WO2025018361A1 - Resin composition and molded article - Google Patents

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

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

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

Traditionally, biodegradable plastics (resins) such as 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) have been known. In addition, polybutylene succinate/adipate (hereinafter abbreviated as PBSA) and polyhydroxyalkanoate (hereinafter abbreviated as PHA) are known as biodegradable resins that are particularly suitable for home composting. 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).

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, for example, poly(3-hydroxybutyrate) (hereinafter also referred to as [PHB]), and shows that such a biodegradable container has heat resistance capable of withstanding high-temperature contents during use, and is biodegradable after use. In addition, in the examples, it is described that a biodegradable container containing PHB and polybutylene succinate (hereinafter also referred to as "PBS") has been produced.

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

Patent Document 3 discloses a molded article made of an aliphatic polyester resin composition comprising an aliphatic polyester resin (A), a polyhydroxyalkanoate (B), and an inorganic filler (C), the polyhydroxyalkanoate (B) being a copolymer containing 3-hydroxybutyrate units and 3-hydroxyhexanoate units as main constituent 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, excellent heat resistance, and water vapor barrier properties/oxygen barrier properties. In the examples, a molded article is described that is made of an aliphatic polyester resin composition containing polybutylene succinate (PBS) or polybutylene succinate adipate (PBSA) as the aliphatic polyester resin (A), polyhydroxyalkanoate (B), and an inorganic filler (C).

JP 2001-341771 A JP 2017-132967 A International Publication No. 2019/189367 Special table 2013-510210 publication Special table 2015-535027 publication

　Demand for biodegradable resins is on the rise in recent years due to the social trend towards stronger environmental protection, particularly environmental pollution caused by the disposal of used plastic products (particularly the impact on marine life of microplastics caused by the disposal of used plastic products in the ocean). In particular, there is a demand for biodegradable resins not only in aerobic compost environments (underground) at relatively high temperatures (58°C or higher), but also in aerobic compost environments (underground) at room temperature (28°C) and in the ocean. Also, from the perspective of practicality, there is a demand for practical materials that combine good moldability with good mechanical properties.

According to the inventors' investigations, the resin composition described in Patent Document 1 still had room for improvement in terms of biodegradability, moldability, and mechanical properties.

In addition, the resin composition described in Patent Document 2 still has room for improvement in terms of mechanical properties.

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

The present invention was made in consideration of the problems inherent in 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 manufacture such molded articles.

The gist of the present invention resides in the following [1] to [36].
[1] An aliphatic polyester resin (A),
At least one selected from the group consisting of polyhydroxyalkanoate (B) and inorganic filler (F),
The aliphatic polyester resin (A) contains 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 includes a repeating structural unit A21 derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms,
A resin composition, wherein the polyhydroxyalkanoate (B) is different from the aliphatic polyester resin (A) and contains 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 not more than 95% by mass.
[6] 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 resin composition according to any one of [1] to [5], wherein the content of aliphatic polyester resin (C') in the resin composition is 0 mass% or more and less than 5 mass%, the aliphatic polyester resin (C') having a repeating structural unit C1 derived from an aliphatic diol different from the aliphatic polyester resin (A) and the polyhydroxyalkanoate (B) and a repeating structural unit C2 derived from an aliphatic dicarboxylic acid, 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 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 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. The resin composition according to any one of [1] to [8].
[10] The resin composition according to [9], wherein the content of the repeating structural unit B11 is 70 mol % or more and 100 mol % or less, based on 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, relative to 100 mol% of all structural units constituting the polyhydroxyalkanoate (B).
[13] The resin composition according to any one 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), 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 further contains an aliphatic polyester-based resin (C),
The aliphatic polyester resin (C) 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, and the repeating structural unit C2 includes a repeating structural unit C21 derived from an aliphatic dicarboxylic acid having 5 to 8 carbon atoms. The resin composition according to any one of [1] to [14].
[16] The resin composition according to [15], wherein the content of the aliphatic polyester resin (C) in the resin composition is 40 mass% or less.
[17] The resin composition further comprises an aliphatic aromatic polyester resin (D),
The aliphatic aromatic polyester resin (D) is different from the aliphatic polyester resin (A) and the polyhydroxyalkanoate (B),
The aliphatic-aromatic polyester resin (D) 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,
The resin composition according to any one of [1] to [16], wherein the repeating structural unit D3 includes 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 the 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 based on JIS K7171:2022 of 500 MPa or more.
[25] The resin composition according to any one of [1] to [24], wherein the injection-molded product has a flexural modulus based on JIS K7171:2022 of 600 MPa or more.
[26] The resin composition according to any one of [1] to [25], 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 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 a 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 body according to [27], which is a filament for a 3D printer or a pellet for a 3D printer.
[32] The molded article according to [27], which is a plastic shopping 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.

The present invention makes it possible to obtain 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 or pellets that can be used to manufacture such a molded article.

The following describes in detail the embodiments of the present invention; however, the present invention is not limited to the following description, and can be modified in any manner without departing from the gist of the present invention.
In this specification, when a numerical value or a physical property value is enclosed before and after the use of "~", the values before and after the range are 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 addition, in this specification, the expression "A or B" can be read 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 "weight %" are synonymous, and "parts by weight" and "parts by mass" are synonymous.
In addition, 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.

As a result of investigations into the above-mentioned problems, the present inventors have found that a resin composition containing an aliphatic polyester resin containing specific repeating units and specific components contributes to achieving the above-mentioned object, and have thus completed the present invention.
That is, the resin composition according to one embodiment 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) contains 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 contains a repeating structural unit A21 derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms.
Moreover, the polyhydroxyalkanoate (B) is different from the aliphatic polyester resin (A) and contains 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.

The resin composition and molded article as described above have excellent biodegradability at room temperature because they contain the aliphatic polyester resin (A). In addition, by containing at least one selected from the group consisting of polyhydroxyalkanoate (B) and inorganic filler (F), it is possible to improve moldability and mechanical properties while maintaining excellent biodegradability.

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

In addition, 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 called 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 called an "aliphatic diol unit," and a repeating unit derived from an aliphatic dicarboxylic acid is also called an "aliphatic dicarboxylic acid unit."

In the present invention, the repeating structural unit A1 derived from an aliphatic diol (aliphatic diol unit A1) means 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, and the repeating structural unit A2 derived from an aliphatic dicarboxylic acid (aliphatic dicarboxylic acid unit A2) means a repeating structural unit corresponding to an aliphatic dicarboxylic acid, i.e., a repeating structural unit formed by the reaction of two carboxyl groups possessed by an aliphatic dicarboxylic acid.
The repeating structural unit A21 derived from succinic acid (succinic acid unit A21) means a structural unit corresponding to succinic acid, that is, 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) means 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 the resin R usually refers to a structural unit that is contained in an amount of 51% by mass or more relative to the resin R, and may be 80% by mass or more, or 90% by mass or more, or may be 100% by mass when no structural unit other than the main structural unit is contained. In addition, "resin R contains A units and B units as main structural units" means that the total content of A units and B units in the resin R is 51% by mass or more relative to the resin R, and may be 80% by mass or more, or 90% by mass or more, or may be 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% by 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.

<Aliphatic polyester resin (A)>
The aliphatic polyester resin (A) (hereinafter, sometimes referred to as "polyester resin (A)") contains an aliphatic diol unit A1 and an aliphatic dicarboxylic acid unit A2, and preferably contains an aliphatic diol unit A1 and an aliphatic dicarboxylic acid unit A2 as main constituent units. The aliphatic dicarboxylic acid unit A2 contains an aliphatic dicarboxylic acid unit A21 having 9 to 36 carbon atoms. From the viewpoints of heat resistance and biodegradability in particular, the aliphatic dicarboxylic acid unit A21 is preferably an aliphatic dicarboxylic acid unit having 9 to 13 carbon atoms, and more preferably an aliphatic carboxylic acid unit having 10 carbon atoms, specifically, for example, a sebacic acid unit.
The aliphatic dicarboxylic acid unit A2 may contain a structural unit other than the aliphatic dicarboxylic acid unit having 9 to 36 carbon atoms.
The aliphatic diol unit A1 is not particularly limited, but 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 that the aliphatic diol unit A11 contains a repeating structural unit A11 derived from an aliphatic diol having 2 to 10 carbon atoms, and the aliphatic diol unit A11 is particularly preferably an aliphatic diol unit having 4 to 6 carbon atoms. Specific examples of such aliphatic diol unit A11 include, for example, an ethylene glycol unit, a 1,3-propanediol unit, a 1,4-butanediol unit, and a 1,4-cyclohexanedimethanol unit. Among them, it is particularly preferable that the aliphatic diol unit A11 is a repeating structural unit A11 derived from 1,4-butanediol, that is, a 1,4-butanediol unit A11.
The aliphatic polyester resin (A) contained in the resin composition may be one type or two or more types. The resin composition may contain an aliphatic polyester resin other than the aliphatic polyester resin (A).

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, more preferably 15% by mass or more, particularly preferably 20% by mass or more, 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 mass% or more and 99 mass% or less, particularly preferably 5 mass% or more and 95 mass% or less, more preferably 10 mass% or more and 95 mass% or less, even more preferably 15 mass% or more and 95 mass% or less, particularly preferably 20 mass% or more and 95 mass% or less, particularly preferably more than 34 mass% and 95 mass% or less, further preferably 40 mass% or more and 80 mass% or less, and particularly preferably 40 mass% or more and 70 mass% or less.
When the content is within the above range, the resin composition has better biodegradability and flow distance, and also has better heat resistance and rigidity.
Here, in the resin composition in which the content of the aliphatic polyester resin (A) in the resin composition is within the above range, the content of the aliphatic polyester resin (C') containing the aliphatic diol unit C1 and the repeating structural unit C22 derived from an aliphatic dicarboxylic acid having 5 to 6 carbon atoms as the aliphatic dicarboxylic acid unit C2 in the resin composition is preferably 0% by mass or more and less than 5% by mass, and particularly 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, a material with a high bio content (higher bio-based carbon content) and lower environmental load can be obtained. Specific examples of the aliphatic polyester resin (C') include polybutylene succinate adipate (PBSA), for example.

