Resin composition and molded article

Abstract

The purpose of the present invention is to provide: a resin composition which exhibits excellent biodegradability, moldability and mechanical properties at room temperature; and a molded article thereof.　Provided is a resin composition which contain: an aliphatic polyester-based resin (A) that contains repeating constituent units derived from an aliphatic diol and repeating constituent units derived from an aliphatic dicarboxylic acid having 9-36 carbon atoms as repeating constituent units derived from an aliphatic dicarboxylic acid; and at least one type selected from the group consisting of a poly(hydroxy alkanoate) (B) containing repeating constituent units derived from a hydroxy alkanoic acid having four or more carbon atoms, and an inorganic filler (F). Also provided is a molded article of the resin composition.

Description

Resin composition and molded article

[0001] The present invention relates to a resin composition and a molded article thereof.

[0002] In recent years, concerns about ecosystem and environmental pollution due to marine disposal of plastic products have become apparent. For example, in Europe, regulations and laws are being enacted that prohibit the use of disposable plastic shopping bags in retail stores and disposable plastic containers such as cups and plates. Various regulations are being enacted around the world from the perspective of preventing environmental pollution. Recently, there has been a demand for biodegradable plastic products (home compostable products) that can be composted in ordinary households, as well as plastic products that combine moldability and quality from the perspectives of cost and practical use.

[0003] Conventionally, known biodegradable plastics (resins) include polybutylene succinate (hereinafter abbreviated as PBS), polybutylene terephthalate / adipate (hereinafter abbreviated as PBAT), polybutylene succinate / terephthalate (hereinafter abbreviated as PBST), and polylactic acid (hereinafter abbreviated as PLA). Furthermore, known biodegradable resins that are particularly suitable for home composting include polybutylene succinate / adipate (hereinafter abbreviated as PBSA) and polyhydroxyalkanoate (hereinafter abbreviated as PHA). PHAs include poly(3-hydroxybutyrate) (hereinafter abbreviated as PHB), poly(3-hydroxybutyrate / 3-hydroxyvalerate) (hereinafter abbreviated as PHBV), poly(3-hydroxybutyrate / 3-hydroxyhexanoate) (hereinafter abbreviated as PHBH), and poly(3-hydroxybutyrate / 4-hydroxybutyrate).

[0004] Patent Document 1 discloses a biodegradable container made of a biodegradable resin composition containing 50% by weight or more of an aliphatic polyester containing 3-hydroxybutyric acid units, such as poly(3-hydroxybutyrate) (hereinafter also referred to as [PHB]), and shows that such a biodegradable container has heat resistance that can withstand high-temperature contents during use and biodegrades after use. Furthermore, in the examples, it describes the production of a biodegradable container containing PHB and polybutylene succinate (hereinafter also referred to as "PBS").

[0005] Patent Document 2 discloses a method for promoting the biodegradation of poly(3-hydroxybutyrate)-based resin, characterized in that the decomposition in seawater is accelerated by blending 1 to 50 parts by weight of an inorganic filler with the poly(3-hydroxybutyrate)-based resin.

[0006] Patent Document 3 discloses a molded article made from an aliphatic polyester resin composition comprising an aliphatic polyester resin (A), a polyhydroxyalkanoate (B), and an inorganic filler (C), wherein the polyhydroxyalkanoate (B) is a copolymer containing 3-hydroxybutyrate units and 3-hydroxyhexanoate units as main structural units, the mass ratio of the aliphatic polyester resin (A) to the polyhydroxyalkanoate (B) being 40 / 60 to 10 / 90, and the content of the inorganic filler (C) relative to the total amount of the aliphatic polyester resin (A), the polyhydroxyalkanoate (B), and the inorganic filler (C) being 15 to 50 mass%. It is also disclosed that such a molded article has excellent moldability, a fast biodegradation rate at room temperature, excellent mechanical properties such as impact resistance, and heat resistance, and possesses both water vapor barrier property and oxygen barrier property. In the examples, a molded article is described that is made of an aliphatic polyester-based resin composition containing polybutylene succinate (PBS) or polybutylene succinate adipate (PBSA) as an aliphatic polyester-based resin (A), polyhydroxyalkanoate (B), and an inorganic filler (C).

[0007] Japanese Patent Application Laid-Open No. 2001-341771 Japanese Patent Application Laid-Open No. 2017-132967 International Publication No. 2019 / 189367 Special Publication No. 2013-510210 Special Publication No. 2015-535027

[0008] In recent years, the social trend toward stronger environmental protection, particularly environmental pollution caused by the disposal of used plastic products (especially the impact on marine life of microplastics caused by the disposal of used plastic products in the ocean), has led to an increasing demand for biodegradable resins. In particular, there is a demand for biodegradable resins not only in aerobic composting environments (soil) at relatively high temperatures (58°C or higher), but also in aerobic composting environments (soil) at room temperature (28°C) and in the ocean. Furthermore, from the perspective of practicality, there is a demand for practical materials that combine good moldability with good mechanical properties.

[0009] According to the investigations of the present inventors, the resin composition described in Patent Document 1 still has room for improvement in terms of biodegradability, moldability, and mechanical properties.

[0010] Furthermore, the resin composition described in Patent Document 2 still has room for improvement in terms of mechanical properties.

[0011] Furthermore, the resin composition described in Patent Document 3 still has room for improvement in terms of moldability.

[0012] The present invention has been made in view of the problems associated with the above-mentioned conventional technologies, and aims to provide a resin composition that is superior in biodegradability, moldability, and mechanical properties at room temperature, a molded article that is superior in biodegradability, moldability, and mechanical properties at room temperature, and an injection molding material and pellets that can be used to produce such a molded article.

[0013] The gist of the present invention resides in the following [1] to

[36] . [1] A resin composition comprising an aliphatic polyester resin (A), and at least one selected from the group consisting of a polyhydroxyalkanoate (B) and an inorganic filler (F), wherein the aliphatic polyester resin (A) comprises a repeating structural unit A1 derived from an aliphatic diol and a repeating structural unit A2 derived from an aliphatic dicarboxylic acid, the repeating structural unit A2 comprises a repeating structural unit A21 derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms, and the polyhydroxyalkanoate (B) is different from the aliphatic polyester resin (A) and comprises a repeating structural unit B1 derived from a hydroxyalkanoic acid having 4 or more carbon atoms. [2] The resin composition according to [1], wherein the content of the polyhydroxyalkanoate (B) in the resin composition is more than 0 mass% and not more than 90 mass%. [3] The resin composition according to [1] or [2], wherein the content of the inorganic filler (F) in the resin composition is 5% by mass or more and 40% by mass or less. [4] The resin composition according to any one of [1] to [3], wherein the content of the aliphatic polyester resin (A) in the resin composition is 15% by mass or more and 95% by mass or less. [5] The resin composition according to any one of [1] to [4], wherein the content of the aliphatic polyester resin (A) in the resin composition is more than 34% by mass and 95% by mass or less. [6] The resin composition according to any one of [1] to [5], wherein the content of the aliphatic polyester resin (A) in the resin composition is 5% by mass or more and 95% by mass or less, and wherein the content of an aliphatic polyester resin (C') in the resin composition is 0% by mass or more and less than 5% by mass, the aliphatic polyester resin (C') having a repeating structural unit C1 derived from an aliphatic diol and a repeating structural unit C2 derived from an aliphatic dicarboxylic acid, the repeating structural unit C2 being different from the aliphatic polyester resin (A) and the polyhydroxyalkanoate (B), wherein the repeating structural unit C2 comprises a repeating structural unit C22 derived from an aliphatic dicarboxylic acid having 5 to 6 carbon atoms. [7] The resin composition according to any one of [1] to [6], wherein the repeating structural unit A2 further includes a repeating structural unit A22 derived from succinic acid.[8] The resin composition according to any one of [1] to [7], wherein the content of the repeating structural unit A21 derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms relative to the repeating structural unit A2 derived from the aliphatic dicarboxylic acid in the aliphatic polyester resin (A) is 1 mol % or more and 50 mol % or less. [9] The resin composition according to any one of [1] to [8], wherein the polyhydroxyalkanoate (B) contains, as the repeating structural unit B1, a repeating structural unit B11 derived from 3-hydroxybutyrate, and the polyhydroxyalkanoate (B) contains the repeating structural unit B11 as a main structural unit.

[10] The resin composition according to [9], wherein the content of the repeating structural unit B11 relative to 100 mol % of all structural units constituting the polyhydroxyalkanoate (B).

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

[10] , wherein the polyhydroxyalkanoate (B) further contains, as the repeating structural unit B1, at least one repeating structural unit selected from the group consisting of a repeating structural unit B12 derived from 3-hydroxyvalerate, a repeating structural unit B13 derived from 3-hydroxyhexanoate, and a repeating structural unit B14 derived from 4-hydroxybutyrate.

[12] The resin composition according to

[11] , wherein the total content of the repeating structural unit B12, the repeating structural unit B13, and the repeating structural unit B14 is 30 mol% or less, based on 100 mol% of all structural units constituting the polyhydroxyalkanoate (B).

[13] The resin composition according to any of [1] to

[12] , wherein the total content of the aliphatic polyester resin (A) and the polyhydroxyalkanoate (B) in the resin composition exceeds 70 mass%.

[14] The resin composition according to any one of [1] to

[13] , wherein the total content of the aliphatic polyester resin (A) and at least one selected from the group consisting of the polyhydroxyalkanoate (B) and the inorganic filler (F) in the resin composition is 90 mass% or more.

[15] The resin composition according to any one of [1] to

[14] , wherein the resin composition further comprises an aliphatic polyester resin (C), which is different from the aliphatic polyester resin (A) and the polyhydroxyalkanoate (B) and has a repeating structural unit C1 derived from an aliphatic diol and a repeating structural unit C2 derived from an aliphatic dicarboxylic acid, wherein the repeating structural unit C2 comprises a repeating structural unit C21 derived from an aliphatic dicarboxylic acid having 5 to 8 carbon atoms.

[16] The resin composition according to

[15] , wherein a content of the aliphatic polyester resin (C) in the resin composition is 40 mass% or less.

[17] The resin composition according to any one of [1] to

[16] , wherein the resin composition further comprises an aliphatic aromatic polyester resin (D), which is different from the aliphatic polyester resin (A) and the polyhydroxyalkanoate (B), and which comprises, as main structural units, a repeating structural unit D1 derived from an aliphatic diol, a repeating structural unit D2 derived from an aliphatic dicarboxylic acid, and a repeating structural unit D3 derived from an aromatic dicarboxylic acid, and the repeating structural unit D3 comprises at least a repeating structural unit D31 derived from an aromatic dicarboxylic acid having 6 to 12 carbon atoms.

[18] The resin composition according to

[17] , wherein a content of the aliphatic aromatic polyester resin (D) in the resin composition is 50 mass% or less.

[19] The resin composition according to any one of [1] to

[18] , wherein the content of repeating structural units derived from aliphatic dicarboxylic acids having 9 to 36 carbon atoms in all of the polyester resins contained in the resin composition is 1 mol% or more and 50 mol% or less relative to the total number of moles of repeating structural units derived from aliphatic dicarboxylic acids in all of the polyester resins contained in the resin composition.

[20] The resin composition according to any one of [1] to

[19] , wherein the content of repeating structural units derived from aliphatic dicarboxylic acids having 5 to 8 carbon atoms in all of the polyester resins contained in the resin composition is 50 mol% or less relative to the total number of moles of repeating structural units derived from aliphatic dicarboxylic acids in all of the polyester resins contained in the resin composition.

[21] The resin composition according to any one of [1] to

[20] , wherein the inorganic filler (F) has a whiteness of 70% or more.

[22] The resin composition according to any one of [1] to

[21] , wherein the inorganic filler (F) has a whiteness of 80% or more.

[23] The resin composition according to any one of [1] to

[22] , wherein the inorganic filler (F) has an average particle size of 1 μm or more and 20 μm or less.

[24] The resin composition according to any one of [1] to

[23] , wherein the injection-molded product has a flexural modulus of 500 MPa or more based on JIS K7171:2022.

[25] The resin composition according to any one of [1] to

[24] , wherein the injection-molded product has a flexural modulus of 600 MPa or more based on JIS K7171:2022.

[26] The resin composition according to any one of [1] to

[25] , wherein the bio-based carbon content of the resin composition is 10% or more, calculated based on ISO 16620-2.

[27] A molded article made of the resin composition according to any one of [1] to

[26] .

[28] The molded article according to

[27] , which is a packaging material.

[29] The molded article according to

[27] , which is an agricultural material, a forestry material, or cutlery.

[30] The molded article according to any one of

[27] to

[29] , which has a shape of a sheet, a film, a tube, a capsule, a pellet, a filament, or a bag.

[31] The molded article according to

[27] , which is a filament or a pellet for a 3D printer.

[32] The molded article according to

[27] , which is a plastic bag or a shopping bag.

[33] The molded article according to

[27] , which is a straw.

[34] A material for injection molding comprising the resin composition according to any one of [1] to

[26] .

[35] A pellet comprising the resin composition according to any one of [1] to

[26] .

[36] Use of the pellet according to

[35] in injection molding.

[0014] According to the present invention, it is possible to obtain a resin composition having superior biodegradability, moldability, and mechanical properties at room temperature, a molded article having superior biodegradability, moldability, and mechanical properties at room temperature, and an injection molding material or pellets that can be used to produce such a molded article.

[0015] Embodiments of the present invention will be described in detail below, but the present invention is not limited to the following description and can be modified as desired without departing from the spirit and scope of the present invention. In this specification, when a numerical value or physical property value is enclosed before and after the prefix "to", the value before and after the prefix is ​​included. When a numerical range is described in stages, any combination of the upper and lower limits of each numerical range is also disclosed. In this specification, the expression "A or B" can be interpreted as "at least one selected from the group consisting of A and B." Furthermore, in this specification, a description such as "at least one selected from the group consisting of XX, YY, and ZZ" means any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ. In this specification, "mass %" and "wt %" are synonymous, and "parts by weight" and "parts by mass" are synonymous. Furthermore, although a number of embodiments are described in this specification, various conditions in each embodiment may be applied to each other to the extent that they are applicable.

[0016] As a result of investigations into the above-mentioned problems, the present inventors discovered that a resin composition containing an aliphatic polyester resin containing a specific repeating unit and a specific component contributes to achieving the above-mentioned object, leading to the completion of the present invention. That is, a resin composition according to one aspect of the present invention comprises an aliphatic polyester resin (A) and at least one selected from the group consisting of a polyhydroxyalkanoate (B) and an inorganic filler (F). The aliphatic polyester resin (A) comprises a repeating structural unit A1 derived from an aliphatic diol and a repeating structural unit A2 derived from an aliphatic dicarboxylic acid, and the repeating structural unit A2 comprises a repeating structural unit A21 derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms. The polyhydroxyalkanoate (B) is different from the aliphatic polyester resin (A) and comprises a repeating structural unit B1 derived from a hydroxyalkanoic acid having 4 or more carbon atoms. A molded article according to one embodiment of the present invention is made of a resin composition, the resin composition comprising an aliphatic polyester resin (A) and at least one selected from the group consisting of a polyhydroxyalkanoate (B) and an inorganic filler (F), the aliphatic polyester resin (A) comprising a repeating structural unit A1 derived from an aliphatic diol and a repeating structural unit A2 derived from an aliphatic dicarboxylic acid, the repeating structural unit A2 comprising a repeating structural unit A21 derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms, and the polyhydroxyalkanoate (B) comprising a repeating structural unit B1 different from the aliphatic polyester resin (A) and derived from a hydroxyalkanoic acid having 4 or more carbon atoms.

[0017] The resin composition and molded article described above have excellent biodegradability at room temperature because they contain the aliphatic polyester resin (A). Furthermore, by containing at least one selected from the group consisting of polyhydroxyalkanoate (B) and inorganic filler (F), they can achieve improved moldability and mechanical properties while maintaining excellent biodegradability.

[0018] In this specification, an aliphatic diol refers to an aliphatic hydrocarbon group to which two hydroxyl groups are bonded, and as the aliphatic hydrocarbon group, a straight-chain aliphatic hydrocarbon group is usually used, but it may have a branched structure, a cyclic structure, or a plurality of these. Also, in this specification, an aliphatic dicarboxylic acid refers to an aliphatic hydrocarbon group to which two carboxyl groups are bonded, and as the aliphatic hydrocarbon group, a straight-chain aliphatic hydrocarbon group is usually used, but it may have a branched structure, a cyclic structure, or a plurality of these.

[0019] In this specification, the aliphatic polyester resin (A) contained in the resin composition is a polymer having repeating structural units, and each repeating structural unit is also referred to as a compound unit corresponding to the compound from which the repeating structural unit is derived. That is, for example, a repeating unit derived from an aliphatic diol is also referred to as an "aliphatic diol unit," and a repeating unit derived from an aliphatic dicarboxylic acid is also referred to as an "aliphatic dicarboxylic acid unit."

[0020] In the present invention, the repeating structural unit A1 derived from an aliphatic diol (aliphatic diol unit A1) refers to a repeating structural unit corresponding to an aliphatic diol, i.e., a repeating structural unit formed by the reaction of two hydroxyl groups possessed by an aliphatic diol. Furthermore, the repeating structural unit A2 derived from an aliphatic dicarboxylic acid (aliphatic dicarboxylic acid unit A2) refers to a repeating structural unit corresponding to an aliphatic dicarboxylic acid, i.e., a repeating structural unit formed by the reaction of two carboxy groups possessed by an aliphatic dicarboxylic acid. The repeating structural unit A21 derived from succinic acid (succinic acid unit A21) refers to a structural unit corresponding to succinic acid, i.e., a structural unit formed by the reaction of two carboxy groups possessed by succinic acid. Furthermore, the repeating structural unit A22 derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms (aliphatic dicarboxylic acid unit A22 having 9 to 36 carbon atoms) refers to a structural unit corresponding to an aliphatic dicarboxylic acid having 9 to 36 carbon atoms, that is, a structural unit formed by the reaction of two carboxy groups possessed by an aliphatic dicarboxylic acid having 9 to 36 carbon atoms. In this specification, the term "main structural unit" in resin R typically refers to a structural unit that accounts for 51% by mass or more of the structural unit relative to resin R, and may be 80% by mass or more, or may be 90% by mass or more, or may even be 100% by mass when no structural units other than the main structural unit are contained. Furthermore, the term "resin R contains A units and B units as main structural units" means that the total content of A units and B units in resin R is 51% by mass or more relative to resin R, and may be 80% by mass or more, or may be 90% by mass or more, or even 100% by mass. More specifically, having aliphatic diol units A1 and aliphatic dicarboxylic acid units A2 as main structural units means that the sum of the masses of the aliphatic diol units A1 and the aliphatic dicarboxylic acid units A2 is 51 mass% or more relative to the aliphatic polyester resin (A).Furthermore, for example, the sum of the masses of the aliphatic diol units A1 and the aliphatic dicarboxylic acid units A2 means the sum of the product of the mass of 1 mole of the aliphatic diol units A1 and the total number of moles of the aliphatic diol units A1, and the product of the mass of 1 mole of the aliphatic dicarboxylic acid units A2 and the total number of moles of the aliphatic dicarboxylic acid units A2, when the smallest ester units in the aliphatic polyester resin (A) are counted as 1 mole of the aliphatic diol units A1 and 1 mole of the aliphatic dicarboxylic acid units A2.

