Copolyesters formed from 3-hydroxybutyric acid and methods of making same

Abstract

According to the present invention, it is possible to provide: a copolyester comprising 3-hydroxybutyric acid, which exhibits high biodegradability and is capable of suppressing hydrolyzability and odor by controlling the acid value derived from a decomposition product to a constant value or less; this copolyester has a structural unit (3HB-U) derived from 3HB, a structural unit (DA-U) derived from DA, and a structural unit (DO-U) derived from DO. The content of 3HB-U is 1-65 mol% with respect to 100 mol of all structural units of the copolyester, the average chain length of 3HB-U in the copolyester is 2-80, and the acid value of the copolyester is 5 or less.

Description

Technical Field

[0001] The present invention relates to copolyesters formed from 3-hydroxybutyric acid and a method for producing the same.

[0002] This application claims priority based on Japanese Patent Application No. 2022-122988 filed in Japan on August 1, 2022, and the contents are incorporated herein by reference. Background Art

[0003] In response to the social issue of global environmental degradation caused by the massive disposal of plastics, there is an increasing demand for sustainable product groups (packaging materials, films) made of resins that are biodegradable in various conditions (seawater, fresh water, soil, compost).

[0004] As a resin that exhibits biodegradability in all of the above environments, polyhydroxyalkanoate (PHA) produced by bacteria can be cited. However, structural control of PHA requires genetic manipulation of bacteria, and the development of a resin corresponding to the desired physical properties requires a lot of time and effort.

[0005] When a polymer is synthesized from monomers corresponding to PHA by chemical polymerization, the degree of freedom of the resin structure becomes high, but since the 3-hydroxybutyric acid monomer, which is the main structural unit of PHA, is easily thermally decomposed, carboxylic acid-based decomposition products are generated, which have the problem of generating unpleasant odors and being easily hydrolyzed. Therefore, there is a need for PHA-based synthetic resins with suppressed decomposition products.

[0006] Patent Document 1 discloses a biodegradable copolyester obtained by reacting 3-hydroxybutyric acid, an aliphatic dicarboxylic acid and an aliphatic diol, wherein the copolyester contains a 3-hydroxybutyric acid unit at a content of 1 to 20 mol % based on all structural units.

[0007] In addition, Non-Patent Document 1 discloses a biodegradable copolyester composed of 3-hydroxybutyric acid, 1,4-butanediol, succinic acid or adipic acid, wherein the content of 3-hydroxybutyric acid units relative to all structural units is 8.8-49% and the average chain length of 3-hydroxybutyric acid is 1.2-19.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2017-25138

[0011] Non-patent literature

[0012] Non-patent literature 1: Thibaud Debuissy, Eric Pollet, Luc Averous, Ohkita, "Titanium-catalyzed transesterification as a route to the synthesis of fullybiobased poly(3-hydroxybutyurate-co-butylenedicarboxylate)copolyesters, from their homopolyesters", European Polymer Journal, 90 (2017) 92-104. Summary of the invention

[0013] Problem that the invention aims to solve

[0014] However, in Patent Document 1 and Non-Patent Document 1, the effects of the content of 3-hydroxybutyric acid units relative to all structural units (hereinafter, sometimes referred to as "3HB content") and the average chain length of 3-hydroxybutyric acid (hereinafter, sometimes referred to as "3HB chain length") on biodegradability are unclear. In addition, since the acid value of the decomposition products derived from 3-hydroxybutyric acid is high, there are problems in terms of unpleasant odor and easy hydrolysis.

[0015] The present invention has been made to solve the above-mentioned problems, and its object is to provide a copolyester formed from 3-hydroxybutyric acid (hereinafter sometimes referred to as "3HB copolyester") and a method for producing the same, wherein the copolyester exhibits high biodegradability at a specific 3HB ratio and 3HB chain length, and can suppress hydrolysis and odor by controlling the acid value derived from the decomposition product to below a certain value.

[0016] Solutions for solving problems

[0017] The contents of the present disclosure include the following embodiments [1] to

[10] .

[0018] [1] A copolyester, which is a copolyester of 3-hydroxybutyric acid (3HB), a dicarboxylic acid (DA) and a diol (DO), characterized in that:

[0019] The copolyester has a structural unit (3HB-U) derived from the 3-hydroxybutyric acid (3HB), a structural unit (DA-U) derived from the dicarboxylic acid (DA), and a structural unit (DO-U) derived from the diol (DO),

[0020] The aforementioned dicarboxylic acid (DA) includes an aliphatic dicarboxylic acid,

[0021] The aforementioned diol (DO) comprises an aliphatic diol,

[0022] The content of the structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB) is 1 to 65 mol% based on 100 mol of all structural units of the copolyester.

[0023] The average chain length of the structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB) in the copolyester is 2 to 80.

[0024] The acid value of the copolyester is 5 or less.

[0025] [2] The copolyester according to [1], which is a reaction product of the poly(3-hydroxybutyric acid) (PHB) and a polyester (PAO), wherein the polyester (PAO) is a polyester of the dicarboxylic acid (DA) and the diol (DO).

[0026] [3] The copolyester according to [2], wherein the number average molecular weight of the poly(3-hydroxybutyric acid) (PHB) is 1,000 to 500,000.

[0027] [4] The copolyester according to [2] or [3], wherein the number average molecular weight of the polyester (PAO) is 5,000 to 500,000.

[0028] [5] The copolyester according to any one of [2] to [4], wherein the acid value of the polyester (PAO) is 5 or less.

[0029] [6] The copolyester according to any one of [1] to [5], wherein the dicarboxylic acid (DA) is an aliphatic dicarboxylic acid.

[0030] [7] The copolyester according to any one of [1] to [6], wherein the diol (DO) is an aliphatic diol.

[0031] [8] A method for producing a copolyester, which is a method for producing the copolyester described in any one of [1] to [7], comprising:

[0032] Poly(3-hydroxybutyric acid) (PHB), which is a polyester of the above-mentioned 3-hydroxybutyric acid (3HB), and

[0033] A step of reacting the dicarboxylic acid (DA) and the polyester (PAO) of the diol (DO).

[0034] [9] A resin composition comprising the copolyester described in any one of [1] to [7].

[0035]

[10] A sheet or a film formed from the resin composition according to [9].

[0036] Effects of the Invention

[0037] According to the present invention, an object is to provide a copolyester composed of 3-hydroxybutyric acid, which exhibits high biodegradability and can suppress hydrolysis and odor by controlling the acid value of decomposition products to a certain value or less, and a method for producing the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The copolyester of Example 1 of the present invention 1 H-NMR spectrum.

[0039] Figure 2 The copolyester of Example 1 of the present invention 13 C-NMR spectroscopy. DETAILED DESCRIPTION

[0040] Hereinafter, the present invention will be described in further detail. In addition, the present invention is not limited only to the embodiments described below.

[0041] The term “to” means that the value is greater than or equal to the value before the term “to” and less than or equal to the value after the term “to”.

[0042] (Copolyester)

[0043] The copolyester of one embodiment of the present invention (copolyester of the present embodiment) is a copolyester of 3-hydroxybutyric acid (3HB), dicarboxylic acid (DA) and diol (DO) (sometimes referred to as HB-DA-DO copolyester). The copolyester of the present embodiment has a structural unit (3HB-U) derived from the aforementioned 3-hydroxybutyric acid (3HB), a structural unit (DA-U) derived from the aforementioned dicarboxylic acid (DA) and a structural unit (DO-U) derived from the aforementioned diol (DO). The aforementioned dicarboxylic acid (DA) includes an aliphatic dicarboxylic acid, and the aforementioned diol (DO) includes an aliphatic diol. The content of the structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB) is 1 to 65 mol% relative to 100 mol of all structural units of the aforementioned copolyester. The average chain length of the structural unit (3HB-U) derived from 3-hydroxybutyric acid in the copolyester of the present embodiment is 2 to 80. The acid value of the copolyester of the present embodiment is 5 or less.

[0044] The structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB) refers to one residue of 3-hydroxybutyric acid in the copolymer, specifically, a structure in which a hydrogen atom in a hydroxyl group and a hydroxyl residue in a carboxyl group of 3-hydroxybutyric acid are removed.

[0045] The structural unit (DA-U) derived from dicarboxylic acid (DA) refers to one residue of dicarboxylic acid (DA) in the copolymer, and specifically refers to a structure obtained by removing a hydroxyl residue in a carboxyl group of dicarboxylic acid (DA).

[0046] The structural unit (DO-U) derived from diol (DO) refers to one residue of diol (DO) in the copolymer, and specifically refers to a structure in which a hydrogen atom in a hydroxyl group of diol (DO) is removed.

[0047] All structural units of the copolyester refer to the total number of moles of structural units derived from all monomers constituting the copolyester. In addition, when the copolyester of the present embodiment has the structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB), the structural unit (DA-U) derived from dicarboxylic acid (DA), and the structural unit (DO-U) derived from diol (DO), and does not contain structural units other than these, all structural units of the copolyester are the total number of moles of the structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB), the structural unit (DA-U) derived from dicarboxylic acid (DA), and the structural unit (DO-U) derived from diol (DO).

[0048] The content (mol%) of the structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB) refers to the percentage of the number of moles of the structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB) relative to the total number of moles of the structural units derived from all monomers constituting the copolyester. The evaluation method is described in the Examples described below.

[0049] The chain structure of the structural unit (3HB-U) derived from 3-hydroxybutyric acid refers to a structure in which one residue of 3-hydroxybutyric acid is continuously ester-bonded, specifically, a structure in which a hydrogen atom in a hydroxyl group of 3-hydroxybutyric acid is removed and a hydroxyl residue in a carboxyl group is continuously ester-bonded.

[0050] The average chain length of the structural unit (3HB-U) derived from 3-hydroxybutyric acid refers to the average number of structural units derived from 3-hydroxybutyric acid that appear consecutively in one molecule of polyester. The evaluation method is described in the Examples below.

[0051] The acid value of the copolyester is the number of milligrams of potassium hydroxide required to neutralize the free acid present in 1 g of the copolyester. The evaluation method is described in the examples below.

[0052] The copolyester of the present embodiment is preferably a reaction product of the aforementioned poly(3-hydroxybutyric acid) (PHB) and a polyester (PAO), wherein the polyester (PAO) is a polyester of the aforementioned dicarboxylic acid (DA) and the aforementioned diol (DO).

[0053] Poly(3-hydroxybutyric acid) (PHB), which is a polyester of 3-hydroxybutyric acid (3HB), refers to a polyester in which structural units derived from 3-hydroxybutyric acid are continuously ester-bonded, and specifically, a polyester in which a structure obtained by removing a hydrogen atom in a hydroxyl group of 3-hydroxybutyric acid and a hydroxyl residue in a carboxyl group is continuously ester-bonded.