The content of the aliphatic diol unit A1 relative to 100 mol% of all the constituent 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 the repeating constituent 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 excellent heat resistance.

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 is preferably 60 mol% or less, particularly preferably 55 mol% or less, and more preferably 51 mol% or less. That is, when the total number of moles of the 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, and 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) has superior biodegradability, and also superior heat resistance and rigidity.

Furthermore, based on the total number of moles of the aliphatic dicarboxylic acid units A2 contained in the aliphatic polyester resin (A) (100 mol%), the content (A21/A2) of the aliphatic dicarboxylic acid units A21 having 9 to 36 carbon atoms is preferably 1 mol% or more, particularly preferably 5 mol% or more, more preferably 11 mol% or more, and also 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 superior in biodegradability and flow distance, and also superior in heat resistance.

In addition, from the viewpoint of heat resistance and rigidity, it is preferable that the aliphatic dicarboxylic acid unit A2 of the aliphatic polyester resin (A) contains succinic acid unit A22 as an aliphatic dicarboxylic acid unit other than the aliphatic dicarboxylic acid unit 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) as the standard (100 mol%), the content of the succinic acid unit 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, from the viewpoint of moldability. In other words, 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. By keeping the content (A21/A2) within the above range, the aliphatic polyester resin (A) can achieve further improvements in biodegradation rate and fluidity, as well as further improvements in the surface appearance of molded articles.

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

The content of the 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 the 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, and particularly preferably 8 mol% or more, and is usually 60 mol% or less, preferably 50 mol% or less, more preferably 40 mol% or less, and particularly preferably 30 mol% or less. In other words, the content of the 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 the 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 keeping the content within the above range, it is possible to obtain a resin composition with superior biodegradability and heat resistance.

The method of calculating the content of the aliphatic dicarboxylic acid unit having 9 to 36 carbon atoms in all the polyester resins contained in the resin composition relative to the total mole number of the aliphatic dicarboxylic acid unit in all the polyester resins contained in the resin composition is not particularly limited, but it can be calculated from the mass ratio of the polyester resin in the resin composition and the content (mol%) of the aliphatic dicarboxylic acid unit in each polyester resin, or it can be calculated by measuring with ¹ H-NMR. As a calculation method using ¹ H-NMR, specifically, it is possible to measure ¹ H-NMR of the resin composition using a Bruker NMR "AVANCE 400" and determine it from the ratio of the integral value of the chemical shift corresponding to each constitutional unit. The chemical shifts corresponding to the aliphatic dicarboxylic acid units can be determined, for example, by utilizing the integral values of 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) corresponding to the sebacic acid unit. The structural units contained in the polyester resin can be analyzed by ¹ H-NMR in the same manner. This analysis can be applied not only to the polyester resin (A) but also to other polyester resins in the same manner.

As described above, the resin composition may contain two or more kinds of 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 contained. That is, for example, a mixture of an aliphatic polyester resin containing an aliphatic dicarboxylic acid unit having 9 to 36 carbon atoms and a succinic acid unit and an aliphatic polyester resin containing only aliphatic dicarboxylic acid units having 9 to 36 carbon atoms may be used. Also, as described above, the resin composition may contain a polyester resin other than the aliphatic polyester resin (A), and further, an aliphatic polyester resin not containing aliphatic dicarboxylic acid units having 9 to 36 carbon atoms may be used. By using such a plurality of kinds of aliphatic polyester resins, it is also possible to adjust the content of the repeating structural unit derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms relative to the total number of moles of the repeating structural units derived from aliphatic dicarboxylic acids in all the polyester resins contained in the above-mentioned resin composition to within the above-mentioned preferred range.

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).
-O-R ¹ -O- (1)
-OC-R ² -CO- (2)

In structural formula (1), ^R1 represents a divalent aliphatic hydrocarbon group, and in structural formula (2), ^R2 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 from a compound derived from a plant raw material, but are preferably derived from a compound derived from a plant raw material.

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.

The aliphatic diol component that gives 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, and among these, 1,4-butanediol is particularly preferred. Note that two or more of the above aliphatic diols can be used. These aliphatic diols may or may not be derivatives.

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 viewpoint 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 one type or two or more types. These aliphatic dicarboxylic acids may or may not be derivatives thereof.

Furthermore, the aliphatic polyester resin (A) may have 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, or the like.
Regarding each compound described in the description of other structural units below, when there is an overlap with compounds other than aliphatic diols and aliphatic dicarboxylic acids having 9 to 36 carbon atoms, the compounds excluding aliphatic diols and aliphatic dicarboxylic acids having 9 to 36 carbon atoms are the subject of the description, unless otherwise specified.

The aliphatic polyester resin (A) may further contain, as the aliphatic dicarboxylic acid unit A2, other dicarboxylic acid units in addition to the succinic acid unit A22 described above or in place of the succinic acid unit A22 as any dicarboxylic acid unit other than the aliphatic dicarboxylic acid unit A21 having 9 to 36 carbon atoms. 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.

The aliphatic polyester resin (A) may further have a repeating unit (aliphatic oxycarboxylic acid unit) derived from an aliphatic oxycarboxylic acid. Specific examples of the aliphatic oxycarboxylic acid component that gives 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, etc., or derivatives such as lower alkyl esters or intramolecular esters of these carboxylic acids. When optical isomers exist, they may be any of D-isomers, L-isomers, or racemic isomers, 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 may be used alone or in combination of two or more.

From the viewpoint of moldability, the content of the aliphatic oxycarboxylic acid units 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), with all the constituent units constituting the aliphatic polyester resin (A) being 100 mol %.

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

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 (aliphatic polyhydric alcohol having three or more functional groups), an aliphatic polycarboxylic acid having three or more carboxyl groups or an acid anhydride thereof (aliphatic polycarboxylic acid having three or more functional groups), and an aliphatic polyoxycarboxylic acid having three or more groups selected from the group consisting of hydroxyl groups and carboxyl groups (aliphatic polyoxycarboxylic acid having three or more functional groups). Hereinafter, these components are collectively referred to as "a component having three or more functional groups".
In addition, although there is a range of tri- or higher functional aliphatic polyoxycarboxylic acids that overlaps with the above-mentioned aliphatic dicarboxylic acids having 9 to 36 carbon atoms, in this specification they are not considered to include the above-mentioned aliphatic dicarboxylic acids having 9 to 36 carbon atoms.

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

Furthermore, trifunctional aliphatic oxycarboxylic acids are divided into (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, and (ii) a type having one carboxyl group and two hydroxyl groups. Either type can be used, but from the viewpoint of moldability, mechanical strength, and the appearance of the molded product, (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, such as malic acid, is preferred, and more specifically, malic acid is preferably used.Furthermore, tetrafunctional aliphatic oxycarboxylic acid components are divided into (i) a type having three carboxyl groups and one hydroxyl group in the same molecule, (ii) a type having two carboxyl groups and two hydroxyl groups in the same molecule, and (iii) a type 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 of two or more types.

When the aliphatic polyester resin (A) contains such constituent units derived from trifunctional or higher functional components, the content thereof, with all constituent units constituting the polyester resin (A) being taken as 100 mol%, is generally 0.00 mol% or more in lower limit, preferably 0.01 mol% or more in upper limit, and generally 5.00 mol% or less in upper limit, preferably 2.50 mol% or less in upper limit. In other words, based on the total number of moles of the constituent units of the aliphatic polyester resin (A), the content of the trifunctional or higher functional component units is preferably 0.00 mol% or more and 5.00 mol% or less, and particularly preferably 0.01 mol% or more and 2.50 mol% or less.

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

When reacting a diol component that forms diol units (also referred to as "diol component that provides diol units") with a dicarboxylic acid component that forms dicarboxylic acid units (also referred to as "dicarboxylic acid that provides dicarboxylic acid units") during the production of aliphatic polyester resin (A), the amounts of the diol component and 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 since the diol component is distilled off during the esterification reaction, it is usually used in a 1 to 50 mol % excess over the dicarboxylic acid component.

<Method for producing aliphatic polyester resin (A)>
The method for producing the aliphatic polyester resin (A) will be described below by taking the continuous production method as an example. Note that, in the following, a method for producing the 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 an ester exchange reaction step, or a step in which both the esterification reaction and the ester exchange reaction are performed.

In the continuous production method, for example, an aliphatic dicarboxylic acid and an aliphatic diol are reacted in multiple continuous reaction vessels, and polyester pellets are obtained continuously through an esterification reaction process and a melt polycondensation reaction process. However, as long as the effects of the present invention are not hindered, the method is not limited to the continuous method, and any conventionally known method for producing polyester can be used.

(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 multiple continuous reaction tanks or in a single reaction tank. In order to reduce variation in the physical properties of the resulting polyester, however, it is preferable to carry out the steps in multiple continuous reaction tanks.