[0021] <Aliphatic Polyester Resin (A)> The aliphatic polyester resin (A) (hereinafter sometimes referred to as "polyester resin (A)") contains aliphatic diol units A1 and aliphatic dicarboxylic acid units A2, and preferably contains aliphatic diol units A1 and aliphatic dicarboxylic acid units A2 as main structural units. The aliphatic dicarboxylic acid units A2 contain aliphatic dicarboxylic acid units A21 having 9 to 36 carbon atoms. From the viewpoints of heat resistance and biodegradability in particular, the aliphatic dicarboxylic acid units A21 are preferably aliphatic dicarboxylic acid units having 9 to 13 carbon atoms, and particularly preferably aliphatic carboxylic acid units having 10 carbon atoms, specifically, for example, sebacic acid units. The aliphatic dicarboxylic acid units A2 may contain structural units other than aliphatic dicarboxylic acid units having 9 to 36 carbon atoms. The aliphatic diol unit A1 is not particularly limited. However, from the viewpoint of the mechanical strength and moldability of the resin layer containing the aliphatic polyester resin (A) and from the viewpoint of easier adjustment, it is preferable for the aliphatic diol unit A11 to contain a repeating structural unit derived from an aliphatic diol having from 2 to 10 carbon atoms. The aliphatic diol unit A11 is particularly preferably an aliphatic diol unit having from 4 to 6 carbon atoms. Specific examples of such aliphatic diol units A11 include ethylene glycol units, 1,3-propanediol units, 1,4-butanediol units, and 1,4-cyclohexanedimethanol units. Of these, it is particularly preferable for the aliphatic diol unit A11 to be a repeating structural unit A11 derived from 1,4-butanediol, i.e., 1,4-butanediol units A11. The aliphatic polyester resin (A) contained in the resin composition may be one type or two or more types. The resin composition may also contain an aliphatic polyester resin other than the aliphatic polyester resin (A).

[0022] The content of the aliphatic polyester resin (A) in the resin composition is not particularly limited, but is preferably 1% by mass or more, particularly preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, particularly preferably 20% by mass or more, and particularly preferably more than 34% by mass, and even more preferably 40% by mass or more. The content is preferably 99% by mass or less, particularly preferably 95% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. That is, the content of the aliphatic polyester resin (A) relative to the mass of the resin composition is preferably 1% by mass or more and 99% by mass or less, particularly preferably 5% by mass or more and 95% by mass or less, more preferably 10% by mass or more and 95% by mass or less, even more preferably 15% by mass or more and 95% by mass or less, particularly preferably 20% by mass or more and 95% by mass or less, particularly preferably more than 34% by mass or more and 95% by mass or less, even more preferably 40% by mass or more and 80% by mass or less, particularly preferably 40% by mass or more and 70% by mass or less. When the content is within the above range, the resin composition becomes more excellent in biodegradability and flow distance, and also in heat resistance and rigidity. In a resin composition in which the content of aliphatic polyester resin (A) is within the above range, the content of aliphatic polyester resin (C') in the resin composition, which includes aliphatic diol units C1 and aliphatic dicarboxylic acid units C22 derived from aliphatic dicarboxylic acids having 5 to 6 carbon atoms, is preferably 0% by mass or more but less than 5% by mass, and particularly preferably 0% by mass or more but 4% by mass or less. By ensuring that the content of aliphatic polyester resin (C') in the resin composition is within the above range, a material with a high bio-content (higher bio-based carbon content) and a lower environmental impact can be obtained. Specific examples of the aliphatic polyester resin (C') include polybutylene succinate adipate (PBSA).

[0023] The content of the aliphatic diol unit A1 relative to 100 mol% of all structural units constituting the aliphatic polyester resin (A) is not particularly limited, but is preferably 10 mol% or more, particularly preferably 20 mol% or more, more preferably 30 mol% or more, even more preferably 45 mol% or more, and is preferably 90 mol% or less, particularly preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 60 mol% or less. That is, when the total number of moles of repeating structural units constituting the aliphatic polyester resin (A) is taken as the standard (100 mol%), the content of the aliphatic diol unit A1 in the aliphatic polyester resin (A) is preferably 10 mol% or more and 90 mol% or less, particularly preferably 20 mol% or more and 80 mol% or less, more preferably 30 mol% or more and 70 mol% or less, and even more preferably 45 mol% or more and 60 mol% or less. When the content is within the above range, the aliphatic polyester resin (A) has excellent biodegradability and heat resistance.

[0024] The content of the aliphatic dicarboxylic acid unit A2 relative to 100 mol% of all structural units constituting the aliphatic polyester resin (A) is not particularly limited, but is preferably 30 mol% or more, particularly preferably 40 mol% or more, more preferably 45 mol% or more, even more preferably 49 mol% or more, and preferably 60 mol% or less, particularly preferably 55 mol% or less, and even more preferably 51 mol% or less. That is, when the total number of moles of repeating structural units constituting the aliphatic polyester resin (A) is taken as the standard (100 mol%), the content of the aliphatic dicarboxylic acid unit A2 in the aliphatic polyester resin (A) is preferably 30 mol% or more and 60 mol% or less, particularly preferably 40 mol% or more and 55 mol% or less, more preferably 45 mol% or more and 51 mol% or less, even more preferably 49 mol% or more and 51 mol% or less. When the content is within the above range, the aliphatic polyester resin (A) becomes more biodegradable and has better heat resistance and rigidity.

[0025] Furthermore, the content (A21 / A2) of aliphatic dicarboxylic acid units A21 having 9 to 36 carbon atoms, based on the total moles of aliphatic dicarboxylic acid units A2 contained in the aliphatic polyester resin (A) (100 mol%), is preferably 1 mol% or more, particularly preferably 5 mol% or more, more preferably 11 mol% or more, and is preferably 50 mol% or less, particularly preferably 40 mol% or less, and more preferably 30 mol% or less. That is, the content (A21 / A2) is preferably 1 mol% or more and 50 mol% or less, particularly preferably 5 mol% or more and 40 mol% or less, and more preferably 11 mol% or more and 30 mol% or less. By setting the content within the above range, the aliphatic polyester resin (A) becomes more excellent in biodegradability and flow distance, and also in heat resistance.

[0026] Furthermore, in the aliphatic polyester resin (A), from the viewpoints of heat resistance and rigidity, the aliphatic dicarboxylic acid units A2 preferably contain succinic acid units A22 as aliphatic dicarboxylic acid units other than the aliphatic dicarboxylic acid units A21 having 9 to 36 carbon atoms. Based on the total number of moles of the aliphatic dicarboxylic acid units A2 contained in the aliphatic polyester resin (A) (100 mol%), from the viewpoint of moldability, the content of the succinic acid units A22 (A22 / A2) is preferably 50 mol% or more, particularly preferably 60 mol% or more, more preferably 70 mol% or more, preferably 99 mol% or less, particularly preferably 95 mol% or less, and even more preferably 89 mol% or less. That is, the content (A21 / A2) is preferably 50 mol% or more and 99 mol% or less, particularly preferably 60 mol% or more and 95 mol% or less, and more preferably 70 mol% or more and 89 mol% or less. When the content ratio (A21 / A2) is within the above range, the aliphatic polyester resin (A) can achieve further improvements in the biodegradation rate and fluidity, and further improvements in the surface appearance of molded articles.

[0027] When the polyester-based resin (A) contains the aliphatic dicarboxylic acid unit A21 having 9 to 36 carbon atoms and the succinic acid unit A22, if the contents of the aliphatic dicarboxylic acid unit A21 having 9 to 36 carbon atoms and the succinic acid unit A22 are each within the above-mentioned preferred ranges, it becomes easier to obtain a resin composition that has improved moldability and is also excellent in heat resistance, easy biodegradability, and surface smoothness of molded articles.

[0028] The content of repeating structural units derived from aliphatic dicarboxylic acids having 9 to 36 carbon atoms in all polyester resins contained in the resin composition relative to the total number of moles of repeating structural units derived from aliphatic dicarboxylic acids in all polyester resins contained in the resin composition is not particularly limited, but is usually 0.5 mol% or more, preferably 1 mol% or more, more preferably 4 mol% or more, even more preferably 6 mol% or more, particularly preferably 8 mol% or more, and usually 60 mol% or less, preferably 50 mol% or less, more preferably 40 mol% or less, and particularly preferably 30 mol% or less. That is, the content of aliphatic dicarboxylic acid units having 9 to 36 carbon atoms in all polyester resins contained in the resin composition relative to the total number of moles of aliphatic dicarboxylic acid units in all polyester resins contained in the resin composition is preferably 0.5 mol% or more and 60 mol% or less, particularly preferably 1 mol% or more and 50 mol% or less, more preferably 4 mol% or more and 40 mol% or less, even more preferably 6 mol% or more and 30 mol% or less, and particularly preferably 8 mol% or more and 30 mol% or less. By setting the content within the above range, a resin composition having superior biodegradability and heat resistance can be obtained.

[0029] The method for calculating the content of aliphatic dicarboxylic acid units having 9 to 36 carbon atoms in all polyester resins contained in the resin composition relative to the total number of moles of aliphatic dicarboxylic acid units in all polyester resins contained in the resin composition is not particularly limited, but it can be calculated from the mass ratio of the polyester resins in the resin composition and the content (mol%) of the aliphatic dicarboxylic acid units in each polyester resin, or １ It can also be calculated by measuring with H-NMR. １ Specifically, the calculation method using H-NMR is to measure the viscosity of the resin composition using a Bruker NMR "AVANCE 400". １The H-NMR can be measured and the chemical shifts corresponding to the respective structural units can be determined from the ratio of integral values ​​of the chemical shifts. Examples of chemical shifts corresponding to the aliphatic dicarboxylic acid units include 2.63 ppm (carbonyl α-position, 4H) corresponding to the succinic acid unit, 2.35 ppm (carbonyl α-position, 4H) corresponding to the adipic acid unit, and 3.0 ppm (carbonyl α-position, 4H) or 1.3 ppm (CH ２ , 8H). The structural units contained in the polyester resin can be determined by the same method. １ The polyester resin (A) can be analyzed by H-NMR. This analysis can be applied not only to the polyester resin (A) but also to other polyester resins.

[0030] As described above, the resin composition may contain two or more aliphatic polyester resins corresponding to the aliphatic polyester resin (A). Specifically, for example, a mixture of aliphatic polyester resins having different amounts of aliphatic dicarboxylic acid units having 9 to 36 carbon atoms may be included. That is, for example, a mixture of an aliphatic polyester resin containing aliphatic dicarboxylic acid units having 9 to 36 carbon atoms and succinic acid units and an aliphatic polyester resin containing only aliphatic dicarboxylic acid units having 9 to 36 carbon atoms may be included. Furthermore, as described above, the resin composition may contain a polyester resin other than the aliphatic polyester resin (A), and may further contain an aliphatic polyester resin that does not contain aliphatic dicarboxylic acid units having 9 to 36 carbon atoms. By using such multiple types of aliphatic polyester resins, it is possible to adjust the content of repeating structural units derived from aliphatic dicarboxylic acids having 9 to 36 carbon atoms relative to the total number of moles of repeating structural units derived from aliphatic dicarboxylic acids in all polyester resins contained in the resin composition to fall within the above-described preferred range.

[0031] One embodiment of the aliphatic polyester resin (A) according to the present invention is, for example, an aliphatic polyester resin containing an aliphatic diol unit A1 represented by the following structural formula (1) and an aliphatic dicarboxylic acid unit A2 represented by the following structural formula (2): １-O- (1) -OC-R ２ -CO- (2)

[0032] In structural formula (1), R １ represents a divalent aliphatic hydrocarbon group. ２ represents a divalent aliphatic hydrocarbon group having 7 to 34 carbon atoms, preferably 7 to 11 carbon atoms. The aliphatic diol unit A1 represented by structural formula (1) and the aliphatic dicarboxylic acid unit A2 represented by structural formula (2) may be derived from a compound derived from petroleum or a compound derived from a plant raw material, but are preferably derived from a compound derived from a plant raw material.

[0033] The aliphatic polyester resin (A) may contain two or more aliphatic diol units A1 represented by structural formula (1) in the molecule, and may also contain two or more aliphatic dicarboxylic acid units A2 represented by structural formula (2) in the molecule.

[0034] The aliphatic diol component that provides the aliphatic diol unit A1 represented by structural formula (1) is not particularly limited, but from the viewpoint of moldability and mechanical strength, an aliphatic diol having 2 to 10 carbon atoms is preferred, and an aliphatic diol having 4 to 6 carbon atoms is particularly preferred. Examples include ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,4-cyclohexanedimethanol, with 1,4-butanediol being particularly preferred. It is also possible to use two or more types of the above aliphatic diols. These aliphatic diols may or may not be derivatives thereof.

[0035] Specific examples of aliphatic dicarboxylic acids that provide the aliphatic dicarboxylic acid unit A21 having 9 to 36 carbon atoms and represented by structural formula (2) include azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, and dimer acid. Among these, from the viewpoints of biodegradability and heat resistance, at least one selected from the group consisting of sebacic acid and azelaic acid is preferred. The aliphatic dicarboxylic acid unit A2 may be contained in one type or in two or more types. These aliphatic dicarboxylic acids may or may not be derivatives thereof.

[0036] Furthermore, the aliphatic polyester resin (A) may contain structural units (other structural units) other than the aliphatic diol unit A1 and the aliphatic dicarboxylic acid unit A21 having 9 to 36 carbon atoms, for the purpose of controlling heat resistance, strength, biodegradability, etc. When the compounds described in the following description of other structural units overlap with compounds other than aliphatic diols and aliphatic dicarboxylic acids having 9 to 36 carbon atoms, the target compounds are compounds excluding aliphatic diols and aliphatic dicarboxylic acids having 9 to 36 carbon atoms, unless otherwise specified.

[0037] The aliphatic polyester resin (A) may further contain, as the aliphatic dicarboxylic acid unit A2, any dicarboxylic acid unit other than the aliphatic dicarboxylic acid unit A21 having 9 to 36 carbon atoms, in addition to or instead of the succinic acid unit A22. Examples of dicarboxylic acid components that provide such other dicarboxylic acid units include oxalic acid, malonic acid, and adipic acid. These aliphatic dicarboxylic acids may or may not be derivatives thereof.

[0038] The aliphatic polyester resin (A) may further contain a repeating unit (aliphatic oxycarboxylic acid unit) derived from an aliphatic oxycarboxylic acid. Specific examples of the aliphatic oxycarboxylic acid component that provides the aliphatic oxycarboxylic acid unit include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, and 2-hydroxyisocaproic acid, as well as derivatives of these carboxylic acids, such as lower alkyl esters or intramolecular esters. When optical isomers exist, they may be in the D-form, L-form, or racemic form, and the raw material may be in the form of a solid, liquid, or aqueous solution. Among these, lactic acid or glycolic acid, or derivatives thereof, are particularly preferred. These aliphatic oxycarboxylic acids can be used alone or in combination of two or more.

[0039] From the viewpoint of moldability, the content of the aliphatic oxycarboxylic acid unit in the aliphatic polyester resin (A) is preferably 20 mol % or less, more preferably 10 mol % or less, even more preferably 5 mol % or less, and particularly preferably 0 mol % (not included or below the detection limit), where all structural units constituting the aliphatic polyester resin (A) are taken as 100 mol %.

[0040] The aliphatic polyester resin (A) may further contain an aromatic dicarboxylic acid unit in addition to the aliphatic dicarboxylic acid unit A2, as long as the effects of the present invention are not impaired. Examples of dicarboxylic acids that provide the aromatic dicarboxylic acid unit include terephthalic acid, isophthalic acid, and furandicarboxylic acid.

[0041] The aliphatic polyester resin (A) may have an increased melt viscosity by copolymerizing at least one component selected from the group consisting of an aliphatic polyhydric alcohol having three or more hydroxyl groups (tri- or higher functional aliphatic polyhydric alcohol), an aliphatic polycarboxylic acid having three or more carboxyl groups or an anhydride thereof (tri- or higher functional aliphatic polycarboxylic acid), and an aliphatic polyoxycarboxylic acid having three or more groups selected from the group consisting of hydroxyl groups and carboxyl groups (tri- or higher functional aliphatic polyoxycarboxylic acid). Hereinafter, these components will be collectively referred to as "tri- or higher functional component." Note that, although the tri- or higher functional aliphatic polyoxycarboxylic acid overlaps with the above-mentioned aliphatic dicarboxylic acid having 9 to 36 carbon atoms in its range, this specification does not include the above-mentioned aliphatic dicarboxylic acid having 9 to 36 carbon atoms.

[0042] Specific examples of trifunctional aliphatic polyhydric alcohols include trimethylolpropane and glycerin, and specific examples of tetrafunctional aliphatic polyhydric alcohols include pentaerythritol. These may be used alone or in combination of two or more. Specific examples of trifunctional aliphatic polycarboxylic acids or acid anhydrides thereof include propanetricarboxylic acid or its acid anhydride, and specific examples of tetrafunctional polycarboxylic acids or its acid anhydrides include cyclopentanetetracarboxylic acid or its acid anhydride. These may be used alone or in combination of two or more.

[0043] Trifunctional aliphatic oxycarboxylic acids are divided into (i) types having two carboxyl groups and one hydroxyl group in the same molecule, and (ii) types having one carboxyl group and two hydroxyl groups. Either type can be used, but from the viewpoints of moldability, mechanical strength, and the appearance of molded products, types having two carboxyl groups and one hydroxyl group in the same molecule, such as malic acid, are preferred, and more specifically, malic acid is preferred. Tetrafunctional aliphatic oxycarboxylic acid components are divided into (i) types having three carboxyl groups and one hydroxyl group in the same molecule, (ii) types having two carboxyl groups and two hydroxyl groups in the same molecule, and (iii) types having three hydroxyl groups and one carboxyl group in the same molecule. Either type can be used, but those having multiple carboxyl groups are preferred, and more specifically, citric acid, tartaric acid, etc. can be mentioned. These can be used alone or in combination.

[0044] When the aliphatic polyester resin (A) contains such tri- or higher functional structural units, the lower limit of the content is usually 0.00 mol% or more, preferably 0.01 mol% or more, and the upper limit is usually 5.00 mol% or less, preferably 2.50 mol% or less, based on the total number of moles of the structural units of the aliphatic polyester resin (A). That is, the content of the tri- or higher functional structural units is preferably 0.00 mol% or more and 5.00 mol% or less, particularly preferably 0.01 mol% or more and 2.50 mol% or less, based on the total number of moles of the structural units of the aliphatic polyester resin (A).

[0045] The aliphatic polyester resin (A) can be produced by a known method for producing polyesters. The polycondensation reaction can be carried out under any suitable conditions that have been conventionally used, and is not particularly limited. Usually, the degree of polymerization is further increased by carrying out a reduced pressure operation after the esterification reaction has proceeded.