[0054] The polyester (PAO) of dicarboxylic acid (DA) and the above-mentioned diol (DO) refers to a polyester in which a structural unit derived from dicarboxylic acid (DA) and a structural unit (DO-U) derived from diol (DO) are continuously ester-bonded.

[0055] Although not particularly limited, preferred examples of the copolyester of the present embodiment include the following formulas (1) to (3).

[0056]

[0057] (In formula (1), o, p and q each independently represent a positive integer)

[0058]

[0059] (In formula (2), o, p, q and r each independently represent a positive integer)

[0060]

[0061] (In formula (3), o, p, q and r each independently represent a positive integer)

[0062] <3-Hydroxybutyric Acid (3HB) and Structural Unit Derived from 3HB (3HB-U)>

[0063] The content of the structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB) of the present embodiment is 1 to 65 mol%, preferably 2 to 60 mol%, more preferably 3 to 50 mol%, and further preferably 5 to 30 mol%, relative to 100 mol of all structural units of the copolyester of the present embodiment. When the structural unit (3HB-U) is less than 1 mol%, the biodegradability of the copolyester is reduced. When the structural unit (3HB-U) exceeds 65 mol%, there are problems such as the easy generation of acidic decomposition products of 3-hydroxybutyric acid, the generation of unpleasant odor, and the easy hydrolysis.

[0064] The average chain length of the structural unit (3HB-U) derived from 3-hydroxybutyric acid in the copolyester of the present embodiment is 2 to 80, preferably 3 to 70, more preferably 4 to 50, and further preferably 6 to 30. When the average chain length of the structural unit (3HB-U) is less than 2, not only the biodegradability of the copolyester is reduced, but also the mechanical properties and melting point are reduced. When the average chain length of the structural unit (3HB-U) exceeds 80, the biodegradability of the copolyester is reduced.

[0065] When the content of the structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB) of the present embodiment is 5 to 30 mol% relative to 100 mol of all the structural units of the copolyester of the present embodiment, and the average chain length of the structural unit (3HB-U) derived from 3-hydroxybutyric acid in the copolyester of the present embodiment is 6 to 30, it is particularly preferred because high biodegradability, mechanical properties and melting point can be achieved together with the inhibition of decomposition of 3-hydroxybutyric acid.

[0066] The content of the structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB) of the present embodiment can be determined by the content of the copolyester of the present embodiment. 1 The content of the structural unit (3HB-U) can be adjusted by the amount of 3-hydroxybutyric acid (3HB) in the raw material (or raw material of the intermediate product) for producing the copolyester in the method for producing the copolyester of the present embodiment described below.

[0067] The average chain length of the structural unit (3HB-U) derived from 3-hydroxybutyric acid in the copolyester of the present embodiment can be determined by the 1 H-NMR, 13 C-NMR spectrum is measured, and in detail, it can be measured by the method described in the examples described later. The average chain length of the structural unit (3HB-U) can be adjusted by controlling (for example, block polymerization, etc.) the esterification reaction of 3-hydroxybutyric acid, the esterification reaction of 3-hydroxybutyric acid and diol, and the esterification reaction of dicarboxylic acid (DA) and diol in the manufacturing method of the copolyester of the present embodiment described later. For example, methods for controlling the order of input of each raw material, methods for adjusting the speed of each reaction, etc. can be cited. For example, it can be listed as: first obtaining an oligomer or polyester (PHB) of 3-hydroxybutyric acid (3HB), and then reacting it with dicarboxylic acid (DA) and diol (DO); first obtaining an oligomer or polyester (PHB) of 3-hydroxybutyric acid (3HB), and then obtaining a polyester (PAO) of dicarboxylic acid (DA) and diol (DO), and then reacting the obtained polyester (PHB) with polyester (PAO).

[0068] The 3-hydroxybutyric acid of the present invention may be used in any of a racemic form, an (R) form, and an (S) form. In order to achieve high biodegradability, mechanical properties, and a melting point, the (R) form is particularly preferably used.

[0069] <Dicarboxylic acid (DA) and structural unit derived from DA (DA-U)>

[0070] The dicarboxylic acid (DA) of the present embodiment comprises an aliphatic dicarboxylic acid. Of all 100 moles of the structure (DA-U) derived from the dicarboxylic acid (DA) contained in the copolyester of the present embodiment, the content of the structure derived from the aliphatic dicarboxylic acid is preferably 20 mol% or more, more preferably 40 mol% or more, and further preferably 70 mol% or more. When the content of the structure derived from the aliphatic dicarboxylic acid is 70 mol% or more, heat resistance, mechanical properties, optical properties, etc. and biodegradability can be taken into account. When the content of the structure derived from the aliphatic dicarboxylic acid is less than 20 mol%, biodegradability is significantly reduced. The dicarboxylic acid (DA) of the present embodiment is preferably an aliphatic dicarboxylic acid. That is, the structural unit (DA-U) derived from the dicarboxylic acid (DA) of the present embodiment is preferably a structural unit derived from an aliphatic dicarboxylic acid.

[0071] The dicarboxylic acid (DA) of the present embodiment may include, for example, alicyclic dicarboxylic acids, aromatic dicarboxylic acids, etc. in addition to aliphatic dicarboxylic acids. The dicarboxylic acid-derived structural unit (DA-U) of the present embodiment may include, for example, alicyclic dicarboxylic acid-derived structural units, aromatic dicarboxylic acid-derived structural units, etc. in addition to aliphatic dicarboxylic acids.

[0072] The dicarboxylic acid (DA) according to the present embodiment can be used alone or in combination of two or more.

[0073] Examples of the aliphatic dicarboxylic acid include alkane dicarboxylic acids (e.g., oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonane dicarboxylic acid, decanedicarboxylic acid, etc.) 1-16 Alkanes-dicarboxylic acids, etc.), unsaturated aliphatic dicarboxylic acids (such as maleic acid, fumaric acid, itaconic acid, etc. 2-10 Olefin-dicarboxylic acid, etc.)

[0074] Examples of the alicyclic dicarboxylic acid include cycloalkane dicarboxylic acids (e.g., 1,4-cyclohexane dicarboxylic acid, etc.) 5-10 Cycloalkane-dicarboxylic acids, etc.), di- or tricycloalkane dicarboxylic acids (e.g., decahydronaphthalene dicarboxylic acid, norbornane dicarboxylic acid, adamantane dicarboxylic acid, tricyclodecane dicarboxylic acid, etc.), cycloolefin dicarboxylic acids (e.g., cyclohexene dicarboxylic acid, etc.), 5-10 Cycloolefin-dicarboxylic acids), tricyclic alkene dicarboxylic acids (such as norbornene dicarboxylic acid, etc.), unsaturated alicyclic dicarboxylic acids (such as tetrahydrophthalic acid, methyltetrahydrophthalic anhydride), etc.

[0075] Examples of the aromatic dicarboxylic acid include monocyclic aromatic dicarboxylic acids [e.g., phthalic acid, terephthalic acid, isophthalic acid, alkylisophthalic acids (e.g., 4-methylisophthalic acid, etc.) 1-4 Alkyl isophthalic acid, etc. 6-10 Aromatic hydrocarbon-dicarboxylic acids, etc.], polycyclic aromatic dicarboxylic acids [for example, condensed polycyclic aromatic dicarboxylic acids [for example, naphthalenedicarboxylic acids (for example, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid having two carboxyl groups on different rings; 1,2-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid having two carboxyl groups on the same ring), anthracene dicarboxylic acid, phenanthrene dicarboxylic acid and other condensed polycyclic C 10-24 Aromatic hydrocarbon-dicarboxylic acid, preferably fused polycyclic C 10-16 Aromatic hydrocarbon-dicarboxylic acid, preferably condensed polycyclic C 10-14 arene-dicarboxylic acids, etc.], aryl arene dicarboxylic acids [for example, biphenyl dicarboxylic acids (for example, 2,2'-biphenyl dicarboxylic acid, 4,4'-biphenyl dicarboxylic acid, etc.) 6-10 Aryl-C 6-10 arene-dicarboxylic acids, etc.], diarylalkane dicarboxylic acids [for example, diphenylalkane dicarboxylic acids (for example, 4,4'-diphenylmethane dicarboxylic acid, etc.) and diC 6-10 Aryl C 1-6 Alkanedicarboxylic acids, etc.], diaryl ketone dicarboxylic acids [for example, diphenyl ketone dicarboxylic acids (for example, 4,4'-diphenyl ketone dicarboxylic acids, etc.) and the like diC 6-10 Aryl ketone-dicarboxylic acid) etc.], dicarboxylic acid having a fluorene skeleton etc.], etc.

[0076] Furthermore, examples of the dicarboxylic acid having a fluorene skeleton include dicarboxyfluorene (e.g., 2,7-dicarboxyfluorene); 9,9-bis(carboxyalkyl)fluorene [e.g., 9,9-bis(2-carboxyethyl)fluorene, 9,9-bis(2-carboxypropyl)fluorene, etc.] 2-6 9-(carboxyl-carboxyalkyl)fluorene [e.g. 9-(1-carboxyl-2-carboxyethyl)fluorene, 9-(2-carboxyl-3-carboxypropyl)fluorene, etc. 9-(carboxyl-carboxy C 2-6 9,9-bis(carboxy aryl)fluorene [for example, 9,9-bis(3-carboxyphenyl)fluorene, 9,9-bis(4-carboxyphenyl)fluorene, 9,9-bis(5-carboxy-1-naphthyl)fluorene, 9,9-bis(6-carboxy-2-naphthyl)fluorene, etc. 9,9-bis(carboxy C 6-129,9-bis(carboxyalkyl-aryl)fluorene [e.g., 9,9-bis(4-(carboxymethyl)phenyl)fluorene, 9,9-bis(4-(2-carboxyethyl)phenyl)fluorene, 9,9-bis(3-(carboxymethyl)phenyl)fluorene, 9,9-bis(5-(carboxymethyl)-1-naphthyl)fluorene, 9,9-bis(6-(carboxymethyl)-2-naphthyl)fluorene, etc. 9,9-bis(carboxyC 1-6 Alkyl-C 6-12 Aryl)fluorene, etc.]

[0077] Among these dicarboxylic acids (DA), from the viewpoint of biodegradability, aliphatic dicarboxylic acids are preferred, succinic acid, adipic acid, and sebacic acid are more preferred, and succinic acid and adipic acid are particularly preferred.

[0078] The structural unit (DA-U) derived from DA in the present embodiment can be introduced using anhydrides of DA, halides of DA, esters of DA (methyl ester, ethyl ester, monoethylene glycol ester, etc.) in addition to dicarboxylic acid (DA).

