystems FC7 to create cross-sections of the sheet molded articles. Scanning probe microscopy (SPM) analysis was performed on the created cross-sections using a Bruker AXS Dimension Icon under the following <SPM analysis conditions> to obtain elastic modulus images. Figures 1 to 5 show the elastic modulus images obtained from each of the sheet molded articles produced using the thermoplastic resin compositions produced in Examples 1 to 5. <SPM analysis conditions> Mode: PeakForceQMN Measurement range: 80 μm x 80 μm Number of data points: 512 x 512 Probe: R-TESPA300.

[0201] The obtained elastic modulus image was visually inspected, and the total number of crosslinked resin particles (C) present in the elastic modulus image and the number of crosslinked resin particles (C) present in the polylactic acid (B) resin were measured. Specifically, each component was observed in the elastic modulus image as follows, and based on these observations, the total number of crosslinked resin particles (C) and the number of crosslinked resin particles (C) present in the polylactic acid (B) resin were measured. - Cross-linked resin particles (C): The darkest contrast area, which is circular, nearly circular, elliptical, or nearly elliptical. - PHA(A) PHBH resin A-1, A-2: The second darkest contrast area, which surrounds the cross-linked resin particles (C). - PHA(A) PHBH resin A-3: The area, which surrounds the cross-linked resin particles (C), which is a contrast area that is as dark as the cross-linked resin particles. - Polylactic acid (B): The brightest contrast area. In the elastic modulus image, anything other than those listed above, such as linear or streaky shapes, which are clearly different in shape from particles, was considered to be noise or foreign matter generated during measurement and not particles.

[0202] Based on the measured number of particles, the ratio of cross-linked resin particles (C) present in polylactic acid (B) to the total number of cross-linked resin particles (C) was calculated, and the calculated value was defined as the "ratio of cross-linked resin particles (C) present in polylactic acid (B)".

[0203] (Biochemical Oxygen Demand Test) The thermoplastic resin compositions produced in Examples 2, 4, and 5 were press-molded under the same conditions as the press temperature conditions described in the (Tensile Impact Strength) section above to obtain a sheet molded body with a thickness of 500 μm. 25 mg of a sample obtained by cryopreserving the 500 μm thick sheet molded body was placed in 250 ml of seawater to which ammonium chloride at a concentration of 0.05 g / L and potassium dihydrogen phosphate at a concentration of 0.1 g / L was added, and the mixture was maintained at 30°C with constant stirring for 40 days. During the period of stirring the sample, the biochemical oxygen demand (BOD) value of the seawater to which the sample was added was measured at 5, 10, 20, 30, and 40 days after the addition of the sample. The same procedure was also performed on 250 ml of seawater prepared in the same manner except that the sample was not added, and the BOD value was measured. The degree of biodegradation (%) of the sample in seawater was calculated by subtracting the BOD value measured in seawater without the sample from the BOD value measured in seawater with the sample added, and then dividing the result by the theoretical oxygen demand (the amount of oxygen required for the sample to be completely decomposed into water and carbon dioxide).

[0204] The BOD value is measured using a pressure sensor type respiratory activity analyzer (Xylem Corporation, Oxitop®) to measure the CO2 generated by microbial respiration. ２ This was done by measuring the pressure loss caused by the absorption of KOH into the KOH tablets.

[0205] [Production Example 1: Production of a mixture of crosslinked resin particles (C) and silica particles] (Preparation of crosslinked resin particles (C)) An aqueous dispersion A containing the uncrosslinked resin particles shown below was prepared. The concentration of the uncrosslinked resin particles in the aqueous dispersion was 20% by weight. ・Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate): Composition of repeating units; (3-hydroxybutyrate) / (3-hydroxyhexanoate) = 72 / 28 (mol / mol), weight-average molecular weight Mw; 500,000 to 1,500,000, glass transition temperature; -7°C The weight-average molecular weight and glass transition temperature were measured by the methods shown in the sections on (weight-average molecular weight) and (glass transition temperature (Tg)).