[0046] When a diol component forming diol units (also referred to as "diol component providing diol units") and a dicarboxylic acid component forming dicarboxylic acid units (also referred to as "dicarboxylic acid providing dicarboxylic acid units") are reacted during the production of the aliphatic polyester resin (A), the amounts of the diol component and the dicarboxylic acid component used are set so that the aliphatic polyester resin (A) produced has the desired composition. Usually, the diol component and the dicarboxylic acid component react in substantially equimolar amounts, but the diol component is usually used in a 1 to 50 mol % excess over the dicarboxylic acid component because it is distilled off during the esterification reaction.

[0047] <Method for producing aliphatic polyester resin (A)> Hereinafter, a method for producing aliphatic polyester resin (A) will be described using a continuous production method as an example. Note that, below, a method for producing aliphatic polyester resin (A) by an esterification reaction step using an aliphatic diol and an aliphatic dicarboxylic acid and a subsequent polycondensation reaction step will be exemplified, but the esterification reaction step may be a transesterification reaction step, or a step in which both the esterification reaction and the transesterification reaction are performed.

[0048] In the continuous production method, for example, an aliphatic dicarboxylic acid and an aliphatic diol are reacted in a plurality of continuous reaction vessels, and polyester pellets are continuously obtained through an esterification reaction step and a melt polycondensation reaction step. However, the method is not limited to a continuous method, and any conventionally known method for producing polyesters can be employed as long as it does not impair the effects of the present invention.

[0049] (Esterification Reaction Step) The esterification reaction step in which a dicarboxylic acid component and a diol component are reacted and the subsequent polycondensation reaction step can be carried out in a plurality of continuous reaction tanks or in a single reaction tank, but it is preferable to carry out the steps in a plurality of continuous reaction tanks in order to reduce fluctuations in the physical properties of the resulting polyester.

[0050] The reaction temperature in the esterification reaction step is not particularly limited as long as it is a temperature at which the esterification reaction can be carried out. However, in order to increase the reaction rate, it is preferably 200°C or higher, more preferably 210°C or higher, and in order to suppress discoloration of the polyester, it is preferably 270°C or lower, more preferably 260°C or lower, and particularly preferably 250°C or lower. That is, the reaction temperature is preferably 200°C or higher and 270°C or lower, particularly preferably 210°C or higher and 260°C or lower, and more preferably 210°C or higher and 250°C or lower. By keeping the reaction temperature within the above range, the esterification reaction can proceed at an appropriate rate, the reaction time can be shortened, and the occurrence of dehydration decomposition of the aliphatic diol can be suppressed. Furthermore, decomposition of the aliphatic diol and aliphatic dicarboxylic acid can be suppressed, the generation of scattered matter in the reaction vessel can be suppressed, the generation of foreign matter can be effectively prevented, and the generation of turbidity (haze) in the reaction product can be prevented. Furthermore, the esterification temperature is preferably a constant temperature. By maintaining a constant temperature, the esterification rate can be stabilized. The constant temperature is the set temperature ±5°C, preferably ±2°C.

[0051] The reaction atmosphere is preferably an inert gas atmosphere such as nitrogen or argon.

[0052] The reaction pressure is preferably 50 to 200 kPa, more preferably 60 kPa or more, even more preferably 70 kPa or more, and more preferably 130 kPa or less, and even more preferably 110 kPa or less. That is, the reaction pressure is preferably 50 kPa or more and 200 kPa or less, particularly 60 kPa or more and 130 kPa or less, and even more preferably 70 kPa or more and 110 kPa or less. By setting the reaction pressure within the above range, the generation of scattered matter in the reaction vessel can be suppressed, the generation of turbidity (haze) in the reaction product can be suppressed, and the increase of foreign matter can be suppressed. Furthermore, the distillation of the aliphatic diol out of the reaction system can be suppressed, and a decrease in the rate of the polycondensation reaction can be prevented. Furthermore, dehydration decomposition of the aliphatic diol can be suppressed, and a decrease in the rate of the polycondensation reaction can be prevented.

[0053] The reaction time is preferably 1 hour or more, and preferably 10 hours or less, more preferably 4 hours or less. That is, the reaction time is preferably 1 hour or more and 10 hours or less, particularly preferably 1 hour or more and 4 hours or less.

[0054] The reaction molar ratio of the aliphatic diol to the total aliphatic dicarboxylic acids undergoing the esterification reaction represents the molar ratio of the aliphatic diol and the esterified aliphatic diol to the aliphatic dicarboxylic acids and the esterified aliphatic dicarboxylic acids present in the gas phase and the reaction liquid phase of the esterification reaction vessel. This does not include aliphatic dicarboxylic acids, aliphatic diols, and their decomposition products that are decomposed in the reaction system and do not contribute to the esterification reaction. Examples of substances that are decomposed and do not contribute to the esterification reaction include the decomposition of the aliphatic diol 1,4-butanediol to tetrahydrofuran; tetrahydrofuran is not included in this molar ratio. The lower limit of the reaction molar ratio is typically 1.10 or more, preferably 1.12 or more, more preferably 1.15 or more, and even more preferably 1.20 or more. The upper limit of the reaction molar ratio is typically 3.00 or less, preferably 2.50 or less, more preferably 2.30 or less, and even more preferably 2.00 or less. That is, the reaction molar ratio is preferably 1.10 or more and 3.00 or less, particularly preferably 1.12 or more and 2.50 or less, more preferably 1.15 or more and 2.30 or less, and even more preferably 1.20 or more and 2.00 or less. By setting the reaction molar ratio within the above range, the esterification reaction is likely to proceed sufficiently, and the polycondensation reaction, which is a reaction in a subsequent step, is likely to proceed easily, making it easier to obtain a polyester with a high degree of polymerization. In addition, the amount of decomposition of the aliphatic diol and / or aliphatic dicarboxylic acid during the reaction can be suppressed. In order to maintain this reaction molar ratio within the preferred range, it is a preferred method to appropriately supply aliphatic diol to the esterification reaction system.

[0055] The terminal acid value of the ester oligomer obtained in the esterification reaction step and supplied to the subsequent polycondensation reaction is preferably 30 to 1000 eq. / ton. By setting the terminal acid value of the ester oligomer within the above range, it is not necessary to prolong the esterification reaction or increase the reaction molar ratio, and as a result, the amount of tetrahydrofuran by-production can be suppressed. Coloration due to deterioration of the terminal balance can also be prevented. Furthermore, catalyst precipitation can be suppressed, which can prevent polymerization inactivation and the amount of tetrahydrofuran by-production due to acid. After obtaining an ester oligomer having a terminal acid value of 30 to 1000 eq. / ton in the esterification reaction step, contacting the ester oligomer with a phosphorus compound and supplying it to the polycondensation reaction step suppresses the by-production of tetrahydrofuran, reduces the refining load on the plant, and produces an aliphatic aromatic polyester with a good color tone. To more reliably achieve the effects of the present invention, the terminal acid value of the ester oligomer is preferably 50 to 800 eq. / ton, and more preferably 100 to 500 eq. / ton. / ton is more preferable.

[0056] The terminal acid value of the ester oligomer can be controlled within the above range by controlling reaction conditions such as the reaction molar ratio of the diol component to the dicarboxylic acid component, the reaction temperature, and the reaction pressure. In other words, increasing the reaction molar ratio of the diol component to the dicarboxylic acid component tends to lower the terminal acid value of the resulting ester oligomer, while decreasing the reaction molar ratio tends to increase the terminal acid value of the resulting ester oligomer. Furthermore, increasing the reaction temperature and lengthening the reaction time tends to lower the terminal acid value of the resulting ester oligomer. Conversely, decreasing the reaction temperature and shortening the reaction time tends to increase the terminal acid value of the resulting ester oligomer. Therefore, by appropriately adjusting these conditions within the preferred ranges described above, an ester oligomer with a terminal acid value of 30 to 1,000 eq. / ton can be obtained. Furthermore, the terminal acid value of the ester oligomer can also be controlled by appropriately selecting the type and amount of catalyst used in the esterification reaction step described below. The terminal acid value of the ester oligomer is measured by the method described in the Examples section below.

[0057] When the aliphatic polyester resin (A) contains any structural unit other than an aliphatic dicarboxylic acid unit having 9 to 36 carbon atoms, the corresponding compound (monomer or oligomer) is reacted so that the desired composition of each of the structural units is achieved. In this case, there are no limitations on the timing or method of introducing the optional component into the reaction system, and any method is acceptable as long as the desired aliphatic polyester resin (A) can be produced.

[0058] For example, the timing and method for introducing the constitutional unit derived from the optional component into the reaction system are not particularly limited as long as it is introduced before the polycondensation reaction, and examples include (1) a method in which the catalyst is dissolved in advance in a solution containing the optional component and then mixed, and (2) a method in which the catalyst is introduced into the reaction system and mixed at the same time when the raw materials are charged.

[0059] The timing of introducing the compound for forming the structural unit derived from the polyfunctional component may be such that the compound is charged simultaneously with other monomers or oligomers at the initial stage of polymerization, or may be such that the compound is charged after the transesterification reaction and before the pressure reduction is started; however, charging the compound simultaneously with other monomers or oligomers is preferred from the viewpoint of simplifying the process.

[0060] (Polycondensation Reaction Step) In the method for producing the aliphatic polyester resin (A), it is preferable to carry out a polycondensation reaction in a polycondensation reaction step following the esterification reaction step. In this case, in the method for producing the aliphatic polyester (A), it is preferable to contact the ester oligomer obtained in the esterification reaction step with a phosphorus compound before supplying it to the polycondensation reaction step. Here, it is preferable that the phosphorus compound is contacted with the ester oligomer having a terminal acid value of 30 to 1000 eq. / ton obtained in the esterification reaction step, and that no phosphorus compound is present in the esterification reaction step. It is also preferable that the phosphorus compound is contacted with the ester oligomer together with an alkaline earth metal compound.

[0061] The polycondensation reaction can be carried out under reduced pressure using multiple consecutive reaction vessels. Therefore, contacting the ester oligomer with a phosphorus compound before the polycondensation reaction step corresponds to contacting the ester oligomer with the phosphorus compound before the reduced pressure condition is applied. The degree of polymerization can be further increased by performing a reduced pressure operation. The reaction pressure in the final polycondensation reaction vessel in the polycondensation reaction step has a lower limit of usually 0.01 kPa or more, preferably 0.03 kPa or more, and an upper limit of usually 1.4 kPa or less, preferably 0.4 kPa or less. That is, the reaction pressure is preferably 0.01 kPa or more and 1.4 kPa or less, and particularly preferably 0.03 kPa or more and 0.4 kPa or less. By maintaining the reaction pressure during polycondensation within the above range, the polycondensation time can be suppressed, and consequently, molecular weight reduction and discoloration due to thermal decomposition of the polyester can be prevented, making it easier to obtain a polyester exhibiting sufficient properties for practical use. Furthermore, there is no need to use ultra-high vacuum polycondensation equipment, which is advantageous in terms of cost.

[0062] The reaction temperature is usually 215°C or higher, preferably 220°C or higher, and usually 270°C or lower, preferably 260°C or lower. That is, the reaction temperature is preferably 215°C or higher and 270°C or lower, particularly preferably 220°C or higher and 260°C or lower. By setting the reaction temperature within the above range, the rate of the polycondensation reaction can be set at an appropriate rate, and the production of a polyester with a high degree of polymerization does not require a long time, and a high-power stirrer is not required, which is advantageous in terms of cost. Furthermore, thermal decomposition of the polyester resin (A) during production can be suppressed, making it easier to obtain a polyester resin with a high degree of polymerization (A).

[0063] The reaction time is usually 1 hour or more and usually 15 hours or less, preferably 10 hours or less, and more preferably 8 hours or less. That is, the reaction time is preferably 1 hour or more and 15 hours or less, and particularly preferably 1 hour or more and 8 hours or less. By setting the reaction time within the above range, the reaction can be sufficiently progressed, making it easier to obtain a polyester-based resin (A) with a high degree of polymerization, and making it possible to more easily obtain a molded article with the desired mechanical properties. In addition, thermal decomposition of the aliphatic polyester-based resin (A) can be suppressed, preventing a decrease in the molecular weight of the aliphatic polyester-based resin (A), and also making it easier to obtain a molded article with the desired mechanical properties. In addition, an increase in the number of carboxyl group terminals due to thermal decomposition, which affects the durability of the polyester-based resin (A), can be prevented.

[0064] By controlling the polycondensation reaction temperature, time, and reaction pressure, a polyester resin (A) having a desired intrinsic viscosity can be obtained.

[0065] The aliphatic polyester resin (A) is usually produced in the presence of a catalyst. The catalyst can be selected from among catalysts that can be used in the production of known polyester resins, as long as the effects of the present invention are not significantly impaired.

[0066] In the polycondensation reaction, the reaction does not proceed easily without a catalyst, so it is preferable to use a catalyst. The polycondensation reaction catalyst may be added at any stage between the esterification reaction step and the polycondensation reaction step. Furthermore, the polycondensation reaction catalyst may be added in multiple batches between the esterification reaction step and the polycondensation reaction step.

[0067] As the polycondensation reaction catalyst, a compound containing at least one metal element selected from Groups 1 to 14 of the periodic table is generally used. Specific examples of the metal element include scandium, yttrium, samarium, titanium, zirconium, vanadium, chromium, molybdenum, tungsten, tin, antimony, cerium, germanium, zinc, cobalt, manganese, iron, aluminum, magnesium, calcium, strontium, sodium, and potassium. Among these, scandium, yttrium, titanium, zirconium, vanadium, molybdenum, tungsten, zinc, iron, and germanium are preferred, with titanium, zirconium, tungsten, iron, and germanium being particularly preferred. Furthermore, in order to reduce the polyester terminal concentration, which affects the thermal stability of the polyester, metal elements selected from Groups 3 to 6 of the periodic table that exhibit Lewis acidity are preferred among the above metals. Specifically, scandium, titanium, zirconium, vanadium, molybdenum, or tungsten is preferred, and titanium or zirconium is particularly preferred because of its availability, and titanium is further preferred in terms of its reactivity. Here, the periodic table refers to the long-form periodic table (Nomenclature of Inorganic Chemistry IUPAC Recommendations 2005).

[0068] In addition, other catalysts may be used in combination as long as the object of the present invention is not impaired. The catalysts may be used alone or in any combination and ratio of two or more.

[0069] The amount of catalyst used is arbitrary as long as it does not significantly impair the effects of the present invention, but is usually 0.0005% by mass or more, more preferably 0.0010% by mass or more, and usually 3.0000% by mass or less, preferably 1.5000% by mass or less, based on the amount of monomer used. That is, the amount of catalyst used is preferably 0.0005% by mass or more and 3.0000% by mass or less, and particularly preferably 0.0010% by mass or more and 1.5000% by mass or less. By setting the amount of catalyst used within the above range, the effects of using the catalyst can be enjoyed, it is advantageous in terms of cost, and excessive coloration of the aliphatic polyester resin (A) and a decrease in hydrolysis resistance can be prevented.

[0070] In this embodiment, a titanium compound is preferably used as a catalyst in the esterification reaction step.

[0071] The titanium compound is preferably a tetraalkyl titanate or a hydrolyzate thereof, and specific examples thereof include tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-t-butyl titanate, tetraphenyl titanate, tetracyclohexyl titanate, tetrabenzyl titanate, mixed titanates thereof, or hydrolyzates thereof.

[0072] Also preferably used are titanium (oxy)acetylacetonate, titanium tetraacetylacetonate, titanium (diisoproxide)acetylacetonate, titanium bis(ammonium lactate)dihydroxide, titanium bis(ethylacetoacetate)diisopropoxide, titanium (triethanolaminate)isopropoxide, polyhydroxytitanium stearate, titanium lactate, titanium triethanolaminate, and butyl titanate dimer.

[0073] Of these, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, titanium(oxy)acetylacetonate, titanium tetraacetylacetonate, titanium bis(ammonium lactate)dihydroxide, polyhydroxytitanium stearate, titanium lactate, and butyl titanate dimer are preferred, and tetra-n-butyl titanate, titanium(oxy)acetylacetonate, titanium tetraacetylacetonate, polyhydroxytitanium stearate, titanium lactate, or butyl titanate dimer are more preferred, and tetra-n-butyl titanate, polyhydroxytitanium stearate, titanium(oxy)acetylacetonate, or titanium tetraacetylacetonate are particularly preferred.

[0074] These titanium compounds are supplied to the esterification reaction step as a catalyst solution prepared using a catalyst dissolving solvent such as an alcohol such as methanol, ethanol, isopropanol, or butanol; a diol such as ethylene glycol, butanediol, or pentanediol; an ether such as diethyl ether or tetrahydrofuran; a nitrile such as acetonitrile; a hydrocarbon compound such as heptane or toluene; water; or a mixture thereof, so that the titanium compound concentration is usually 0.05 to 5% by weight.

[0075] The timing of introducing the catalyst is not particularly limited as long as it is before the polycondensation reaction, and it may be introduced when the raw materials are charged or when pressure reduction is started. When an aliphatic oxycarboxylic acid unit is introduced, it is preferably introduced simultaneously with a monomer or oligomer that forms an aliphatic oxycarboxylic acid unit, such as lactic acid or glycolic acid, when the raw materials are charged, or by dissolving the catalyst in an aqueous aliphatic oxycarboxylic acid solution and introducing it. In particular, the method of dissolving the catalyst in an aqueous aliphatic oxycarboxylic acid solution and introducing it is preferred because it increases the polymerization rate.

[0076] Specific examples of the phosphorus compound to be contacted with the ester oligomer having a terminal acid value of 30 to 1000 eq. / ton obtained in the esterification reaction step include orthophosphoric acid, polyphosphoric acid, and pentavalent phosphorus compounds such as trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, tris(triethylene glycol) phosphate, ethyl diethylphosphonoacetate, methyl acid phosphate, ethyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, monobutyl phosphate, dibutyl phosphate, dioctyl phosphate, and triethylene glycol acid phosphate, as well as trivalent phosphorus compounds such as phosphorous acid, hypophosphorous acid, diethyl phosphite, trisdodecyl phosphite, trisnonyldecyl phosphite, and triphenyl phosphite. Among these, acidic phosphate ester compounds are preferred, and as the acidic phosphate ester compound, those having an ester structure of phosphoric acid having at least one hydroxyl group, represented by the following general formula (I) and / or (II), are preferably used.

[0077]

[0078] In the above formula, R, R', and R" each independently represent an alkyl group having 1 to 6 carbon atoms, a cyclohexyl group, an aryl group, or a 2-hydroxyethyl group, and in formula (I), R and R' may be the same or different.

[0079] Specific examples of such acidic phosphate ester compounds include methyl acid phosphate, ethyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, and octyl acid phosphate, and ethyl acid phosphate and butyl acid phosphate are preferred. These acidic phosphate ester compounds may be used alone or in combination of two or more.

[0080] The acidic phosphate ester compound may be a monoester represented by the above formula (II) or a diester represented by the above formula (I), but it is preferable to use the monoester or a mixture of the monoester and diester because a catalyst exhibiting high catalytic activity can be obtained. When a mixture of the monoester (II) and diester (I) is used, the weight ratio of the monoester to the diester (monoester:diester) is preferably 80:20 or more, more preferably 70:30 or more, even more preferably 60:40 or more, and also preferably 20:80 or more, more preferably 30:70 or more, and even more preferably 40:60 or less.