[0079] <Diol (DO) and structural unit derived from DO (DO-U)>

[0080] The diol (DO) of the present embodiment comprises an aliphatic diol. Of all 100 moles of the structure (DO-U) derived from the diol (DO) contained in the copolyester of the present embodiment, the content of the structure derived from the aliphatic diol is preferably 20 mol% or more, more preferably 40 mol% or more, and further preferably 70 mol% or more. When the content of the structure derived from the aliphatic diol is 70 mol% or more, heat resistance, mechanical properties, optical properties, etc. and biodegradability can be taken into account. When the content of the structure derived from the aliphatic diol is less than 20 mol%, biodegradability is significantly reduced. The diol (DO) of the present embodiment is preferably an aliphatic diol. That is, the structure (DO-U) derived from the diol (DO) of the present embodiment is preferably a structural unit derived from an aliphatic diol.

[0081] The diol (DO) of the present embodiment may include, for example, alicyclic diols, aromatic diols, etc. in addition to aliphatic diols. The structural unit (DA-U) derived from the diol (DO) of the present embodiment may include, for example, alicyclic diols, aromatic diols, etc. in addition to aliphatic diols.

[0082] The diol (DO) according to the present embodiment may be used alone or in combination of two or more.

[0083] Examples of the aliphatic diol include alkane diols (e.g., ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2-methyl-1,3-propylene glycol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, methylpentanediol, dimethylbutanediol, butylethylpropylene glycol, etc.) 2-10 Alkanediols, etc.), polyalkanediols (e.g. diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, etc., di- or tri-C 2-4 Alkanediols, etc.)

[0084] Examples of the alicyclic diol include cycloalkane diol (e.g., cyclohexanediol, etc.) 5-8 Cycloalkanediols), di(hydroxyalkyl)cycloalkanes (e.g., 1,3-bis(2-hydroxypropyl)cyclopentane, 1,3-bis(2-hydroxybutyl)cyclopentane, 1,4-bis(hydroxymethyl)cyclohexane, 1,4-bis(2-hydroxypropyl)cyclohexane, 1,4-bis(2-hydroxybutyl)cyclohexane, etc.) 1-4 Alkyl)C 5-8 Cycloalkanes, etc.), isosorbide, etc.

[0085] Examples of the aromatic diol include dihydroxy aromatic hydrocarbons (e.g., hydroquinone, resorcinol, etc.), di(hydroxyalkyl) aromatic hydrocarbons (e.g., di(hydroxyalkyl) aromatic hydrocarbons such as 1,3-benzenedimethanol, 1,4-benzenedimethanol, 1,4-benzenediethanol, etc.), and di(hydroxyalkyl) aromatic hydrocarbons. 1-4 Alkyl)C 6-10 aromatic hydrocarbons, etc.), bisphenols (e.g. biphenol, bisphenol A, etc., bis(hydroxyphenyl) C 1-10 Alkanes, etc.), alkylene oxide adducts of bisphenols, diols having a fluorene skeleton, 1,4-bis(2-hydroxyethoxy)benzene, etc.

[0086] Among these diols (DO), from the viewpoint of biodegradability, aliphatic diols are preferred, ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, and 1,6-hexanediol are more preferred, and 1,4-butanediol is particularly preferred.

[0087] <Other hydroxycarboxylic acid units>

[0088] The copolyester of the present embodiment may contain, in addition to the structural unit derived from 3HB (3HB-U), the structural unit derived from DA (DA-U), and the structural unit derived from DO (DO-U), a unit (HA-U) derived from a hydroxycarboxylic acid (HA) other than 3-hydroxybutyric acid as another structural unit.

[0089] When the copolyester of the present embodiment contains other structural units in addition to the structural units derived from 3HB (3HB-U), the structural units derived from DA (DA-U), and the structural units derived from DO (DO-U), the molar content of the other structural units is preferably 60 mol% or less, more preferably 40 mol% or less, and further preferably 20 mol% or less, relative to 100 mol of all the structural units of the copolyester of the present embodiment. In addition, the molar content of the other structural units may be 1 mol% or more relative to 100 mol of all the structural units of the copolyester of the present embodiment.

[0090] As other hydroxycarboxylic acid units, for example, hydroxyalkanoic acid, hydroxycycloalkane carboxylic acid (hydroxycyclohexane carboxylic acid, etc.), hydroxybenzoic acid (hydroxyaromatic carboxylic acid, etc.) and other units can be listed. These hydroxycarboxylic acid units can be used alone or in combination of two or more. Among these hydroxycarboxylic acid units, hydroxyalkanoic acid units are preferred from the perspective of excellent biodegradability.

[0091] Examples of the hydroxyalkanoic acid unit include glycolic acid, 2-hydroxypropionic acid (lactic acid), 3-hydroxypropionic acid, 2-hydroxybutyric acid (2-hydroxybutyric acid), 4-hydroxybutyric acid, 3-hydroxy-3-methylbutyric acid, 2-hydroxyvaleric acid (2-hydroxyvaleric acid), 3-hydroxyvaleric acid, 5-hydroxyvaleric acid, 2-hydroxy-2-methylvaleric acid, 3-hydroxyhexanoic acid, 6-hydroxyhexanoic acid, 6-hydroxyheptanoic acid, 3-hydroxyheptanoic acid, 7-hydroxyheptanoic acid, 3-hydroxyoctanoic acid, 8-hydroxyoctanoic acid, 3-hydroxynonanoic acid, 9-hydroxynonanoic acid, 3-hydroxydecanoic acid, 10-hydroxydecanoic acid, and the like. 1-6 Alkyl hydroxyl C 2-15 Alkane acid, 12-hydroxystearic acid, ricinoleic acid and other units.

[0092] It should be noted that the hydroxyalkanoic acid unit may be a corresponding lactone unit. Examples of the lactone unit include β-propiolactone, β-dimethylpropiolactone, γ-butyrolactone, γ-dimethylbutyrolactone, δ-valerolactone, ε-caprolactone, etc., which may have di-C 1-12 Alkyl C 3-15 Lactone units.

[0093] These hydroxyalkanoic acid units and lactone units may be used alone or in combination of two or more. Among these hydroxyalkanoic acid units, hydroxy C 6-hydroxypropionic acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 3-hydroxyhexanoic acid, 3-hydroxyheptanoic acid, 3-hydroxyoctanoic acid, 3-hydroxynonanoic acid, 3-hydroxydecanoic acid, 6-hydroxyhexanoic acid, 10-hydroxydecanoic acid, etc. are preferred from the viewpoint of biodegradability. 3-10 Alkyl acid units (hydroxy C other than 3-hydroxybutyric acid) 3-10 alkanoic acid unit) or the corresponding lactone unit.

[0094] Examples of the method for introducing other hydroxycarboxylic acid units include a method of reacting the polyester (PHB) of 3-hydroxybutyric acid (3HB) in advance, a method of reacting the polyester (PAO) of dicarboxylic acid (DA) and the aforementioned diol (DO) in advance, and a method of adding the polyester (PHB) of 3-hydroxybutyric acid (3HB) during the reaction with the polyester (PAO) of dicarboxylic acid (DA) and the aforementioned diol (DO).

[0095] Examples of the form of the hydroxycarboxylic acid include hydroxycarboxylic acid monomers, hydroxycarboxylic acid lactones, hydroxycarboxylic acid ester-bonded polymers, hydroxycarboxylic acid esters (methyl ester, ethyl ester, monoethylene glycol ester, etc.), hydroxycarboxylic acid halides, and hydroxycarboxylic acid anhydrides.

[0096] <Structure and Properties of Copolyester>

[0097] The copolyester of the present embodiment is a copolyester of 3-hydroxybutyric acid (3HB), dicarboxylic acid (DA) and diol (DO), and is preferably a reaction product of the aforementioned poly(3-hydroxybutyric acid) (PHB) and the aforementioned polyester (PAO) of the aforementioned dicarboxylic acid (DA) and diol (DO).

[0098] In the copolyester of the present embodiment, it is preferred that the content of the structural unit (HB-U) derived from 3-hydroxybutyric acid (3HB) is 2 to 60 mol% relative to 100 mol of all structural units of the copolyester, the average chain length of the 3-hydroxybutyric acid unit in the copolyester is 2 to 80, and the acid value of the copolyester is 5 or less. In addition, it is more preferred that the content of the structural unit (HB-U) derived from 3-hydroxybutyric acid (3HB) is 3 to 50 mol% relative to 100 mol of all structural units of the copolyester, the average chain length of the 3-hydroxybutyric acid unit in the copolyester is 3 to 70, and the acid value of the copolyester is 3 or less. In addition, it is further preferred that the content of the structural unit (HB-U) derived from 3-hydroxybutyric acid (3HB) is 5 to 30 mol% relative to 100 mol of all structural units of the copolyester, the average chain length of the 3-hydroxybutyric acid unit in the copolyester is 6 to 30, and the acid value of the copolyester is 2 or less.

[0099] The acid value (unit: mgKOH / g) of the copolyester of this embodiment is preferably 5 or less, more preferably 3 or less, and further preferably 2 or less. The acid value of the copolyester of this embodiment may be 0.1 or more. When the acid value of the copolyester of this embodiment is 2 or less, hydrolysis and odor can be suppressed.

[0100] The method for evaluating the acid value of the copolyester is described in detail in the examples described later.

[0101] When the number average molecular weight (Mn) of the copolyester of the present embodiment is measured by gel permeation chromatography (GPC), in terms of polystyrene conversion, the lower limit can be 5,000 or more, 6,000 or more, 7,000 or more, 8,000 or more, 10,000 or more, and the upper limit can be 1,000,000 or less, 500,000 or less, 100,000 or less, 50,000 or less, or 30,000 or less. These upper and lower limits can be used in any combination. When the number average molecular weight (Mn) of the copolyester is 1,000,000 or less, molding processing becomes easy. In addition, when the number average molecular weight (Mn) of the copolyester is 5,000 or more, sufficient mechanical properties are displayed.

[0102] The copolyester of the present embodiment can improve biodegradability by having the above structure, so it can highly take into account both biodegradability and mechanical properties. In addition, the copolyester of the present embodiment can appropriately select the above preferred structural range according to the purpose, etc. For example, by adjusting the content of the structural unit derived from 3-hydroxybutyric acid, the biodegradability can be easily adjusted.

[0103] <Poly (3-hydroxybutyric acid) (PHB)>

[0104] The poly(3-hydroxybutyric acid) (PHB) of the present embodiment is preferably a poly(3-hydroxybutyric acid) obtained by esterifying 3-hydroxybutyric acid (3HB) with each other. The poly(3-hydroxybutyric acid) (PHB) of the present embodiment includes a poly(3-hydroxybutyric acid) structure obtained by esterifying 3-hydroxybutyric acid (3HB) with each other.