[0206] In a glass container equipped with a stirrer, baffles, nitrogen inlet / outlet, and a thermometer, aqueous dispersion A was weighed to contain 100 parts by weight of uncrosslinked resin particles. To this, 2 parts by weight of peroxide, 0.95 parts by weight of sodium dioctyl sulfosuccinate, and 0.5 parts by weight of a polyfunctional compound were added to prepare aqueous dispersion B. The peroxide used was di-sec-butyl peroxydicarbonate (Luperox® 225, manufactured by Arkema Yoshitomi Co., Ltd., with a half-life of 1 hour at 69°C). The polyfunctional compound used was triallyl isocyanurate.

[0207] The obtained aqueous dispersion B was stirred at 30°C to 35°C, and at the same time, the inside of the glass container was purged with nitrogen. Subsequently, the aqueous dispersion B was stirred at room temperature for 1 hour, thereby impregnating the inside of the uncrosslinked resin particles with the peroxide and the polyfunctional compound in the dispersion B.

[0208] Subsequently, the aqueous dispersion B was heated until its temperature reached 75°C. After the aqueous dispersion B reached 75°C, it was left standing at that temperature for 5.5 hours. As a result, the resin constituting the uncrosslinked resin particles reacted with the peroxide and the polyfunctional compound in the aqueous dispersion B, forming a crosslinked structure in the resin, and the uncrosslinked resin particles were transformed into crosslinked resin particles (C). As a result, an aqueous dispersion C in which the crosslinked resin particles (C) were dispersed in water was obtained.

[0209] The obtained aqueous dispersion C was divided into three parts to obtain aqueous dispersion C1, aqueous dispersion C2, and aqueous dispersion C3. Using aqueous dispersion C1, the volume-average particle diameter of the obtained cross-linked resin particles (C) was measured using the method described in the (Volume-average particle diameter) section above. Also, using aqueous dispersion C2, the gel fraction of the obtained cross-linked resin particles (C) was measured using the method described in the (Gel fraction) section above. As a result, the volume-average particle diameter of the obtained cross-linked resin particles (C) was 1.70 μm, and the gel fraction was 95%.

[0210] <Mixing of Crosslinked Resin Particles (C) and Silica Particles> An aqueous dispersion C3 and an aqueous dispersion in which silica particles are dispersed in water (Snowtex ZL, manufactured by Nissan Chemical Corporation) were mixed to obtain a mixture, with a solid content ratio of aqueous dispersion C3 / silica particle aqueous dispersion = 90.9% by weight / 9.1% by weight. The pH of the obtained mixture was then adjusted using sulfuric acid to be between 3.6 and 3.8 at a liquid temperature of 50°C. Subsequently, the obtained mixture was spray-dried using an OD-50 spray dryer manufactured by Okawara Chemical Machinery Co., Ltd. under the conditions of a hot air temperature of 150°C, an exhaust air temperature of 70°C, and a disk rotation speed of 10,000 rpm. A mixture of crosslinked resin particles (C) and silica particles was produced by this operation. Furthermore, when the total weight of the manufactured mixture is taken as 100% by weight, the content of cross-linked resin particles (C) in the mixture was 90.9% by weight, and the content of silica particles in the mixture was 9.1% by weight.

[0211] [Examples 1 to 20, Comparative Examples 1 to 9] Thermoplastic resin compositions were prepared by kneading the following PHA(A), polylactic acid (B), a mixture of crosslinked resin particles (C) and silica particles produced in Production Example 1, a nucleating agent, and a lubricant in the amounts shown in Table 1 below. The weight-average molecular weight of PHA(A) shown below was measured by the method described in the (Weight-Average Molecular Weight) section above. <PHA(A)> • (A-1): PHBH (Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)): Manufactured by Kaneka Corporation, Kaneka Biodegradable Polymer PHBH®, Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), Composition of repeating units; (3-hydroxybutyrate) / (3-hydroxyhexanoate) = 94.4 / 5.6 (mol / mol), Weight-average molecular weight Mw: 530,000 • (A-2): PHBH (Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)): Manufactured by Kaneka Corporation, Kaneka Biodegradable Polymer PHBH®, Poly(3-hydroxybutyrate- Co-3-hydroxyhexanoate), composition of repeating units; (3-hydroxybutyrate) / (3-hydroxyhexanoate) = 97.2 / 2.8 (mol / mol), weight-average molecular weight Mw: 620,000 (A-3): PHBH (Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)): Manufactured by Kaneka Corporation, Kaneka Biodegradable Polymer PHBH®, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), composition of repeating units; (3-hydroxybutyrate) / (3-hydroxyhexanoate) = 71.8 / 28.2 (mol / mol), weight-average molecular weight Mw: 620,000 <Polylactic acid (B)> ・(B-1): PLA: Manufactured by Total Corbion PLA, LUMINY® LX975 ・(B-2): PLA: Manufactured by Total Corbion PLA, LUMINY® LX175 ・(B-3): PLA: Manufactured by Natureworks, Ingeo® 2003D <Crystal nucleating agent> ・Pentaerythritol: Neurizer P manufactured by Nippon Synthetic Chemical Co., Ltd. <Lubricant> ・Behenamide: BNT22H manufactured by Nippon Seika Co., Ltd.