[0081] It is also preferred to contact an alkaline earth metal compound with the ester oligomer together with these phosphorus compounds, and examples of the alkaline earth metal compound include various compounds such as beryllium, magnesium, calcium, strontium, and barium. From the viewpoints of ease of handling and availability and catalytic effect, magnesium and calcium compounds are preferred, and among these, magnesium compounds with excellent catalytic effect are preferred. Specific examples of the magnesium compound include magnesium acetate, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium alkoxide, and magnesium hydrogen phosphate, and among these, magnesium acetate is preferred.

[0082] The phosphorus compound and alkaline earth metal compound are preferably added to the ester oligomer to be supplied to the polycondensation reaction step as a catalyst solution prepared using a solvent exemplified above as a catalyst dissolving solvent used in preparing the catalyst solution of the titanium compound, so that the concentration of the phosphorus compound is 0.01 to 7.6 wt % and the concentration of the alkaline earth metal compound is 0.02 to 9.7 wt %.

[0083] The amounts and ratios of the titanium compound used in the esterification reaction step and the phosphorus compound and alkaline earth metal compound used in the polycondensation reaction step are not particularly limited, but for example, the titanium compound is preferably used so that the amount added, calculated as Ti, relative to the polymer produced is 5 to 100 ppm by weight. The phosphorus compound is preferably used so that the molar ratio of the added titanium compound in terms of P relative to the molar amount added in terms of Ti (P / Ti molar ratio) is 0.5 to 2.5, and the alkaline earth metal compound is preferably used so that the molar ratio of the added titanium compound in terms of alkaline earth metal relative to the molar amount added in terms of Ti (alkaline earth metal / Ti molar ratio) is 0.5 to 3.0. Using either catalyst compound so that the above-mentioned conditions are satisfied is not only advantageous in terms of cost, but also prevents the terminal acid value in the final polyester from increasing, thereby preventing a decrease in the thermal stability and hydrolysis resistance of the polyester resin (A) due to an increase in the terminal acid value and residual catalyst concentration. Furthermore, since the reactivity can be maintained, thermal decomposition of the polyester during the polyester production can be prevented, and a polyester resin (A) exhibiting practically useful physical properties can be more easily obtained.

[0084] When producing aliphatic polyester resin (A), a chain extender such as a carbonate compound and / or a diisocyanate compound can also be used.In this case, the amount of chain extender is such that the total proportion of carbonate bonds and urethane bonds in the aliphatic polyester resin (A) is preferably 10 mol% or less, particularly preferably 5 mol% or less, more preferably 3 mol% or less, when the total structural units constituting the aliphatic polyester resin (A) obtained by using the chain extender are taken as 100 mol%.However, when using a carbonate compound as a chain extender, from the viewpoint of maintaining good biodegradability of the aliphatic polyester resin (A), it is preferable to adjust the amount of carbonate compound used so that the carbonate bonds are preferably less than 1 mol%, more preferably 0.5 mol% or less, even more preferably 0.1 mol% or less, based on the total structural units constituting the aliphatic polyester resin (A). Furthermore, when a diisocyanate compound is used as a chain extender, it is preferable to adjust the amount of the diisocyanate compound used so that the urethane bond content is preferably 0.55 mol% or less, more preferably 0.3 mol% or less, even more preferably 0.12 mol% or less, and particularly preferably 0.05 mol% or less, relative to the total structural units constituting the aliphatic polyester resin (A). This amount, calculated per 100 parts by mass of the aliphatic polyester resin (A), is preferably 0.9 parts by mass or less, more preferably 0.5 parts by mass or less, even more preferably 0.2 parts by mass or less, and particularly preferably 0.1 parts by mass or less. In particular, by adjusting the amount of urethane bonds in the aliphatic polyester resin (A) as described above, it is possible to prevent the generation of smoke and odor from the molten film at the die outlet due to the decomposition of urethane bonds during the film formation process, etc., and also to prevent the occurrence of film breakage due to foaming in the molten film, thereby enabling more stable molding. The carbonate bond content and urethane bond content in the aliphatic polyester resin (A) are １ H-NMR and １３ It can be determined by calculation from the results of NMR measurements such as C-NMR.

[0085] Specific examples of carbonate compounds as the chain extender include diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, ethylene carbonate, diamyl carbonate, dicyclohexyl carbonate, etc. In addition, carbonate compounds composed of the same or different hydroxy compounds derived from hydroxy compounds such as phenols or alcohols can also be used.

[0086] Specific examples of the diisocyanate compound include known diisocyanates such as 2,4-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, 2,4,6-triisopropylphenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, and tolidine diisocyanate.

[0087] Other chain extenders that may be used include dioxazoline, silicate esters, etc. Specific examples of silicate esters include tetramethoxysilane, dimethoxydiphenylsilane, dimethoxydimethylsilane, and diphenyldihydroxysilane.

[0088] High molecular weight polyester resins using these chain extenders (coupling agents) can also be produced using conventional techniques. After polycondensation is complete, the chain extender is added to the reaction system in a homogeneous molten state without a solvent, and reacted with the polyester obtained by polycondensation.

[0089] More specifically, a polyester having substantially hydroxyl terminal groups and a weight-average molecular weight (Mw) of 20,000 or more, preferably 40,000 or more, obtained by catalytically reacting a diol component with a dicarboxylic acid component, can be reacted with the chain extender to obtain a polyester resin with a higher molecular weight. A prepolymer having a weight-average molecular weight of 20,000 or more can be produced by using a small amount of chain extender without the influence of residual catalyst, even under severe conditions such as a molten state, and thus can produce a high-molecular-weight polyester resin without forming a gel during the reaction. The weight-average molecular weight (Mw) of the polyester resin is determined by gel permeation chromatography (GPC) using chloroform as the solvent at 40°C, converted into a monodisperse polystyrene value.

[0090] Therefore, when the polyester resin is further increased in molecular weight using, for example, the diisocyanate compound as a chain extender, it is preferable to use a prepolymer having a weight-average molecular weight of typically 20,000 or more, preferably 40,000 or more. When the weight-average molecular weight is 20,000 or more, the amount of diisocyanate compound used for increasing the molecular weight is not too large, and a decrease in the heat resistance of the resulting aliphatic polyester resin (A) can be more reliably prevented. Using such a prepolymer, a polyester resin having urethane bonds with a linear structure linked via urethane bonds derived from the diisocyanate compound is produced.

[0091] The pressure during chain extension is usually 0.01 MPa or more, preferably 0.05 MPa or more, more preferably 0.07 MPa or more, and usually 1 MPa or less, preferably 0.5 MPa or less, more preferably 0.3 MPa or less, with normal pressure (0.1 MPa) being most preferred.

[0092] The reaction temperature during chain extension has a lower limit of usually 100°C or higher, preferably 150°C or higher, more preferably 190°C or higher, and most preferably 200°C or higher, and an upper limit of usually 250°C or lower, preferably 240°C or lower, and more preferably 230°C or lower. That is, the reaction temperature during chain extension is preferably 100°C or higher and 250°C or lower, particularly preferably 150°C or higher and 240°C or lower, more preferably 190°C or higher and 230°C or lower, and particularly preferably 200°C or higher and 230°C or lower. When the reaction temperature during chain extension is within the above range, a more uniform reaction can be carried out, high stirring power is not required, and gelation and decomposition of the aliphatic polyester resin (A) can be more reliably prevented.

[0093] The lower limit of the time for chain extension is usually 0.1 minute or more, preferably 1 minute or more, and more preferably 5 minutes or more, and the upper limit is usually 5 hours or less, preferably 1 hour or less, more preferably 30 minutes or less, and most preferably 15 minutes or less. That is, the time for chain extension is preferably 0.1 minutes or more and 5 hours or less, particularly preferably 1 minute or more and 1 hour or less, more preferably 5 minutes or more and 30 minutes or less, and even more preferably 5 minutes or more and 15 minutes or less. By setting the chain extension time within the above range, the effect of adding the chain extender can be more reliably enjoyed, and gelation and decomposition of the aliphatic polyester resin (A) can be more reliably prevented.

[0094] (Reaction Tank) Any known esterification reaction tank can be used, and may be any type such as a vertical agitated complete mixing tank, a vertical thermal convection mixing tank, or a tower-type continuous reaction tank, and may be a single tank or a plurality of tanks of the same or different types connected in series. Among these, a reaction tank having an agitator is preferred, and as the agitator, not only a normal type consisting of a power unit, a bearing, a shaft, and an agitator blade, but also a high-speed rotating type such as a turbine stator type high-speed rotating agitator, a disk mill type agitator, or a rotor mill type agitator can be used.

[0095] There are no limitations on the type of stirring, and in addition to the usual stirring method of directly stirring the reaction liquid in the reaction tank from the top, bottom, or side of the reaction tank, a method can also be used in which a part of the reaction liquid is taken out of the reaction tank via piping or the like and stirred with a line mixer or the like to circulate the reaction liquid. The type of stirring blade can also be selected from known types, and specific examples include propeller blades, screw blades, turbine blades, fan turbine blades, disk turbine blades, Pfaudler blades, full zone blades, and Max Blend blades.

[0096] There are no particular limitations on the type of polycondensation reaction tank, and examples thereof include a vertical stirring polymerization tank, a horizontal stirring polymerization tank, a thin-film evaporation polymerization tank, etc. The polycondensation reaction tank may be a single tank, or a plurality of tanks of the same or different types connected in series, but in the later stage of polycondensation when the viscosity of the reaction liquid increases, it is preferable to select a horizontal stirring polymerization tank having a thin-film evaporation function that is excellent in interface renewal, plug flow properties, and self-cleaning properties.

[0097] The molecular weight of the aliphatic polyester resin (A) is not particularly limited, but can be measured by gel permeation chromatography (GPC), and the weight average molecular weight (Mw) using monodisperse polystyrene as the standard substance is usually 10,000 or more, preferably 20,000 or more, more preferably 50,000 or more, even more preferably 100,000 or more, and usually 1,000,000 or less, preferably 500,000 or less, more preferably 400,000 or less, and even more preferably 300,000 or less, from the viewpoint of moldability and mechanical strength. That is, the weight average molecular weight (Mw) of the aliphatic polyester resin (A) is preferably 10,000 or more and 1,000,000 or less, particularly preferably 20,000 or more and 500,000 or less, more preferably 50,000 or more and 400,000 or less, more preferably 100,000 or more and 300,000 or less.

[0098] The melt flow rate (MFR) of the aliphatic polyester resin (A) is not particularly limited, but from the viewpoint of moldability and mechanical strength, it is usually 0.1 g / 10 min or more, preferably 1.0 g / 10 min or more, more preferably 2.0 g / 10 min or more, and usually 100 g / 10 min or less, preferably 40.0 g / 10 min or less, more preferably 30.0 g / 10 min or less, as measured at a temperature of 160 ° C. and a load of 2.16 kg according to JIS K7210-1:2014. That is, the MFR of the aliphatic polyester resin (A) is usually preferably 0.1 g / 10 min or more and 100.0 g / 10 min or less, particularly preferably 1.0 g / 10 min or more and 40.0 g / 10 min or less, and more preferably 2.0 g / 10 min or more and 30.0 g / 10 min or less. The MFR of the aliphatic polyester resin (A) can be adjusted by the molecular weight of the aliphatic polyester resin (A). That is, the MFR can be reduced by increasing the molecular weight, and the MFR can be increased by decreasing the molecular weight.

[0099] The melting point (Tm) of the aliphatic polyester resin (A) is not particularly limited, but is preferably 50°C or higher, more preferably 70°C or higher, even more preferably 80°C or higher, and preferably 160°C or lower, more preferably 140°C or lower, and particularly preferably 120°C or lower. That is, the melting point of the aliphatic polyester resin (A) is preferably 50°C or higher and 160°C or lower, particularly preferably 70°C or higher and 140°C or lower, and more preferably 80°C or higher and 120°C or lower. When multiple melting points are present, it is preferable that at least one of the melting points is within the above range. Having a melting point within the above range can improve the moldability of the resin composition. The melting point of the aliphatic polyester resin (A) can be adjusted, for example, by changing the number of carbon atoms or the content of the repeating structural unit derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms. It can also be adjusted by changing the type and amount of other minor copolymerization components.

[0100] The glass transition temperature (Tg) of the aliphatic polyester resin (A) is not particularly limited, but from the viewpoint of moldability and impact strength, it is preferably −100° C. or higher, more preferably −70° C. or higher, even more preferably −60° C. or higher, and preferably 10° C. or lower, more preferably 0° C. or lower, even more preferably −10° C. or lower, and particularly preferably −20° C. or lower. That is, the glass transition temperature of the aliphatic polyester resin (A) is preferably −100° C. or higher and 10° C. or lower, particularly preferably −70° C. or higher and 0° C. or lower, more preferably −60° C. or higher and −10° C. or lower, and even more preferably −60° C. or higher and −20° C. or lower. The glass transition temperature can be adjusted by changing the number of carbon atoms or the content of the repeating structural unit derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms, and can also be adjusted by changing the type and amount of other minor copolymerization components.

[0101] The melting point (Tm) and glass transition temperature (Tg) can be measured, for example, using a differential scanning calorimeter (manufactured by PerkinElmer, Inc., product name: DSC 8500). Specifically, for example, about 5 mg of a sample is precisely weighed, heated and melted under a nitrogen gas flow at a flow rate of 40 mL / min, cooled at a rate of 10°C / min, and then heated at a rate of 10°C / min, whereby the glass transition temperature and melting point (peak top) can be measured.

[0102] <Polyhydroxyalkanoate (B)> Polyhydroxyalkanoate (hereinafter sometimes referred to as "PHA") (B) does not include those equivalent to the above-mentioned aliphatic polyester resin (A). In other words, polyhydroxyalkanoate (B) is different from aliphatic polyester resin (A). Furthermore, polyhydroxyalkanoate (B) has a repeating structural unit B1 derived from a hydroxyalkanoic acid having 4 or more carbon atoms (hereinafter sometimes referred to as "C4 or more"). Examples of such polyhydroxyalkanoate (B) include aliphatic polyester resins that do not contain aliphatic dicarboxylic acid units A22 having 9 to 36 carbon atoms, which are contained as an essential constituent of aliphatic polyester resin (A), and that contain a repeating structural unit represented by the following structural formula (3) as a main structural unit: [-CHR ３ -CH ２ -CO-O-]...(3) (In structural formula (3), R ３ is an alkyl group having 1 to 15 carbon atoms.

[0103] The polyhydroxyalkanoate (B) preferably contains a C4 or higher hydroxyalkanoic acid unit B1 as the main structural unit, and may be composed solely of the C4 or higher hydroxyalkanoic acid unit B1. Alternatively, the polyhydroxyalkanoate (B) may be composed solely of the C4 or higher hydroxyalkanoic acid unit B1 and repeating structural units derived from other monomers. The C4 or higher hydroxyalkanoic acid unit B1 may be composed solely of one type of hydroxyalkanoic acid unit, or may be composed of two or more types of hydroxyalkanoic acid units. Specific examples of homopolymer polyhydroxyalkanoates (B) containing only one type of hydroxyalkanoic acid unit, i.e., composed solely of the C4 or higher hydroxyalkanoic acid unit B1, include poly(3-hydroxybutyrate) (P3HB), poly(4-hydroxybutyrate) (P4HB), poly(3-hydroxyvalerate) (P3HV), and poly(3-hydroxyhexanoate) (P3HH). Furthermore, examples of the polyhydroxyalkanoate (B) that is a copolymer (copolymer resin) containing two or more types of hydroxyalkanoic acid units and consisting only of C4 or larger hydroxyalkanoic acid units B1 include poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin (PHBH), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer resin (PHBV), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) copolymer resin (PHBVH), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer resin (P3HB4HB), etc. In particular, from the viewpoint of moldability, the polyhydroxyalkanoate (B) is preferably a polymer (copolymer) that contains at least the repeating structural unit B11 derived from 3-hydroxybutyrate as a main structural unit.

[0104] In particular, when the polyhydroxyalkanoate (B) contains 3-hydroxybutyrate units B11 as the main structural unit, the content of 3-hydroxybutyrate units B11 relative to 100 mol% of all structural units constituting the polyhydroxyalkanoate (B) is preferably 60 mol% or more, particularly preferably 70 mol% or more, and may be 100 mol%, 100 mol% or less, or less than 100 mol%, preferably 97 mol% or less, and more preferably 95 mol% or less. That is, the content is preferably 60 mol% or more and 100 mol% or less, particularly preferably 70 mol% or more and 100 mol% or less. It may also be 70 mol% or more and less than 100 mol%, 70 mol% or more and 97 mol% or less, or even 70 mol% or more and 95 mol% or less. Having the content within the above range more reliably prevents the crystallization of the resin composition from slowing down, thereby further improving the productivity of molded products. Furthermore, since it is possible to more reliably prevent the molding temperature and the thermal decomposition temperature from becoming close to each other, it is possible to further improve molding processability.

[0105] Furthermore, when the polyhydroxyalkanoate (B) contains 3-hydroxybutyrate units B11 as the main structural unit and also contains C4 or larger hydroxyalkanoic acid units other than 3-hydroxybutyrate units B11, from the viewpoint of moldability, it preferably contains at least one repeating structural unit selected from the group consisting of repeating structural units B12 derived from 3-hydroxyvalerate, repeating structural units B13 derived from 3-hydroxyhexanoate, and repeating structural units B14 derived from 4-hydroxybutyrate. A particularly preferred example of such polyhydroxyalkanoate (B) is poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin, i.e., PHBH. Furthermore, when polyhydroxyalkanoate (B) contains, in addition to the repeating structural unit B11, at least one repeating structural unit selected from the group consisting of repeating structural units B12, B13, and B14, the total content of repeating structural units B12 to B14, relative to 100 mol% of all repeating structural units in polyhydroxyalkanoate (B), is more preferably 40 mol% or less, and even more preferably 30 mol% or less. By keeping the total content of repeating structural units B12 to B14 at 40 mol% or less, preferably 30 mol% or less, it is possible to more reliably prevent the molding temperature and the thermal decomposition temperature from becoming close to each other, which can be expected to further improve molding processability and also more reliably prevent slow crystallization, thereby further improving the productivity of molded products.

[0106] The ratio of each monomer unit in polyhydroxyalkanoate (B) can be measured, for example, by gas chromatography as follows: 2 mL of a sulfuric acid / methanol mixture (15 / 85 (mass ratio)) and 2 mL of chloroform are added to approximately 20 mg of dried PHA, the container is sealed, and heated at 100°C for 140 minutes to obtain the methyl ester of the PHA decomposition product. After cooling, 1.5 g of sodium bicarbonate is added little by little to neutralize the mixture, and the mixture is left to stand until the evolution of carbon dioxide gas stops. 4 mL of diisopropyl ether is added and mixed well, and the monomer unit composition of the PHA decomposition product in the supernatant is analyzed by capillary gas chromatography to determine the ratio of each monomer in polyhydroxyalkanoate (B).