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, but from the viewpoint of increasing the reaction rate, it is preferably 200° C. or higher, more preferably 210° C. or higher, and in order to suppress coloration 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 speed, the reaction time can be shortened, and the occurrence of dehydration decomposition of the aliphatic diol can be suppressed. In addition, the decomposition of the aliphatic diol and the aliphatic dicarboxylic acid can be suppressed, the occurrence of scattered matter in the reaction tank can be suppressed, the occurrence of foreign matter can be effectively prevented, and the occurrence of turbidity (haze) in the reaction product can be prevented. In addition, the esterification temperature is preferably a constant temperature. The esterification rate is stabilized by keeping the temperature constant. The constant temperature is the set temperature ±5°C, preferably ±2°C.

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

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 preferred reaction pressure is 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 tank 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 the rate of the polycondensation reaction can be prevented from decreasing. Furthermore, the dehydration decomposition of the aliphatic diol can be suppressed, and the rate of the polycondensation reaction can be prevented from decreasing.

The reaction time is preferably 1 hour or more, and is also preferably 10 hours or less, and more preferably 4 hours or less. In other words, the reaction time is preferably 1 hour or more and 10 hours or less, and particularly preferably 1 hour or more and 4 hours or less.

The reaction molar ratio of the aliphatic diol to the total of the aliphatic dicarboxylic acids to be subjected to the esterification reaction represents the molar ratio of the aliphatic diol and the esterified aliphatic diol to the aliphatic dicarboxylic acid and the esterified aliphatic dicarboxylic acid present in the gas phase and the reaction liquid phase of the esterification reaction tank, and 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 those that are decomposed and do not contribute to the esterification reaction include 1,4-butanediol, an aliphatic diol, which is decomposed to tetrahydrofuran, and tetrahydrofuran is not included in this molar ratio. The lower limit of the reaction molar ratio is usually 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 usually 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 above 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 further 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 be sufficient, and the polycondensation reaction, which is a reaction in a subsequent step, is likely to proceed, so that a polyester with a high polymerization degree is likely to be obtained. In addition, the amount of decomposition of the aliphatic diol and/or the aliphatic dicarboxylic acid during the reaction can be suppressed. In order to keep this reaction molar ratio within a preferred range, it is a preferred method to appropriately supply the aliphatic diol to the esterification reaction system.

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 above reaction molar ratio, and as a result, the amount of tetrahydrofuran by-product can be suppressed. In addition, coloring due to deterioration of the terminal balance can be prevented. Furthermore, precipitation of the catalyst can be suppressed, and inactivation of the polymerization and the amount of tetrahydrofuran by-product caused by the acid can be prevented.
After obtaining an ester oligomer having a terminal acid value of 30 to 1000 eq./ton in the esterification reaction step, the ester oligomer is contacted with a phosphorus compound and fed to a polycondensation reaction step, thereby suppressing the by-production of tetrahydrofuran, reducing the purification load on the plant, and obtaining an aliphatic aromatic polyester having a good color tone. In order to more reliably obtain such effects of the present invention, the terminal acid value of the ester oligomer is preferably 50 to 800 eq./ton, more preferably 100 to 500 eq./ton.

In order to control the terminal acid value of the ester oligomer within the above range, it is sufficient to control the reaction conditions such as the reaction molar ratio of the diol component to the dicarboxylic acid component, the reaction temperature, and the reaction pressure. That is, when the reaction molar ratio of the diol component to the dicarboxylic acid component is increased, the terminal acid value of the obtained ester oligomer tends to be low, and when it is decreased, the terminal acid value of the obtained ester oligomer tends to be high. In addition, when the reaction temperature is increased and the reaction time is increased, the terminal acid value of the obtained ester oligomer tends to be low, and conversely, when the reaction temperature is decreased and the reaction time is decreased, the terminal acid value of the obtained ester oligomer tends to be high. Therefore, by appropriately adjusting these conditions within the above-mentioned preferred range, an ester oligomer with a terminal acid value of 30 to 1000 eq./ton can be obtained.
In addition, the terminal acid value of the ester oligomer can be controlled by appropriately selecting the type and amount of the 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.

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 optional structural units also have the desired composition. In this case, there are no limitations on the timing or method of introducing the optional components into the reaction system, and any method is acceptable as long as the desired aliphatic polyester resin (A) can be produced.

For example, the timing and method of introducing the constituent units derived from the optional components into the reaction system are not particularly limited as long as they are 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 components and mixed therein, 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.

The timing of introducing the compound for forming the structural units derived from the polyfunctional component may be simultaneous with other monomers or oligomers at the beginning of the polymerization, or may be simultaneous with the other monomers or oligomers after the ester exchange reaction and before the pressure reduction is started. However, in terms of simplifying the process, it is preferable to introduce the compound simultaneously with other monomers or oligomers.

(Polycondensation reaction process)
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.

The polycondensation reaction can be carried out under reduced pressure using a plurality of continuous reaction vessels. Therefore, contacting the phosphorus compound with the ester oligomer before the polycondensation reaction step corresponds to contacting the phosphorus compound with the ester oligomer before the reduced pressure condition. By carrying out the reduced pressure operation, the degree of polymerization can be further increased.
The reaction pressure in the final polycondensation reaction tank in the polycondensation reaction step is usually 0.01 kPa or more, preferably 0.03 kPa or more, and 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, particularly preferably 0.03 kPa or more and 0.4 kPa or less.
By setting the reaction pressure during polycondensation within the above range, it is possible to prevent the polycondensation time from being prolonged, and accordingly, it is possible to prevent the molecular weight reduction and coloring of the polyester due to thermal decomposition, and it is possible to more easily obtain a polyester that exhibits sufficient properties for practical use. In addition, it is not necessary to use ultra-high vacuum polycondensation equipment, which is also advantageous in terms of cost.

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, and 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 made moderate, a long time is not required to produce a polyester with a high degree of polymerization, and a high-power agitator is not required, which is advantageous in terms of cost. In addition, thermal decomposition of the polyester resin (A) during production can be suppressed, making it easier to obtain a polyester resin (A) with a high degree of polymerization.

The reaction time is usually 1 hour or more, 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 allowed to proceed sufficiently, making it easier to obtain a polyester resin (A) with a high degree of polymerization, and making it easier to obtain a molded product with the desired mechanical properties. In addition, the thermal decomposition of the aliphatic polyester resin (A) can be suppressed, and a decrease in the molecular weight of the aliphatic polyester resin (A) can be prevented, making it easier to obtain a molded product with the desired mechanical properties. In addition, an increase in the amount of carboxyl group terminals due to thermal decomposition, which affects the durability of the polyester resin (A), can be prevented.

By controlling the polycondensation reaction temperature, time, and reaction pressure, it is possible to obtain a polyester resin (A) with the desired intrinsic viscosity.

The aliphatic polyester resin (A) is usually produced in the presence of a catalyst. Any catalyst that can be used in the production of known polyester resins can be selected as the catalyst as long as it does not significantly impair the effects of the present invention.

Since the polycondensation reaction does not proceed easily without a catalyst, it is preferable to use a catalyst. The polycondensation reaction catalyst may be added at any stage between the esterification reaction process and the polycondensation reaction process. The polycondensation reaction catalyst may also be added in multiple batches between the esterification reaction process and the polycondensation reaction process.

As the polycondensation reaction catalyst, a compound containing at least one of the metal elements of 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 them, scandium, yttrium, titanium, zirconium, vanadium, molybdenum, tungsten, zinc, iron, or germanium is preferred, and titanium, zirconium, tungsten, iron, or germanium is particularly preferred. Furthermore, in order to reduce the polyester terminal concentration that affects the thermal stability of the polyester, among the above metals, metal elements of Groups 3 to 6 of the periodic table that exhibit Lewis acidity are preferred. Specifically, scandium, titanium, zirconium, vanadium, molybdenum, or tungsten is preferred, and titanium or zirconium is particularly preferred because of its availability, with titanium being even more preferred in terms of its reaction activity.
Here, the periodic table refers to the long-form periodic table (Nomenclature of Inorganic Chemistry IUPAC Recommendations 2005).

Furthermore, other catalysts may be used in combination as long as the purpose of the present invention is not impaired. Note that one catalyst may be used alone, or two or more catalysts may be used in any combination and ratio.

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. In other words, 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 keeping the amount of catalyst used within the above range, the effect of using the catalyst can be enjoyed, it is also advantageous in terms of cost, and excessive coloring of the aliphatic polyester resin (A) and a decrease in hydrolysis resistance can be prevented.

In this embodiment, a titanium compound is preferably used as a catalyst in the esterification reaction process.

The titanium compound is preferably a tetraalkyl titanate or a hydrolyzate thereof, specifically, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-t-butyl titanate, tetraphenyl titanate, tetracyclohexyl titanate, tetrabenzyl titanate, or a mixed titanate thereof, or a hydrolyzate thereof.

Also preferably used are titanium (oxy) acetylacetonate, titanium tetraacetylacetonate, titanium (diisopropoxide) acetylacetonate, titanium bis(ammonium lactate) dihydroxide, titanium bis(ethylacetoacetate) diisopropoxide, titanium (triethanolamine) isopropoxide, polyhydroxytitanium stearate, titanium lactate, titanium triethanolamine, or butyl titanate dimer.

Among 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, with tetra-n-butyl titanate, titanium (oxy)acetylacetonate, titanium tetraacetylacetonate, polyhydroxytitanium stearate, titanium lactate, and butyl titanate dimer being more preferred, and tetra-n-butyl titanate, polyhydroxytitanium stearate, titanium (oxy)acetylacetonate, and titanium tetraacetylacetonate being particularly preferred.

These titanium compounds are supplied to the esterification reaction step as a catalyst solution prepared using a catalyst dissolving solvent such as alcohols such as methanol, ethanol, isopropanol, or butanol; diols such as ethylene glycol, butanediol, or pentanediol; ethers such as diethyl ether or tetrahydrofuran; nitriles such as acetonitrile; hydrocarbons such as heptane or toluene; water; or a mixture of these, so that the titanium compound concentration is usually 0.05 to 5% by weight.

