Degradation accelerator for biodegradable resins, biodegradable resin composition, molded object, and method for degradating biodegradable resin

Abstract

Provided is a biodegradation accelerator for improving the biodegradability of biodegradable resins. Specifically, the biodegradation accelerator is a degradation accelerator for biodegradable resins which is a polyester obtained from reactants comprising: one or more amine compounds selected from the group consisting of aliphatic diamines, aliphatic aminocarboxylic acids, aromatic aminocarboxylic acids, and aliphatic amino alcohols; one or more carbonyl compounds selected from the group consisting of aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and hydroxycarboxylic acids; and an aliphatic diol. The polyester has a number-average molecular weight in the range of 300-5,000.

Description

Biodegradable resin decomposition accelerator, biodegradable resin composition, molded body, and method for decomposing biodegradable resin

[0001] The present invention relates to a biodegradable resin decomposition accelerator, a biodegradable resin composition, a molded article, and a method for decomposing a biodegradable resin.

[0002] General-purpose plastics such as polyvinyl chloride (PVC) are used for a wide range of purposes. However, because these general-purpose plastics are difficult to decompose, there has been a recent trend toward switching from general-purpose plastics to biodegradable resins in light of the emphasis on "sustainability."

[0003] Biodegradable resins are resins that can be decomposed into carbon dioxide and water by the action of microorganisms present in soil, water, the ocean, etc., and are generally known to be biodegraded over a period of several months to several years.

[0004] For example, general-purpose plastic disposable containers used in retail businesses have an extremely short product cycle, so if the raw material for disposable containers is switched from general-purpose plastic to biodegradable resin, the biodegradability of the biodegradable resin must be such that the decomposition cycle is shorter.

[0005] The decomposition of biodegradable resins can be accelerated by placing them in a hot and humid environment. To further accelerate biodegradation, various proposals have been made focusing on improving the biodegradability of biodegradable resins (e.g., Patent Documents 1 to 5).

[0006] JP 2023-514059 A1 WO2021 / 201185A1 WO2021 / 201186A1 JP 2022-157778 A JP 2023-055589 A

[0007] The problem to be solved by the present invention is to provide a biodegradation accelerator that improves the biodegradability of biodegradable resins. Another problem to be solved by the present invention is to provide a biodegradable resin composition with improved biodegradability and a molded article thereof. Another problem to be solved by the present invention is to provide a method for decomposing biodegradable resins that can decompose biodegradable resins in a shorter time.

[0008] As a result of intensive research to solve the above problems, the present inventors discovered that the biodegradability of a biodegradable resin can be improved by adding a polyester having a specific structure to the biodegradable resin, and thus completed the present invention.

[0009] That is, the present invention relates to a biodegradable resin degradation accelerator, etc. 1. A biodegradable resin degradation accelerator that is a polyester having, as reaction components, one or more amine compounds selected from the group consisting of aliphatic diamines, aliphatic aminocarboxylic acids, aromatic aminocarboxylic acids, and aliphatic amino alcohols, one or more carbonyl compounds selected from the group consisting of aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and hydroxycarboxylic acids, and an aliphatic diol, wherein the number average molecular weight of the polyester is in the range of 300 to 5,000. 2. The biodegradable resin degradation accelerator according to 1, wherein the amine compound is one or more selected from the group consisting of compounds represented by the following general formula (N-1), compounds represented by the following general formula (N-2), and compounds represented by the following general formula (N-3): (In the general formula (N-1), general formula (N-2) and general formula (N-3), R Ｎ１ is an alkylene group having 1 to 12 carbon atoms or a heteroalkylene group having 1 to 12 carbon atoms, R Ｎ２ is an alkylene group having 1 to 12 carbon atoms, a heteroalkylene group having 1 to 12 carbon atoms, an aryl group having 5 to 15 carbon atoms, or a heteroaryl group having 5 to 15 carbon atoms, and R Ｎ３ is an alkylene group having 1 to 12 carbon atoms or a heteroalkylene group having 1 to 12 carbon atoms.) 3. The biodegradable resin decomposition accelerator according to 1 or 2, wherein the carbonyl compound is one or more compounds selected from the group consisting of compounds represented by the following general formula (A) and compounds represented by the following general formula (L): (In the general formula (A) and general formula (L), R Ａ is a single bond, an alkylene group having 1 to 12 carbon atoms, a heteroalkylene group having 1 to 12 carbon atoms, an aryl group having 5 to 15 carbon atoms, or a heteroaryl group having 5 to 15 carbon atoms; R Ｌis an alkylene group having 1 to 18 carbon atoms or a heteroalkylene group having 1 to 18 carbon atoms. 4. The biodegradable resin degradation accelerator according to any one of 1-3, wherein the proportion of the amine compound in the reaction components is in the range of 10 to 35 mass%. 5. The biodegradable resin degradation accelerator according to any one of 1-4, wherein the polyester is a polyester obtained by reacting the amine compound with a polyester having the aliphatic dicarboxylic acid and the aliphatic diol as reaction components. 6. A biodegradable resin composition containing a biodegradable resin and the biodegradable resin degradation accelerator according to any one of 1-5. 7. The biodegradable resin composition according to 6, wherein the biodegradable resin is one or more selected from the group consisting of polylactic acid, polybutylene succinate, polybutylene adipate terephthalate, polyhydroxyalkanoic acid, polybutylene succinate adipate, and polyethylene terephthalate succinate. 8. The biodegradable resin composition according to 6 or 7, containing the biodegradable resin decomposition accelerator in an amount ranging from 1 to 250 parts by mass per 100 parts by mass of the biodegradable resin. 9. A molded product of the biodegradable resin composition according to any one of 6 to 8. 10. A method for decomposing a biodegradable resin, comprising adding the biodegradable resin decomposition accelerator according to any one of 1 to 5 to a biodegradable resin.

[0010] The present invention provides a biodegradation accelerator that improves the biodegradability of a biodegradable resin. The present invention provides a biodegradable resin composition and a molded article thereof with improved biodegradability. The present invention provides a method for decomposing a biodegradable resin that can decompose a biodegradable resin in a shorter time.

[0011] An embodiment of the present invention will be described below. The present invention is not limited to the following embodiment, and can be carried out by making appropriate modifications within the scope that does not impair the effects of the present invention. The compounds in this specification may be derived from fossil resources or biological resources.

[0012] [Biodegradable Resin Decomposition Accelerator] The biodegradable resin degradation accelerator of the present invention is a polyester having, as reaction components, one or more amine compounds (N) selected from the group consisting of aliphatic diamines, aliphatic aminocarboxylic acids, aromatic aminocarboxylic acids, and aliphatic amino alcohols, one or more carbonyl compounds (C) selected from the group consisting of aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and hydroxycarboxylic acids, and an aliphatic diol (G), and the number average molecular weight of the polyester is in the range of 300 to 5,000.

[0013] The term "reactive components" refers to components that constitute the polyester, which is the biodegradable resin degradation accelerator of the present invention, and does not include solvents or catalysts that do not constitute polyester. The biodegradable resin degradation accelerator of the present invention is a polymer that may contain not only ester bonds but also amide bonds, but for convenience, this polymer will be referred to as "polyester" in the present application.