[0107] The weight-average molecular weight (hereinafter sometimes referred to as "Mw") of polyhydroxyalkanoate (B) can be measured by the aforementioned gel permeation chromatography (GPC), and the weight-average molecular weight (Mw) using monodisperse polystyrene as the standard substance is preferably 200,000 or more, particularly preferably 250,000 or more, more preferably 300,000 or more, and preferably 2,500,000 or less, particularly preferably 2,000,000 or less, and more preferably 1,000,000 or less. That is, the weight-average molecular weight of polyhydroxyalkanoate (B) is preferably 200,000 or more and 2,500,000 or less, particularly preferably 250,000 or more and 2,000,000 or less, and more preferably 300,000 or more and 1,000,000 or less. When the weight average molecular weight of the polyhydroxyalkanoate (B) is within the above range, the mechanical strength and moldability of the resin composition can be further improved.

[0108] The melt flow rate (MFR) of the polyhydroxyalkanoate (B) is not particularly limited, but is preferably 0.1 g / 10 min or more and 100.0 g / 10 min or less, as measured at a temperature of 160 ° C. and a load of 2.16 kg according to JIS K7210:1999. From the viewpoint of moldability and mechanical strength, it is more preferably 80.0 g / 10 min or less, and particularly preferably 50.0 g / 10 min or less. That is, the MFR of the polyhydroxyalkanoate (B) is preferably 0.1 g / 10 min or more and 100.0 g / 10 min or less, particularly preferably 0.1 g / 10 min or more and 80.0 g / 10 min or less, and more preferably 0.1 g / 10 min or more and 50.0 g / 10 min or less. The MFR of the polyhydroxyalkanoate (B) can be adjusted by the molecular weight of the polyhydroxyalkanoate (B).

[0109] The melting point of the polyhydroxyalkanoate (B) is not particularly limited, but is preferably 100° C. or higher, more preferably 120° C. or higher, and preferably 180° C. or lower, more preferably 170° C. or lower, and particularly preferably lower than 160° C. That is, the melting point of the polyhydroxyalkanoate (B) is preferably 100° C. or higher and 180° C. or lower, particularly preferably 120° C. or higher and 170° C. or lower, and more preferably 120° C. or higher and lower than 160° C. When the polyhydroxyalkanoate (B) has multiple melting points, it is preferable that at least one of the melting points is within the above range.

[0110] The polyhydroxyalkanoate (B) is preferably produced by a microorganism, such as Alcaligenes eutrophus AC32 strain (international deposit under the Budapest Treaty, international deposit authority: National Institute of Advanced Industrial Science and Technology International Patent Organism Depositary (6-1 Central, 1-1 Higashi, Tsukuba, Ibaraki Prefecture, Japan), original deposit date: August 12, 1996, transferred on August 7, 1997, deposit number FERM BP-6038 (transferred from original deposit FERM P-15786)) (J. Bacteriol., 179, 4821 (1997)).

[0111] As the polyhydroxyalkanoate (B), commercially available products can also be used. For example, commercially available products of the polyhydroxyalkanoate (B) containing 3-hydroxybutyrate units and 3-hydroxyhexanoate units as main constituent units include "Kaneka Biodegradable Biopolymer Green Planet (registered trademark) X131N," "Kaneka Biodegradable Biopolymer Green Planet (registered trademark) X131A," "Kaneka Biodegradable Biopolymer Green Planet (registered trademark) X331N," and "Kaneka Biodegradable Biopolymer Green Planet (registered trademark) 151C," all manufactured by Kaneka Corporation.

[0112] The resin composition may contain one type of polyhydroxyalkanoate (B), or may contain two or more types of polyhydroxyalkanoates (B) that differ in the type of constituent unit, the ratio of constituent units, the production method, the physical properties, etc.

[0113] When the resin composition contains the aliphatic polyester resin (A) and further a polyhydroxyalkanoate (B), the content of the polyhydroxyalkanoate (B) in the resin composition is preferably more than 0% by mass, particularly preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, from the perspective of the balance between rigidity, impact strength, and moldability, and is preferably 99% by mass or less, particularly preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. That is, when the resin composition contains polyhydroxyalkanoate (B) together with polyhydroxyalkanoate (A), the content of polyhydroxyalkanoate (B) based on the mass of the resin composition is preferably more than 0 mass% and not more than 99 mass%, particularly preferably more than 0 mass% and not more than 90 mass%, more preferably 5 mass% or more and not more than 90 mass%, even more preferably 10 mass% or more and not more than 80 mass%, and particularly preferably 20 mass% or more and not more than 70 mass%.

[0114] In addition, when the resin composition contains the aliphatic polyester resin (A) and the polyhydroxyalkanoate (B), the total content of the aliphatic polyester resin (A) and the polyhydroxyalkanoate (B) in the resin composition is not particularly limited, but is preferably 60% by mass or more, particularly preferably more than 60% by mass, more preferably 70% by mass or more, even more preferably more than 70% by mass, particularly preferably 80% by mass or more, even more preferably more than 80% by mass, 90% by mass or more, and even more preferably more than 90% by mass. The upper limit is not particularly limited, but may be 100% by mass or less, may be less than 100% by mass, may be 98% by mass or less, may be 97% by mass or less, may be 95% by mass or less, or may be 93% by mass or less. That is, when the resin composition contains aliphatic polyester resin (A) and polyhydroxyalkanoate (B), the total content of the aliphatic polyester resin (A) and polyhydroxyalkanoate (B) based on the mass of the resin composition is preferably 60% by mass or more and 100% by mass or less, particularly preferably more than 60% by mass and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, even more preferably more than 70% by mass and 100% by mass or less, particularly preferably 80% by mass or more and 98% by mass or less, 90% by mass or more and 97% by mass or less, more than 90% by mass and 95% by mass or less, and even more preferably more than 90% by mass and 93% by mass or less. By having the total content in the above range, the biodegradability, heat resistance and moldability of the resin composition can be further improved.

[0115] <Aliphatic Polyester Resin (C)> The resin composition may contain an aliphatic polyester resin (C) (hereinafter sometimes referred to as "polyester resin (C)") as an aliphatic polyester resin other than the aliphatic polyester resin (A) and the polyhydroxyalkanoate (B). The aliphatic polyester resin (C) has a repeating structural unit C1 derived from an aliphatic diol and a repeating structural unit C2 derived from an aliphatic dicarboxylic acid, and includes a repeating structural unit C21 derived from an aliphatic dicarboxylic acid having 5 to 8 carbon atoms as the aliphatic dicarboxylic acid unit C2. Specific examples of the aliphatic dicarboxylic acid unit C21 having 5 to 8 carbon atoms include a glutaric acid unit, an adipic acid unit, a pimelic acid unit, and a suberic acid unit. Among these, an adipic acid unit is particularly preferred from the viewpoints of biodegradability, mechanical properties, availability, and cost. Furthermore, the aliphatic polyester resin (C) preferably contains, as main structural units, aliphatic diol units C1 and aliphatic dicarboxylic acid units C21 having 5 to 8 carbon atoms. The aliphatic polyester resin (C) does not contain any of the aforementioned aliphatic polyester resins (A) and polyhydroxyalkanoate (B). In other words, the resin composition is different from the aliphatic polyester resin (A) and polyhydroxyalkanoate (B). The aliphatic polyester resin (C) being different from the aliphatic polyester resin (A) means that the aliphatic polyester resin (C) is substantially free of aliphatic dicarboxylic acid units having 9 to 36 carbon atoms, and the aliphatic polyester resin (C) being different from the polyhydroxyalkanoate (B) means that the aliphatic polyester resin (C) is substantially free of hydroxyalkanoic acid units B1 having 4 or more carbon atoms.

[0116] In addition to the repeating structural units derived from the aliphatic dicarboxylic acid having 5 to 8 carbon atoms, the aliphatic polyester resin (C) preferably contains, as a repeating structural unit derived from the aliphatic dicarboxylic acid, a repeating structural unit derived from a linear or branched aliphatic dicarboxylic acid having 2 to 4 carbon atoms. Specifically, for example, one or more dicarboxylic acid units selected from the group consisting of an oxalic acid unit, a malonic acid unit, and a succinic acid unit are preferred. Among these, succinic acid units are particularly preferred from the viewpoints of cost, moldability, and biodegradability.

[0117] The content of the repeating structural unit C21 derived from an aliphatic dicarboxylic acid having 5 to 8 carbon atoms relative to the total number of moles of repeating structural units derived from dicarboxylic acids in the aliphatic polyester resin (C) is not particularly limited, but is preferably 90 mol% or less, more preferably 70 mol% or less, even more preferably 50 mol% or less, and even more preferably 30 mol% or less. The lower limit is not particularly limited, and may be 1 mol% or more, 5 mol% or more, 10 mol% or more, 20 mol% or more, or 25 mol% or more. That is, the content of the aliphatic dicarboxylic acid unit C21 having 5 to 8 carbon atoms relative to the total number of moles of dicarboxylic acid units in the aliphatic polyester resin (C) is preferably 1 mol% or more and 90 mol% or less, particularly preferably 5 mol% or more and 70 mol% or less, more preferably 10 mol% or more and 50 mol% or less, even more preferably 20 mol% or more and 30 mol% or less, and particularly preferably 25 mol% or more and 30 mol% or less.

[0118] In the aliphatic polyester resin (C), the aliphatic diol unit C1 is not particularly limited. However, from the viewpoint of moldability and mechanical strength, it is preferably an aliphatic diol unit having 2 to 10 carbon atoms, and particularly preferably an aliphatic diol unit having 4 to 6 carbon atoms. Specific examples include one or more aliphatic diol units selected from the group consisting of ethylene glycol units, 1,3-propanediol units, 1,4-butanediol units, and 1,4-cyclohexanedimethanol units. Among these, it is particularly preferred that the aliphatic diol unit C1 contains a 1,4-butanediol unit. The aliphatic diols may be used alone or in combination of two or more. Specifically, the aliphatic polyester resin (C) is preferably polybutylene succinate adipate (PBSA). The aliphatic dicarboxylic acid units and aliphatic diol units may be derived from compounds derived from petroleum or from compounds derived from plant materials, but are preferably derived from compounds derived from plant materials.

[0119] The melting point of the aliphatic polyester resin (C) is not particularly limited, but from the viewpoint of heat resistance and kneadability, it is preferably 70° C. or higher, more preferably 75° C. or higher, and preferably 170° C. or lower, more preferably 150° C. or lower, and particularly preferably less than 130° C. That is, the melting point of the aliphatic polyester resin (C) is preferably 70° C. or higher and 170° C. or lower, particularly preferably 75° C. or higher and 150° C. or lower, and more preferably 75° C. or higher and lower than 130° C. When there are multiple melting points, it is preferable that at least one of the melting points is within the above range.

[0120] The molecular weight of the aliphatic polyester resin (C) is not particularly limited, but can be measured by gel permeation chromatography (GPC). The weight average molecular weight (Mw) of the aliphatic polyester resin (C) using monodisperse polystyrene as the standard is usually 10,000 or more and 1,000,000 or less. However, because this is advantageous in terms of moldability and mechanical strength, it is preferably 20,000 or more and 500,000 or less, and more preferably 50,000 or more and 400,000 or less.

[0121] The melt flow rate (MFR) of the aliphatic polyester resin (C) is not particularly limited, but is typically 0.1 g / 10 min or more and 100.0 g / 10 min or less, as measured at a temperature of 160 ° C. and a load of 2.16 kg according to JIS K7210-1:2014. From the viewpoint of moldability and mechanical strength, it is preferably 50.0 g / 10 min or less, particularly preferably 30.0 g / 10 min or less. That is, from the viewpoint of moldability and mechanical strength, the MFR of the aliphatic polyester resin (C) is preferably 0.1 g / 10 min or more and 100.0 g / 10 min or less, particularly preferably 0.1 g / 10 min or more and 50.0 g / 10 min or less, and more preferably 0.1 g / 10 min or more and 30.0 g / 10 min or less. The MFR of the aliphatic polyester resin (C) can be adjusted by the molecular weight.

[0122] The content of the aliphatic polyester resin (C) in the resin composition is not particularly limited, but from the viewpoint of moldability and heat resistance, it is preferably 70% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. It may also be 0% by mass (less than the detection limit), more than 0% by mass, 1% by mass or more, 3% by mass or more, 5% by mass or more, or 10% by mass or more. That is, the content of the aliphatic polyester resin (C) in the resin composition is preferably 0% by mass (less than the detection limit) or more and 70% by mass or less, particularly preferably more than 0% by mass and 50% by mass or less, more preferably 1% by mass or more and 40% by mass or less, even more preferably 3% by mass or more and 40% by mass or less, particularly preferably 5% by mass or more and 40% by mass or less, and even more preferably 10% by mass or more and 40% by mass or less. The aliphatic polyester resin (C) may be used alone, or two or more aliphatic polyester resins (C) different in the type and ratio of constituent units, production method, physical properties, etc. may be blended and used. As described above, in a resin composition in which the content of the aliphatic polyester resin (A) in the resin composition is within a predetermined range, specifically, for example, 1% by mass or more and 99% by mass or less, particularly 5% by mass or more and 95% by mass or less, among the aliphatic polyester resins belonging to the aliphatic polyester resin (C), the content of the aliphatic polyester resin (C') having aliphatic diol units C1 and aliphatic dicarboxylic acid units C2, and in which the aliphatic dicarboxylic acid units C22 having 5 to 6 carbon atoms, in the resin composition, is preferably the following content, separate from the content of the aliphatic polyester resin (C) in the resin composition. That is, the content of the aliphatic polyester resin (C') relative to the mass of the resin composition is preferably 0% by mass or more and less than 5% by mass, and more preferably 0% by mass or more and 4% by mass or less. By setting the content of the aliphatic polyester resin (C') in the resin composition within the above range, it is possible to obtain a material with a high bio-content (higher bio-based carbon content) and a lower environmental impact.The resin composition containing 0% by mass of the aliphatic polyester resin (C') may or may not contain an aliphatic polyester resin (C) other than the aliphatic polyester resin (C'). Specific examples of the aliphatic polyester resin (C') include polybutylene succinate adipate (PBSA).

[0123] Furthermore, the aliphatic polyester resin (C) may have a repeating unit (aliphatic oxycarboxylic acid unit) derived from an aliphatic oxycarboxylic acid. Specific examples of the aliphatic oxycarboxylic acid component that provides the aliphatic oxycarboxylic acid unit include, for example, lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, and the like, as well as derivatives thereof, such as lower alkyl esters or intramolecular esters. When optical isomers exist, they may be in the D-form, L-form, or racemic form, and may be in the form of a solid, liquid, or aqueous solution. Among these, lactic acid or glycolic acid, or derivatives thereof, are particularly preferred. These aliphatic oxycarboxylic acids can be used alone or as a mixture of two or more.

[0124] When the aliphatic polyester resin (C) contains an aliphatic oxycarboxylic acid unit, the content thereof is, from the viewpoint of moldability, preferably 10 mol % or less, more preferably 5 mol % or less, even more preferably 2 mol % or less, and most preferably 0 mol % (not contained or below the detection limit), based on 100 mol % of all structural units constituting the polyester resin (C).

[0125] The aliphatic polyester resin (C) may have an increased melt viscosity by copolymerizing at least one component selected from the group consisting of an aliphatic polyhydric alcohol having three or more hydroxyl groups (tri- or higher functional aliphatic polyhydric alcohol), an aliphatic polycarboxylic acid having three or more carboxyl groups or an anhydride thereof (tri- or higher functional aliphatic polycarboxylic acid), and an aliphatic polyoxycarboxylic acid having three or more groups selected from the group consisting of hydroxyl groups and carboxyl groups (tri- or higher functional aliphatic polyoxycarboxylic acid). These components are hereinafter collectively referred to as "tri- or higher functional components." Note that although the tri- or higher functional aliphatic polyoxycarboxylic acid overlaps with the above-mentioned aliphatic dicarboxylic acids having 5 to 8 carbon atoms in some range, this specification does not include the above-mentioned aliphatic dicarboxylic acids having 5 to 8 carbon atoms.

[0126] Specific examples of trifunctional aliphatic polyhydric alcohols include trimethylolpropane, glycerin, etc., and specific examples of tetrafunctional aliphatic polyhydric alcohols include pentaerythritol, etc. These may be used alone or in combination of two or more.

[0127] Specific examples of trifunctional aliphatic polycarboxylic acids or acid anhydrides thereof include propanetricarboxylic acid or its acid anhydride, etc., and specific examples of tetrafunctional polycarboxylic acids or its acid anhydrides include cyclopentanetetracarboxylic acid or its acid anhydride, etc. These may be used alone or in combination of two or more.

[0128] Trifunctional aliphatic oxycarboxylic acids are divided into (i) types having two carboxyl groups and one hydroxyl group in the same molecule, and (ii) types having one carboxyl group and two hydroxyl groups. Either type can be used, but from the viewpoints of moldability, mechanical strength, and the appearance of molded products, types having two carboxyl groups and one hydroxyl group in the same molecule, such as malic acid, are preferred, and more specifically, malic acid is preferred. Tetrafunctional aliphatic oxycarboxylic acid components are divided into (i) types having three carboxyl groups and one hydroxyl group in the same molecule, (ii) types having two carboxyl groups and two hydroxyl groups in the same molecule, and (iii) types having three hydroxyl groups and one carboxyl group in the same molecule. Either type can be used, but those having multiple carboxyl groups are preferred, and more specifically, citric acid, tartaric acid, etc. can be mentioned. These can be used alone or in combination.

[0129] When the aliphatic polyester resin (C) contains such structural units derived from trifunctional or higher functional components, the content thereof, based on 100 mol% of all structural units constituting the aliphatic polyester resin (C), is usually 0 mol% or more, preferably 0.01 mol% or more, and usually 5 mol% or less, preferably 2.5 mol% or less. Here, the content of repeating structural units derived from aliphatic dicarboxylic acids having 5 to 8 carbon atoms in all polyester resins contained in the resin composition relative to the total number of moles of repeating structural units derived from aliphatic dicarboxylic acids in all polyester resins contained in the resin composition is not particularly limited, but is preferably 0 mol% or more and 50 mol% or less, particularly preferably 0 mol% or more and 10 mol% or less, and more preferably 0 mol% or more and 5 mol% or less. By keeping this content within the above range, a resin composition with a high bio-content (higher bio-based carbon content) and a lower environmental impact can be obtained.