[0105] The method for producing poly(3-hydroxybutyric acid) is not particularly limited, and examples thereof include the same method as the method for producing polylactic acid described in the following non-patent literature.

[0106] [Non-patent document A] Shinji Yamada, Aknori Takasu, Sadatsugu Takayama, Kazuhiko Kawamura, Microwave-assisted solution polycondensation of L-lactic acid using a Dean-Stark apparatus for a non-thermal microwave polymerization effect induced by the electric field, Polym. Chem., 5 (2014) 5283-5288.

[0107] As a specific example, the following method can be cited: an acid catalyst such as p-toluenesulfonic acid is added to 3-hydroxybutyric acid, and a dehydration esterification reaction is carried out in a solvent such as toluene at a temperature of 80°C to 150°C. After distilling off the solvent such as toluene, a solvent such as dichlorobenzene is added, and an alcohol solvent such as methanol is added to precipitate a solid.

[0108] The reaction may be carried out in the absence of a catalyst or in the presence of a catalyst. Examples of the catalyst used in the reaction include metal catalysts, base catalysts, phosphine catalysts, and acid catalysts.

[0109] Examples of the metal catalyst include alkali metals (sodium, etc.), alkaline earth metals (magnesium, calcium, barium, etc.), transition metals (manganese, zinc, cadmium, lead, cobalt, titanium, etc.), metals of Group 13 of the periodic table (aluminum, etc.), metals of Group 14 of the periodic table (germanium, tin, etc.), metal compounds of Group 15 of the periodic table (antimony, etc.), and the like.

[0110] Examples of the base catalyst include tertiary amines (trialkylamines such as trimethylamine and triethylamine, and quaternary ammonium salts (tetraalkylammonium halides such as tetraethylammonium chloride and tetraethylammonium bromide, and benzyltrialkylammonium halides such as benzyltrimethylammonium chloride, and the like).

[0111] Examples of the phosphine catalyst include trialkylphosphines (trimethylphosphine, triethylphosphine, tri-n-butylphosphine, tri-tert-butylphosphine, tricyclohexylphosphine, etc.), triarylphosphines (triphenylphosphine, tri(o-tolyl)phosphine), and the like.

[0112] Examples of the acid catalyst include inorganic acids (e.g., sulfuric acid, hydrogen chloride (or hydrochloric acid), nitric acid, phosphoric acid, etc.), organic acids (e.g., sulfonic acids (alkanesulfonic acids such as methanesulfonic acid, ethanesulfonic acid, trifluoromethanesulfonic acid, etc., aromatic hydrocarbonsulfonic acids such as p-toluenesulfonic acid, etc.) and the like.

[0113] Examples of the metal compound include organic acid salts (acetates, propionates, etc.), inorganic acid salts (borates, carbonates, etc.), metal oxides (germanium oxide, etc.), metal chlorides (tin chloride, etc.), metal alkoxides (titanium tetraalkoxide, titanium tetra-tert-butoxide, aluminum isopropoxide, zinc tert-butoxide, potassium tert-butoxide, etc.), alkyl metals (trialkylaluminum, etc.), etc. These catalysts may be used alone or in combination of two or more.

[0114] From the viewpoint of improving the activity of the esterification reaction, it is preferred to use an acid catalyst, and from the viewpoint of stability in handling and activity as a catalyst, an aromatic hydrocarbon sulfonic acid such as p-toluenesulfonic acid is preferred.

[0115] The amount of the catalyst used is usually in the range of 0.001 to 5.0% by mass relative to the mass of 3-hydroxybutyric acid (3HB).

[0116] The reaction can be carried out in the presence or absence of a solvent. Examples of the solvent include hydrocarbons (aliphatic hydrocarbons such as hexane, octane, and cyclohexane, aromatic hydrocarbons such as toluene, xylene, trimethylolbenzene, tetralin, chlorobenzene, o-dichlorobenzene, and 1,2,4-trichlorobenzene), halogenated hydrocarbons (dichloromethane, chloroform, carbon tetrachloride, and ethylene dichloride), ethers (dioxane, tetrahydrofuran, and diphenyl ether), ketones (acetone, methyl ethyl ketone, and the like), esters (methyl acetate, ethyl acetate, and butyl acetate), amides (dimethylformamide, diethylformamide, dimethylacetamide, diethylacetamide, and N-methylpyrrolidone), sulfoxides (dimethyl sulfoxide, and the like), and cellosolve acetates (ethyl cellosolve acetate, and the like). 1-4 These solvents may be used alone or in combination of two or more.

[0117] The reaction atmosphere may be air or an inert gas (nitrogen, helium, etc.) atmosphere, and the reaction pressure may be normal pressure or reduced pressure. In addition, the reaction is facilitated by distilling water generated in the esterification reaction out of the reaction system.

[0118] The lower limit of the number average molecular weight (Mn) of poly (3-hydroxybutyric acid) (PHB) may be 1,000 or more, 2,000 or more, 4,000 or more, 8,000 or more, or 10,000 or more, and the upper limit may be 1,000,000 or less, 500,000 or less, 100,000 or less, 50,000 or less, or 10,000 or less. These upper and lower limits may be used in any combination. When the number average molecular weight (Mn) of the copolyester is 1,000,000 or more, the reaction of the aforementioned dicarboxylic acid (DA) with the aforementioned polyester (PAO) of the diol (DO) becomes significantly difficult. In addition, when the number average molecular weight (Mn) of the copolyester is 1,000 or less, it is difficult to control the chain length in the reaction of the aforementioned dicarboxylic acid (DA) with the aforementioned polyester (PAO) of the diol (DO).

[0119] <Polyester (PAO) of dicarboxylic acid (DA) and the above diol (DO)>

[0120] The polyester (PAO) of the present embodiment is a reaction product obtained by subjecting a reaction raw material containing the aforementioned dicarboxylic acid (DA) and the aforementioned diol (DO) to an esterification reaction.

[0121] The amount of the diol (DO) in the polyester (PAO) of the present embodiment relative to 100 mol of the dicarboxylic acid (DA) is preferably 100 to 110 mol, more preferably 100.1 to 105 mol, and further preferably 100.2 to 101 mol. This is because, when the amount of the diol (DO) is 110 mol or more, the molecular weight of the polyester (PAO) becomes low, and heat resistance, mechanical properties, optical properties, etc. are no longer exhibited. This is because, when the amount of the diol (DO) is less than 100 mol, the acid value tends to become high when used as a raw material for the copolyester of the present embodiment due to the excessive presence of carboxyl groups relative to hydroxyl groups.

[0122] The method for producing the polyester (PAO) of the dicarboxylic acid (DA) and the diol (DO) is not particularly limited, and examples thereof include the method described in the following non-patent literature. [Non-patent literature B] Shuangbao Peng, Zhiyang Bu, Linbo Wu, Bo-Geng Li, Philippe Dubois, High molecular weight poly (butylenesuccinate-co-furandicarboxylate) with 10 mol% of BF unit: Synthesis, crystallization-melting behavior and mechanical properties, European Polymer Journal 96 (2017) 248-255.

[0123] For example, when the dicarboxylic acid (DA) is an aliphatic dicarboxylic acid such as succinic acid, and the aforementioned diol (DO) is an aliphatic diol such as 1,4-butanediol, examples of methods for producing these polyesters include a method in which a mixture containing 1,4-butanediol and succinic acid is reacted at a temperature of 100° C. to 250° C., a catalyst such as tetraisopropoxytitanium is added, and the mixture is further reacted at 100° C. to 250° C. to produce the polyester.

[0124] The reaction can be carried out in the absence of a catalyst or in the presence of a catalyst. As the catalyst used in the reaction, for example, an acid catalyst can be cited. As the acid catalyst, for example, tin catalysts such as monobutyltin oxide and dibutyltin oxide, titanium catalysts such as tetraisopropoxytitanium and acetylacetonate, zirconium oxide catalysts such as tetrabutylzirconate, etc. can be cited. From the perspective of being able to improve the activity of transesterification and esterification, it is preferred to use a titanium catalyst. As a titanium catalyst, tetramethylol titanium, tetraethoxytitanium, tetraisopropoxytitanium, tetra-n-propoxytitanium, tetra-n-butoxytitanium, tetra(2-ethylhexyloxy)titanium, tetrastearyloxytitanium, etc. can be cited. From the perspective of stability in handling and activity as a catalyst, tetraisopropoxytitanium is preferred.

[0125] The amount of the catalyst used is usually in the range of 0.001 to 5.0% by mass based on the total mass of the dicarboxylic acid (DA) and the diol (DO).

[0126] The reaction atmosphere may be air or an inert gas (nitrogen, helium, etc.) atmosphere, and the reaction pressure may be normal pressure or reduced pressure. In addition, the reaction is facilitated by distilling water, diol (DO), etc. generated in the esterification reaction out of the reaction system.

[0127] The reaction time is usually 1 to 48 hours, and the reaction is preferably carried out until the dicarboxylic acid (DA) and diol (DO) as raw materials no longer remain in the reaction system. The reaction can be carried out by tracking the decrease of dicarboxylic acid (DA) by acid value measurement, for example.

[0128] The acid value (unit: mgKOH / g) of the polyester (PAO) of the dicarboxylic acid (DA) and the diol (DO) of the present embodiment is preferably 5 or less, more preferably 3 or less, and further preferably 2 or less. This is because when the acid value of the polyester (PAO) exceeds 5, the acid value of the copolyester of the present embodiment tends to become high. In addition, when the acid value of the polyester (PAO) is 5 or less, the acid value of the copolyester of the present embodiment can be reduced, and hydrolysis and odor can be suppressed.

[0129] (Method for producing copolyester)

[0130] The method for producing the copolyester of the present embodiment (sometimes simply referred to as the production method of the present embodiment) is a method for producing the copolyester of the present embodiment described above.

[0131] The production method of the present embodiment includes a step of reacting poly(3-hydroxybutyric acid) (PHB) with a polyester (PAO) of the above-mentioned dicarboxylic acid (DA) and the above-mentioned diol (DO).

[0132] The production method of the present embodiment preferably includes the following first to third steps.

[0133] The first step is a step of reacting the aforementioned 3-hydroxybutyric acids with each other to obtain the aforementioned poly(3-hydroxybutyric acid) (PHB);

[0134] The second step is a step of obtaining a polyester (PAO) of the dicarboxylic acid (DA) and the diol (DO) by reacting the dicarboxylic acid (DA) and the diol (DO);

[0135] The third step is a step of reacting the poly(3-hydroxybutyric acid) (PHB) obtained in the above step 1 with the polyester (PAO) obtained in the above step 2.