The timing of catalyst introduction 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 the pressure reduction starts. When introducing aliphatic oxycarboxylic acid units, it is preferable to introduce it simultaneously with monomers or oligomers that form aliphatic oxycarboxylic acid units, such as lactic acid or glycolic acid, when the raw materials are charged, or to dissolve the catalyst in an aqueous aliphatic oxycarboxylic acid solution and introduce it. In particular, the method of dissolving the catalyst in an aqueous aliphatic oxycarboxylic acid solution and introducing it is preferable because it increases the polymerization rate.

Specific examples of phosphorus compounds that can be brought into contact 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 diethyl phosphonoacetate, 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.

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.

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, with ethyl acid phosphate and butyl acid phosphate being preferred. These acidic phosphate ester compounds may be used alone or in combination of two or more.

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

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

These phosphorus compounds and alkaline earth metal compounds are preferably added to the ester oligomer supplied to the polycondensation reaction step as a catalyst solution prepared using the solvents exemplified above as catalyst dissolving solvents used to prepare the titanium compound catalyst solution, so that the phosphorus compound has a concentration of 0.01 to 7.6% by weight and the alkaline earth metal compound has a concentration of 0.02 to 9.7% by weight.

The amount and ratio 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 in terms of Ti to the resulting polymer is 5 to 100 ppm by weight. The phosphorus compound is preferably used so that the molar ratio of P added 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 alkaline earth metal added to the molar amount added in terms of Ti (alkaline earth metal/Ti molar ratio) is 0.5 to 3.0. By using either catalyst compound so as to satisfy the above-mentioned regulations, not only is it advantageous in terms of cost, but it is also possible to prevent the terminal acid value in the finally obtained polyester from becoming high, and it is also possible to prevent a decrease in the thermal stability and hydrolysis resistance of the polyester resin (A) due to an increase in the terminal acid value and the residual catalyst concentration. In addition, because the reaction activity can be maintained, thermal decomposition of the polyester during polyester production can be prevented, making it easier to obtain polyester resin (A) that exhibits practically useful physical properties.

When producing the 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 the chain extender is such that the total ratio 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 the carbonate compound used so that the carbonate bonds are preferably less than 1 mol%, more preferably 0.5 mol% or less, and even more preferably 0.1 mol% or less, relative to the total structural units constituting the aliphatic polyester resin (A). In addition, when a diisocyanate compound is used as a chain extender, it is preferable to adjust the amount of the diisocyanate compound so that the urethane bond 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, based on the total constitutional units constituting the aliphatic polyester resin (A), from the same viewpoint as above. This amount 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, calculated per 100 parts by mass of the aliphatic polyester resin (A). 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 from the die outlet due to the decomposition of urethane bonds in the film formation process, etc., and also to prevent the occurrence of film breakage due to foaming in the molten film, and more stable molding can be achieved.
The carbonate bond amount and urethane bond amount in the aliphatic polyester resin (A) can be determined by calculation from the results of NMR measurements such as ¹ H-NMR and ¹³ C-NMR.

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

Specific examples of diisocyanate compounds 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.

Other chain extenders such as dioxazoline or silicate ester may also be used.
Specific examples of the silicate ester include tetramethoxysilane, dimethoxydiphenylsilane, dimethoxydimethylsilane, and diphenyldihydroxysilane.

It is also possible to manufacture high molecular weight polyester resins using these chain extenders (coupling agents) using conventional technology. After polycondensation is complete, the chain extender is added to the reaction system in a homogeneous molten state without a solvent, and is reacted with the polyester obtained by polycondensation.

More specifically, a polyester resin with a higher molecular weight can be obtained by reacting the chain extender with a polyester obtained by catalytically reacting a diol component with a dicarboxylic acid component, which has substantially hydroxyl end groups and a weight average molecular weight (Mw) of 20,000 or more, preferably 40,000 or more. A prepolymer with a weight average molecular weight of 20,000 or more can be produced with the use of a small amount of chain extender without forming a gel during the reaction, because it is not affected by the remaining catalyst even under harsh conditions such as a molten state. Here, the weight average molecular weight (Mw) of the polyester resin is calculated as a monodisperse polystyrene conversion value from the measured value obtained by gel permeation chromatography (GPC) at a measurement temperature of 40°C using chloroform as a solvent.

Therefore, when the polyester resin is to be made to have a higher molecular weight, for example by using the above-mentioned diisocyanate compound as a chain extender, it is preferable to use a prepolymer having a weight average molecular weight of usually 20,000 or more, preferably 40,000 or more. If the weight average molecular weight is 20,000 or more, the amount of diisocyanate compound used for the higher molecular weight is not too large, and the deterioration of 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.

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.

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

The time for chain extension is usually 0.1 minutes 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. In other words, 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 keeping 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.

(Reaction tank)
The esterification reaction tank may be any of the known types, 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, in addition to a normal type consisting of a power unit, a receiver, a shaft, and an agitator blade, 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 may also be used.

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 of taking part of the reaction liquid outside the reaction tank via piping or the like and stirring it with a line mixer or the like to circulate the reaction liquid can also be used. 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, Pfaudle blades, full zone blades, and Max Blend blades.

There are no particular limitations on the type of polycondensation reaction tank, and examples include vertical agitation polymerization tanks, horizontal agitation polymerization tanks, and thin-film evaporation polymerization tanks. The polycondensation reaction tank can be a single tank, or a multiple tank configuration in which multiple tanks of the same or different types are connected in series. However, in the later stages of polycondensation when the viscosity of the reaction liquid increases, it is preferable to select a horizontal agitation polymerization machine with thin-film evaporation function that has excellent interface renewal properties, plug flow properties, and self-cleaning properties.

The molecular weight of the aliphatic polyester resin (A) is not particularly limited, but can be measured by gel permeation chromatography (GPC). From the viewpoint of moldability and mechanical strength, the weight average molecular weight (Mw) using monodisperse polystyrene as the standard is usually 10,000 or more, preferably 20,000 or more, more preferably 50,000 or more, and even more preferably 100,000 or more, and is 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. In other words, 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, and particularly preferably 100,000 or more and 300,000 or less.

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. In other words, 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.

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 also 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 there are multiple melting points, it is preferable that at least one of the melting points is within the above range. By having the melting point within the above range, the moldability of the resin composition can be improved. 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, and can also be adjusted by changing the type and amount of other minor copolymerization components.

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. In other words, 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, even 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 carbon number and content of the repeating structural unit derived from the 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.

The melting point (Tm) and glass transition temperature (Tg) can be measured, for example, using a differential scanning calorimeter (PerkinElmer, Inc., product name: DSC 8500). Specifically, for example, about 5 mg of 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.

<Polyhydroxyalkanoate (B)>
Polyhydroxyalkanoate (hereinafter sometimes referred to as "PHA") (B) does not include any equivalent to the above-mentioned aliphatic polyester resin (A). In other words, polyhydroxyalkanoate (B) is different from aliphatic polyester resin (A). Polyhydroxyalkanoate (B) also 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 polyhydroxyalkanoates (B) include aliphatic polyester resins that do not contain the aliphatic dicarboxylic acid unit A22 having 9 to 36 carbon atoms that is contained as an essential constituent in the aliphatic polyester resin (A) and that contain a repeating constituent unit represented by the following structural formula (3) as a main constituent unit.
[-CHR ³ -CH ₂ -CO-O-]...(3)
(In structural formula (3), ^R3 is an alkyl group having 1 to 15 carbon atoms.)

The polyhydroxyalkanoate (B) preferably contains a C4 or higher hydroxyalkanoic acid unit B1 as a main structural unit, and may be composed of only a C4 or higher hydroxyalkanoic acid unit B1, for example. Alternatively, it may be composed of a C4 or higher hydroxyalkanoic acid unit B1 and a repeating structural unit derived from another monomer. In addition, the C4 or higher hydroxyalkanoic acid unit B1 may be composed of only one type of hydroxyalkanoic acid unit, or may be composed of two or more types of hydroxyalkanoic acid units.
Specific examples of the homopolymer polyhydroxyalkanoate (B) containing only one type of hydroxyalkanoic acid unit and consisting only of C4 or higher hydroxyalkanoic acid units B1 include poly(3-hydroxybutyrate) (P3HB), poly(4-hydroxybutyrate) (P4HB), poly(3-hydroxyvalerate) (P3HV), poly(3-hydroxyhexanoate) (P3HH), and the like.
In addition, examples of polyhydroxyalkanoates (B) that are copolymers (copolymer resins) containing two or more types of hydroxyalkanoic acid units and consisting only of C4 or higher 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), and the like.
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.

In particular, when polyhydroxyalkanoate (B) contains 3-hydroxybutyrate unit B11 as a main structural unit, the content of 3-hydroxybutyrate unit B11 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, relative to 100 mol% of all structural units constituting polyhydroxyalkanoate (B). 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 can 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. When the content is within the above range, it is possible to more reliably prevent the crystallization of the resin composition from slowing down, and as a result, it is possible to further improve the productivity of molded products. In addition, it is possible to more reliably prevent the molding temperature and the thermal decomposition temperature from becoming close to each other, which further improves molding processability.