[0014] The polyester that is the biodegradable resin degradation accelerator of the present invention (hereinafter sometimes referred to as "the polyester of the present invention") not only accelerates the decomposition of biodegradable resins by functioning as an acid catalyst itself, but also contains nitrogen atoms known as a nutrient source for microorganisms, which are presumably used to attract and grow microorganisms and accelerate the decomposition of biodegradable resins. Furthermore, because the biodegradable resin degradation accelerator of the present invention is an oligomer with a number-average molecular weight in the range of 300 to 5,000, it is easily taken up as a nutrient by microorganisms, and the decomposition accelerator itself is also highly degradable.

[0015] It is thought that adding an amine compound alone to a biodegradable resin can also attract and grow microorganisms, but amine compounds are generally highly polar and therefore have poor compatibility with biodegradable resins, which may result in insufficient promotion of biodegradation. In the present invention, this problem can be solved by introducing a structure derived from an amine compound into a polyester. Each reactive component of the polyester is described below.

[0016] (Amine Compound (N)) The amine compound (N) is at least one selected from the group consisting of an aliphatic diamine, an aliphatic aminocarboxylic acid, an aromatic aminocarboxylic acid, and an aliphatic amino alcohol, and is preferably at least one selected from the group consisting of a compound represented by the following general formula (N-1), a compound represented by the following general formula (N-2), and a compound represented by the following general formula (N-3).

[0017] (In the general formula (N-1), general formula (N-2) and general formula (N-3), R Ｎ１ is an alkylene group having 1 to 12 carbon atoms or a heteroalkylene group having 1 to 12 carbon atoms, R Ｎ２ is an alkylene group having 1 to 12 carbon atoms, a heteroalkylene group having 1 to 12 carbon atoms, an aryl group having 5 to 15 carbon atoms, or a heteroaryl group having 5 to 15 carbon atoms, and R Ｎ３ is an alkylene group having 1 to 12 carbon atoms or a heteroalkylene group having 1 to 12 carbon atoms.

[0018] In the general formulae (N-1), (N-2) and (N-3), R Ｎ１ , R Ｎ２ and R Ｎ３ The alkylene group having 1 to 12 carbon atoms may be linear or branched, and may contain an alicyclic structure. Ｎ１ , R Ｎ２ and R Ｎ３ The alkylene group having 1 to 12 carbon atoms is preferably an alkylene group having 1 to 6 carbon atoms.

[0019] R Ｎ１ , R Ｎ２ and R Ｎ３ Specific examples of the alkylene group having 1 to 12 carbon atoms include a methylene group, an ethylene group, a propylene group, a 1-methylmethylene group, a 1,1-dimethylmethylene group, a 1-methylethylene group, a 1,1-dimethylethylene group, a 1,2-dimethylethylene group, a butylene group, a 1-methylpropylene group, a 2-methylpropylene group, a pentylene group, a hexylene group, a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, and a cyclohexylene group.

[0020] In the general formulae (N-1), (N-2) and (N-3), R Ｎ１ , R Ｎ２ and R Ｎ３ The heteroalkylene group having 1 to 12 carbon atoms is, for example, a group in which the alkylene group having 1 to 12 carbon atoms further contains one or more bonds selected from an ether bond (—O—), a sulfide bond (—S—), and an amino bond (—NH—). Ｎ１ , R Ｎ２ and R Ｎ３ The heteroalkylene group having 1 to 12 carbon atoms is preferably a heteroalkylene group having 2 to 10 carbon atoms, and more preferably a heteroalkylene group having 4 to 8 carbon atoms.

[0021] In the general formula (N-2), R Ｎ２ Examples of the aryl group having 5 to 15 carbon atoms include a phenylene group and a naphthalenylene group.

[0022] In the general formula (N-2), R Ｎ２ The heteroaryl group having 5 to 15 carbon atoms is, for example, a group in which one or more carbon atoms in the aromatic ring of the aryl group having 5 to 15 carbon atoms is substituted with a heteroatom (oxygen atom, nitrogen atom, sulfur atom), and examples thereof include a furan ring, an imidazole ring, and an oxazole ring.

[0023] R Ｎ２ The alkylene group having 1 to 12 carbon atoms and the heteroalkylene group having 1 to 12 carbon atoms may be substituted with, for example, an aryl group having 5 to 15 carbon atoms or a heteroaryl group having 5 to 15 carbon atoms. Ｎ２ The aryl group having 5 to 15 carbon atoms and the heteroaryl group having 5 to 15 carbon atoms may be substituted on the aromatic ring or hetero ring with, for example, an alkyl group having 1 to 6 carbon atoms.

[0024] The compound represented by the general formula (N-2) may be a compound having at least one amino group and at least one carboxyl group, and may also be a compound having two or more amino groups and / or two or more carboxyl groups. For example, aspartic acid is a compound represented by the general formula (N-2) in which two carboxyl groups and one amino group are substituted on an alkylene group. Similarly, lysine is a compound represented by the general formula (N-2) in which one carboxyl group and two amino groups are substituted on an alkylene group.

[0025] Specific examples of the aliphatic diamine include propanediamine, hexanediamine, isophoronediamine, bis(3-aminopropyl)ether, 3,3'-iminobis(propylamine), N,N-bis(3-aminopropyl)methylamine, 1,2-bis(3-aminopropoxy)ethane, 1,4-bis(3-aminopropyl)piperazine, etc. The aliphatic diamines used may be one type alone or two or more types may be used in combination.

[0026] Specific examples of aliphatic aminocarboxylic acids and aromatic aminocarboxylic acids include 4-aminobutyric acid, glycine, methionine, phenylalanine, aspartic acid, glutamic acid, lysine, histidine, 12-aminolauric acid, etc. The aliphatic aminocarboxylic acids used may be one type alone or two or more types may be used in combination. Similarly, the aromatic aminocarboxylic acids used may be one type alone or two or more types may be used in combination.

[0027] Specific examples of the aliphatic amino alcohol include ethanolamine, 3-amino-1-propanol, 2-amino-1-propanol, 1-amino-2-propanol, 4-amino-1-butanol, 1-amino-2-butanol, 2-amino-1-butanol, 3-amino-1-butanol, 2-(3-aminopropylamino)ethanol, 2-(2-aminoethylamino)ethanol, 1-[(2-aminoethyl)amino]-2-propanol, 2-(2-aminoethoxy)ethanol, etc. The aliphatic amino alcohols used may be one type alone, or two or more types may be used in combination.

[0028] (Carbonyl Compound (C)) The carbonyl compound (C) is at least one selected from the group consisting of aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and hydroxycarboxylic acids, and is preferably at least one selected from the group consisting of compounds represented by the following general formula (A) and compounds represented by the following general formula (L): (In the general formula (A) and general formula (L), R Ａ is a single bond, an alkylene group having 1 to 12 carbon atoms, a heteroalkylene group having 1 to 12 carbon atoms, an aryl group having 5 to 15 carbon atoms, or a heteroaryl group having 5 to 15 carbon atoms; R Ｌ is an alkylene group having 1 to 18 carbon atoms or a heteroalkylene group having 1 to 18 carbon atoms.