[0136] As a production method of the present embodiment, for example, there can be mentioned a method of obtaining the copolyester of the present embodiment by subjecting a mixed solution containing poly(3-hydroxybutyric acid) (PHB), the aforementioned dicarboxylic acid (DA) and the aforementioned diol (DO) to an ester exchange reaction. As the ester exchange reaction, there can be mentioned a method described in Non-Patent Document 1, etc.

[0137] For example, when the dicarboxylic acid (DA) is an aliphatic dicarboxylic acid such as succinic acid and the diol (DO) is an aliphatic diol such as 1,4-butanediol, as a method for producing the copolyester of the present embodiment, for example, there can be cited a method of obtaining the copolyester of the present embodiment by subjecting a mixed solution containing poly(3-hydroxybutyric acid) (PHB), an aliphatic dicarboxylic acid such as succinic acid and a polyester (PAO) such as an aliphatic diol such as 1,4-butanediol to an ester exchange reaction. The temperature of the ester exchange reaction is preferably 100 to 250° C., for example.

[0138] In the production method of the present embodiment, when poly(3-hydroxybutyric acid) (PHB) is used for the transesterification reaction with the polyester (PAO) of the aforementioned dicarboxylic acid (DA) and the aforementioned diol (DO), the input molar ratio of the polyester (PHB) to the polyester (PAO) is not particularly limited as long as the content of the structural unit (3HB-U) of 3-hydroxybutyric acid (3HB) in the copolyester of the present embodiment produced, the average chain length of the structural unit of 3-hydroxybutyric acid (3HB), and the acid value of the copolyester of the present embodiment are within the aforementioned ranges. For example, the input molar ratio of the polyester (PHB) to the polyester (PAO) is usually 1 to 65 mol%, preferably 2 to 60 mol%, more preferably 3 to 50 mol%, and further preferably 5 to 30 mol%. When the input molar ratio of the poly(3-hydroxybutyric acid) (PHB) to the polyester (PAO) exceeds 65 mol%, the poly(3-hydroxybutyric acid) (PHB) is easily decomposed, and the acid value of the copolyester of the present embodiment becomes high. When the charging molar ratio of polyester (PHB) to polyester (PAO) is less than 1 mol%, the average chain length of the structural unit of 3-hydroxybutyric acid (3HB) becomes extremely short.

[0139] As the catalyst used in the transesterification reaction, a titanium catalyst is preferably used. Examples of the titanium catalyst include tetramethoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium, tetra-n-propoxytitanium, tetra-n-butoxytitanium, tetra(2-ethylhexyloxy)titanium, and tetrastearyloxytitanium. From the viewpoint of stability in handling and activity as a catalyst, tetraisopropoxytitanium is preferred.

[0140] The amount of the catalyst used is usually in the range of 0.001 to 5.0% by mass relative to the total mass of the polyester (PAO) of poly(3-hydroxybutyric acid) (PHB), the dicarboxylic acid (DA) and the diol (DO).

[0141] The reaction atmosphere may be air or an inert gas (nitrogen, helium, etc.) atmosphere, and the reaction pressure may be normal pressure or reduced pressure.

[0142] The reaction is carried out until the average chain length of the structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB) becomes 2 to 80. The reaction temperature is usually 80°C to 250°C, preferably 100°C to 200°C, more preferably 110°C to 160°C, and further preferably 125°C to 150°C. The reaction time is usually 1 minute to 48 hours, preferably 5 minutes to 24 hours, more preferably 10 minutes to 12 hours, and further preferably 15 minutes to 8 hours.

[0143] In the manufacturing method of the present embodiment, the transesterification reaction and the esterification reaction can be carried out simultaneously. By carrying out the transesterification reaction and the esterification reaction simultaneously, the terminal carboxyl group of poly (3-hydroxybutyric acid) (PHB) or the terminal carboxyl group of polyester (PAO) and the terminal hydroxyl group of poly (3-hydroxybutyric acid) (PHB) or the terminal hydroxyl group of polyester (PAO) can be esterified, so that the two terminal groups in the structural formula of the copolyester of the present embodiment can be hydroxyl groups. Since the carboxyl group is reduced, the acid value of the copolyester of the present embodiment can be reduced.

[0144] (Polyurethane)

[0145] Examples of applications of the copolyester of the present embodiment include polyurethanes derived from the copolyester of the present embodiment (sometimes referred to as “polyurethanes of the present embodiment”) obtained by using the copolyester of the present embodiment.

[0146] The polyurethane of the present embodiment is obtained, for example, by reacting the copolyester of the present embodiment with polyisocyanate. As required, polyols other than the copolyester of the present embodiment, chain extenders, chain terminators, and crosslinking agents may also be used in combination. The copolyester of the present embodiment used to obtain the polyurethane is preferably polyester polyol.

[0147] Specifically, the polyurethane of the present embodiment is obtained by reacting a polyol with a polyisocyanate, and as the polyol, at least the copolyester of the present embodiment is used. Therefore, the polyurethane is a reaction product obtained by the reaction of a polyol with a polyisocyanate, and the polyurethane has a structural unit derived from a polyol and a structural unit derived from a polyisocyanate, and at least has a structural unit derived from the copolyester of the present embodiment.

[0148] The copolyester of the present embodiment is preferably polyester polyol.

[0149] As the chain extender, for example, aliphatic polyol compounds such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, hexamethylene glycol, sucrose, methylene glycol, glycerol, sorbitol, and neopentyl glycol; aromatic polyols such as bisphenol A, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, and hydroquinone can be used. Compounds; water; amine compounds such as ethylenediamine, 1,2-propylenediamine, 1,6-hexamethylenediamine, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, 3,3'-dimethyl-4,4'-dicyclohexylmethanediamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, aminoethylethanolamine, hydrazine, diethylenetriamine, and triethylenetetramine. These chain extenders may be used alone or in combination of two or more. Among them, aliphatic polyol compounds are preferred, and neopentyl glycol is more preferred.

[0150] The content of the copolyester of the present embodiment in 100% by mass of all the polyols used for the polyurethane synthesis is preferably 10 to 100% by mass, and more preferably 50 to 100% by mass.

[0151] As polyisocyanates, for example, 1,3- and 1,4-phenylene diisocyanate, 1-methyl-2,4-phenylene diisocyanate, 1-methyl-2,6-phenylene diisocyanate, 1-methyl-2,5-phenylene diisocyanate, 1-methyl-2,6-phenylene diisocyanate, 1-methyl-3,5-phenylene diisocyanate, 1-ethyl-2,4-phenylene diisocyanate, 1-isopropyl-2,4-phenylene diisocyanate, 1,3-dimethyl-2,4-phenylene diisocyanate, 1,3-diisocyanate, Methyl-4,6-phenylene diisocyanate, 1,4-dimethyl-2,5-phenylene diisocyanate, diethylphenylene diisocyanate, diisopropylphenylene diisocyanate, 1-methyl-3,5-diethylphenylene diisocyanate, 3-methyl-1,5-diethylbenzene-2,4-diisocyanate, 1,3,5-triethylbenzene-2,4-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, 1-methyl-naphthalene-1,5-diisocyanate, naphthalene-2,6-diisocyanate, naphthalene-2,7-diisocyanate, Aromatic polyisocyanates such as 1,1-dinaphthyl-2,2'-diisocyanate, biphenyl-2,4'-diisocyanate, biphenyl-4,4'-diisocyanate, 3-3'-dimethylbiphenyl-4,4'-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, diphenylmethane-2,4-diisocyanate, and toluene diisocyanate; aliphatic polyisocyanates such as tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, and trimethylhexamethylene diisocyanate Cyanate; 1,3-cyclopentylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, lysine diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate, 2,2'-dicyclohexylmethane diisocyanate, 3,3'-dimethyl-4,4'-dicyclohexylmethane diisocyanate and other alicyclic polyisocyanates. They can be used alone or in combination of two or more. Among them, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate and toluene diisocyanate are more preferred.

[0152] In order to control the molecular weight of the obtained polyurethane, a chain terminator having one active hydrogen group may be used as required. Examples of these chain terminators include aliphatic monohydroxy compounds such as methanol, ethanol, propanol, butanol and hexanol having a hydroxyl group, and aliphatic monoamines such as morpholine, diethylamine, dibutylamine, monoethanolamine and diethanolamine having an amino group. These may be used alone or in combination of two or more.

[0153] In order to improve the heat resistance and strength of the obtained polyurethane, a cross-linking agent having three or more active hydrogen groups or isocyanate groups may be used as necessary.

[0154] The polyurethane of the present embodiment can be obtained by a known method for producing polyurethane. Specifically, for example, a method for producing by adding a polyol, a polyisocyanate and the aforementioned chain extender and reacting them can be cited. These reactions are preferably carried out at a temperature of 50° C. to 100° C. for 3 hours to 10 hours. In addition, the reaction can also be carried out in an organic solvent.

[0155] As the organic solvent, for example, ketone solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, methyl ethyl ketone, methyl n-propyl ketone, acetone, and methyl isobutyl ketone; ester solvents such as methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, isopropyl acetate, isobutyl acetate, isobutyl acetate, and sec-butyl acetate can be used. These organic solvents can be used alone or in combination of two or more.

[0156] The content of the structural unit derived from the copolyester of the present embodiment in 100% by mass of the polyurethane of the present embodiment is preferably 10% by mass to 98% by mass, and more preferably 20% by mass to 98% by mass.

[0157] Thereby, there is a tendency to obtain the effect more appropriately.

[0158] In this specification, the content of each structural unit in the polyurethane is measured by NMR.

[0159] The lower limit of the number average molecular weight (Mn) of the polyurethane of the present embodiment may be 5,000 or more, 6,000 or more, 7,000 or more, 8,000 or more, or 10,000 or more, and the upper limit may be 1,000,000 or less, 500,000 or less, 100,000 or less, 500,000 or less, or 15,000 or less. These upper and lower limits may be used in any combination.

[0160] The number average molecular weight (Mn) of the polyurethane may be 5,000 to 1,000,000, 6,000 to 500,000, 7,000 to 100,000, 8,000 to 500,000, or 10,000 to 15,000.

[0161] If it is within the above range, there is a tendency that the effect can be obtained more appropriately. In addition, in this specification, the number average molecular weight (Mn) of polyurethane is a value measured by GPC.

[0162] (Resin composition)

[0163] Examples of the resin composition of the present embodiment include a thermoplastic resin composition or a thermosetting resin composition containing the copolyester or polyurethane of the present embodiment.