Furthermore, when the polyhydroxyalkanoate (B) contains 3-hydroxybutyrate units B11 as the main structural unit and also contains hydroxyalkanoic acid units of C4 or more 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. As such polyhydroxyalkanoate (B), for example, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin, i.e., PHBH, is particularly preferred.
Furthermore, when polyhydroxyalkanoate (B) contains at least one repeating unit selected from the group consisting of repeating units B12, B13 and B14 in addition to the repeating unit B11, the total content of repeating units B12 to B14 is more preferably 40 mol% or less, and even more preferably 30 mol% or less, relative to 100 mol% of all repeating units in polyhydroxyalkanoate (B). By making the total content of repeating units B12 to B14 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 is expected to further improve molding processability, and also to more reliably prevent crystallization from becoming slow, thereby further improving the productivity of molded products.

The ratio of each monomer unit in the polyhydroxyalkanoate (B) can be measured, for example, by gas chromatography as follows.
To approximately 20 mg of dried PHA, 2 mL of a sulfuric acid/methanol mixture (15/85 (mass ratio)) and 2 mL of chloroform are added, 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 gradually added to neutralize the mixture, and the mixture is left to stand until the evolution of carbon dioxide gas stops. After adding 4 mL of diisopropyl ether and mixing well, 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).

The weight average molecular weight (hereinafter sometimes referred to as "Mw") of the polyhydroxyalkanoate (B) can be measured by the above-mentioned 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 the 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.

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, and is more preferably 80.0 g/10 min or less, and particularly preferably 50.0 g/10 min or less, from the viewpoint of moldability and mechanical strength. 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).

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 is preferably 180° C. or lower, more preferably 170° C. or lower, and particularly preferably less 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 less than 160° C.
When the polyhydroxyalkanoate (B) has a plurality of melting points, it is preferable that at least one of the melting points is within the above range.

The polyhydroxyalkanoate (B) is preferably produced by a microorganism.
Polyhydroxyalkanoate (B) can be produced by, for example, a microorganism such as Alcaligenes eutrophus AC32 strain (international deposit under the Budapest Treaty, international depositary authority: National Institute of Advanced Industrial Science and Technology Patent Organism Depositary Center (1-1-1 Central 6, Higashi 1-chome, Tsukuba City, 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)) in which a PHA synthase gene derived from Aeromonas caviae has been introduced into Alcaligenes eutrophus.

As the polyhydroxyalkanoate (B), commercially available products can be used. For example, commercially available products of 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.

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 units, the ratio of constituent units, the production method, the physical properties, etc.

When the resin composition contains the aliphatic polyester resin (A) and further a polyhydroxyalkanoate (B), the content of polyhydroxyalkanoate (B) in the resin composition is preferably more than 0 mass%, particularly preferably 5 mass% or more, more preferably 10 mass% or more, and even more preferably 20 mass% or more, and is preferably 99 mass% or less, particularly preferably 90 mass% or less, more preferably 80 mass% or less, and even more preferably 70 mass% or less, in terms of the balance between rigidity, impact strength, and moldability. 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%.

In addition, when the resin composition contains polyhydroxyalkanoate (B) together with aliphatic polyester resin (A), 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, and 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, 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 93% by mass or less. That is, when the resin composition contains polyhydroxyalkanoate (B) together with aliphatic polyester resin (A), 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, more 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 less than 100% by mass, and even more preferably more than 80% by mass 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 the total content being in the above range, the biodegradability, heat resistance, and moldability of the resin composition can be further improved.

<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 contains 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, the adipic acid unit is particularly preferred from the viewpoints of biodegradability, mechanical properties, availability, and price. The aliphatic polyester resin (C) preferably contains the aliphatic diol unit C1 and the aliphatic dicarboxylic acid unit C21 having 5 to 8 carbon atoms as main structural units.
The aliphatic polyester resin (C) does not include those equivalent to the aliphatic polyester resin (A) and polyhydroxyalkanoate (B) described above. That is, 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) does not substantially contain an aliphatic dicarboxylic acid unit 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) does not substantially contain a hydroxyalkanoic acid unit B1 having 4 or more carbon atoms.

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

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, and 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. In other words, 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 especially preferably 25 mol% or more and 30 mol% or less.

In the aliphatic polyester resin (C), the aliphatic diol unit C1 is not particularly limited, but 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 unit, 1,3-propanediol unit, 1,4-butanediol unit, and 1,4-cyclohexanedimethanol unit, and among these, it is particularly preferable that the aliphatic diol unit C1 contains 1,4-butanediol unit. The above aliphatic diols may be used alone or in combination of two or more kinds. Specifically, the aliphatic polyester resin (C) is preferably polybutylene succinate adipate (PBSA).
The aliphatic dicarboxylic acid unit and the aliphatic diol unit may be derived from a compound derived from petroleum or from a compound derived from a plant raw material, but are preferably derived from a compound derived from a plant raw material.

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. In other words, 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 less 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.

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) using monodisperse polystyrene as the standard is usually 10,000 or more and 1,000,000 or less, but is preferably 20,000 or more and 500,000 or less, and more preferably 50,000 or more and 400,000 or less, because this is advantageous in terms of moldability and mechanical strength.

The melt flow rate (MFR) of the aliphatic polyester resin (C) is not particularly limited, but is usually 0.1 g/10 min or more and 100.0 g/10 min or less, measured at a temperature of 160 ° C. and a load of 2.16 kg based on JIS K7210-1:2014, but 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, 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, from the viewpoint of moldability and mechanical strength.
The MFR of the aliphatic polyester resin (C) can be adjusted by the molecular weight.

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, and may 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 in the form of a blend of two or more aliphatic polyester resins (C) differing in the types and ratios of constituent units, production methods, physical properties, and the like.
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, the content of the aliphatic polyester resin (C') in the resin composition, which has an aliphatic diol unit C1 and an aliphatic dicarboxylic acid unit C2 and in which the aliphatic dicarboxylic acid unit C22 has 5 to 6 carbon atoms, is preferably as follows, in addition to the content of the aliphatic polyester resin (C) in the resin composition. That is, the content of the aliphatic polyester resin (C') is preferably 0% by mass or more and less than 5% by mass, and is preferably 0% by mass or more and 4% by mass or less, relative to the mass of the resin composition. By setting the content of the aliphatic polyester resin (C') in the resin composition within the above range, a material having a high bio-content (higher bio-based carbon content) and a lower environmental impact can be obtained.
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).

The aliphatic polyester resin (C) may also 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, or derivatives thereof such as lower alkyl esters or intramolecular esters. When optical isomers exist in these, they may be in any of the D-form, L-form, or racemic form, and may be in any of the forms of solid, liquid, or aqueous solution. Among these, lactic acid or glycolic acid, or derivatives thereof, are particularly preferred. These aliphatic oxycarboxylic acids may be used alone or as a mixture of two or more.

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 % being the total of all constituent units constituting the polyester resin (C).

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 (aliphatic polyhydric alcohol having three or more functional groups), an aliphatic polycarboxylic acid having three or more carboxyl groups or an acid anhydride thereof (aliphatic polycarboxylic acid having three or more functional groups), and an aliphatic polyoxycarboxylic acid having three or more groups selected from the group consisting of hydroxyl groups and carboxyl groups (aliphatic polyoxycarboxylic acid having three or more functional groups) (hereinafter, these components are collectively referred to as "a component having three or more functional groups").
In addition, although there is a range of tri- or higher functional aliphatic polyoxycarboxylic acids that overlaps with the above-mentioned aliphatic dicarboxylic acids having 5 to 8 carbon atoms, in this specification they are not considered to include the above-mentioned aliphatic dicarboxylic acids having 5 to 8 carbon atoms.

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 their anhydrides include propanetricarboxylic acid or its anhydride, and specific examples of tetrafunctional polycarboxylic acids or their anhydrides include cyclopentanetetracarboxylic acid or its anhydride. These may be used alone or in combination of two or more.

Furthermore, trifunctional aliphatic oxycarboxylic acids are divided into (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, and (ii) a type having one carboxyl group and two hydroxyl groups. Either type can be used, but from the viewpoint of moldability, mechanical strength, and the appearance of the molded product, (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, such as malic acid, is preferred, and more specifically, malic acid is preferably used.Furthermore, tetrafunctional aliphatic oxycarboxylic acid components are divided into (i) a type having three carboxyl groups and one hydroxyl group in the same molecule, (ii) a type having two carboxyl groups and two hydroxyl groups in the same molecule, and (iii) a type 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 of two or more.

When the aliphatic polyester resin (C) contains such a structural unit derived from a trifunctional or higher component, the content thereof, based on all structural units constituting the aliphatic polyester resin (C) being 100 mol %, is generally 0 mol % or more in lower limit, preferably 0.01 mol % or more in upper limit, and generally 5 mol % or less, preferably 2.5 mol % or less in upper limit.
Here, the content of repeating 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 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 setting the content within the above range, a resin composition with a high bio content (higher bio-based carbon content) and a lower environmental load can be obtained.

<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.
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). That is, the aliphatic aromatic polyester resin (D) is different from the aliphatic polyester resin (A), polyhydroxyalkanoate (B), and 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) does not substantially contain an aliphatic dicarboxylic acid unit 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) does not substantially contain a hydroxyalkanoic acid unit B1 having 4 or more carbons, 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 which is substantially not contained in the aliphatic polyester resin (C).

In the aliphatic aromatic polyester resin (D), the aliphatic dicarboxylic acid unit D2 is not particularly limited, but in view of the balance between cost, mechanical properties, thermal properties, and biodegradability, it is usually 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 them, succinic acid, sebacic acid, adipic acid, or azelaic acid, or derivatives thereof such as alkyl esters, are preferred, and succinic acid or adipic acid, or derivatives thereof are particularly preferred. The derivatives may be their acid anhydrides. These aliphatic dicarboxylic acid components may be used alone or in combination of two or more.