[0029] The alkylene group having 1 to 12 carbon atoms, the heteroalkylene group having 1 to 12 carbon atoms, the aryl group having 5 to 15 carbon atoms, and the heteroaryl group having 5 to 15 carbon atoms in the general formulae (A) and (L) are the same as the alkylene group having 1 to 12 carbon atoms, the heteroalkylene group having 1 to 12 carbon atoms, the aryl group having 5 to 15 carbon atoms, and the heteroaryl group having 5 to 15 carbon atoms in the general formulae (N-1), (N-2) and (N-3), respectively.

[0030] R Ａ The alkylene group having 1 to 12 carbon atoms is preferably an alkylene group having 2 to 12 carbon atoms. Ｌ The alkylene group having 1 to 18 carbon atoms is preferably an alkylene group having 4 to 18 carbon atoms.

[0031] R Ａ Specific examples of the alkylene group having 1 to 12 carbon atoms include a methylene group, an ethylene group, a propylene group, a 1-methylmethylene group, a 1,1-dimethylmethylene group, a 1-methylethylene group, a 1,1-dimethylethylene group, a 1,2-dimethylethylene group, a butylene group, a 1-methylpropylene group, a 2-methylpropylene group, a pentylene group, a hexylene group, a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, and a cyclohexylene group. ＬSpecific examples of the alkylene group having 1 to 18 carbon atoms include the above-mentioned specific examples of the alkylene group having 1 to 12 carbon atoms, as well as a hexadecanyl group and a heptadecanyl group.

[0032] Specific examples of the aliphatic dicarboxylic acid include oxalic acid, succinic acid, adipic acid, maleic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, cyclohexanedicarboxylic acid, dodecanedicarboxylic acid, hexahydrophthalic acid, etc., and preferred are succinic acid, sebacic acid, maleic acid, adipic acid, etc. The aliphatic dicarboxylic acid used may be one type alone or two or more types may be used in combination.

[0033] Specific examples of aromatic dicarboxylic acids include phthalic acid, furandicarboxylic acid, etc. The aromatic dicarboxylic acids may be used alone or in combination of two or more.

[0034] Specific examples of hydroxycarboxylic acids include hydroxycarboxylic acids in which one hydroxyl group is substituted on the fatty chain of an aliphatic carboxylic acid, such as propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, capric acid, caprylic acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, and stearic acid, and preferred are lactic acid, 9-hydroxystearic acid, 12-hydroxystearic acid, and 6-hydroxycaproic acid. The hydroxycarboxylic acids used may be one type alone or two or more types in combination.

[0035] (Aliphatic Diol (G)) The aliphatic diol (G) is preferably an aliphatic diol having 2 to 12 carbon atoms. Specific examples of aliphatic diols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, and 1,9-nonanediol.

[0036] The aliphatic diol having 2 to 12 carbon atoms may contain an alicyclic structure and / or an ether bond (—O—). Examples of the aliphatic diol having 2 to 12 carbon atoms and containing an alicyclic structure include 1,3-cyclopentanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol. Examples of the aliphatic diol having 2 to 12 carbon atoms and containing an ether bond include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol.

[0037] The aliphatic diol having 2 to 12 carbon atoms is preferably an aliphatic diol having 2 to 8 carbon atoms, more preferably ethylene glycol, diethylene glycol, 1,3-propylene glycol, 1,6-hexanediol, or 1,4-butanediol. By using a linear aliphatic diol as the aliphatic diol (G), compatibility with biodegradable resins can be improved.

[0038] The aliphatic diols used may be one type alone or two or more types in combination.

[0039] The reaction components used include derivatives such as the above esters, acid chlorides, acid anhydrides, etc. For example, hydroxycarboxylic acids also include compounds having a lactone structure such as ε-caprolactone.

[0040] The reactive components of the polyester of the present invention may contain the carbonyl compound (C), the aliphatic diol (G), and the amine compound (N), and may contain other components. The reactive components of the polyester of the present invention preferably contain the carbonyl compound (C), the aliphatic diol (G), and the amine compound (N) in an amount of 90 mass% or more, more preferably 95 mass% or more, of the total amount of the reactive components, and even more preferably contain only the carbonyl compound (C), the aliphatic diol (G), and the amine compound (N).

[0041] The reaction of the amine compound (N), the carbonyl compound (C), and the aliphatic diol (G) can be carried out by a known method. For example, the amine compound (N), the carbonyl compound (C), and the aliphatic diol (G) may be reacted at once, or the carbonyl compound (C) and the aliphatic diol (G) may be reacted to form a polyester, and the amine compound (N) may then be reacted with the polyester.

[0042] The polyester of the present invention is preferably a terminal amine-modified polyester obtained by reacting a polyester having a carbonyl compound (C) and an aliphatic diol (G) as reaction components with an amine compound (N), and more preferably a terminal amine-modified polyester obtained by reacting a polyester having an aliphatic dicarboxylic acid and an aliphatic diol as reaction components with an amine compound (N). A polyester whose terminals are modified with an amine compound (N) can be expected to have a high microbial attracting effect and a high microbial proliferation effect.

[0043] In the reaction components, the contents of the carbonyl compound (C) and the aliphatic diol (G) may be set, for example, so that the equivalent of the carboxyl group contained in the reaction components is equal to or less than the equivalent of the hydroxyl group.

[0044] The content of the amine compound (N) in the reaction components is, for example, in the range of 1 to 50 mass% of the total amount of the reaction components, preferably in the range of 5 to 40 mass% of the total amount of the reaction components, more preferably in the range of 10 to 35 mass% of the total amount of the reaction components, and even more preferably in the range of 15 to 30 mass% of the total amount of the reaction components.

[0045] In the production of the polyester of the present invention, the reaction of the reaction components may be carried out as an esterification reaction, for example, in the presence of an esterification catalyst at a temperature of 180 to 250° C. for 10 to 25 hours. The conditions of the esterification reaction, such as the temperature and time, are not particularly limited and may be set appropriately.

[0046] Examples of the esterification catalyst include titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate; zinc-based catalysts such as zinc acetate; tin-based catalysts such as dibutyltin oxide; and organic sulfonic acid-based catalysts such as p-toluenesulfonic acid.

[0047] The amount of the esterification catalyst used may be appropriately determined, but is usually in the range of 0.001 to 0.1 parts by mass per 100 parts by mass of the total amount of the reaction components.

[0048] The number average molecular weight (Mn) of the polyester of the present invention is, for example, in the range of 100 to 6,000, preferably in the range of 300 to 5,000, more preferably in the range of 500 to 4,000, even more preferably in the range of 500 to 3,000, and particularly preferably in the range of 500 to 2,000. The number average molecular weight (Mn) is a value calculated in terms of polystyrene based on gel permeation chromatography (GPC) measurement, and is measured by the method described in the Examples.