[0164] <Thermoplastic resin composition>

[0165] When the resin composition of the present embodiment is a thermoplastic resin composition, for example, other resins, a crystal nucleating agent, a heat stabilizer, an anti-hydrolysis agent, other additives, etc. may be further included as necessary.

[0166] [Crystallization nucleating agent]

[0167] The crystal nucleating agent used for the thermoplastic resin composition of the present embodiment may be any crystal nucleating agent as long as it can be used for thermoplastic resins derived from biomass resources, such as polylactic acid or polybutylene succinate. For example, it is preferred to use a talc-based nucleating agent, a nucleating agent formed by a metal salt-based material having a phenyl group, a nucleating agent formed by a benzoyl compound-based nucleating agent, etc. Other well-known crystal nucleating agents, such as lactate, benzoate, silica, phosphate salt-based nucleating agents, etc., may also be used.

[0168] [Heat stabilizer and anti-hydrolysis agent]

[0169] The thermoplastic polyester composition of the present embodiment preferably contains a phenolic antioxidant and a phosphite antioxidant as a heat stabilizer for the resin composition, and preferably contains a carbodiimide compound-based anti-hydrolysis agent, such as a polycarbodiimide resin (trade name: CARBODILITE, manufactured by Nisshinbo Chemical Co., Ltd.) as an anti-hydrolysis agent. The added heat stabilizer and anti-hydrolysis agent may be one selected from the above three additives, but the above two heat stabilizers and anti-hydrolysis agents have different functions, and it is preferred that each additive be added together. The amount of the heat stabilizer and anti-hydrolysis agent added varies depending on the type, and is generally preferably about 0.1 to 5 parts by mass relative to 100 parts by mass of the thermoplastic polyester composition.

[0170] [Other additives]

[0171] It is preferred that the thermoplastic resin composition of the present embodiment further contains silicone-based flame retardants, organic metal salt-based flame retardants, organic phosphorus-based flame retardants, metal oxide-based flame retardants, metal hydroxide-based flame retardants, etc. This improves the flame retardancy and can suppress the spread of fire, and the fluidity of the biodegradable resin composition is improved, so that more excellent moldability can be ensured.

[0172] Fillers can be added to the thermoplastic resin composition of the present embodiment. As fillers, talc, mica, montmorillonite, kaolin, etc. can be cited. By making these fillers into crystal nuclei, the crystallization of the copolyester is promoted, and the impact strength and heat resistance of the molded body are improved. In addition, the rigidity of the molded body can also be increased.

[0173] In the thermoplastic resin composition of the present embodiment, antioxidants, anti-blocking agents, colorants, flame retardants, mold release agents, anti-fogging agents, surface wetting improvers, incineration aids, lubricants, dispersing aids, various surfactants, plasticizers, expanders, weathering improvers, ultraviolet light absorbers, processing aids, antistatic agents, colorants, lubricants, various additives such as mold release agents can also be appropriately mixed. As plasticizer, the known ones usually used as plasticizers for polymers can be used without particular restrictions, for example, polyester plasticizers, glycerol plasticizers, polycarboxylic acid ester plasticizers, polyalkylene glycol plasticizers and epoxy plasticizers can be cited. Expanders are not particularly limited as long as they are materials that function as expanders for copolymers A and copolymers B. As expanders, inorganic fillers, glycidyl compounds, polymer compounds grafted or copolymerized with anhydrides and organometallic compounds can be cited, and one or more of them can be used. By kneading these, heat resistance, flexural strength, impact strength, flame retardancy, etc. are also improved, and thus the application in molded bodies such as housings for electronic devices represented by notebook computers, mobile phones, etc. is further promoted.

[0174] In addition, various fillers known in the past can also be mixed as fillers. As functional additives, fertilizers, soil conditioners, plant active agents, etc. can also be added. The fillers are roughly divided into inorganic fillers and organic fillers. They can be used as one or a mixture of two or more.

[0175] Examples of the inorganic filler include anhydrous silica, mica, talc, titanium oxide, calcium carbonate, diatomaceous earth, allophane, bentonite, potassium titanate, zeolite, sepiolite, montmorillonite, kaolin, kaolinite, glass, limestone, carbon, wollastonite, calcined pearlite, silicates such as calcium silicate and sodium silicate, hydroxides such as aluminum oxide, magnesium carbonate and calcium hydroxide, iron carbonate, zinc oxide, iron oxide, aluminum phosphate, salts such as barium sulfate, etc. The content of the inorganic filler is usually 1 to 80% by weight, preferably 3 to 70% by weight, and more preferably 5 to 60% by weight in the total composition.

[0176] Examples of organic fillers include raw starch, processed starch, pulp, chitin / chitosan, coconut shell powder, wood powder, bamboo powder, bark powder, kenaf or straw powder, etc. These can be used alone or as a mixture of two or more. The amount of organic filler added is usually 0.01 to 70% by weight in the total composition.

[0177] The preparation of the composition can all apply the known mixing / mixing technology in the past. As a mixer, a mixer such as a horizontal cylindrical type, a V-shaped, a double cone type mixer, a ribbon mixer, a super mixer and various continuous mixers etc. can be used. In addition, as a mixer, an intermittent mixer such as a roller, a Banbury mixer, a one-stage type, a two-stage type continuous mixer, a twin screw extruder, a single screw extruder etc. can be used. As a method for mixing, the method of adding various additives, fillers, thermoplastic resins to be blended when heated and melted can be enumerated. In addition, in order to make the aforementioned various additives uniformly dispersed, mixing oil etc. can also be used.

[0178] <Thermosetting resin composition>

[0179] When the resin composition of the present embodiment is a thermosetting resin composition, for example, it contains other resins, the copolyester of the present embodiment having reactive groups such as hydroxyl groups and carboxyl groups as a thermosetting resin main agent, and also contains curing agents such as isocyanate curing agents and polyamine curing agents that can thermally react with the aforementioned reactive groups.

[0180] Examples of the curing agent of the present embodiment include polyisocyanates having an aromatic structure in their molecular structures, such as toluene diisocyanate, diphenylmethane diisocyanate, polymerized diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, and xylylene diisocyanate, and compounds obtained by modifying a portion of the isocyanate groups of these polyisocyanates with carbodiimide; allophanate compounds derived from these polyisocyanates; polyisocyanates having an alicyclic structure in their molecular structures, such as isophorone diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,3-(isocyanatomethyl)cyclohexane; 1,6-hexamethylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and the like. esters and their allophanate compounds; isocyanurate forms of these polyisocyanates; allophanate forms derived from these polyisocyanates; biuret forms derived from these polyisocyanates; trimethylolpropane-modified adducts; polyisocyanates such as reaction products of the aforementioned various polyisocyanates and polyol components; ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexyleneheptamine, heptaethyleneoctamine, octaethylenenonamine, nonaethylenedecaamine, piperazine or polyethylene polyamines such as N-aminoalkylpiperazine having an alkyl chain of 2 to 6 carbon atoms, and amine compounds such as 3-aminomethyl-3,5,5-trimethylcyclohexylamine (isophoronediamine or IPDA).

[0181] <Cured product of resin composition>

[0182] The cured product of the resin composition of the present embodiment is a cured product of the resin composition which is the aforementioned thermoplastic resin composition or a cured product of the polyester composition which is the aforementioned thermosetting resin composition.

[0183] The copolyester of this embodiment can be used for various purposes. Specifically, it can be used for a wide range of purposes such as artificial leather, synthetic leather, shoes, thermoplastic resins, foamed resins, thermosetting resins, coatings, laminating adhesives, elastic fibers, urethane raw materials, automobile parts, sporting goods, etc. Since the copolyester of this embodiment with excellent biodegradability is used, the products of the above-mentioned purposes have excellent biodegradability.

[0184] The polyurethane of this embodiment can be used for various purposes. Specifically, it can be used for a wide range of purposes such as artificial leather, synthetic leather, shoes, thermoplastic resins, foamed resins, thermosetting resins, coatings, laminating adhesives, vibration-proof materials, vibration-damping materials, automobile parts, sporting goods, fiber treatment agents, adhesives, etc. Since the copolyester of this embodiment with excellent biodegradability is used, the products of the above-mentioned purposes have excellent biodegradability.

[0185] The resin composition of the present embodiment can be used for various purposes. Specifically, it can be used for a wide range of purposes such as artificial leather, synthetic leather, shoes, thermoplastic resins, foamed resins, thermosetting resins, coatings, laminating adhesives, vibration-proof materials, vibration-damping materials, automobile parts, sporting goods, fiber treatment agents, adhesives, etc. Since the copolyester of the present embodiment having excellent biodegradability is used, the products of the above-mentioned purposes have excellent biodegradability.

[0186] (Coating agent)

[0187] The coating agent contains the copolyester of the present embodiment and further contains other components such as other resins, water, and an organic solvent as necessary.

[0188] The coating agent can be applied to various substrates. An example of the use of the coating agent is described below.

[0189] The coating agent is used, for example, as a surface coating of a substrate of a food packaging container. As the substrate, for example, plastic films such as styrene resin films, polyolefin resin films, polyester resin films, nylon resin films, or laminates thereof can be cited. As the substrate, for example, paper, metallized films, aluminum foil, etc. can be cited. The coating agent is suitable for biodegradable substrates. For example, biodegradable substrates can include paper, polyester films, polyolefin films, starch films, etc.

[0190] The coating agent can be used as ink, adhesive, or the like.

[0191] (Ink)

[0192] The ink contains the copolyester of the present embodiment and a colorant, and further contains other components such as a pigment dispersant, water, and an organic solvent as necessary.

[0193] The ink is, for example, printing ink.

[0194] The ink may be, for example, a water-based ink or an ink not containing water (solvent-based ink).

[0195] (Adhesive)

[0196] The adhesive contains the copolyester of the present embodiment and further contains other components such as other resins, a curing agent, and an organic solvent as necessary.

[0197] The adhesive can also be used as an adhesive composition for lamination, which is used when laminating on the above-mentioned various substrates to produce a composite film mainly used as a packaging material for food, medicines, detergents, etc.

[0198] Such adhesives may be, for example, two-component curing adhesives containing the copolyester, polyester polyol and polyisocyanate of the present embodiment, or one-component adhesives formed of acrylic resins, urethane resins, and ethylene-vinyl acetate copolymers. These adhesives may be solvent-based, solvent-free, water-based, or alcohol-based adhesives as required.

[0199] (piece)

[0200] The sheet is formed using the resin composition of the present embodiment. The resin composition may contain other resins and various additives in addition to the copolyester of the present embodiment. Various additives include plasticizers, antistatic agents, antioxidants, ultraviolet absorbers, lubricants, antiblocking agents, and thermal stabilizers.