In the aliphatic aromatic polyester resin (D), the aliphatic diol unit D1 is not particularly limited, but from the viewpoint 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, and among these, 1,4-butanediol is particularly preferred. These aliphatic diols may be used alone or in combination of two or more.

In the aliphatic aromatic polyester resin (D), the aromatic dicarboxylic acid unit D3 is not particularly limited, but from the perspective of the balance between 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, for example, terephthalic acid, isophthalic acid, furandicarboxylic acid, naphthalenedicarboxylic acid, or diphenyldicarboxylic acid, or lower alkyl esters of these aromatic dicarboxylic acids. These aromatic dicarboxylic acids may be acid anhydrides. Among these, terephthalic acid, isophthalic acid, or furandicarboxylic acid, or lower alkyl (e.g., alkyl having 1 to 4 carbon atoms) esters of these aromatic dicarboxylic acids are preferred, and terephthalic acid or its lower alkyl (e.g., alkyl having 1 to 4 carbon atoms) esters are particularly preferred. These aromatic dicarboxylic acid components may be used alone or in combination of two or more.

The ratio (molar ratio) of the aliphatic dicarboxylic acid units D2 and 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 and aromatic dicarboxylic acid units D3 is within the above range, the aliphatic aromatic polyester resin (D) exhibits particularly excellent properties in terms of biodegradability, heat resistance, flexibility, etc.

Also, 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 gives 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 (aliphatic polyhydric alcohol having three or more functionalities), an aliphatic polycarboxylic acid having three or more carboxyl groups (three or more carboxyl groups) or an acid anhydride thereof (aliphatic polycarboxylic acid having three or more functionalities), and an aliphatic polyoxycarboxylic acid having three or more groups selected from the group consisting of hydroxyl groups and carboxyl groups (aliphatic polyoxycarboxylic acid having three or more functionalities) (hereinafter, these components are also collectively referred to as "a component having three or more functionalities").

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.

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

Furthermore, trifunctional aliphatic oxycarboxylic acids are divided into (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, and (ii) a type having one carboxyl group and two hydroxyl groups. Either type can be used, but from the viewpoint of moldability, mechanical strength, and the appearance of the molded product, (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, such as malic acid, is preferred, and more specifically, malic acid is preferably used.Furthermore, tetrafunctional aliphatic oxycarboxylic acid components are divided into (i) a type having three carboxyl groups and one hydroxyl group in the same molecule, (ii) a type having two carboxyl groups and two hydroxyl groups in the same molecule, and (iii) a type 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 of two or more types.

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 the diisocyanate 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, or isophorone diisocyanate. Specific examples of the silicate ester include tetramethoxysilane, dimethoxydiphenylsilane, dimethoxydimethylsilane, or diphenyldihydroxylane. These may be used alone or in combination of two or more.
The abundance ratio (molar ratio) of the structural units can be determined from an integrated value obtained by ¹ H-NMR measurement.

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, more than 1% by mass, or more than 5% by mass, and 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 and 40% by mass or less, more preferably 1% by mass or more and 30% by mass or less, even 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) becomes more excellent in biodegradability.

The melt flow rate (MFR) of the aliphatic aromatic polyester resin (D) is not particularly limited, but is a value 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 usually 100 g/10 min or less, preferably 40 g/10 min or less, and more preferably 30 g/10 min or less. In other words, 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 the molecular weight.

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 also preferably 180°C or lower, more preferably 160°C or lower, and particularly preferably 140°C or lower. In other words, 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 of the melting points is within the above range. By having a melting point within the above range, the moldability of the resin composition containing the aliphatic aromatic polyester resin (D) can be further improved.

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 be further improved.

The method for adjusting the melting point and glass transition temperature of the aliphatic-aromatic polyester resin (D) is not particularly limited, but it is possible to adjust them, for example, by selecting the type of copolymerization component of the aliphatic dicarboxylic acid or aromatic dicarboxylic acid, adjusting the copolymerization ratio of each, or combining them.

The melting point and glass transition temperature of the aliphatic aromatic polyester resin (D) can be measured using a differential scanning calorimeter (PerkinElmer, Inc., product name: DSC 8500). Specifically, about 5 mg of a sample is precisely weighed out, 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, allowing the glass transition temperature and melting point (peak top) to be measured.

The method for producing the aliphatic aromatic polyester resin (D) can adopt a known method for producing polyester. In addition, the polycondensation reaction at this time can set appropriate conditions that have been used in the past, and is not particularly limited. Usually, a method is adopted in which the polymerization degree is further increased by carrying out a decompression operation after the esterification and/or transesterification reaction has progressed.
For example, a known method for producing polyester can be used, and for example, the method described in Patent Document 4 or Patent Document 5 can be used for production.

Examples of suitable aliphatic aromatic polyester resins (D) include polybutylene adipate terephthalate (PBAT), polybutylene sebacate terephthalate (PBSeT), polybutylene azelate terephthalate (PBAzT), polybutylene succinate terephthalate (PBST), and polybutylene succinate furanate.

Commercially available products can also be used as the aliphatic aromatic polyester resin (D). Specifically, for polybutylene adipate terephthalate, BASF's "Ecoflex (registered trademark) Blend C1200" and Tunhe's "PBAT TH801T" can be used.

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

The shape of the inorganic filler (F) is not particularly limited and may be fibrous, granular, plate-like, needle-like or the like, with granular or plate-like shapes being particularly preferred.
Examples of the powdered inorganic filler (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 ground 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;
Examples of the particles include metal sulfate particles such as barium sulfate or calcium sulfate; or carbon particles such as carbon black.
Examples of the plate-like inorganic filler (F) include mica.
From the viewpoint of preventing blocking between the films, it is preferable to use, as the inorganic filler (F), at least one selected from the group consisting of talc, calcium carbonate, and silica.

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, and 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. By having the average particle size of the inorganic filler (F) within the above range, handling is improved, and the above-mentioned effect of adding the inorganic filler (F) can be better enjoyed. The inorganic filler (F) may be contained alone or in combination of two or more types. The average particle size of the inorganic filler (F) can be measured using a known method, for example, a method of determining the number average particle size using a laser diffraction method.

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. By having the whiteness of the inorganic filler (F) 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 effect 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.

Particularly preferred inorganic fillers (F) are at least one inorganic filler selected from the group consisting of talc, calcium carbonate, and silica, taking into consideration the environmental impact after biodegradation. 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.

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 made into a film. Furthermore, by performing the surface treatment, it is expected that the content of additives such as fillers and plasticizers to be mixed into the resin composition can be reduced. The surface treatment of the filler can be performed by a commonly known method using a surface treatment agent and the filler, and the treatment method is not particularly limited. Examples of the surface treatment agent include linear fatty acids having 6 to 40 carbon atoms, branched fatty acids having 6 to 40 carbon atoms, and ester compounds thereof.

The specific surface area value of the inorganic filler (F) is not particularly limited, but is usually 8000 cm ² /g or more, preferably 10000 cm ² /g or more, and is usually 50000 cm ² /g or less, preferably 40000 cm ² /g or less. That is, the specific surface area of the inorganic filler (F) is preferably 8000 to 50000 cm ² /g, and particularly preferably 10000 to 40000 cm ² /g. By having the specific surface area value within the above range, the rigidity of the molded article made of the resin composition according to the present disclosure can be more sufficiently improved.

There is no particular restriction on the hardness of the inorganic filler (F), but the Mohs hardness is usually 9 or less, preferably 8 or less, more preferably 7 or less, 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 ranges makes it possible to further improve physical properties such as rigidity and heat resistance, and to more reliably prevent the occurrence of poor appearance and reduced strength of the film caused by the inorganic filler (F). The Mohs hardness refers to the value obtained by rubbing a standard substance with a sample substance and measuring the hardness based on the presence or absence of scratches. 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.

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 sum of the masses of the aliphatic polyester resin (A), polyhydroxyalkanoate (B) and inorganic filler (F) relative 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, more preferably more than 80% by mass, more preferably more than 90% by mass, 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 of only the aliphatic polyester resin (A) and at least one selected from the group consisting of polyhydroxyalkanoate (B) and inorganic filler (F). The 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), the polyhydroxyalkanoate (B) and the 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 100% by mass or less, and further preferably more than 80% by mass 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 further 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 has better biodegradability and moldability.

<Other resins>
The resin composition may contain, in addition to the above-mentioned aliphatic polyester resin (A), a resin (other resin) that does not fall into 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 synthetic resins such as aliphatic polyester resins (E) not corresponding to the above-mentioned polyester resins (A) to (D), aromatic polyester resins, polycarbonate, polyamide, polystyrene, polyolefin, acrylic resin, amorphous polyolefin, ABS, AS (acrylonitrile styrene), polylactic acid, polycaprolactone, polyvinyl alcohol, and 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.

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 entire polyester resin contained in the composition.

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.

Examples of the aliphatic dicarboxylic acid having 2 to 4 carbon atoms which provides the repeating structural unit E21 include one or more dicarboxylic acids selected from the group consisting of oxalic acid, malonic acid and succinic acid.
When the aliphatic polyester resin (E) contains an aliphatic dicarboxylic acid unit E21 having 2 to 4 carbon atoms, the content (E21/E2) of the aliphatic dicarboxylic acid unit E21 having 2 to 4 carbon atoms 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.

When the aliphatic polyester resin (E) contains aliphatic diol units E11 having 2 to 4 carbon atoms, the aliphatic diol units E11 having 2 to 4 carbon atoms, when the total number of moles of the constituent units constituting the polyester resin (E) is taken as the standard (100 mol%), is preferably 10 mol% or more, more preferably 30 mol% or more, even more preferably 45 mol% or more, and also preferably 75 mol% or less, more preferably 60 mol% or less, and even more preferably 55 mol% or less, from the viewpoint of moldability. In other words, the above 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.