[0212] Specifically, in Examples 1 to 20, a mixture A was prepared by mixing PHA (A), polylactic acid (B), a mixture of crosslinked resin particles (C) and silica particles, the crystal nucleating agent, and the lubricant. The mixing was carried out using a twin-screw kneader (ULT Nano 05, manufactured by Technovel Co., Ltd.) with the barrel temperature heated to 140°C or higher, up to 165°C, at a screw rotation speed of 80 rpm. The resulting kneaded product was used as a thermoplastic resin composition.

[0213] In Comparative Examples 1 to 9, the same method as in Example 1 was used to obtain the compound, except that the raw materials indicated as having a "0" blending amount in Tables 1 and 2 were not used. The obtained compound was then used as the thermoplastic resin composition.

[0214] [Results] The types and amounts of raw materials used in each example and comparative example, as well as the physical properties of the molded articles made from the manufactured thermoplastic resin compositions, measured and evaluated by the method described above, are shown in Tables 1 to 4 below. Note that the amount of each raw material refers to the content of each raw material in the manufactured thermoplastic resin composition. Although images are omitted, the ratio of the number of crosslinked resin particles (C) present in polylactic acid (B) to the total number of crosslinked resin particles (C) in the thermoplastic resin compositions obtained in Examples 6 to 20 was 20% or less in all cases. Furthermore, Table 5 shows the degree of biodegradability measured by biochemical oxygen demand tests for the thermoplastic resin compositions manufactured in Examples 2, 4, and 5.

[0215] As shown in Tables 1 to 4, the thermoplastic resin compositions produced in Examples 1 to 20 correspond to the present resin composition. Furthermore, as shown in Tables 1 to 4, the molded articles made from the thermoplastic resin compositions produced in Examples 1 to 20 exhibit well-balanced and high values ​​for tensile impact strength, tensile properties, and especially elastic modulus and storage modulus at 70°C, as evaluated by the method described above.

[0216] On the other hand, as shown in Tables 1 and 2, the thermoplastic resin compositions produced in Comparative Examples 1 to 9 do not correspond to the present resin composition. Furthermore, as shown in Tables 1 and 2, the molded articles made from the thermoplastic resin compositions produced in Comparative Examples 1 to 9 have lower tensile impact strength, tensile properties, particularly elastic modulus, and storage modulus at 70°C compared to the example where the amount of crosslinked resin particles (C) is the same.

[0217] Here, a high tensile impact strength means that the molded article has excellent impact resistance, and a high tensile property, particularly a high modulus of elasticity, means that the molded article has excellent rigidity. Furthermore, a high storage modulus of elasticity at 70°C means that the molded article produced from the resin composition has excellent heat resistance.

[0218] Therefore, it was shown that the thermoplastic resin compositions produced in Examples 1 to 20, which correspond to the present resin composition, can produce molded articles with a good balance of impact resistance, rigidity, and heat resistance. On the other hand, it was shown that the thermoplastic resin compositions produced in Comparative Examples 1 to 9, which do not correspond to the present resin composition, have low impact resistance, rigidity, or heat resistance in the molded articles produced from them.

[0219] Therefore, it was found that this resin composition has the effect of producing molded articles with a good balance of impact resistance, rigidity, and heat resistance.