[0049] The acid value of the polyester of the present invention is, for example, 25 mgKOH / g or more, and is preferably 27 mgKOH / g or more, 30 mgKOH / g or more, 40 mgKOH / g or more, 50 mgKOH / g or more, and more than 50 mgKOH / g, in that order. The upper limit of the acid value of the polyester of the present invention is not particularly limited, but is, for example, 400 mgKOH / g or less, and is preferably 250 mgKOH / g or less, 200 mgKOH / g or less, 150 mgKOH / g or less, 120 mgKOH / g or less, 100 mgKOH / g or less, and more preferably 95 mgKOH / g or less. The acid value of the polyester is confirmed by the method described in the Examples.

[0050] The hydroxyl value of the polyester of the present invention may be, for example, 0 or more, and is preferably in the range of 10 to 200 mgKOH / g, more preferably in the range of 20 to 150 mgKOH / g, and even more preferably in the range of 30 to 120 mgKOH / g. The hydroxyl value of the polyester is confirmed by the method described in the examples.

[0051] The properties of the polyester of the present invention vary depending on the number average molecular weight, composition, etc., but are usually liquid, solid, paste, etc. at room temperature (25°C), preferably solid or liquid at room temperature (25°C), more preferably solid at room temperature (25°C).

[0052] [Biodegradable resin composition] The biodegradable resin composition of the present invention contains the biodegradable resin degradation accelerator of the present invention and a biodegradable resin. When the biodegradable resin composition contains the biodegradable resin degradation accelerator of the present invention, the degradation of the biodegradable resin can be further accelerated. In addition, the biodegradable resin degradation accelerator of the present invention can also function as a plasticizer for the biodegradable resin, and molded articles can be produced from the biodegradable resin composition of the present invention without using conventional plasticizers such as benzoate esters, phthalate esters, and pyromellitic esters.

[0053] The content of the biodegradable resin decomposition accelerator of the present invention is not particularly limited, but is, for example, in the range of 1 to 250 parts by mass, preferably 1 to 50 parts by mass, and more preferably 1 to 30 parts by mass of the biodegradable resin decomposition accelerator per 100 parts by mass of the biodegradable resin.

[0054] The biodegradable resin contained in the biodegradable resin composition of the present invention includes polylactic acid (PLA), polyethylene succinate (PES), polyethylene terephthalate succinate (PETS), polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT), polyethylene adipate terephthalate (PEAT), polybutylene succinate terephthalate (PBST), polyethylene succinate terephthalate (PEST), polybutylene succinate terephthalate (PEST), polybutylene succinate terephthalate (PET ... Examples of the biodegradable resin include poly(ethylene succinate-adipate) (PBSA), polybutylene succinate-carbonate (PEC), polybutylene succinate-adipate-terephthalate (PBSAT), polyethylene succinate-adipate-terephthalate (PESAT), polytetramethylene adipate-terephthalate (PTMAT), polyhydroxyalkanoic acid, polycaprolactone (PCL), polycaprolactone-butylene succinate (PCLBS), cellulose acetate, etc. The biodegradable resin to be used may be determined depending on the intended use, and the above biodegradable resins may be used alone or in combination of two or more.

[0055] The polyhydroxyalkanoic acid includes polyhydroxybutyric acid (PHB), polyhydroxybutyric acid-hydroxyhexanoic acid (PHBH), and the like.

[0056] The biodegradable resin is preferably one or more selected from the group consisting of polylactic acid, polybutylene succinate, polybutylene adipate terephthalate, polyhydroxyalkanoic acid, polybutylene succinate adipate, and polyethylene terephthalate succinate.

[0057] The biodegradable resin composition of the present invention may contain an inorganic filler. The inorganic filler contained in the biodegradable resin composition of the present invention is not particularly limited, and examples thereof include calcium carbonate, talc, silica, alumina, clay, antimony oxide, aluminum hydroxide, magnesium hydroxide, hydrotalcite, calcium silicate, magnesium oxide, potassium titanate, barium titanate, titanium oxide, calcium oxide, magnesium oxide, manganese dioxide, boron nitride, and aluminum nitride. The inorganic fillers may be used alone or in combination of two or more.

[0058] The inorganic filler is preferably at least one selected from the group consisting of calcium carbonate, silica, alumina, aluminum hydroxide, barium titanate, talc, boron nitride, and aluminum nitride, and more preferably at least one selected from the group consisting of calcium carbonate, alumina, aluminum hydroxide, and talc.

[0059] The particle size, fiber length, fiber diameter, and other shapes of the inorganic filler are not particularly limited and may be appropriately adjusted depending on the intended use. The surface treatment state of the inorganic filler is also not particularly limited, and the surface may be modified with, for example, saturated fatty acid depending on the intended use.

[0060] The content of the inorganic filler is, for example, in the range of 1 to 200 parts by mass relative to 100 parts by mass of the biodegradable resin, and may be in the range of 1 to 100 parts by mass, 5 to 70 parts by mass, 10 to 60 parts by mass, or 15 to 55 parts by mass.

[0061] As described above, the biodegradable resin decomposition accelerator of the present invention can also function as a plasticizer, but the biodegradable resin composition of the present invention may further contain a plasticizer other than the biodegradable resin decomposition accelerator of the present invention. Examples of the plasticizer include benzoate esters such as diethylene glycol dibenzoate; phthalate esters such as dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DOP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), diundecyl phthalate (DUP), and ditridecyl phthalate (DTDP); terephthalate esters such as bis(2-ethylhexyl) terephthalate (DOTP); isophthalate esters such as bis(2-ethylhexyl) isophthalate (DOIP); pyromellitic acid esters such as tetra-2-ethylhexyl pyromellitic acid (TOPM); di-2-ethylhexyl adipate (DOA), diisononyl adipate (DINA), diisodecyl adipate (DIDA), di-2-ethylhexyl sebacate (DOS), and sebacic acid esters such as bis(2-ethylhexyl) terephthalate (DOTP). Examples of suitable plasticizers include aliphatic dibasic acid esters such as diisononyl phosphate (DINS); phosphate esters such as tri-2-ethylhexyl phosphate (TOP) and tricresyl phosphate (TCP); alkyl esters of polyhydric alcohols such as pentaerythritol; polyesters having a molecular weight of 800 to 4,000 synthesized by polyesterification of a dibasic acid such as adipic acid with a glycol; epoxidized esters such as epoxidized soybean oil and epoxidized linseed oil; alicyclic dibasic acids such as diisononyl hexahydrophthalate; fatty acid glycol esters such as 1,4-butanediol dicaprate; acetyl tributyl citrate (ATBC); chlorinated paraffins obtained by chlorinating paraffin wax or n-paraffin; chlorinated fatty acid esters such as chlorinated stearic acid ester; and higher fatty acid esters such as butyl oleate. The plasticizer to be used may be determined depending on the intended application, and the above plasticizers may be used alone or in combination of two or more.