[0201] Examples of the sheet include a non-stretched sheet, a biaxially stretched sheet, and a foamed sheet.

[0202] The application of the sheet is not particularly limited, and the sheet can be widely used in, for example, food packaging containers, building materials, home appliances, sundries, and the like.

[0203] (film)

[0204] The film is formed using the resin composition of the present embodiment. The resin composition may contain other resins and various additives in addition to the copolyester of the present embodiment. Various additives include plasticizers, antistatic agents, antioxidants, ultraviolet absorbers, lubricants, antiblocking agents, and thermal stabilizers.

[0205] As the film, for example, an unstretched film, a biaxially stretched film, a uniaxially stretched film, etc. can be listed, for example, it can be produced by melting the pellets of the film raw material with an extruder, and then forming a film using a T-die or an inflation method. In the case of the T-die method, the longitudinal stretching can be performed using the speed difference of the rollers, and the transverse stretching can be performed using a tenter, thereby obtaining a biaxially stretched film.

[0206] (Laminated body)

[0207] The laminate has at least one selected from the sheet and film of the present embodiment, and further has other components such as a printed layer and a resin film as necessary.

[0208] The laminate can be obtained, for example, by laminating a film or sheet on one or both sides of at least one of the sheets and films selected from the present embodiment to impart mechanical strength, chemical resistance, etc. Specifically, a polystyrene-based inflation film can be thermally laminated on at least one side of the surface side and the back side of the sheet or film, or an olefin-based film (CPP) can be laminated using an adhesive.

[0209] The adhesive to be used is not particularly limited, and may be, for example, the adhesive of the present embodiment or a known adhesive.

[0210] (formed body)

[0211] The molded product is obtained by molding at least one selected from the sheet, film, and laminate of the present embodiment.

[0212] The formed body is obtained, for example, by thermoforming the sheet, film, or laminate of the present embodiment. Examples of thermoforming methods include hot plate contact thermoforming, vacuum forming, vacuum pressure forming, and plug assisted forming. Indirect thermoforming using an infrared heater as a heat source is particularly preferred.

[0213] [Example]

[0214] Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

[0215] <Determination of number average molecular weight (Mn) and weight average molecular weight (Mw)>

[0216] In Examples and Comparative Examples, the molecular weight of the resin is a value measured under the following conditions using gel permeation chromatography (GPC).

[0217] Measurement device: System controller Waters 600Controller

[0218] Liquid delivery pump Waters Model Code 60F

[0219] RI (differential refractometer) detector Waters 2414

[0220] Waters 717plus Autosampler

[0221] Data processing: Waters Empower3

[0222] Determination conditions: column temperature 40°C

[0223] Eluent: chloroform (CHCl 3 )

[0224] Flow rate 1.0ml / min

[0225] Standard: Polystyrene

[0226] Column: Shodex GPC LF-G 1 piece

[0227] Shodex GPC LF-804 4pcs

[0228] Sample: A chloroform solution having a resin solid content of 0.4% by mass was filtered through a microfilter (100 μl)

[0229] < 1 Determination of H-NMR spectrum>

[0230] Measuring device: JEOL RESONANCE "JNM-ECM400S"

[0231] Magnetic field strength: 400MHz

[0232] Solvent: deuterated chloroform

[0233] Sample concentration: 100mg / 1.0mL

[0234] < 13 C-NMR spectrum>

[0235] Measuring device: JEOL RESONANCE "JNM-ECM400S"

[0236] Magnetic field strength: 100MHz

[0237] Solvent: deuterated chloroform

[0238] Sample concentration: 100mg / 1.0mL

[0239] <Calculation of 3-hydroxybutyric acid content>

[0240] Determined by the above method 1H-NMR spectrum. Figure 1 The copolyester of Example 1 1 H-NMR spectrum.

[0241] for 1 The 3HB content was calculated based on the peaks on the H-NMR spectrum based on the following formula.

[0242] 3HB content = (integrated value of 5.2 ppm) / {(integrated value of 4.1 ppm - integrated value of 3.6 ppm) / 4 + integrated value of 5.2 ppm + integrated value of 2.6 ppm / 4}

[0243] <Evaluation of average chain length>

[0244] Determined by the above method 13 C-NMR spectroscopy. Figure 2 The copolyester of Example 1 13 C-NMR spectroscopy.

[0245] [Peak Ownership]

[0246] Refer to non-patent document 1, 13 Assignment of triad (combination of three monomer chains) peaks in C-NMR spectrum.

[0247] [Calculation of average chain length]

[0248] The average chain length was calculated based on the formula shown below.

[0249]

[0250] In formulas (4) to (5), S, B, H, and L are BS , L 3HB ,I X-Y-Z , χ represent the following contents respectively.

[0251] S: Structural unit derived from succinic acid

[0252] B: Structural unit derived from 1,4-butanediol

[0253] H: Structural unit derived from 3-hydroxybutyric acid

[0254] I X-Y-Z : Peak integration value derived from the triad of structural units X, Y and Z (where X, Y and Z are any of S, B and H)

[0255] L BS : Average chain length of a diad (combination of dimonomer chains) of a structural unit derived from 1,4-butanediol and a structural unit derived from succinic acid

[0256] L3HB : Average chain length of structural units derived from 3-hydroxybutyric acid

[0257] χ: An index indicating the randomness of the copolyester, with a value of 0 to 2

[0258] <Biodegradability Evaluation Method>

[0259] The biodegradability evaluation method was evaluated by referring to the method described in "2.3. Biodegradation with seawater by BOD method" of the following non-patent document A. The evaluation method of non-patent document A is obtained by replacing the plant source of JIS K6950 with seawater from activated sludge.

[0260] Non-patent document C: Atsuyoshi Nakayama*, Naoko Yamano, Norioki Kawasaki, Biodegradation in seawater of aliphatic polyesters, Polymer Degradation and Stability 166 (2019) 290-299.

[0261] [Plant source]

[0262] The seawater collected from Nanko, Osaka Prefecture (latitude: 34.634905, longitude: 135.418919) was used as the source of the collected plants.

[0263] [Test conditions]

[0264] Biodegradation Degree Measurement Method: Soda lime (carbon dioxide absorbent) and a pressure sensor (manufactured by WTW, OxiTop-IDS (registered trademark)) were installed in a test bottle, and BOD (biochemical oxygen demand) was measured under the following conditions to calculate the biodegradation degree.

[0265] Culture temperature: 27°C, dark

[0266] Cultivation period: 28 days

[0267] [Calculation of biodegradability]

[0268] The biodegradability of the test material was calculated based on the following formula.

[0269] Biodegradability (%) = (BOD 0 -BOD B ) / ThOD×100

[0270] BOD 0 : Biochemical oxygen demand of test material (measured value: mg)

[0271] BOD B : Average biochemical oxygen demand of blank test (measured value: mg)

[0272] ThOD: Theoretical oxygen demand required for complete oxidation of the test material (calculated value: mg)

[0273] <Determination of Acid Value>

[0274] The measurement was carried out according to the method described in JIS K 0070: 1992. Specifically, about 1 g of the sample was weighed in a conical flask, 20 mL of chloroform was added to dissolve it, and phenolphthalein test solution was added as an indicator. Then, 0.1 N alcoholic potassium hydroxide solution was used to titrate the solution until it turned light red, and the acid value was calculated by the following formula.

[0275] Acid value (mgKOH / g) = (5.611×a×F) / S

[0276] S: Sample collection amount (g)

[0277] a: Consumption of 0.1N alcoholic potassium hydroxide solution (mL)

[0278] F: Factor of 0.1N alcoholic potassium hydroxide solution

[0279] <Evaluation of stability against hydrolysis>

[0280] 1 g of the test material was placed in a glass bottle, 2% by mass of water was added, the bottle was tightly covered, and then left to stand for 1 week in a thermostatic chamber set at 50° C. The weight average molecular weight (Mw) of the test material before and after heating was measured by GPC, and the molecular weight retention (%) was calculated using the following formula.

[0281] Molecular weight retention rate = {(Mw before heating) - (Mw after heating)} / (Mw before heating) × 100

[0282] The stability against hydrolysis was evaluated based on the molecular weight retention rate. The evaluation criteria are as follows.

[0283] Evaluation criteria: 0: Molecular weight retention rate is 80-100%

[0284] ×: Molecular weight retention rate is less than 80%

[0285] <Evaluation of odor>

[0286] The test materials were placed in glass bottles and the odor was sensory evaluated. The evaluation criteria were as follows.

[0287] Evaluation criteria:

[0288] None: Odorless

[0289] Yes: There is a bad smell

[0290] (Synthesis example 1)

[0291] "Synthesis of poly(3-hydroxybutyric acid)"

[0292] In a 100 mL three-necked flask equipped with a nitrogen inlet tube, a thermometer, a stirrer, and a dean-stark trap, 21.3 g (0.205 mol) of 3HB, 0.380 g (0.00200 mol) of p-toluenesulfonic acid monohydrate, and 40 mL of toluene were added, and heated at an internal temperature of 95°C for 19 hours. Toluene was distilled off, and 60 mL of o-dichlorobenzene was added. The reflux state was adjusted by reducing pressure, and then heated to reflux at 95°C for 18 hours. The reaction solution was cooled to room temperature, 100 mL of methanol was added to precipitate a solid, and filtered to obtain 12.7 g of poly (3-hydroxybutyric acid).

[0293] The average molecular weight was measured using the above-described method for measuring the average molecular weight. The number average molecular weight Mn was 3,400, and the weight average molecular weight Mw was 7,300.

[0294] Use the above record 1 H-NMR measurement method, determination 1 H-NMR spectrum. The results are as follows.

[0295] 1 H-NMRδ(CDCl 3 ): 1.25 (m, 3H), 2.55 (m, 2H), 4.15 (m, tr), 5.23 (m, 1H), 5.75 (d, trace), 6.95 (m, trace)

[0296] (Synthesis example 2)

[0297] "Synthesis of polyester of succinic acid and 1,4-butanediol (poly(butylene succinate): PBS)"

[0298] 478 g (5.30 mol) of 1,4-butanediol and 559 g (4.73 mol) of succinic acid (1,4-butanediol to 100 mol of succinic acid = 112 mol) were added to a removable flask equipped with a nitrogen inlet tube, a thermometer, a cooling tube, and a mechanical stirrer, and the temperature was raised to 160°C in 1 hour. The temperature was further raised to 200°C in 1 hour. After the distillation of water stabilized, the cooling tube was removed, and 0.01% by mass of tetraisopropoxytitanium was added, and then maintained at 200°C. When the acid value reached less than 1, the mixture was cooled and taken out to obtain PBS. The molar ratio of the structure derived from 1,4-butanediol to 100 mol of the structure derived from succinic acid in PBS was 101.7 mol.