When the aliphatic polyester resin (E) contains aliphatic dicarboxylic acid units E21 having 2 to 4 carbon atoms, the content of the aliphatic dicarboxylic acid units E21 having 2 to 4 carbon atoms when the total number of moles of the constituent units constituting the polyester resin (E) is taken as the standard (100 mol%) is, from the viewpoint of moldability, preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 35 mol% or more. 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. In other words, the above 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.

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) above. 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.

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 ensuring the effects of the present invention sufficiently, it is preferably 50% by mass or less, and more preferably 40% by mass or less. In other words, 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.

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. In other words, 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 less than 150°C. When there are multiple melting points, it is preferable that at least one of the melting points is within the above range.

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) using monodisperse polystyrene as the standard is usually 10,000 or more and 1,000,000 or less, but is preferably 20,000 or more and 500,000 or less, and more preferably 50,000 or more and 400,000 or less, because this is advantageous in terms of moldability and mechanical strength.

The melt flow rate (MFR) of the aliphatic polyester resin (E) is not particularly limited, but is usually 0.1 g/10 min to 100 g/10 min, 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, and particularly preferably 30 g/10 min or less. In other words, the MFR of the aliphatic polyester resin (E) is preferably 0.1 g/10 min to 100 g/10 min, particularly preferably 0.1 g/10 min to 50 g/10 min, and more preferably 0.1 g/10 min to 30 g/10 min. The MFR of the aliphatic polyester resin (E) can be adjusted by the molecular weight.

When the resin composition contains other resins, in order to effectively obtain the effects obtained by including the aliphatic polyester resin (A) as a resin component, and further, when polyhydroxyalkanoate (B) is included, 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 resin (A), polyhydroxyalkanoate (B), and other resins.

<Other ingredients>
The resin composition may contain components other than the above-mentioned components (other components), such as lubricants, plasticizers, antistatic agents, antioxidants, light stabilizers, ultraviolet absorbers, dyes, pigments, hydrolysis inhibitors, crystal nucleating agents, antiblocking agents, light resistance agents, plasticizers, heat stabilizers, flame retardants, release agents, antifogging agents, surface wetting improvers, incineration aids, dispersion aids, various surfactants, various additives such as slip agents, starch, cellulose, paper, wood flour, chitin/chitosan, coconut shell powder, or animal/plant material fine powder such as walnut shell powder, etc. The other components may be used alone or in combination of two or more.
The resin composition may further contain a functional additive as one of the other components. Specifically, a freshness-preserving agent or an antibacterial agent may be blended.

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

The resin composition has a flexural modulus of 500 MPa or more, more preferably 600 MPa or more, and even more preferably 1000 MPa or more, and preferably 3000 MPa or less, more preferably 2750 MPa or less, and even more preferably 2500 MPa or less. That is, the resin composition has a flexural modulus of 500 MPa or more and 3000 MPa or less, more preferably 600 MPa or more and 2750 MPa or less, and even more preferably 1000 MPa or more and 2500 MPa or less, based on JIS K7171:2022.
When the flexural modulus of the injection molded product is within the above range, the injection molded product does not easily deform during use and can more reliably maintain the required shape, and when applied to applications requiring drilling, such as coffee capsule applications, holes can be easily drilled. The injection molding conditions for obtaining the injection molded product are not particularly limited, and can be carried out, for example, under the conditions described in the examples described below. In addition, in order to enable the resin composition to form an injection molded product that satisfies the above flexural modulus, for example, the resin blending ratio or the content of the inorganic filler (F) can be adjusted. Specifically, for example, the rigidity can be further increased by increasing the content of the inorganic filler (F) within the above range.

<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 viewpoint 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 need to set an 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.
The above bio-based carbon content does not have to be satisfied by each of the materials constituting the resin composition, but may be satisfied by the entire resin composition.
The bio-based carbon content can be controlled by adjusting the ratio of monomer units produced from plant-derived raw materials to all 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 biobased carbon content can be calculated from the proportion of carbon-14 ( ¹⁴ C) in the total carbon mass in the composition in accordance with ISO 16620-2: 2015. In addition, for example, when determining the biobased carbon content of an aliphatic polyester resin contained in a composition, it can also be determined by calculation from the biobased carbon contents and polymerization ratios of the respective raw materials, that is, an aliphatic diol component, an aliphatic dicarboxylic acid component, and an aromatic dicarboxylic acid component.

<Method of producing resin composition>
The method for producing the resin composition is not particularly limited, but a method of mixing at least an aliphatic polyester resin (A) and at least one selected from the group consisting of polyhydroxyalkanoate (B) and inorganic filler (F) simultaneously or in any order using a mixer such as a tumbler, V-type blender, Nauter mixer, Banbury mixer, kneading roll, or extruder can be adopted. From the viewpoint of dispersibility, it is particularly preferable to adopt a method of mixing by melt kneading. As a method for feeding the raw materials, a method of blending the raw materials in advance and feeding them all at once into an extruder and melt mixing, a method of not blending the raw materials and feeding each of them separately from a feeder into an extruder and melt mixing, or a method of feeding only some of the raw materials individually into an extruder and melt mixing, etc. can be mentioned.
The extruder may be a single-screw or twin-screw extruder. The resin kneaded in the twin-screw extruder can be pelletized with 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 also 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.

The temperature during melt kneading is not particularly limited, but is preferably 120 to 220° C., and more preferably 130 to 180° C. Within this temperature range, it is possible to shorten the time required for melt kneading, prevent deterioration of color tone due to deterioration of the resin, and further improve practical physical properties such as mechanical properties.
Regarding the melt-kneading time, from the viewpoint of more reliably avoiding the deterioration of the resin as described above, unnecessary lengthening should be avoided, and the time is preferably from 20 seconds to 20 minutes, and more preferably from 30 seconds to 15 minutes.
It is preferable to set the melt-kneading temperature and time conditions so as to satisfy the above conditions.

<Molded body>
The molded article according to another embodiment of the present invention is a molded article made of the above-mentioned resin composition. The method for producing the molded article is not particularly limited, and the molded article can be obtained by molding the molded article by 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, for example, a method in which a film-like material, sheet-like material, or cylindrical material extruded to a predetermined thickness from a T die, I die, or round die is cooled and solidified by a cooling roll, water, compressed air, or the like can be mentioned. That is, the resin composition according to the present invention can be an injection molding material that can be applied to injection molding applications, and the molded article according to the present invention can be, for example, an injection molded article.

The shape of the molded product is not particularly limited, and examples thereof include a sheet shape, a film shape, a tube shape, a capsule shape, a pellet shape, a filament shape, and a bag shape.
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 shape and size of the pellet are suitable for use in a known plastic processing method such as injection molding or extrusion molding. Specific examples of the shape include a cylindrical shape, an elliptical cylindrical shape, a rectangular prism shape, a disk shape, and a spherical shape. The size and mass of one pellet may be a general size and mass for 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.

<Applications>
The applications of the above-mentioned 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 in each application is not particularly limited, and specific examples of packaging materials include candy bags. In addition, in the case of 3D printer filaments, it is preferable that they are filament-shaped, in the case of 3D printer pellets, it is preferable that they are pellet-shaped, in the case of plastic bags or shopping bags, it is preferable that they are bag-shaped, and in the case of straws, it is preferable that they are tubular.
The above-mentioned use may be the use of the above-mentioned resin composition or molded article, or may be the use of a composite having the resin composition or the molded article.

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 it does not deviate from the gist of the invention. The various manufacturing conditions and evaluation result values in the following examples are meant as preferred upper or lower limit values in the embodiments of the present invention, and the preferred range may be a range defined by a combination of the above-mentioned upper or lower limit values and the values of the following examples or values between the examples.

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

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

<Evaluation 2: Flexural modulus>
The test pieces obtained by the above-mentioned injection molding were measured for flexural modulus in accordance with JIS K7171: 2022. If the flexural modulus is less than 500 MPa, the material is easily deformed during use and it is difficult to maintain the required shape, whereas if the flexural modulus is more than 3000 MPa, the material is too hard for applications requiring holes, such as coffee capsule applications, making it difficult to drill holes and making the material difficult to use.

<Evaluation 3: Deflection temperature under load>
The test pieces obtained by the above-mentioned injection molding were subjected to measurement of deflection temperature under load (HDT) by the B method flatwise based on JIS K7191-2: 2015. For coffee capsule applications in which the capsule comes into contact with hot water, the HDT is preferably 65°C or higher.

<Evaluation 4: Charpy impact strength>
The Charpy impact strength of the test pieces obtained by the above-mentioned injection molding was measured based on JIS K7111-1: 2012. In the expected applications, 2.0 J/ ^m2 or more is preferable, and an impact strength of less than 2.0 J/ ^m2 may easily break when dropped.

<Evaluation 5: Flow distance (spiral flow)>
Using a Japan Steel Works J110AD-180H injection molding machine, a spiral mold having a groove 2 mm thick and 8 mm wide was used to measure the flow distance of each resin composition obtained by the method described below. 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 allows evaluation taking into account the effects of both fluidity and solidification speed, and a longer flow distance is considered to indicate better moldability.