[0062] The content of the plasticizer is not particularly limited, but is preferably in the range of 10 to 300 parts by mass, more preferably 20 to 200 parts by mass, per 100 parts by mass of the biodegradable resin.

[0063] The additives contained in the biodegradable resin composition of the present invention are not limited to the biodegradable resin decomposition accelerator and the plasticizer, and may include other additives such as viscosity reducers, flame retardants, stabilizers, stabilization aids, colorants, processing aids, fillers, antioxidants (antiaging agents), UV absorbers, light stabilizers, lubricants, antistatic agents, and crosslinking aids.

[0064] The biodegradable resin composition of the present invention may contain a non-biodegradable resin to the extent that the effects of the present invention are not impaired. The non-biodegradable resin is not particularly limited, and examples thereof include polyolefin, polyester, polysulfide, polyvinyl chloride, modified polysulfide, silicone resin, modified silicone resin, acrylic urethane resin, epoxy resin, polyurethane, acrylic resin, polyester, and unsaturated polyester.

[0065] [Method for Producing Biodegradable Resin Composition] The method for producing the biodegradable resin composition of the present invention is not particularly limited. For example, the biodegradable resin composition can be obtained by melt-kneading a biodegradable resin, an inorganic filler, a flowability modifier, and optionally a plasticizer and the other additives described above using a melt-kneader such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a Brabender mixer, or various kneaders.

[0066] [Molded Articles of Biodegradable Resin Composition] The biodegradable resin composition of the present invention can be molded by various molding methods applicable to general-purpose plastics. Examples of such molding methods include compression molding (compression molding, laminate molding, stampable molding), injection molding, extrusion molding, co-extrusion molding (film molding by inflation method or T-die method, laminate molding, pipe molding, electric wire / cable molding, molding of profiled materials), heat press molding, blow molding (various blow moldings), calendar molding, solid molding (uniaxial stretch molding, biaxial stretch molding, roll molding, stretch-oriented nonwoven fabric molding, thermoforming (vacuum forming, pressure forming), plastic processing, powder molding (rotational molding), and various nonwoven fabric moldings (dry method, adhesive method, entanglement method, spunbond method, etc.). Injection molding, extrusion molding, compression molding, or heat press molding is preferably applied. Specific shapes that are preferably applied to sheets, films, and containers are preferred.

[0067] The molded article obtained as described above may be subjected to secondary processing, such as embossing, painting, bonding, printing, metallizing (plating, etc.), machining, and surface treatment (antistatic treatment, corona discharge treatment, plasma treatment, photochromism treatment, physical vapor deposition, chemical vapor deposition, coating, etc.).

[0068] The decomposition of the molded article obtained from the biodegradable resin composition of the present invention can be accelerated by the biodegradable resin decomposition accelerator of the present invention, and the molded article can be suitably used as a product with a relatively short product life, such as a disposable container.

[0069] Molded articles obtained from the biodegradable resin composition of the present invention are suitable for a wide range of applications, such as packaging materials for packaging liquids, powders, and solids, agricultural materials, construction materials, etc. Specific applications include injection-molded articles (e.g., trays for fresh food, fast food containers, coffee capsule containers, cutlery, outdoor leisure products, etc.), extrusion-molded articles (e.g., films, sheets, fishing lines, fishing nets, vegetation nets, sheets for secondary processing, water-retaining sheets, etc.), blow-molded articles (bottles, etc.), etc.

[0070] Applications are not limited to those described above, and the material can also be used for agricultural films, coating materials, fertilizer coating materials, seedling pots, laminated films, plates, stretched sheets, monofilaments, nonwoven fabrics, flat yarns, staples, crimped fibers, creased tape, split yarns, composite fibers, blown bottles, shopping bags, garbage bags, compost bags, cosmetic containers, detergent containers, bleach containers, ropes, binding materials, sanitary cover stock materials, cooler boxes, cushioning films, multifilaments, synthetic paper, and medical applications such as surgical thread, sutures, artificial bones, artificial skin, microcapsules, and wound dressings.

[0071] Furthermore, the material can be suitably used for, for example, a microbial carrier, a zooplankton breeding facility, a water treatment carrier, a foam, a drainage material, a downhole tool component, a flak plug, a shell for a firework, a battery material, a capacitor, a sensor, a shape-memory material, and a stent.

[0072] A microbial carrier according to one embodiment is used for water purification and can improve, for example, denitrification efficiency. The shape of the microbial carrier is not particularly limited, and examples include film, pellet, and hollow cylindrical shapes. To increase the surface area of ​​the carrier, it may be porous. Furthermore, the porosity of the microbial carrier containing biodegradable resin can be reduced, and it can be a rod-shaped carrier with a cross-sectional shape having recesses on the periphery. The microbial carrier according to this embodiment can be used to support various microorganisms, and the type of microorganism is not particularly limited. Suitable examples of the microorganism include denitrifying bacteria, particularly heterotrophic denitrifying bacteria. In particular, as described below, the oxygen concentration in the vicinity of a biofilm formed by the supported microorganisms is reduced, and therefore the carrier is preferably used to support anaerobic microorganisms, such as denitrifying bacteria that perform denitrification under anaerobic conditions. When the microbial carrier according to this embodiment is used to support heterotrophic microorganisms, such as denitrifying bacteria, it is preferable to support biodegradable resin-degrading bacteria capable of decomposing biodegradable resins in addition to the denitrifying bacteria. By allowing biodegradable resin-degrading bacteria to decompose the biodegradable resin in the microbial carrier, the denitrifying bacteria are provided with sufficient carbon necessary for denitrifying nitrite nitrogen and / or nitrate nitrogen in the water to be treated. This promotes the growth, development, and activity of denitrifying bacteria, thereby improving the denitrification rate and amount. Denitrifying bacteria, biodegradable resin-degrading bacteria, and the like can be appropriately selected from known bacteria. Highly degradable biodegradable polyesters are preferred as biodegradable resins. Among biodegradable polyesters, biodegradable polyesters having highly degradable dicarboxylic acid-derived structural units are particularly preferred, with biodegradable polyesters having dicarboxylic acid-derived structural units and diol-derived structural units being more preferred. The microbial carrier has, for example, a rod-like shape, a cross section perpendicular to the longitudinal direction of which has a recess on the periphery, and a perimeter ratio of 0.5 mm-1 or more and 4.5 mm-1 or less. The recess on the periphery of the cross section of the microbial carrier is derived from a groove continuously formed in the longitudinal direction of the microbial carrier. When a microbial carrier having such a shape is used for water treatment with microorganisms supported thereon, it is possible to improve the water treatment efficiency, particularly the denitrification efficiency, compared to conventional microbial carriers. For details of the microbial carrier, see Japanese Patent Application Laid-Open No. 2022-153873.