[0130] <Aliphatic Aromatic Polyester Resin (D)> The resin composition may further contain an aliphatic aromatic polyester resin (D) (hereinafter sometimes referred to as "polyester resin (D)") as an aliphatic polyester resin other than the aliphatic polyester resin (A), the polyhydroxyalkanoate (B), and the aliphatic polyester resin (C). The aliphatic aromatic polyester resin (D) contains, as main structural units, a repeating structural unit D1 derived from an aliphatic diol, a repeating structural unit D2 derived from an aliphatic dicarboxylic acid, and a repeating structural unit D3 derived from an aromatic dicarboxylic acid. Note that the aliphatic aromatic polyester resin (D) does not include those equivalent to the above-mentioned aliphatic polyester resin (A), polyhydroxyalkanoate (B), and aliphatic polyester resin (C). In other words, the aliphatic aromatic polyester resin (D) is different from the aliphatic polyester resin (A), the polyhydroxyalkanoate (B), and the aliphatic polyester resin (C). The aliphatic aromatic polyester resin (D) being different from the aliphatic polyester resin (A) means that the aliphatic aromatic polyester resin (D) is substantially free of aliphatic dicarboxylic acid units having 9 to 36 carbon atoms, and the aliphatic aromatic polyester resin (D) being different from the polyhydroxyalkanoate (B) means that the aliphatic polyester resin (D) is substantially free of hydroxyalkanoic acid units B1 having 4 or more carbon atoms, and the aliphatic aromatic polyester resin (D) being different from the aliphatic polyester resin (C) means that the aliphatic aromatic polyester resin (D) contains a repeating structural unit D3 derived from an aromatic dicarboxylic acid that is substantially not contained in the aliphatic polyester resin (C).

[0131] In the aliphatic aromatic polyester resin (D), the aliphatic dicarboxylic acid unit D2 is not particularly limited. However, in terms of the balance between cost, mechanical properties, thermal properties, and biodegradability, it is generally an aliphatic dicarboxylic acid unit having 2 to 30 carbon atoms, preferably 4 to 20 carbon atoms, and more preferably 4 to 10 carbon atoms, and particularly preferably a linear aliphatic dicarboxylic acid unit having 4 to 6 carbon atoms. Specific examples of aliphatic dicarboxylic acids that provide such aliphatic dicarboxylic acid units include succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, azelaic acid, dodecanedioic acid, etc., or derivatives thereof such as alkyl esters. Among these, succinic acid, sebacic acid, adipic acid, azelaic acid, or derivatives thereof such as alkyl esters are preferred, with succinic acid or adipic acid, or derivatives thereof being particularly preferred. The derivatives may also be their acid anhydrides. These aliphatic dicarboxylic acid components may be used alone or in combination of two or more.

[0132] In the aliphatic aromatic polyester resin (D), the aliphatic diol unit D1 is not particularly limited, but from the viewpoints of moldability and mechanical strength, an aliphatic diol unit having 2 to 10 carbon atoms is preferred, and an aliphatic diol unit having 4 to 6 carbon atoms is particularly preferred. Specific examples of aliphatic diols that provide such aliphatic diol units include ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,4-cyclohexanedimethanol, with 1,4-butanediol being particularly preferred. These aliphatic diols may be used alone or in combination of two or more.

[0133] In the aliphatic aromatic polyester resin (D), the aromatic dicarboxylic acid unit D3 is not particularly limited. However, from the perspective of balancing cost, mechanical properties, thermal properties, and biodegradability, it is preferable that the aromatic dicarboxylic acid unit D3 contains at least a repeating structural unit D31 derived from an aromatic dicarboxylic acid having 6 to 20 carbon atoms. The aromatic dicarboxylic acid unit D31 is preferably an aromatic dicarboxylic acid unit having 6 to 12 carbon atoms, more preferably an aromatic dicarboxylic acid unit having 8 to 12 carbon atoms, even more preferably an aromatic dicarboxylic acid unit having 8 to 10 carbon atoms, and particularly preferably an aromatic dicarboxylic acid unit having 8 carbon atoms. Specific examples of aromatic dicarboxylic acids that provide such aromatic dicarboxylic acid units D3 include terephthalic acid, isophthalic acid, furandicarboxylic acid, naphthalenedicarboxylic acid, or diphenyldicarboxylic acid, as well as lower alkyl esters of these aromatic dicarboxylic acids. These aromatic dicarboxylic acids may also be acid anhydrides. Among these, terephthalic acid, isophthalic acid, or furandicarboxylic acid, or lower alkyl (e.g., C1 to C4 alkyl) esters of these aromatic dicarboxylic acids are preferred, and terephthalic acid or its lower alkyl (e.g., C1 to C4 alkyl) esters are particularly preferred. These aromatic dicarboxylic acid components may be used alone or in combination of two or more.

[0134] The molar ratio of the aliphatic dicarboxylic acid units D2 to the aromatic dicarboxylic acid units D3 in the aliphatic-aromatic polyester resin (D) is not particularly limited, but is preferably 10:90 to 90:10 (D2:D3). This ratio is more preferably 30:70 to 70:30, and even more preferably 40:60 to 60:40. When the ratio of the aliphatic dicarboxylic acid units D2 to the aromatic dicarboxylic acid units D3 is within the above range, the aliphatic-aromatic polyester resin (D) exhibits particularly excellent properties such as biodegradability, heat resistance, and flexibility.

[0135] From the viewpoint of film formability, the aliphatic aromatic polyester resin (D) is preferably a quaternary copolymer having an increased melt viscosity obtained by copolymerizing a component that provides the aliphatic diol unit D1, the aliphatic dicarboxylic acid unit D2, and the aromatic dicarboxylic acid unit D3 with at least one component selected from the group consisting of an aliphatic polyhydric alcohol having three or more hydroxyl groups (a trifunctional or higher aliphatic polyhydric alcohol), an aliphatic polycarboxylic acid having three or more carboxyl groups (three or more carboxyl groups) or an acid anhydride thereof (a trifunctional or higher aliphatic polycarboxylic acid), and an aliphatic polyoxycarboxylic acid having three or more groups selected from the group consisting of hydroxyl groups and carboxyl groups (a trifunctional or higher aliphatic polyoxycarboxylic acid) (hereinafter, these components are also collectively referred to as "a trifunctional or higher component").

[0136] Specific examples of trifunctional aliphatic polyhydric alcohols include trimethylolpropane and glycerin, and specific examples of tetrafunctional aliphatic polyhydric alcohols include pentaerythritol. These may be used alone or in combination of two or more. Among these, trimethylolpropane or glycerin is preferred, and trimethylolpropane is more preferred.

[0137] Specific examples of trifunctional aliphatic polycarboxylic acids or acid anhydrides thereof include propanetricarboxylic acid or its acid anhydride, etc., and specific examples of tetrafunctional polycarboxylic acids or its acid anhydrides include cyclopentanetetracarboxylic acid or its acid anhydride, etc. These may be used alone or in combination of two or more.

[0138] Trifunctional aliphatic oxycarboxylic acids are divided into (i) types having two carboxyl groups and one hydroxyl group in the same molecule, and (ii) types having one carboxyl group and two hydroxyl groups. Either type can be used, but from the viewpoints of moldability, mechanical strength, and the appearance of molded products, types having two carboxyl groups and one hydroxyl group in the same molecule, such as malic acid, are preferred, and more specifically, malic acid is preferred. Tetrafunctional aliphatic oxycarboxylic acid components are divided into (i) types having three carboxyl groups and one hydroxyl group in the same molecule, (ii) types having two carboxyl groups and two hydroxyl groups in the same molecule, and (iii) types having three hydroxyl groups and one carboxyl group in the same molecule. Either type can be used, but those having multiple carboxyl groups are preferred, and more specifically, citric acid, tartaric acid, etc. can be mentioned. These can be used alone or in combination.

[0139] In the production of the aliphatic aromatic polyester resin (D), a chain extender such as a diisocyanate, diphenyl carbonate, dioxazoline, or silicate ester may be used. Specific examples of diisocyanates include known diisocyanates such as 2,4-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. Specific examples of silicate esters include tetramethoxysilane, dimethoxydiphenylsilane, dimethoxydimethylsilane, and diphenyldihydroxylane. These may be used alone or in combination of two or more. The molar ratio of the constituent units is as follows: １ It can be determined from the integral value obtained by H-NMR measurement.

[0140] The content of the aliphatic aromatic polyester resin (D) in the resin composition is not particularly limited, but may be 0% by mass or more, more than 0% by mass, 1% by mass or more, or 5% by mass or more. It is usually 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, more preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. That is, the content of the aliphatic aromatic polyester resin (D) relative to the mass of the resin composition is preferably 0% by mass or more and 50% by mass or less, particularly preferably more than 0% by mass or less and 40% by mass or less, more preferably 1% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 20% by mass or less, particularly preferably 5% by mass or more and 15% by mass or less, and even more preferably 5% by mass or more and 10% by mass or less. When the content is within the above range, the aliphatic aromatic polyester resin (D) has excellent biodegradability.

[0141] The melt flow rate (MFR) of the aliphatic aromatic polyester resin (D) is not particularly limited, but is measured at a temperature of 160 ° C. and a load of 2.16 kg with reference to JIS K7210-1:2014. From the viewpoint of moldability and mechanical strength, it is usually 0.1 g / 10 min or more, preferably 1.0 g / 10 min or more, more preferably 2.0 g / 10 min or more, and also usually 100 g / 10 min or less, preferably 40 g / 10 min or less, more preferably 30 g / 10 min or less. That is, the MNR of the aliphatic aromatic polyester resin (D) is preferably 0.1 g / 10 min or more and 100.0 g / 10 min or less, particularly preferably 1.0 g / 10 min or more and 40.0 g / 10 min or less, and more preferably 2.0 g / 10 min or more and 30.0 g / 10 min or less. The MFR can be adjusted by molecular weight.

[0142] The melting point of the aliphatic aromatic polyester resin (D) is not particularly limited, but is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, and preferably 180 ° C. or lower, more preferably 160 ° C. or lower, and particularly preferably 140 ° C. or lower. That is, the melting point of the aliphatic aromatic polyester resin (D) is preferably 80 ° C. or higher and 180 ° C. or lower, particularly preferably 100 ° C. or higher and 160 ° C. or lower, and more preferably 100 ° C. or higher and 140 ° C. or lower. When there are multiple melting points, it is preferable that at least one melting point is within the above range. When the melting point is within the above range, the moldability of the resin composition containing the aliphatic aromatic polyester resin (D) can be further improved.

[0143] The glass transition temperature (Tg) of the aliphatic aromatic polyester resin (D) is not particularly limited, but is usually −60° C. or higher, more preferably −50° C. or higher, even more preferably −40° C. or higher, and usually 30° C. or lower, preferably 5° C. or lower, and even more preferably 0° C. or lower. That is, the glass transition temperature (Tg) of the aliphatic aromatic polyester resin (D) is preferably −60° C. or higher and 30° C. or lower, particularly preferably −50° C. or higher and 5° C. or lower, and more preferably −40° C. or higher and 0° C. or lower. When the glass transition temperature is within the above range, the aliphatic aromatic polyester resin (D) has an appropriate crystallization rate, and the resin composition containing the aliphatic aromatic polyester resin (D) can be more easily molded, and the impact strength of the molded body can also be further improved.

[0144] The method for adjusting the melting point and glass transition temperature of the aliphatic-aromatic polyester resin (D) is not particularly limited. For example, the melting point and glass transition temperature can be adjusted by selecting the types of copolymerization components of aliphatic dicarboxylic acids and aromatic dicarboxylic acids, adjusting the copolymerization ratios of each, or combining them.

[0145] The melting point and glass transition temperature of the aliphatic aromatic polyester resin (D) can be measured using a differential scanning calorimeter (manufactured by PerkinElmer, Inc., product name: DSC 8500). Specifically, about 5 mg of a sample is precisely weighed, heated and melted in a nitrogen stream at a flow rate of 40 mL / min, cooled at a rate of 10°C / min, and then heated at a rate of 10°C / min, whereby the glass transition temperature and melting point (peak top) can be measured.

[0146] The aliphatic aromatic polyester resin (D) can be produced by a known method for producing polyesters. The polycondensation reaction can be carried out under conventionally suitable conditions, and is not particularly limited. Usually, the degree of polymerization is further increased by carrying out a reduced pressure operation after the esterification and / or transesterification reaction has proceeded. For example, a known method for producing polyesters can be used, and the resin can be produced by the methods described in Patent Document 4 or Patent Document 5.

[0147] Suitable examples of the aliphatic aromatic polyester resin (D) include polybutylene adipate terephthalate (PBAT), polybutylene sebacate terephthalate (PBSeT), polybutylene azelate terephthalate (PBAzT), polybutylene succinate terephthalate (PBST), and polybutylene succinate furanate.

[0148] Commercially available aliphatic aromatic polyester resins (D) can also be used. Specifically, examples of polybutylene adipate terephthalate that can be used include "Ecoflex (registered trademark) Blend C1200" manufactured by BASF and "PBAT TH801T" manufactured by Tunhe.

[0149] <Inorganic Filler (F)> The resin composition may contain an inorganic filler (F) instead of or together with the polyhydroxyalkanoate (B). The inclusion of the inorganic filler (F) can improve the rigidity and moldability of a molded product of the resin composition. When the resin composition contains the inorganic filler (F), the content of the inorganic filler (F) in the resin composition is usually greater than 0% by mass, preferably 0.05% by mass or more, more preferably 5% by mass or more, and usually 70% by mass or less, preferably 50% by mass or less, and even more preferably 40% by mass or less. That is, the content of the inorganic filler (F) in the resin composition is preferably greater than 0% by mass and 70% by mass or less, particularly preferably 0.05% by mass or more and 50% by mass or less, and even more preferably 5% by mass or more and 40% by mass or less. Furthermore, when the molded product of the resin composition is a film, the inclusion of the inorganic filler (F) can prevent blocking between the films. In addition, it is possible to improve the gas barrier property, light blocking property, and light reflectivity of the film. Furthermore, it is possible to control the orientation of the film and improve its mechanical properties. Furthermore, by containing the inorganic filler (F), when the molded product of the resin composition is a sheet, necking during sheet molding can be improved, and sagging and crystallization rate can be improved during vacuum molding, so that an improvement in moldability can be expected.

[0150] The shape of the inorganic filler (F) is not particularly limited, and may be fibrous, granular, plate-like, or needle-like, with granular or plate-like shapes being particularly preferred. Examples of granular inorganic fillers (F) include: mineral particles such as talc, zeolite, diatomaceous earth, kaolin, clay, silica, or quartz powder; metal carbonate particles such as calcium carbonate, magnesium carbonate, or heavy calcium carbonate; metal silicate particles such as calcium silicate, aluminum silicate, or magnesium silicate; metal oxide particles such as alumina, silica, zinc oxide, or titanium oxide; metal hydroxide particles such as aluminum hydroxide, calcium hydroxide, or magnesium hydroxide; metal sulfate particles such as barium sulfate or calcium sulfate; or carbon particles such as carbon black. Examples of plate-like inorganic fillers (F) include mica. From the viewpoint of preventing blocking between the films, it is preferable to use at least one selected from the group consisting of talc, calcium carbonate, and silica as the inorganic filler (F).

[0151] The particle size of the inorganic filler (F) is not particularly limited, but the average particle size is preferably 0.08 μm or more, more preferably 0.1 μm or more, even more preferably 1 μm or more, and preferably 25 μm or less, more preferably 20 μm or less. That is, the average particle size of the inorganic filler (F) is preferably 0.08 μm or more and 25 μm or less, particularly preferably 0.1 μm or more and 20 μm or less, and even more preferably 1 μm or more and 20 μm or less. When the average particle size of the inorganic filler (F) is within the above range, handling is improved and the above-mentioned effects of adding the inorganic filler (F) can be better enjoyed. One type of inorganic filler (F) may be contained alone, or two or more types may be contained. The average particle size of the inorganic filler (F) can be measured using known methods, such as a method of determining the number average particle size using laser diffraction.

[0152] The whiteness of the inorganic filler (F) is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. The upper limit of the whiteness is not particularly limited, but is preferably 100% or less. That is, the whiteness of the inorganic filler (F) is preferably 70% or more and 100% or less, particularly preferably 80% or more and 100% or less, and even more preferably 90% or more and 100% or less. When the whiteness of the inorganic filler (F) is within the above range, the compatibility of the inorganic filler (F) with resin components such as the aliphatic polyester resin (A) can be improved, and the effects of containing the inorganic filler (F) can be better enjoyed. The whiteness of the inorganic filler (F) can be measured based on JIS Z8722:2009.

[0153] In consideration of the environment after biodegradation, the inorganic filler (F) is particularly preferably at least one inorganic filler selected from the group consisting of talc, calcium carbonate, and silica. More specifically, examples of talc include "LMS100," "LMR100," "PKP80," "PKP53S," "MG115," and "SG95" manufactured by Fuji Talc Co., Ltd., "K-1" and "SSS" manufactured by Nippon Talc Co., Ltd., and "3S" manufactured by Matsumura Sangyo Co., Ltd. Examples of calcium carbonate include "Softon 1200" and "Softon 2200" manufactured by Bihoku Funka Kogyo Co., Ltd., "NITOREX 30P", "NITOREX 23P", and "NS#100" manufactured by Nitto Funka Co., Ltd., "NITOREX 30PS", "NCC#2310", "NCC#1010", "NCC-V2300", and "NCC-V1000" from the NCC series, and "Whiscal A" manufactured by Maruo Calcium Co., Ltd. Examples of silica particles include "Aerosil 200" and "Aerosil 300" manufactured by Nippon Aerosil Co., Ltd.

[0154] The inorganic filler (F) may be surface-treated. The surface-treated inorganic filler (F) may improve dispersibility in the resin composition, improve the fluidity of the resin composition, and improve the smoothness and opening property when formed into a film. Furthermore, surface treatment is expected to reduce the content of additives such as fillers and plasticizers blended into the resin composition. The surface treatment of the filler can be carried out by a commonly known method using a surface treatment agent and the filler, and the treatment method is not particularly limited. Examples of types of surface treatment agents include linear fatty acids having 6 to 40 carbon atoms, branched fatty acids having 6 to 40 carbon atoms, and ester compounds thereof.

[0155] The specific surface area of ​​the inorganic filler (F) is not particularly limited, but is usually 8000 cm ２ / g or more, preferably 10,000 cm ２ / g or more, while usually 50000cm ２ / g or less, preferably 40,000 cm ２ That is, the specific surface area of ​​the inorganic filler (F) is 8000 to 50000 cm ２ / g is preferred, and 10,000 to 40,000 cm ２ When the specific surface area is within the above range, the rigidity of the molded article made from the resin composition according to the present disclosure can be more sufficiently improved.

[0156] The hardness of the inorganic filler (F) is not particularly limited, but is usually 9 or less, preferably 8 or less, more preferably 7 or less, on the Mohs hardness scale, and usually 1 or more, preferably 2 or more, more preferably 3 or more. That is, the Mohs hardness of the inorganic filler (F) is preferably 1 to 9, particularly preferably 2 to 8, and even more preferably 3 to 7. Having a Mohs hardness within the above range can further improve physical properties such as rigidity and heat resistance, and can more reliably prevent the occurrence of poor appearance and reduced film strength caused by the inorganic filler (F). The Mohs hardness refers to the value measured by rubbing a standard substance with a sample substance and determining whether or not scratches are left. The standard substances are as follows: Hardness: 1) Talc, Hardness: 2) Gypsum, Hardness: 3) Calcite, Hardness: 4) Fluorite, Hardness: 5) Apatite, Hardness: 6) Orthoclase, Hardness: 7) Quartz, Hardness: 8) Jade, Hardness: 9) Corundum, Hardness: 10) Diamond.