[0220] As shown in Tables 1 to 4, molded articles produced using the thermoplastic resin compositions manufactured in Examples 1 to 20 by the method described in the column for (percentage of crosslinked resin particles (C) present in polylactic acid (B)) correspond to the present molded article and other present molded articles. On the other hand, as shown in Tables 1 and 2, molded articles produced using the thermoplastic resin compositions manufactured in Comparative Examples 1 to 9 by the method described in the column for (percentage of crosslinked resin particles (C) present in polylactic acid (B)) correspond to the present molded article and other present molded articles.

[0221] As described above, the molded articles produced by molding the thermoplastic resin compositions manufactured in Examples 1 to 20, which correspond to the present molded article and other present molded articles, exhibit a good balance of impact resistance, rigidity, and heat resistance. On the other hand, the molded articles produced by molding the thermoplastic resin compositions manufactured in Comparative Examples 1 to 9, which do not correspond to the present molded article and other present molded articles, exhibit low impact resistance, rigidity, or heat resistance.

[0222] Therefore, it was found that this molded body and another molded body have excellent and well-balanced impact resistance, rigidity, and heat resistance, and because of their superior heat resistance, they have a wide operating temperature range and can be applied to a wide range of products.

[0223] Furthermore, as shown in Table 5, this resin composition exhibited a biodegradability of 40% or more after 30 days in a biochemical oxygen demand test in seawater, demonstrating its potential for excellent marine biodegradability.

[0224] According to one embodiment of the present invention, a molded article can be provided that exhibits a good balance of impact resistance, rigidity, and heat resistance. Therefore, one embodiment of the present invention can be suitably used in agriculture, fisheries, forestry, horticulture, medicine, hygiene products, the food industry, clothing, non-clothing products, packaging, automobiles, building materials, and other fields.

Claims

1. A thermoplastic resin composition comprising a polyhydroxyalkanoate resin (A), polylactic acid (B), and crosslinked resin particles (C), wherein the ratio of the number of crosslinked resin particles (C) present in the polylactic acid (B) to the total number of crosslinked resin particles (C) is 0% or more and 20% or less.

2. The thermoplastic resin composition according to claim 1, wherein the crosslinked resin particles (C) have a gel fraction of 50% or more.

3. The thermoplastic resin composition according to claim 1, wherein the crosslinked resin particles (C) include a biodegradable resin having a glass transition temperature of less than 0°C.

4. The thermoplastic resin composition according to claim 1, wherein the crosslinked resin particles (C) include a polyhydroxyalkanoate resin.

5. The thermoplastic resin composition according to claim 4, wherein the polyhydroxyalkanoate resin contained in the crosslinked resin particles (C) is a poly(3-hydroxyalkanoate) resin.

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

7. The thermoplastic resin composition according to claim 6, wherein the crosslinked resin particles (C) are crosslinked in the presence of the peroxide and the polyfunctional compound.

8. The thermoplastic resin composition according to claim 1, wherein the crosslinked resin particles (C) are not foamed.

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

10. The thermoplastic resin composition according to claim 1, which is a marine biodegradable composition.

11. The thermoplastic resin composition according to claim 1, wherein the degree of biodegradation after 30 days in seawater in a biochemical oxygen demand test is 40% or more.

12. The thermoplastic resin composition according to claim 1, comprising: 2% by weight or more and 72% by weight or less of the polyhydroxyalkanoate resin (A); 5% by weight or more and 90% by weight or less of the polylactic acid (B); and 2% by weight or more and 44% by weight or less of the crosslinked resin particles (C) [provided that the total amount of the polyhydroxyalkanoate resin (A), the polylactic acid (B), and the crosslinked resin particles (C) is 100% by weight].

13. A molded article obtained by molding a thermoplastic resin composition according to any one of claims 1 to 12.

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

15. A molded article comprising a polyhydroxyalkanoate resin (A), polylactic acid (B), and crosslinked resin particles (C), wherein the ratio of the number of crosslinked resin particles (C) present in the polylactic acid (B) to the total number of crosslinked resin particles (C) is 0% or more and 20% or less.

16. The molded article according to claim 15, wherein the crosslinked resin particles (C) have a gel fraction of 50% or more.

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