[0073] One embodiment of the zooplankton rearing equipment includes a culture tank containing zooplankton culture water and a molded article of a biodegradable resin composition. By containing the molded article of the biodegradable resin composition in the culture tank, the culture water contains the zooplankton and the biodegradable resin during culture, thereby promoting the proliferation of the zooplankton. One embodiment of the zooplankton rearing equipment includes a culture tank, an aeration pipe, a blower, a liquid drain pipe, a liquid drain valve, a zooplankton food tank, and a zooplankton food supply pump. The aeration pipe is installed in the culture tank, and the blower installed outside the culture tank is connected to the aeration pipe by piping. Furthermore, a liquid drain pipe is connected to the culture tank, and the liquid drain pipe is provided with a liquid drain valve. Furthermore, the culture tank and the food tank are connected by piping equipped with a food supply pump.

[0074] One embodiment of the water treatment device comprises a water reservoir that stores water to be treated, a denitrification tank containing denitrification carriers supporting denitrifying bacteria, and a microorganism reduction treatment unit that reduces the number of aerobic heterotrophic bacteria in the water to be treated. The microorganism reduction treatment unit is disposed midway along the water to be treated transfer path from the water reservoir to the denitrification tank. By using a molded article of a biodegradable resin composition as the denitrification carrier, consumption of the denitrification carrier during denitrification treatment is reduced, and the denitrification rate per unit weight of the denitrification carrier can be improved.

[0075] In one embodiment, a foam is obtained by foam molding a molded article of a biodegradable resin composition. The biodegradable resin composition has favorable melt tension and high gas retention, resulting in good foam moldability and shapability, suppressing the occurrence of swirl marks, and providing a good appearance. The shape of the foam is not particularly limited, and examples include various shapes such as containers, plates, cylinders, columns, sheets, boards, and blocks. It can be used as an insulating material or cushioning material for daily necessities, toys, industrial materials, industrial supplies, and cooler boxes.

[0076] One embodiment of the drainage material is used in the plastic board drainage method, and comprises, for example, a plate-shaped core material with grooves formed on at least one side thereof extending the entire length in the longitudinal direction, and a sheet-shaped permeable material covering at least the grooved surface of the core material, the plate-shaped core material being a molded product of a biodegradable resin composition. This allows the drainage material structure to be maintained until soil consolidation is achieved, and the drainage material decomposes quickly after soil consolidation.

[0077] In one embodiment, the shell of a firework uses a biodegradable resin composition as a matrix that is completely or partially decomposed by microorganisms in soil or water (including seawater), and is molded by mixing this with an incompatible biodegradable resin or an insoluble natural organic material such as wood flour or rice husks, resulting in a heterogeneous structure with a mesh-like interface that is weaker than the matrix strength.The pressure at the time of explosion causes the shell to break down at the mesh-like interface into small pieces of about a few millimeters.

[0078] The downhole tool component of one embodiment can be used as a component of a frac plug. It is particularly preferred to use it as a mandrel, load ring, socket, cone, ball, or ball seat of a frac plug. By forming the downhole tool component into a molded article of the biodegradable resin composition, it is possible to mold it into a secondary molded product of a desired shape by machining such as cutting, drilling, or shearing, particularly a downhole tool component to be provided in a sealing plug.

[0079] One embodiment of the biodegradable stent comprises a stent body formed by braiding a plurality of filament threads made of a molded article of a biodegradable resin composition into a cylindrical braid, with elastic threads arranged on the outside of the stent body in the longitudinal direction. The elastic threads are arranged along at least a portion of the length of the stent body, including the vicinity of each end of the stent body. One end of the elastic thread is fixed near the end of the stent body, and the other end is fixed somewhere on the stent body. When the stent body is contracted, tension is applied to the elastic threads. As a result, when the stent body is expanded from the contracted state, the contractile force of the elastic threads acts near each end of the stent body to spread the stent body outward, thereby ensuring reliable expansion of the ends of the stent body.

[0080] In addition, since the molded article of the present invention has biocompatibility and biodegradability, it can be used in medical sensors and shape-memory materials, as well as battery materials, capacitors, and the like, where these properties are required.

[0081] [Method for Degrading Biodegradable Resins] The decomposition of biodegradable resins can be accelerated by adding the biodegradable resin decomposition accelerator of the present invention to the biodegradable resin. The type of biodegradable resin, the amount of biodegradable resin decomposition accelerator added, and the like are the same as those explained for the biodegradable resin composition of the present invention.

[0082] The decomposition-accelerating effect is obtained not only in the state of a composition containing a biodegradable resin decomposition accelerator and a biodegradable resin, but also in the state of a molded article of a biodegradable resin composition containing a biodegradable resin and a biodegradable resin decomposition accelerator.

[0083] The decomposition-accelerating effect can be obtained as long as the biodegradable resin decomposition accelerator and biodegradable resin are mixed together, and the decomposition can be carried out regardless of the environment. Therefore, the decomposition can be carried out either indoors or outdoors (including in soil and underwater).

[0084] The decomposition conditions (e.g., temperature, humidity, etc.) may be appropriately set according to the desired decomposition rate. Generally, the decomposition of biodegradable resins is accelerated under high temperature and humidity, so when it is desired to further accelerate the decomposition of biodegradable resins, it is advisable to carry out the decomposition method of the present invention under a high temperature and humidity environment.

[0085] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0086] In the examples of the present application, the acid value, hydroxyl value, and viscosity values ​​were evaluated by the following methods. <Method for measuring acid value> Measured by a method conforming to JIS K0070-1992. <Method for measuring hydroxyl value> Measured by a method conforming to JIS K0070-1992.

[0087] In the examples of the present application, the number average molecular weight of the polyester is a value calculated as polystyrene based on GPC measurement, and the measurement conditions are as follows. [GPC measurement conditions] Measurement apparatus: High-speed GPC apparatus "HLC-8320GPC" manufactured by Tosoh Corporation Column: "TSK GURDCOLUMN SuperHZ-L" manufactured by Tosoh Corporation + "TSK gel SuperHZM-M" manufactured by Tosoh Corporation + "TSK gel SuperHZM-M" manufactured by Tosoh Corporation + "TSK gel SuperHZ-2000" manufactured by Tosoh Corporation + "TSK gel SuperHZ-2000" manufactured by Tosoh Corporation Detector: RI (differential refractometer) Data processing: "EcoSEC Data Analysis Version 1.07" manufactured by Tosoh Corporation Column temperature: 40°C Developing solvent: tetrahydrofuran Flow rate: 0.35 mL / min Measurement sample: 7.5 mg of sample was dissolved in 10 ml of tetrahydrofuran, and the resulting solution was filtered through a microfilter to prepare the measurement sample. Sample injection amount: 20 μl Standard sample: The following monodisperse polystyrene with known molecular weight was used in accordance with the measurement manual for the "HLC-8320GPC".