[0157] The total content of the aliphatic polyester resin (A) and at least one selected from the group consisting of polyhydroxyalkanoate (B) and inorganic filler (F) in the resin composition is not particularly limited, but the ratio (total content) of the total mass of the aliphatic polyester resin (A), polyhydroxyalkanoate (B) and inorganic filler (F) to the mass of the resin composition is preferably 60% by mass or more, particularly preferably more than 60% by mass, more preferably more than 70% by mass, even more preferably more than 70% by mass, particularly preferably more than 80% by mass, even more preferably more than 80% by mass, 90% by mass or more, and even more preferably more than 90% by mass. The upper limit is not particularly limited, but may be 100% by mass. That is, the resin composition can be composed only of the aliphatic polyester resin (A) and at least one selected from the group consisting of polyhydroxyalkanoate (B) and inorganic filler (F). Furthermore, this ratio may be 100% by mass or less, less than 100% by mass, 98% by mass or less, 97% by mass or less, 95% by mass or less, or even 93% by mass or less. That is, the ratio of the total mass of the aliphatic polyester resin (A), polyhydroxyalkanoate (B), and inorganic filler (F) to the mass of the resin composition is preferably 60% by mass or more and 100% by mass or less, particularly preferably more than 60% by mass and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, even more preferably more than 70% by mass and 100% by mass or less, particularly preferably 80% by mass or more and 98% by mass or less, 90% by mass or more and 97% by mass or less, more than 90% by mass and 95% by mass or less, or even more preferably more than 90% by mass and 93% by mass or less. When the total content is within the above range, the resin composition or a molded article of the resin composition will have better biodegradability and moldability.

[0158] <Other Resins> In addition to the aliphatic polyester resin (A) described above, the resin composition may contain a resin (other resin) that does not fall under any of the polyhydroxyalkanoate (B), the aliphatic polyester resin (C), and the aliphatic aromatic polyester resin (D), as long as the effects of the present invention are not impaired. Examples of other resins include aliphatic polyester resins (E) that do not fall under any of the polyester resins (A) to (D) described above, aromatic polyester resins, polycarbonate, polyamide, polystyrene, polyolefin, acrylic resin, amorphous polyolefin, ABS, AS (acrylonitrile styrene), polylactic acid, polycaprolactone, polyvinyl alcohol, or synthetic resins such as cellulose ester. In particular, biodegradable resins such as polylactic acid and polycaprolactone are preferred, and these may be used alone or in combination of two or more.

[0159] The aliphatic polyester resin (E) is not particularly limited as long as it is an aliphatic polyester resin that does not correspond to the above-mentioned resins (A) to (D). Specific examples include aliphatic polyester resins that contain, as main structural units, a repeating structural unit E1 derived from an aliphatic diol having 2 to 4 carbon atoms as the repeating structural unit E1 derived from an aliphatic diol, and a repeating structural unit E21 derived from an aliphatic dicarboxylic acid having 2 to 4 carbon atoms as the repeating structural unit E2 derived from an aliphatic dicarboxylic acid. The aliphatic polyester resin (E) makes it easy to adjust the content of a specific structural unit (for example, an aliphatic dicarboxylic acid unit having 9 to 36 carbon atoms in the polyester resin (A)) relative to the total polyester resin contained in the composition.

[0160] Examples of aliphatic diols having 2 to 4 carbon atoms that provide the repeating structural unit E11 include ethylene glycol, 1,3-propanediol, and 1,4-butanediol, with 1,4-butanediol being preferred.

[0161] Examples of the aliphatic dicarboxylic acid having 2 to 4 carbon atoms that provides the repeating structural unit E21 include one or more dicarboxylic acids selected from oxalic acid, malonic acid, and succinic acid. When the aliphatic polyester resin (E) contains the aliphatic dicarboxylic acid unit E21 having 2 to 4 carbon atoms, the content of the aliphatic dicarboxylic acid unit E21 having 2 to 4 carbon atoms (E21 / E2) relative to the total number of moles of the repeating structural unit E2 derived from the dicarboxylic acid contained in the aliphatic polyester resin (E) is not particularly limited, but is preferably 20 mol% or more, more preferably 40 mol% or more, even more preferably 60 mol% or more, and particularly preferably 100 mol%, and the upper limit is not particularly limited, and may be 100 mol%, 100 mol% or less, less than 100 mol%, 97 mol% or less, or 95 mol% or less. That is, the content (E21 / E2) is preferably 20 mol % or more and 100 mol % or less, particularly preferably 40 mol % or more and less than 100 mol %, and more preferably 60 mol % or more and 95 mol % or less.

[0162] When the aliphatic polyester resin (E) contains the aliphatic diol unit E11 having 2 to 4 carbon atoms, the content of the aliphatic diol unit E11 having 2 to 4 carbon atoms, based on the total number of moles of the structural units constituting the polyester resin (E) (100 mol%), is preferably 10 mol% or more, more preferably 30 mol% or more, even more preferably 45 mol% or more, and preferably 75 mol% or less, more preferably 60 mol% or less, and even more preferably 55 mol% or less, from the viewpoint of moldability. That is, the content is preferably 10 mol% or more and 75 mol% or less, particularly preferably 30 mol% or more and 60 mol% or less, and more preferably 45 mol% or more and 55 mol% or less.

[0163] When the aliphatic polyester resin (E) contains the aliphatic dicarboxylic acid unit E21 having 2 to 4 carbon atoms, the content of the aliphatic dicarboxylic acid unit E21 having 2 to 4 carbon atoms, based on the total number of moles of the structural units constituting the polyester resin (E) (100 mol%), is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 35 mol% or more, from the viewpoint of moldability. The upper limit is not particularly limited, and may be 100 mol%, 100 mol% or less, less than 100 mol%, 97 mol% or less, or 95 mol% or less. That is, the content is preferably 10 mol% or more and 100 mol% or less, particularly preferably 20 mol% or more and less than 100 mol%, more preferably 35 mol% or more and 97 mol% or less, and even more preferably 35 mol% or more and 95 mol% or less.

[0164] The aliphatic polyester resin (E) may contain diol units and / or dicarboxylic acid units (other component units) other than the aliphatic diol unit E11 having 2 to 4 carbon atoms and the aliphatic dicarboxylic acid unit E21 having 2 to 4 carbon atoms. Examples of such other components include the components described for each of the resins (A) to (D). The diol component other than the aliphatic diol having 2 to 4 carbon atoms may be an aliphatic diol or an aromatic diol, and the dicarboxylic acid component other than the aliphatic dicarboxylic acid having 2 to 4 carbon atoms may be an aliphatic dicarboxylic acid or an aromatic dicarboxylic acid.

[0165] The content of the aliphatic polyester resin (E) in the resin composition is not particularly limited, and may be 0% by mass or more, 1% by mass or more, 5% by mass or more, or 10% by mass or more. From the viewpoint of fully ensuring the effects of the present invention, it is preferably 50% by mass or less, and more preferably 40% by mass or less. That is, the content of the aliphatic polyester resin (E) in the resin composition is preferably 0% by mass or more and 50% by mass or less, particularly preferably 1% by mass or more and 40% by mass or less, more preferably 5% by mass or more and 40% by mass or less, and even more preferably 10% by mass or more and 40% by mass or less.

[0166] The melting point of the aliphatic polyester resin (E) is not particularly limited, but from the viewpoint of heat resistance and kneadability, it is preferably 60°C or higher, more preferably 90°C or higher, and even more preferably 110°C or higher. It is also preferably 250°C or lower, more preferably 200°C or lower, and particularly preferably less than 150°C. That is, the melting point of the aliphatic polyester resin (E) is preferably 60°C or higher and 250°C or lower, particularly preferably 90°C or higher and 200°C or lower, and more preferably 110°C or higher and lower than 150°C. When there are multiple melting points, it is preferable that at least one melting point is within the above range.

[0167] The molecular weight of the aliphatic polyester resin (E) is not particularly limited, but can be measured by gel permeation chromatography (GPC). The weight average molecular weight (Mw) of the aliphatic polyester resin (E) using monodisperse polystyrene as the standard is usually 10,000 or more and 1,000,000 or less. However, because this is advantageous in terms of moldability and mechanical strength, it is preferably 20,000 or more and 500,000 or less, and more preferably 50,000 or more and 400,000 or less.

[0168] The melt flow rate (MFR) of the aliphatic polyester resin (E) is not particularly limited, but is typically 0.1 g / 10 min or more and 100 g / 10 min or less, as measured at a temperature of 160 ° C. and a load of 2.16 kg according to JIS K7210-1:2014. From the viewpoint of moldability and mechanical strength, it is preferably 50 g / 10 min or less, particularly preferably 30 g / 10 min or less. That is, the MFR of the aliphatic polyester resin (E) is preferably 0.1 g / 10 min or more and 100 g / 10 min or less, particularly preferably 0.1 g / 10 min or more and 50 g / 10 min or less, and more preferably 0.1 g / 10 min or more and 30 g / 10 min or less. The MFR of the aliphatic polyester resin (E) can be adjusted by the molecular weight.

[0169] When the resin composition contains other resins, in order to effectively obtain the effects obtained by including the aliphatic polyester-based resin (A) as a resin component, and further, when the resin composition contains polyhydroxyalkanoate (B), the effects obtained by including these resins, the content of the other resins is preferably 50 parts by mass or less per 100 parts by mass of the total of the aliphatic polyester-based resin (A), polyhydroxyalkanoate (B), and other resins.

[0170] <Other Components> The resin composition may contain components (other components) other than the above-mentioned components, such as lubricants, plasticizers, antistatic agents, antioxidants, light stabilizers, UV absorbers, dyes, pigments, hydrolysis inhibitors, crystal nucleating agents, antiblocking agents, light resistance agents, plasticizers, heat stabilizers, flame retardants, release agents, anti-fogging agents, surface wetting improvers, incineration aids, dispersing aids, various surfactants, or various additives such as slip agents, starch, cellulose, paper, wood flour, chitin / chitosan, coconut shell powder, or walnut shell powder, etc. The other components may be used alone or in combination of two or more. The resin composition may also contain a functional additive as one of the other components, specifically, a freshness-preserving agent or an antibacterial agent, etc.

[0171] The content of these other components is not particularly limited, but in order not to impair the physical properties of the resin composition, it is usually preferable that the total amount of the components contained be 0.01 mass % or more and 15 mass % or less relative to the total amount of the resin composition.

[0172] The resin composition preferably has a flexural modulus of 500 MPa or more, more preferably 600 MPa or more, and even more preferably 1000 MPa or more, as evaluated in accordance with JIS K7171:2022 for an injection-molded product of the resin composition. It is also preferably 3000 MPa or less, more preferably 2750 MPa or less, and even more preferably 2500 MPa or less. That is, the resin composition preferably has a flexural modulus of 500 MPa or more and 3000 MPa or less, particularly preferably 600 MPa or more and 2750 MPa or less, and even more preferably 1000 MPa or more and 2500 MPa or less, as evaluated in accordance with JIS K7171:2022. Having the flexural modulus of the injection-molded product within the above range prevents the injection-molded product from easily deforming during use and allows the required shape to be more reliably maintained. Furthermore, when the injection-molded product is used in applications requiring perforation, such as coffee capsule applications, perforation can be easily performed. The injection molding conditions for obtaining an injection-molded article are not particularly limited, and can be, for example, the conditions described in the Examples below. In order to enable the resin composition to form an injection-molded article satisfying the above-mentioned flexural modulus, for example, the resin blending ratio or the content of the inorganic filler (F) can be adjusted. Specifically, for example, by increasing the content of the inorganic filler (F) within the above-mentioned range, it is possible to further increase the rigidity.

[0173] <Bio-based carbon content of resin composition> The bio-based carbon content of the resin composition as defined in ISO 16620-2:2015 is not particularly limited, but from the perspective of protecting the global environment, it is preferably 10% or more, more preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more. There is no particular upper limit, and it may be 100%, 90% or less, 80% or less, or 70% or less. That is, the bio-based carbon content of the resin composition is preferably 10% or more and 100% or less, particularly preferably 20% or more and 90% or less, more preferably 30% or more and 80% or less, and even more preferably 40% or more and 70% or less. Increasing the bio-based carbon content can reduce fossil fuel consumption and carbon dioxide emissions, which is beneficial from the perspective of protecting the global environment. Note that the above bio-based carbon content does not have to be satisfied by each material constituting the resin composition, but only needs to be satisfied by the resin composition as a whole. The bio-based carbon content can be controlled by adjusting the proportion of monomer units produced from plant-derived raw materials relative to the total structural units of all resins contained in the resin composition, and can also be controlled by appropriately using a naturally derived polymer such as starch in combination. The bio-based carbon content is calculated based on the carbon-14 ( １４ Furthermore, for example, when determining the bio-based carbon content of an aliphatic polyester resin contained in a composition, it can also be determined by calculation from the bio-based carbon contents and polymerization ratios of the aliphatic diol component, the aliphatic dicarboxylic acid component, and the aromatic dicarboxylic acid component, which are raw materials.

[0174] <Method for Producing Resin Composition> The method for producing the resin composition is not particularly limited, but may involve mixing at least an aliphatic polyester resin (A) with at least one selected from the group consisting of a polyhydroxyalkanoate (B) and an inorganic filler (F) simultaneously or in any order using a mixer such as a tumbler, V-type blender, Nauta mixer, Banbury mixer, kneading roll, or extruder. From the viewpoint of dispersibility, this production method is particularly preferably a method of mixing by melt kneading. Examples of methods for feeding the raw materials include a method in which the raw materials are blended in advance and then introduced into an extruder all at once to be melt-mixed, a method in which the raw materials are not blended but are introduced separately from a feeder into an extruder to be melt-mixed, or a method in which only some of the raw materials are introduced individually into an extruder to be melt-mixed. The extruder may be a single-screw or twin-screw extruder. The resin kneaded in the twin-screw extruder can be pelletized using a pelletizer or underwater cutter, and the pellets can be used in various subsequent molding processes. When the amount of filler or additives is small and the raw material is not classified, it is possible to directly feed the raw material into a molding machine and obtain a molded product such as a film, sheet, or injection molded product.

[0175] The temperature during melt-kneading is not particularly limited, but is preferably 120 to 220°C, and more preferably 130 to 180°C. This temperature range makes it possible to shorten the time required for melt-kneading, prevents deterioration of color tone due to resin degradation, and further improves practical physical properties such as mechanical properties. Furthermore, from the viewpoint of more reliably avoiding the same resin degradation as described above, unnecessary lengthening of the melt-kneading time should be avoided, and a time of 20 seconds to 20 minutes is preferred, and a time of 30 seconds to 15 minutes is more preferred. It is preferable to set the melt-kneading temperature and time conditions so as to satisfy the above conditions.

[0176] <Molded Article> A molded article according to another embodiment of the present invention is a molded article made from the resin composition described above. The method for producing the molded article is not particularly limited, and the molded article can be obtained by molding using a known polyester molding method. The molding method is not particularly limited, and known methods such as compression molding, lamination molding, injection molding, extrusion molding, vacuum molding, pressure molding, blow molding, inflation molding, or stretch molding can be used. More specifically, examples of methods include a method in which a film-like, sheet-like, or cylindrical article extruded to a predetermined thickness from a T-die, I-die, or round die is cooled and solidified using a cooling roll, water, compressed air, or the like. That is, the resin composition according to the present invention can be an injection molding material applicable to injection molding applications, and the molded article according to the present invention can be, for example, an injection-molded article.

[0177] The shape of the molded product is not particularly limited, and examples thereof include sheet, film, tube, capsule, pellet, filament, and bag shapes. When the molded product of the resin composition is a pellet, the shape and size of the pellet are not particularly limited, and it is preferable that the pellet have a shape and size suitable for use in known plastic processing methods such as injection molding and extrusion molding. Specific shapes include, for example, cylindrical, elliptical, rectangular, disc-like, and spherical. The size and mass of a single pellet may be a size and mass common to pellets. Specifically, from the viewpoint of ensuring uniform melting of the pellet when the pellet is used to produce a further molded product by injection molding or extrusion molding, the size is preferably about 0.7 to 12 mm in diameter or one side, and the mass is preferably 1 to 50 mg, particularly preferably 3 to 40 mg, and more preferably 5 to 30 mg.

[0178] <Applications> The applications of the above-described resin composition or molded article are not particularly limited, and examples thereof include packaging materials, agricultural materials, forestry materials, cutlery, 3D printer filaments, 3D printer pellets, plastic bags, shopping bags, straws, gardening supplies, packaging materials, strings, sheets, films, bags, tubular bodies, and capsules. The shape of the resin composition or molded article for each application is not particularly limited, but specific examples of packaging materials include candy bags. In addition, in the case of 3D printer filaments, filament-like shapes are preferred, in the case of 3D printer pellets, pellet-like shapes are preferred, in the case of plastic bags or shopping bags, bag-like shapes are preferred, and in the case of straws, tubular shapes are preferred. In addition, the above-described applications may be applications of the above-described resin composition or molded article, or applications of composites including the resin composition or the molded article.

[0179] Specific embodiments of the present invention will be described in more detail below using examples, but the present invention is not limited to the following examples as long as the gist of the invention is not exceeded. Note that the values ​​of various production conditions and evaluation results in the following examples represent preferred upper or lower limit values ​​in the embodiments of the present invention, and preferred ranges may be defined by a combination of the above-mentioned upper or lower limit values ​​and the values ​​in the following examples or values ​​between the examples.

[0180] [Evaluation Methods] The methods for evaluating various physical properties and characteristics in the examples and comparative examples are as follows.

[0181] <Evaluation 1: Measurement of Melt Flow Rate (MFR)> Based on JIS K7210-1:2014, the melt flow rate (MFR) was measured at a temperature of 160°C and a load of 2.16 kg using a melt indexer for each resin used. The unit is g / 10 min.

[0182] <Evaluation 2: Flexural Modulus> The flexural modulus of the test pieces obtained by the above-described injection molding was measured in accordance with JIS K7171: 2022. If the flexural modulus is less than 500 MPa, the material will easily deform during use, making it difficult to maintain the required shape. On the other hand, if the flexural modulus exceeds 3000 MPa, the material will be too hard for applications requiring drilling, such as coffee capsule applications, making drilling difficult and making it difficult to use.

[0183] <Evaluation 3: Deflection temperature under load> The deflection temperature under load (HDT) of the test pieces obtained by the above-mentioned injection molding was measured by the B method flatwise in accordance with JIS K7191-2: 2015. For applications such as coffee capsules that come into contact with hot water, the HDT is preferably 65°C or higher.

[0184] <Evaluation 4: Charpy impact strength> The test pieces obtained by the above-mentioned injection molding were measured for Charpy impact strength in accordance with JIS K7111-1:2012. In the expected use, ２ More than 2.0 J / m is preferable. ２ If the impact strength is less than this, the film may easily break when dropped.

[0185] <Evaluation 5: Flow Distance (Spiral Flow)> Using a J110AD-180H injection molding machine manufactured by The Japan Steel Works, Ltd., the flow distance of each resin composition obtained by the method described below was measured in a spiral mold with a groove 2 mm thick and 8 mm wide. The flow distances when the cylinder temperature was set to 160°C or 170°C, the mold temperature was set to 40°C, and the injection pressure was set to 50 MPa are shown in each table. Measuring the flow distance using a spiral mold makes it possible to evaluate the properties while taking into account the effects of both fluidity and solidification rate, and a longer flow distance is considered to indicate better moldability.