[0299] The average molecular weight was measured using the above-described method for measuring the average molecular weight. The number average molecular weight Mn was 10,200, and the weight average molecular weight Mw was 38,000.

[0300] The acid value was measured using the above-described method for measuring the acid value and found to be 0.44 mg-KOH / g.

[0301] Use the above record 1 H-NMR measurement method, determination 1 H-NMR spectrum. The results are as follows.

[0302] 1 H-NMRδ(CDCl 3 ): 1.70 (t, 2H), 2.62 (s, 4H), 3.23 (m, tr, terminal CH 2 OH), 4.12 (t, 2H))

[0303] (Synthesis example 3)

[0304] PBS was obtained by the same method as in Synthesis Example 2 except that 270 g (3.00 mol) of 1,4-butanediol and 338 g (2.86 mol) of succinic acid (the number of moles of 1,4-butanediol relative to 100 mol of succinic acid = 104.7 mol) were used. The molar ratio of the structure derived from 1,4-butanediol in PBS to 100 mol of the structure derived from succinic acid was 100.9 mol.

[0305] The average molecular weight was measured using the above-described method for measuring the average molecular weight. The number average molecular weight Mn was 19,800, and the weight average molecular weight Mw was 42,000.

[0306] The acid value was measured using the above-described method for measuring the acid value and was found to be 0.52 mg-KOH / g.

[0307] (Example 1)

[0308] 0.41 g (4.8 mmol) of poly (3-hydroxybutyric acid) obtained in Synthesis Example 1, 5.70 g (66.2 mmol) of PBS obtained in Synthesis Example 3, and 0.01% by mass of tetraisopropoxytitanium were added to a test tube equipped with a stirrer and a nitrogen inlet tube. The water generated by the esterification reaction was removed under reduced pressure, and the ester exchange reaction was carried out at a temperature of 140°C for 15 minutes. As the copolyester of this embodiment, a copolyester of 3-hydroxybutyric acid-succinic acid-1,4-butanediol was obtained. The input mass ratio of PHB to PBS was 6.7 / 93.3. The average molecular weight was determined using the above-described method for determining the average molecular weight. The number average molecular weight Mn was 7,100, and the weight average molecular weight Mw was 17,400.

[0309] The content of the structure derived from 3-hydroxybutyric acid was measured by the method described in <Calculation of the content of 3-hydroxybutyric acid>.

[0310] The average chain length of the structure derived from 3-hydroxybutyric acid was measured by the method described in <Evaluation of Average Chain Length> above. The results are shown in Table 1.

[0311] The biodegradability was evaluated by the method described in the above <Evaluation of Biodegradability>.

[0312] The acid value was evaluated based on the above <Measurement of Acid Value>. The results are shown in Table 1.

[0313] (Example 2)

[0314] The poly (3-hydroxybutyric acid) obtained in Synthesis Example 1 and the PBS obtained in Synthesis Example 3 were subjected to the same method as in Example 1 for 15 minutes at a temperature of 130°C. The input mass ratio is shown in Table 1. In addition, a copolyester of 3-hydroxybutyric acid-succinic acid-1,4-butanediol was obtained as the copolyester of the present embodiment by the same method as in Example 1. The average molecular weight was determined using the above-described method for determining the average molecular weight. The number average molecular weight Mn was 7,600, and the weight average molecular weight Mw was 20,100. The content, average chain length, acid value, and biodegradability of 3-hydroxybutyric acid were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0315] (Example 3)

[0316] At a temperature of 150°C for 2 hours, the input mass ratio of the poly (3-hydroxybutyric acid) obtained in Synthesis Example 1 and the PBS obtained in Synthesis Example 3 is shown in Table 1. In addition, by the same method as in Example 1, a copolyester of 3-hydroxybutyric acid-succinic acid-1,4-butanediol is obtained as the copolyester of this embodiment. The average molecular weight is determined using the above-described method for determining the average molecular weight. The number average molecular weight Mn is 10,400, and the weight average molecular weight Mw is 17,800. The content, average chain length, acid value, and biodegradability of 3-hydroxybutyric acid are evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0317] (Example 4)

[0318] At a temperature of 150°C for 15 minutes, the input mass ratio of the poly (3-hydroxybutyric acid) obtained in Synthesis Example 1 and the PBS obtained in Synthesis Example 3 is shown in Table 1. In addition, by the same method as in Example 1, a copolyester of 3-hydroxybutyric acid-succinic acid-1,4-butanediol is obtained as the copolyester of this embodiment. The average molecular weight is determined using the above-described method for determining the average molecular weight. The number average molecular weight Mn is 7,600, and the weight average molecular weight Mw is 16,100. The content, average chain length, acid value, and biodegradability of 3-hydroxybutyric acid are evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0319] (Example 5)

[0320] The reaction was carried out at a temperature of 150°C for 2 hours. The input mass ratio of the poly (3-hydroxybutyric acid) obtained in Synthesis Example 1 and the PBS obtained in Synthesis Example 2 was shown in Table 1. In addition, a copolyester of 3-hydroxybutyric acid-succinic acid-1,4-butanediol was obtained as the copolyester of this embodiment by the same method as in Example 1. The average molecular weight was determined using the above-described method for determining the average molecular weight. The number average molecular weight Mn was 7,500, and the weight average molecular weight Mw was 19,200. The content, average chain length, acid value, and biodegradability of 3-hydroxybutyric acid were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0321] (Comparative Example 1)

[0322] At a temperature of 175°C for 2 hours, the poly(3-hydroxybutyric acid) obtained in Synthesis Example 1 and the PBS obtained in Synthesis Example 3 were fed in the same manner as in Example 1 except that the mass ratios were as shown in Table 1. A copolyester of 3-hydroxybutyric acid-succinic acid-1,4-butanediol was obtained. The average molecular weight was measured using the above-described method for measuring the average molecular weight. The number average molecular weight Mn was 13,000, and the weight average molecular weight Mw was 25,600.

[0323] The content, average chain length, acid value and biodegradability of 3-hydroxybutyric acid were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0324] (Comparative Example 2)

[0325] The reaction was carried out at a temperature of 175°C for 2 hours. The input mass ratio of the poly(3-hydroxybutyric acid) obtained in Synthesis Example 1 and the PBS obtained in Synthesis Example 3 was shown in Table 1. In addition, a copolyester of 3-hydroxybutyric acid-succinic acid-1,4-butanediol was obtained by the same method as in Example 1. The average molecular weight was measured using the above-described method for measuring the average molecular weight. The number average molecular weight Mn was 8,200, and the weight average molecular weight Mw was 15,200.

[0326] The content, average chain length, acid value and biodegradability of 3-hydroxybutyric acid were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0327] (Comparative Example 3)

[0328] By the method described in Example 1 of Patent Document 1, a copolyester of 3-hydroxybutyric acid-succinic acid-1,4-butanediol was obtained.

[0329] The content, average chain length, acid value and biodegradability of 3-hydroxybutyric acid were evaluated by the same method as in Example 1 of the present application. The results are shown in Table 1.

[0330] (Comparative Example 4)

[0331] By the method described in Non-Patent Document 1, a copolyester of 3-hydroxybutyric acid-succinic acid-1,4-butanediol shown in "Copo-BS-12" in Table 3 of Non-Patent Document 1 was obtained.

[0332] The content, average chain length, acid value and biodegradability of 3-hydroxybutyric acid were evaluated by the same method as in Example 1 of the present application. The results are shown in Table 1.

[0333] (Comparative Example 5)

[0334] By the method described in Non-Patent Document 1, a copolyester of 3-hydroxybutyric acid-succinic acid-1,4-butanediol shown in "Copo-BS-6" in Table 3 of Non-Patent Document 1 was obtained.

[0335] The content, average chain length, acid value and biodegradability of 3-hydroxybutyric acid were evaluated by the same method as in Example 1 of the present application. The results are shown in Table 1.

[0336] [Table 1]

[0337]

[0338] (Inspection)

[0339] When a highly biodegradable structure derived from 3-hydroxybutyric acid is arranged in a specific average chain length in a copolyester, the structural units derived from 3-hydroxybutyric acid are cleaved by enzymes secreted by microorganisms in the environment, whereby the copolyester becomes oligomers that can be metabolized by microorganisms, and the copolyester is biodegraded as a whole.

[0340] Furthermore, by controlling the acid value to a certain value or less, hydrolyzability and odor can be suppressed.

[0341] Industrial Applicability

[0342] The copolyester of the present embodiment has a structure derived from 3-hydroxybutyric acid, and while exhibiting biodegradability, by controlling the acid value derived from the decomposition product to a certain value or less, hydrolysis and odor can be suppressed. Therefore, the resin composition containing the copolyester of the present embodiment can be expected to be used in various applications such as sustainable product groups (packaging materials, films).

Claims

1. A copolyester, characterized in that: The copolyester has a structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB), a structural unit (DA-U) derived from a dicarboxylic acid (DA), and a structural unit (DO-U) derived from a diol (DO). The dicarboxylic acid (DA) comprises an aliphatic dicarboxylic acid, The diol (DO) comprises an aliphatic diol, The content of the structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB) is 1 to 65 mol% relative to 100 mol of all structural units of the copolyester. The average chain length of the structural unit (3HB-U) derived from 3-hydroxybutyric acid (3HB) in the copolyester is 2 to 80. The acid value of the copolyester is 5 or less.

2. The copolyester according to claim 1, which is a reaction product of the poly(3-hydroxybutyric acid) (PHB) and a polyester (PAO), wherein the polyester (PAO) is a polyester of the dicarboxylic acid (DA) and the diol (DO).

3. The copolyester according to claim 2, wherein The number average molecular weight of the poly(3-hydroxybutyric acid) (PHB) is 1,000 to 500,000.

4. The copolyester according to claim 2, wherein The number average molecular weight of the polyester (PAO) is 5,000 to 500,000.

5. The copolyester according to claim 2, wherein The acid value of the polyester (PAO) is 5 or less.

6. The copolyester according to claim 1, wherein The dicarboxylic acid (DA) is an aliphatic dicarboxylic acid.

7. The copolyester according to claim 1, wherein The diol (DO) is an aliphatic diol.

8. A method for producing a copolyester, which is a method for producing the copolyester according to any one of claims 1 to 7, comprising: Poly(3-hydroxybutyric acid) (PHB), which is a polyester of the 3-hydroxybutyric acid (3HB), and A step of reacting the dicarboxylic acid (DA) and the polyester (PAO) of the diol (DO). 9 . A resin composition comprising the copolyester according to claim 1 . 10 . A sheet or a film formed from the resin composition according to claim 9 .

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