[0088] (Monodisperse polystyrene) "A-300" manufactured by Tosoh Corporation "A-500" manufactured by Tosoh Corporation "A-1000" manufactured by Tosoh Corporation "A-2500" manufactured by Tosoh Corporation "A-5000" manufactured by Tosoh Corporation "F-1" manufactured by Tosoh Corporation "F-2" manufactured by Tosoh Corporation "F-4" manufactured by Tosoh Corporation "F-10" manufactured by Tosoh Corporation "F-20" manufactured by Tosoh Corporation "F-40" manufactured by Tosoh Corporation "F-80" manufactured by Tosoh Corporation "F-128" manufactured by Tosoh Corporation "F-288" manufactured by Tosoh Corporation

[0089] Synthesis Example 1 Synthesis of Decomposition Accelerator A 194 g of sebacic acid, 80 g of ethylene glycol, and 0.02 g of tetraisopropyl titanate as an esterification catalyst were charged into a 500 mL four-neck flask equipped with a thermometer, a stirrer, and a reflux condenser, and the temperature was raised stepwise to 220°C with stirring under a nitrogen stream. Stirring was continued at 220°C until the acid value reached 1 or less, and the generated water was continuously removed. After the reaction, 50 g of 4-aminobutyric acid was further charged into the reaction vessel, and the reaction was completed at 220°C to obtain Decomposition Accelerator A (white solid, acid value: 0.7 mgKOH / g, hydroxyl value: 106 mgKOH / g, number average molecular weight: 1,200, no residual amino groups).

[0090] The presence or absence of residual amino groups in decomposition accelerator A was confirmed by the ninhydrin reaction. Specifically, 100 mg of decomposition accelerator, 10 mg of ninhydrin, and 10 mL of benzyl alcohol were charged into a flask and stirred at 120°C for 10 minutes, after which the appearance of the solution was confirmed. If the solution was not colored, the ninhydrin reaction was determined to be negative, indicating that there were no residual amino groups. If the solution turned red to purple, the ninhydrin reaction was determined to be positive, indicating that there were residual amino groups.

[0091] Synthesis Example 2: Synthesis of Decomposition Accelerator B 204 g of sebacic acid and 65 g of ethylene glycol were charged into a 500 mL four-neck flask equipped with a thermometer, a stirrer, and a reflux condenser, and the temperature was raised stepwise to 220°C while stirring under a nitrogen stream. Stirring was continued at 220°C until the acid value reached 60 or less, and the generated water was continuously removed. After the reaction, 52 g of 4-aminobutyric acid was further charged into the reaction vessel, and the reaction was completed at 170°C to obtain Decomposition Accelerator B (white solid, acid value: 60 mgKOH / g, hydroxyl value: 86 mgKOH / g, number average molecular weight: 900, no residual amino groups).

[0092] (Synthesis Example 3: Synthesis of Decomposition Accelerator C) 169 g of sebacic acid and 77 g of 1,4-butanediol were charged into a 500 mL four-neck flask equipped with a thermometer, a stirrer, and a reflux condenser, and the temperature was raised stepwise to 200°C while stirring under a nitrogen stream. Stirring was continued at 220°C until the acid value reached 60 or less, and the generated water was continuously removed. After the reaction, 41 g of 4-aminobutyric acid was further charged into the reaction vessel, and the reaction was completed at 170°C to obtain decomposition accelerator C (white solid, acid value: 43 mgKOH / g, hydroxyl value: 71 mgKOH / g, number average molecular weight: 1,400, no residual amino groups).

[0093] Synthesis Example 4: Synthesis of Decomposition Accelerator D 204 g of sebacic acid and 65 g of ethylene glycol were charged into a 500 mL four-neck flask equipped with a thermometer, a stirrer, and a reflux condenser, and the temperature was raised stepwise to 220°C while stirring under a nitrogen stream. Stirring was continued at 220°C until the acid value reached 60 or less, and the generated water was continuously removed. After the reaction, 110 g of 12-aminolauric acid was further charged into the reaction vessel, and the reaction was completed at 190°C to obtain Decomposition Accelerator D (white solid, acid value: 56 mgKOH / g, hydroxyl value: 61 mgKOH / g, number average molecular weight: 1,200, no residual amino groups).

[0094] Synthesis Example 5: Synthesis of Decomposition Accelerator E 204 g of sebacic acid and 65 g of ethylene glycol were charged into a 500 mL four-neck flask equipped with a thermometer, a stirrer, and a reflux condenser, and the temperature was raised stepwise to 220°C while stirring under a nitrogen stream. Stirring was continued at 220°C until the acid value reached 60 or less, and the generated water was continuously removed. After the reaction, 76 g of methionine was further charged into the reaction vessel, and the reaction was completed at 200°C to obtain Decomposition Accelerator E (yellow paste, acid value: 25 mgKOH / g, hydroxyl value: 37 mgKOH / g, number average molecular weight: 800, no residual amino groups).

[0095] Synthesis Example 6: Synthesis of Decomposition Accelerator F 204 g of sebacic acid and 65 g of ethylene glycol were charged into a 500 mL four-neck flask equipped with a thermometer, a stirrer, and a reflux condenser, and the temperature was raised stepwise to 220°C while stirring under a nitrogen stream. Stirring was continued at 220°C until the acid value reached 60 or less, and the generated water was continuously removed. After the reaction, 75 g of glutamic acid was further charged into the reaction vessel, and the reaction was completed at 180°C to obtain Decomposition Accelerator F (white paste, acid value: 113 mgKOH / g, hydroxyl value: 56 mgKOH / g, number average molecular weight: 660, no residual amino groups).

[0096] Synthesis Example 7 Synthesis of Decomposition Accelerator G 142 g of sebacic acid, 22 g of ethylene glycol, and 37 g of 2-(2-aminoethoxy)ethanol were placed in a 500 mL four-neck flask equipped with a thermometer, a stirrer, and a reflux condenser, and the temperature was gradually increased to 220°C with stirring under a nitrogen stream. The generated water was continuously removed, thereby obtaining decomposition accelerator G (white paste, acid value: 58 mgKOH / g, hydroxyl value: 57 mgKOH / g, number average molecular weight: 1,100, no residual amino groups).

[0097] Synthesis Example 8 Synthesis of Decomposition Accelerator H 142 g of sebacic acid, 32 g of ethylene glycol, and 24 g of 3,3′-iminobis(propylamine) were charged into a 500 mL four-neck flask equipped with a thermometer, a stirrer, and a reflux condenser, and the temperature was gradually increased to 220° C. with stirring under a nitrogen stream. The generated water was continuously removed, thereby obtaining decomposition accelerator H (yellow paste, acid value: 44 mg KOH / g, hydroxyl value: 84 mg KOH / g, number average molecular weight: 600, no residual amino groups).

[0098] (Examples 1 to 8 and Reference Example 1: Biodegradability Test of Decomposition Accelerators) 200 g of seawater collected from the coast of Chiba Minato and 30 mg of a decomposition accelerator shown in Table 1 were placed in a glass container with a stirrer. ２ 10 mL of 0.2 M sodium hydroxide solution was further added as an absorbent, and the glass container was sealed and stirred continuously for 4 weeks in a thermostatic bath at 30° C. After stirring was completed, the unreacted sodium hydroxide was titrated with 0.1 M hydrochloric acid solution to measure the CO generated in the container.２ The amount of CO was calculated (the amount of NaOH before the test - the amount of HCl added). ２ Calculate the amount of CO generated and ２ Amount of CO ２ Amount generated (with decomposition accelerator) - CO ２ The amount of CO generated in the vessel (without decomposition accelerator) was calculated. ２ Amount of CO generated when the decomposition accelerator is completely biodegraded ２ The biodegradation rate of the decomposition accelerator was evaluated by multiplying the calculated amount by 100. The results are shown in Table 1.