[0186] <Evaluation 6: Biodegradation Test in Soil at Room Temperature> Resin pellets melted at a temperature of 190 to 220°C were press-molded to obtain a film with a thickness of 100 μm. The obtained film was stored in soil (moisture content 15 to 30%) collected from a farm in Mie Prefecture at 28±2°C for 3 months, after which its weight was measured and the decomposition rate calculated using the following formula was evaluated for biodegradability in soil at room temperature according to the following criteria: Decomposition rate (%) = 100 - (sample weight after 3 months / sample weight before test) x 100 Rank +++: Decomposition rate is 90% or higher Rank ++: Decomposition rate is 30% or higher but less than 90% Rank +: Decomposition rate is less than 30%

[0187] <Evaluation 7: Bio-based Carbon Content> The bio-based carbon content (bio-degree) of the resin composition was calculated and evaluated based on ISO 16620-2. Specifically, the composition was burned, carbon dioxide was collected, and the carbon atoms in the composition were recovered as graphite by reducing it with hydrogen and a catalyst. Next, the carbon isotope ratio was measured using an accelerator mass spectrometer. Carbon isotope ratios are present in the atmosphere at a certain rate. １４ Because carbon is present in biomass (bio-based carbon), the same proportion of carbon is present in biomass. １４ C is included. １４ Since C decreases with a half-life of 5730 years, carbon derived from fossil resources １４ Therefore, the standard amount of carbon in the modern atmosphere is １４ C ratio in the sample １４ The bio-based carbon content was determined by calculating the proportion of C.

[0188] [Raw Materials Used] In the Examples and Comparative Examples, the following polymerized resins or commercially available products were used.

[0189] [Preparation of Polycondensation Catalyst] 343.5 parts by weight of magnesium acetate tetrahydrate was placed in a reactor equipped with a stirrer, and 1,434 parts by weight of absolute ethanol (purity 99% by weight or higher) was added. 218.3 parts by weight of ethyl acid phosphate (monoester and diester mixed in a weight ratio of 45:55) was then added, and the mixture was stirred at 23°C. After confirming that the magnesium acetate was completely dissolved, 410.0 parts by weight of tetra-n-butyl titanate was added. Stirring was continued for an additional 10 minutes, yielding a homogeneous mixed solution. This mixed solution was concentrated under reduced pressure while maintaining a temperature below 60°C. Approximately half of the ethanol added was distilled off, leaving a translucent, viscous liquid. 1,108 parts by weight of 1,4-butanediol was added, and the mixture was further concentrated under reduced pressure while maintaining a temperature below 80°C, yielding a catalyst solution with a titanium atom content of 3.5% by weight.

[0190] [Production Example of Aliphatic Polyester Resin A-1] A reaction vessel equipped with a stirrer, a nitrogen inlet, a heater, a thermometer, and a pressure reducing port was charged with the following raw materials: 57.8 parts by weight of succinic acid, 12.3 parts by weight of sebacic acid, 64.4 parts by weight of 1,4-butanediol, 0.125 parts by weight of trimethylolpropane, and 0.60 parts by weight of the above catalyst solution. The molar ratio of succinic acid to sebacic acid was 89:11, and the molar ratio of 1,4-butanediol to the total molar amount of succinic acid and sebacic acid was 1.30.

[0191] While stirring the contents of the vessel, nitrogen gas was introduced into the vessel, and the system was purged with nitrogen by vacuum substitution. Next, the raw materials were dissolved at 160°C. After confirming that the raw materials were completely dissolved and the temperature of the distillation section reached 50°C, the temperature was raised from 160°C to 230°C over 1 hour while stirring the system, and the esterification reaction was continued at 230°C under normal pressure for 1 hour. The terminal acid value of the obtained ester oligomer was measured and found to be 345 eq / ton. Five minutes before the end of the esterification reaction, a catalyst solution was added. After the esterification reaction, the temperature was raised from 230°C to 250°C over 30 minutes, and simultaneously, 0.07 x 10 ３The pressure was reduced to 100 Pa or less, and polymerization was continued while maintaining the heated and reduced pressure state. The polymerization was terminated when the desired viscosity was reached, yielding an aliphatic polyester resin (A-1). The content of repeating structural units derived from aliphatic dicarboxylic acids having 9 to 36 carbon atoms relative to the total number of moles of repeating structural units derived from aliphatic dicarboxylic acids in the resulting resin was 11 mol%, and the content of succinic acid was 89 mol%. Furthermore, the content of aliphatic dicarboxylic acid units relative to 100 mol% of all structural units constituting the resulting resin was 50 mol%, the content of aliphatic diol units was 49 mol%, and the content of trifunctional aliphatic polyhydric alcohol was 0.085 mol%. The melting point of the resulting resin was 102°C, the glass transition temperature was -45°C, and the MFR, measured by the method described in Evaluation 1 above, was 16.7 g / 10 min.

[0192] [Production of Aliphatic Polyester Resin A-2] The same procedure as in the Production Example of Aliphatic Polyester Resin A-1 was carried out, except that 44.9 parts by weight of succinic acid, 27.1 parts by weight of sebacic acid, 60.2 parts by weight of 1,4-butanediol, 0.125 parts by weight of trimethylolpropane, and 0.60 parts by weight of the above catalyst solution were used, and the molar ratio of succinic acid to sebacic acid was 74:26, to obtain Aliphatic Polyester Resin (A-2). The content of repeating structural units derived from aliphatic dicarboxylic acids having 9 to 36 carbon atoms relative to the total number of moles of repeating structural units derived from aliphatic dicarboxylic acids in the resulting resin was 26 mol%, and the succinic acid content was 74 mol%. Furthermore, the content of aliphatic dicarboxylic acid units relative to 100 mol% of all structural units constituting the resulting resin was 50 mol%, the content of aliphatic diol units was 49 mol%, and the content of trifunctional aliphatic polyhydric alcohol was 0.091 mol%. The resulting resin had a melting point of 86° C., a glass transition temperature of −52° C., and an MFR of 16.4 g / 10 min as measured by the method described in Evaluation 1 above.

[0193] The following commercially available products were used as the polyhydroxyalkanoate (B), the aliphatic polyester resin (C), the aliphatic-aromatic polyester resin (D), the aliphatic polyester resin (E), the inorganic filler (F), and the heat stabilizer.

[0194] Polyhydroxyalkanoate (B): Poly 3-hydroxybutyrate-co-3-hydroxyhexanoate, "Kaneka Biodegradable Biopolymer Green Planet (registered trademark) X131A" manufactured by Kaneka Corporation (3HB / 3HH molar ratio: 94 / 6, MFR measured by the method described in Evaluation 1 above: 0.6 g / 10 min, melting point: 140°C)

[0195] Aliphatic polyester resin (C): polybutylene succinate adipate, "BioPBS (registered trademark) FD72PM" manufactured by PTTMCC Biochem (amount of succinic acid units in total dicarboxylic acid units: 74 mol%, amount of adipic acid units: 26 mol%, amount of 1,4-butanediol units in all structural units: 49 mol%, MFR measured by the method described in Evaluation 1 above: 16.1 g / 10 min, melting point: 85°C, glass transition temperature: -46°C, weight average molecular weight: 120,000)

[0196] Aliphatic aromatic polyester resin (D): polybutylene adipate terephthalate, "Ecoflex (registered trademark) Blend C1200" manufactured by BASF (adipic acid unit amount in total dicarboxylic acid unit amount: 53 mol%, terephthalic acid unit amount: 47 mol%, 1,4-butanediol unit amount in all structural units: 49 mol%, MFR measured by the method described in Evaluation 1 above: 1.5 g / 10 min, melting point: 120°C, glass transition temperature: -32°C, weight average molecular weight: 130,000)

[0197] Aliphatic polyester resin (E): polybutylene succinate, "BioPBS (registered trademark) FZ71PM" manufactured by PTTMCC Biochem (amount of succinic acid units in total dicarboxylic acid units: 100 mol%, amount of 1,4-butanediol units in all structural units: 49 mol%, MFR measured by the method described in Evaluation 1 above: 14.5 g / 10 min, melting point: 115°C, glass transition temperature: -31°C, weight average molecular weight: 120,000)

[0198] Inorganic filler (F): Filler 1: talc, MG115 (manufactured by Fuji Talc Co., Ltd., average particle size: 14.0 μm, whiteness: 94%) Filler 2: calcium carbonate Softon 1200 (manufactured by Bihoku Funka Kogyo Co., Ltd., average particle size: 1.8 μm, whiteness: 95%) Filler 3: talc, SSS (manufactured by Nippon Talc Co., Ltd., average particle size: 12.0 μm, whiteness: 80%) Filler 4: talc, 3S (manufactured by Matsumura Sangyo Co., Ltd., average particle size: 16.0 μm, whiteness: 72%)

[0199] Heat stabilizer: Irganox 1010 (manufactured by BASF)

[0200] [Example 1] 30% by mass of the aliphatic polyester resin (A-1) produced in Production Example 1, 60% by mass of polyhydroxyalkanoate (B), and 0.05% by mass of Irganox 1010 were dry blended and fed to a twin-screw extruder using a feeder. At the same time, 10% by mass of filler 1 was fed to the twin-screw extruder using a separate feeder, and the extruded strands were kneaded at 145 to 160 ° C. and water-cooled, followed by cutting to obtain pellets of a resin composition. For the resulting pellets, the content of sebacic acid units (having 10 carbon atoms) in all polyester resins contained in the resin composition relative to the total number of moles of aliphatic dicarboxylic acid units in all polyester resins contained in the resin composition constituting the pellets (hereinafter also referred to as "Se content") was 11 mol%. Furthermore, the MFR measured by the method described in Evaluation 1 above was 4.2 g / 10 min. The bio-based carbon content of the pellets obtained above was calculated using the method described in Evaluation 7 above, and was found to be 84%. Furthermore, the pellets obtained above were used to measure the flow distance at a cylinder temperature of 160°C using the method described in Evaluation 5 above. The pellets obtained above were press-molded into a film, and the biodegradability of the resulting film was evaluated using the method described in Evaluation 6 above. Furthermore, standard test specimens were molded using an electric injection molding machine (product name: SE18D; manufactured by Sumitomo Heavy Industries, Ltd., maximum clamping force: 18 tons) using the pellets obtained above. The molding conditions were a mold temperature of 40°C and a cylinder temperature of 160°C, and the standard test specimens had a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The obtained standard test specimens were subjected to Evaluations 2 to 4 above. The Se content and the results of Evaluations 1 and 7 are shown in Table 1. The results of Evaluations 2 to 6 are shown in Table 2.

[0201] Examples 2 to 20, Comparative Examples 1 to 7 Pellets made of resin compositions were obtained in the same manner as in Example 1, except that the raw material types and their blending ratios for the resin compositions were changed as shown in Table 1. Using the obtained pellets, the Se content, MFR (Evaluation 1), and bio-based carbon content (Evaluation 7) of the resin composition constituting each pellet were determined. Furthermore, the flow distance of each pellet was measured using the method described in Evaluation 5 above. For Examples 1 to 11 and Comparative Examples 1 to 6, the flow distance was measured at a cylinder temperature of 160°C, while for Examples 12 to 20 and Comparative Example 7, the flow distance was measured at a cylinder temperature of 170°C. Furthermore, biodegradability was evaluated using films obtained by press-molding each pellet using the method described in Evaluation 6. Furthermore, standard test pieces were prepared using each pellet in the same manner as in Example 1 and subjected to Evaluations 2 to 4. The Se content, Evaluations 1, and Evaluation 7 results for the resin compositions of Examples 2 to 20 and Comparative Examples 1 to 7 are shown in Table 1. The results of Evaluations 2 to 6 are also shown in Table 2.

[0202]

[0203]

[0204] It can be seen from Tables 1 and 2 above that the resin compositions / molded articles according to Examples 1 to 20 were excellent in room temperature biodegradability in soil, heat resistance, impact resistance, and fluidity when melted. Furthermore, these evaluation results show that the resin compositions / molded articles according to the present invention can be suitably used for capsules, cutlery, sheets, food trays, medical packaging materials, agricultural materials, forestry materials, etc.

Claims

1. A resin composition comprising: an aliphatic polyester resin (A); and at least one selected from the group consisting of a polyhydroxyalkanoate (B) and an inorganic filler (F), wherein the aliphatic polyester resin (A) comprises a repeating structural unit A1 derived from an aliphatic diol and a repeating structural unit A2 derived from an aliphatic dicarboxylic acid, the repeating structural unit A2 comprises a repeating structural unit A21 derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms, and the polyhydroxyalkanoate (B) comprises a repeating structural unit B1 different from the aliphatic polyester resin (A) and derived from a hydroxyalkanoate having 4 or more carbon atoms.

2. The resin composition according to claim 1, wherein the content of the polyhydroxyalkanoate (B) in the resin composition is greater than 0 mass% and not more than 90 mass%.

3. The resin composition according to claim 1, wherein the content of the inorganic filler (F) in the resin composition is 5% by mass or more and 40% by mass or less.

4. A resin composition according to claim 1, wherein the content of the aliphatic polyester resin (A) in the resin composition is 15% by mass or more and 95% by mass or less.

5. A resin composition according to claim 1, wherein the content of the aliphatic polyester resin (A) in the resin composition is greater than 34 mass% and not more than 95 mass%.

6. The resin composition according to claim 1, wherein the content of the aliphatic polyester resin (A) in the resin composition is 5% by mass or more and 95% by mass or less, and the content of aliphatic polyester resin (C') in the resin composition is 0% by mass or more and less than 5% by mass, the aliphatic polyester resin (C') having a repeating structural unit C1 derived from an aliphatic diol and a repeating structural unit C2 derived from an aliphatic dicarboxylic acid different from the aliphatic polyester resin (A) and the polyhydroxyalkanoate (B), the repeating structural unit C2 including a repeating structural unit C22 derived from an aliphatic dicarboxylic acid having 5 to 6 carbon atoms.

7. The resin composition according to claim 1, wherein the repeating structural unit A2 further comprises a repeating structural unit A22 derived from succinic acid.

8. The resin composition according to claim 1, wherein the content of the repeating structural unit A21 derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms relative to the repeating structural unit A2 derived from the aliphatic dicarboxylic acid in the aliphatic polyester resin (A) is 1 mol % or more and 50 mol % or less.

9. The resin composition according to claim 1, wherein the polyhydroxyalkanoate (B) contains a repeating structural unit B11 derived from 3-hydroxybutyrate as the repeating structural unit B11, and the polyhydroxyalkanoate (B) contains the repeating structural unit B11 as a main structural unit.

10. The resin composition according to claim 9, wherein the content of the repeating structural unit B11 is 70 mol % or more and 100 mol % or less relative to 100 mol % of all structural units constituting the polyhydroxyalkanoate (B).

11. The resin composition according to claim 9, wherein the polyhydroxyalkanoate (B) further contains, as the repeating structural unit B1, at least one repeating structural unit selected from the group consisting of a repeating structural unit B12 derived from 3-hydroxyvalerate, a repeating structural unit B13 derived from 3-hydroxyhexanoate, and a repeating structural unit B14 derived from 4-hydroxybutyrate.

12. A resin composition according to claim 11, wherein the total content of the repeating structural unit B12, the repeating structural unit B13, and the repeating structural unit B14 is 30 mol % or less, relative to 100 mol % of all structural units constituting the polyhydroxyalkanoate (B).

13. The resin composition according to claim 1, wherein the total content of the aliphatic polyester resin (A) and the polyhydroxyalkanoate (B) in the resin composition exceeds 70 mass%.

14. A resin composition according to claim 1, wherein the total content of the aliphatic polyester resin (A), the polyhydroxyalkanoate (B), and at least one selected from the group consisting of the inorganic filler (F) in the resin composition is 90 mass% or more.

15. The resin composition according to claim 1, further comprising an aliphatic polyester-based resin (C), which is different from the aliphatic polyester-based resin (A) and the polyhydroxyalkanoate (B) and has a repeating structural unit C1 derived from an aliphatic diol and a repeating structural unit C2 derived from an aliphatic dicarboxylic acid, and the repeating structural unit C2 comprises a repeating structural unit C21 derived from an aliphatic dicarboxylic acid having 5 to 8 carbon atoms.

16. The resin composition according to claim 15, wherein the content of the aliphatic polyester resin (C) in the resin composition is 40 mass % or less.

17. The resin composition according to claim 1, further comprising an aliphatic aromatic polyester resin (D), which is different from the aliphatic polyester resin (A) and the polyhydroxyalkanoate (B), and which comprises, as main structural units, a repeating structural unit D1 derived from an aliphatic diol, a repeating structural unit D2 derived from an aliphatic dicarboxylic acid, and a repeating structural unit D3 derived from an aromatic dicarboxylic acid, and which comprises at least a repeating structural unit D31 derived from an aromatic dicarboxylic acid having 6 to 12 carbon atoms.

18. The resin composition according to claim 17, wherein the content of the aliphatic aromatic polyester resin (D) in the resin composition is 50 mass % or less.

19. A resin composition according to claim 1, wherein the content of repeating structural units derived from aliphatic dicarboxylic acids having 9 to 36 carbon atoms in all of the polyester resins contained in the resin composition is 1 mol % or more and 50 mol % or less relative to the total number of moles of repeating structural units derived from aliphatic dicarboxylic acids in all of the polyester resins contained in the resin composition.

20. A resin composition according to claim 1, wherein the content of repeating structural units derived from aliphatic dicarboxylic acids having 5 to 8 carbon atoms in all polyester resins contained in the resin composition is 50 mol % or less relative to the total number of moles of repeating structural units derived from aliphatic dicarboxylic acids in all polyester resins contained in the resin composition.

21. The resin composition according to claim 1, wherein the inorganic filler (F) has a whiteness of 70% or more.

22. The resin composition according to claim 1, wherein the inorganic filler (F) has a whiteness of 80% or more.

23. The resin composition according to claim 1, wherein the inorganic filler (F) has an average particle size of 1 μm or more and 20 μm or less.

24. The resin composition according to claim 1, wherein the injection molded product has a flexural modulus of elasticity of 500 MPa or more based on JIS K7171:2022.

25. The resin composition according to claim 1, in which the injection-molded product has a flexural modulus of elasticity of 600 MPa or more based on JIS K7171:2022.

26. The resin composition according to claim 1, wherein the resin composition has a bio-based carbon content of 10% or more, calculated based on ISO 16620-2.

27. A molded article made of the resin composition according to claim 1.

28. The molded article according to claim 27, which is a packaging material.

29. The molded article according to claim 27, which is an agricultural material, a forestry material, or a cutlery.

30. The molded article according to claim 27, which is in the form of a sheet, film, tube, capsule, pellet, filament, or bag.

31. The molded article according to claim 27, which is a filament for a 3D printer or a pellet for a 3D printer.

32. The molded article according to claim 27, which is a plastic bag or a shopping bag.

33. The molded article according to claim 27, which is a straw.

34. An injection molding material comprising the resin composition of claim 1.

35. A pellet comprising the resin composition of claim 1.

36. Use of the pellets according to claim 35 in injection molding.

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