<Evaluation 6: Soil biodegradation test at room temperature>
A film with a thickness of 100 μm was obtained by press molding resin pellets melted at a temperature of 190 to 220° C. The obtained film was stored in soil (moisture content 15 to 30%) collected from a farm in Mie Prefecture for 3 months at 28±2° C., after which the weight was measured and the decomposition degree expressed by the following formula was calculated, and the biodegradability in soil at room temperature was evaluated 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 more Rank ++: Decomposition rate is 30% or more but less than 90% Rank +: Decomposition rate is less than 30%

<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 the carbon dioxide with hydrogen and a catalyst. Next, the carbon isotope ratio was measured using an accelerator mass spectrometer. Since ¹⁴ C exists in the atmosphere at a certain rate, the same rate of ¹⁴ C is also contained in carbon derived from biomass (bio-based carbon). On the other hand, since ¹⁴ C decreases with a half-life of 5730 years, carbon derived from fossil resources does not contain ¹⁴ C. Therefore, the bio-based carbon content was calculated by calculating the ratio of ¹⁴ C in the sample to the standard ratio of ¹⁴ C contained in the modern atmosphere.

[Ingredients used]
In the examples and comparative examples, the following polymerized resins or commercially available products were used.

[Preparation of polycondensation catalyst]
343.5 parts by weight of magnesium acetate tetrahydrate was placed in a reactor equipped with a stirrer, and 1434 parts by weight of anhydrous ethanol (purity 99% by weight or more) was added. 218.3 parts by weight of ethyl acid phosphate (mixture weight ratio of monoester and diester is 45:55) was added and stirred at 23°C. After confirming that magnesium acetate was completely dissolved, 410.0 parts by weight of tetra-n-butyl titanate was added. Stirring was continued for another 10 minutes to obtain a homogeneous mixed solution. This mixed solution was concentrated under reduced pressure while controlling the temperature at 60°C or less. Approximately half of the amount of ethanol added was distilled off, leaving a translucent viscous liquid. 1108 parts by weight of 1,4-butanediol was added thereto, and further concentration was performed under reduced pressure while controlling the temperature at 80°C or less to obtain a catalyst solution with a titanium atom content of 3.5% by weight.

[Production Example of Aliphatic Polyester Resin A-1]
In a reaction vessel equipped with a stirrer, a nitrogen inlet, a heater, a thermometer, and a pressure reducing port, 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 were charged as raw materials. The molar ratio of succinic acid to sebacic acid was 89:11, and the proportion of the substance amount of 1,4-butanediol to the total substance amount of succinic acid and sebacic acid was 1.30.

Nitrogen gas was introduced into the vessel while stirring the contents of the vessel, and the system was placed under a nitrogen atmosphere by vacuum replacement. Next, the raw materials were dissolved at 160°C, and after confirming that the raw materials were completely dissolved and the distillation part temperature 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 for 1 hour at 230°C and normal pressure. The terminal acid value of the obtained ester oligomer was measured and found to be 345 eq/ton. A catalyst solution was added 5 minutes before the end of the esterification reaction. After the esterification reaction, the temperature was raised from 230°C to 250°C over 30 minutes, and at the same time, the pressure was reduced to 0.07 x 10 ³ Pa or less over 85 minutes, and polymerization was continued while maintaining the heated and reduced pressure state, and polymerization was terminated when a predetermined viscosity was reached, to obtain an aliphatic polyester resin (A-1). The content of repeating units derived from aliphatic dicarboxylic acids having 9 to 36 carbon atoms relative to the total number of moles of repeating units derived from aliphatic dicarboxylic acids in the obtained 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 obtained 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 obtained 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.

[Production of Aliphatic Polyester Resin A-2]
In the production example of the aliphatic polyester resin A-1, 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. The same procedure was carried out to obtain an 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 obtained resin was 26 mol%, and the content of succinic acid was 74 mol%. In addition, the content of aliphatic dicarboxylic acid units relative to 100 mol% of all structural units constituting the obtained 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.

The following commercially available products were used for polyhydroxyalkanoate (B), aliphatic polyester resin (C), aliphatic aromatic polyester resin (D), aliphatic polyester resin (E), inorganic filler (F), and heat stabilizer.

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)

- 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 total constituent 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)

- Aliphatic aromatic polyester resin (D): Polybutylene adipate terephthalate, BASF Ecoflex (registered trademark) Blend C1200 (adipic acid unit amount in total dicarboxylic acid unit amount: 53 mol%, terephthalic acid unit amount: 47 mol%, 1,4-butanediol unit amount in total constitutional 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)

- 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 total constituent 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)

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%)

Heat stabilizer: Irganox 1010 (manufactured by BASF)

[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 strand extruded by kneading at 145°C to 160°C was water-cooled and then cut to obtain pellets made of a resin composition.
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%. In addition, the MFR measured by the method described in Evaluation 1 above was 4.2 g/10 min.
Furthermore, the bio-based carbon content of the pellets obtained above was calculated by 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. by the method described in the above evaluation 5. Furthermore, the pellets obtained above were press-molded into a film, and the biodegradability of the film was evaluated by the method described in the above evaluation 6.
Furthermore, the pellets obtained above were used to mold standard test pieces using an electric injection molding machine (product name: SE18D; manufactured by Sumitomo Heavy Industries, Ltd., maximum mold clamping force 18 tons). The molding conditions were set to a mold temperature of 40°C and a cylinder temperature of 160°C, and the shape of the standard test piece was 80 mm in length, 10 mm in width, and 4 mm in thickness. The obtained standard test piece was subjected to the evaluations 2 to 4 described 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.

[Examples 2 to 20, Comparative Examples 1 to 7]
Pellets made of a resin composition were obtained in the same manner as in Example 1, except that the raw material types of the resin composition and their blending ratios 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 was measured for each pellet by the method described in the above evaluation 5. For Examples 1 to 11 and Comparative Examples 1 to 6, the flow distance was measured at a cylinder temperature of 160° C., and for Examples 12 to 20 and Comparative Example 7, the flow distance was measured at a cylinder temperature of 170° C.
Furthermore, a biodegradability evaluation was performed using a film obtained by press-molding each pellet by the method described in Evaluation 6. Furthermore, a standard test piece was prepared using each pellet in the same manner as in Example 1, and subjected to Evaluations 2 to 4. The Se content of the resin compositions according to Examples 2 to 20 and Comparative Examples 1 to 7, and the results of Evaluations 1 and 7 are shown in Table 1. Furthermore, the results of Evaluations 2 to 6 are shown in Table 2.

 

 

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, from these evaluation results, it can be seen 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, and the like.

Claims (36)

An aliphatic polyester resin (A),
At least one selected from the group consisting of polyhydroxyalkanoate (B) and inorganic filler (F),
The aliphatic polyester resin (A) contains 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 includes a repeating structural unit A21 derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms,
A resin composition, wherein the polyhydroxyalkanoate (B) is different from the aliphatic polyester resin (A) and contains a repeating structural unit B1 derived from a hydroxyalkanoic acid having 4 or more carbon atoms. The resin composition according to claim 1, wherein the content of the polyhydroxyalkanoate (B) in the resin composition is more than 0% by mass and not more than 90% by mass. 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. The 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. The resin composition according to claim 1, wherein the content of the aliphatic polyester resin (A) in the resin composition is more than 34% by mass and not more than 95% by mass. 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 resin composition according to claim 1, wherein the content of aliphatic polyester resin (C') in the resin composition is 0 mass% or more and less than 5 mass% and has 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), and the repeating structural unit C2 containing a repeating structural unit C22 derived from an aliphatic dicarboxylic acid having 5 to 6 carbon atoms. The resin composition according to claim 1, wherein the repeating structural unit A2 further includes a repeating structural unit A22 derived from succinic acid. 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. 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 B1, and the polyhydroxyalkanoate (B) contains the repeating structural unit B11 as a main structural unit. 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). 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. The resin composition according to claim 11, wherein the total content of the repeating structural units B12, B13, and B14 is 30 mol% or less relative to 100 mol% of all structural units constituting the polyhydroxyalkanoate (B). 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%. The 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. The resin composition further comprises an aliphatic polyester resin (C),
The resin composition according to claim 1, wherein the aliphatic polyester resin (C) 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, and the repeating structural unit C2 includes a repeating structural unit C21 derived from an aliphatic dicarboxylic acid having 5 to 8 carbon atoms. 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. The resin composition further comprises an aliphatic aromatic polyester resin (D),
The aliphatic aromatic polyester resin (D) is different from the aliphatic polyester resin (A) and the polyhydroxyalkanoate (B),
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,
2. The resin composition according to claim 1, wherein the repeating structural unit D3 includes at least a repeating structural unit D31 derived from an aromatic dicarboxylic acid having 6 to 12 carbon atoms. 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. The 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 polyester resins contained in the resin composition is 1 mol% or more and 50 mol% or less with respect to the total number of moles of repeating structural units derived from aliphatic dicarboxylic acids in all polyester resins contained in the resin composition. The 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. The resin composition according to claim 1, wherein the inorganic filler (F) has a whiteness of 70% or more. The resin composition according to claim 1, wherein the inorganic filler (F) has a whiteness of 80% or more. 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. 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. The resin composition according to claim 1, in which the flexural modulus of the injection molded product based on JIS K7171:2022 is 600 MPa or more. The resin composition according to claim 1, wherein the bio-based carbon content of the resin composition is 10% or more, calculated based on ISO 16620-2. A molded article made of the resin composition according to claim 1. The molded article according to claim 27, which is a packaging material. The molded article according to claim 27, which is an agricultural material, a forestry material, or cutlery. The molded article according to claim 27, which has a shape of a sheet, a film, a tube, a capsule, a pellet, a filament, or a bag. The molded article according to claim 27, which is a filament for a 3D printer or a pellet for a 3D printer. The molded article according to claim 27, which is a plastic shopping bag or a shopping bag. The molded article according to claim 27, which is a straw. 　An injection molding material comprising the resin composition according to claim 1. Pellets containing the resin composition according to claim 1. Use of the pellets according to claim 35 in injection molding.