[0099]

[0100] In Table 1, PHB in Reference Example 1 is polyhydroxybutyric acid, which is a biodegradable resin. It can be seen that the degradation accelerators of the Examples have biodegradability at the same level as known biodegradable resins.

[0101] (Examples 9-14 and Comparative Examples 1-2: Preparation and Evaluation of PBS Compositions) Biodegradable resin compositions were prepared by kneading the components shown in Table 2 at 130°C for 5 minutes using a mixer. The resulting biodegradable resin composition was hot-pressed to a thickness of 1 mm and then powdered using a frozen grinder ("JFC-300" manufactured by Japan Analytical Industry Co., Ltd.). 30 g of soil (water content: 30 wt%) collected from a field in Ichihara City, Chiba Prefecture, was mixed with 30 mg of the powdered biodegradable resin composition, and the resulting mixture was filled into a glass container. 3 mL of 1 M sodium hydroxide solution was added as a carbon dioxide absorbent to the glass container, and the glass container was then sealed and placed in a thermostatic chamber at 30°C. After 4 weeks, unreacted sodium hydroxide was titrated with 0.1 M hydrochloric acid solution to calculate the amount of carbon dioxide generated in the container (amount of NaOH before the test minus amount of HCl added). The same procedure as above was also performed on soil that did not contain the biodegradable resin composition to determine the amount of CO2. ２ Calculate the amount of CO generated and ２ Amount of CO ２ Amount generated (with biodegradable resin composition) - CO ２ The amount of CO generated (without the biodegradable resin composition) was calculated. ２Amount generated / CO generated when the biodegradable resin composition is completely biodegraded ２ The biodegradability was evaluated as the amount (calculated value) x 100. The results are shown in Table 2.

[0102] The polybutylene succinate used in Table 2 is "BioPBS FZ71PM" manufactured by PTT MCC Biochem.

[0103]

[0104] In Table 2, 4-aminobutyric acid in Comparative Example 1 is the amino acid used in Synthesis Example 1. It is presumed that 4-aminobutyric acid attracts and proliferates microorganisms in Comparative Example 1, thereby increasing biodegradability compared to the blank Comparative Example 2. However, because 4-aminobutyric acid is not very compatible with PBS, the degradation promoting effect is not as good as that of the degradation promoters in Examples 9-14.

[0105] (Examples 15-19 and Comparative Example 3: Preparation and Evaluation of PLA Compositions) Biodegradable resin compositions were prepared by kneading the components shown in Table 3 in a mixer at 170°C for 5 minutes. The resulting biodegradable resin composition was heat-pressed to a thickness of 1 mm, and the resulting film was cut into 2 cm x 2 cm pieces to prepare test specimens. A glass bottle was filled with soil (moisture content: 30 wt%) collected from a field in Ichihara City, Chiba Prefecture, and the test specimens were buried in the soil. The bottle was then closed and allowed to stand in a constant temperature bath at 45°C for two weeks. The change in the number-average molecular weight of polylactic acid in the test specimens before and after standing was measured, and the number-average molecular weight retention rate (number-average molecular weight of polylactic acid after standing / number-average molecular weight of polylactic acid before standing × 100) was calculated. In this test, the number average molecular weight was measured using a Tosoh Corporation "EcoSEC Data Analysis Version 1.15" system, because polylactic acid does not dissolve in tetrahydrofuran.

[0106] The polylactic acid used in Table 3 is "Luminy LX-175" manufactured by Total Corbion PLA.

[0107]

[0108] In Table 3, it can be seen that in Examples 15 to 19, the decomposition of PLA was accelerated by the decomposition accelerators of the synthesis examples (the number average molecular weight of PLA could not be maintained).

Claims

1. A biodegradable resin decomposition accelerator which is a polyester having as reaction components one or more amine compounds selected from the group consisting of aliphatic diamines, aliphatic aminocarboxylic acids, aromatic aminocarboxylic acids, and aliphatic aminoalcohols, one or more carbonyl compounds selected from the group consisting of aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and hydroxycarboxylic acids, and an aliphatic diol, wherein the number average molecular weight of the polyester is in the range of 300 to 5,000.

2. The biodegradable resin decomposition accelerator according to claim 1, wherein the amine compound is at least one selected from the group consisting of a compound represented by the following general formula (N-1), a compound represented by the following general formula (N-2), and a compound represented by the following general formula (N-3). (In the general formula (N-1), general formula (N-2) and general formula (N-3), R Ｎ１ is an alkylene group having 1 to 12 carbon atoms or a heteroalkylene group having 1 to 12 carbon atoms; R Ｎ２ is an alkylene group having 1 to 12 carbon atoms, a heteroalkylene group having 1 to 12 carbon atoms, an aryl group having 5 to 15 carbon atoms, or a heteroaryl group having 5 to 15 carbon atoms; R Ｎ３ is an alkylene group having 1 to 12 carbon atoms or a heteroalkylene group having 1 to 12 carbon atoms.

3. A biodegradable resin decomposition accelerator according to claim 1 or 2, wherein the carbonyl compound is one or more compounds selected from the group consisting of compounds represented by the following general formula (A) and compounds represented by the following general formula (L): (In the above general formula (A) and general formula (L), R Ａ is a single bond, an alkylene group having 1 to 12 carbon atoms, a heteroalkylene group having 1 to 12 carbon atoms, an aryl group having 5 to 15 carbon atoms, or a heteroaryl group having 5 to 15 carbon atoms; R Ｌ is an alkylene group having 1 to 18 carbon atoms or a heteroalkylene group having 1 to 18 carbon atoms.

4. A biodegradable resin decomposition accelerator according to claim 1 or 2, wherein the proportion of the amine compound in the reaction components is in the range of 10 to 35 mass %.

5. A biodegradable resin decomposition accelerator according to claim 1 or 2, wherein the polyester is a polyester having the aliphatic dicarboxylic acid and the aliphatic diol as reaction components, which is reacted with the amine compound.

6. A biodegradable resin composition comprising a biodegradable resin and the biodegradable resin decomposition accelerator according to claim 1 or 2.

7. The biodegradable resin composition according to claim 6, wherein the biodegradable resin is one or more selected from the group consisting of polylactic acid, polybutylene succinate, polybutylene adipate terephthalate, polyhydroxyalkanoic acid, polybutylene succinate adipate and polyethylene terephthalate succinate.

8. The biodegradable resin composition according to claim 6, containing the biodegradable resin decomposition accelerator in an amount ranging from 1 to 250 parts by mass per 100 parts by mass of the biodegradable resin.

9. A molded article made from the biodegradable resin composition according to claim 6.

10. A method for decomposing a biodegradable resin, which comprises adding the biodegradable resin decomposition promoter according to claim 1 or 2 to the biodegradable resin.

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