Degradation accelerator for biodegradable resin, biodegradable resin composition, method for degrading biodegradable resin and molded article

Abstract

Provided is a biodegradability accelerator for improving the biodegradability of a biodegradable resin. Specifically, the degradation accelerator for a biodegradable resin is an amide ester comprising reaction constituents that are an amino alcohol and at least one dicarboxylic acid selected from the group consisting of aliphatic dicarboxylic acids and aromatic dicarboxylic acids.

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 in a wide range of applications. While these plastics have excellent mechanical properties, they are not easily degraded. In recent years, there has been a growing trend to switch from general-purpose plastics to biodegradable resins in light of the increasing 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 long period of time, from 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 and 2).

[0006] 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 an amide ester to the biodegradable resin, and thus completed the present invention.

[0009] That is, the present invention relates to a biodegradable resin decomposition accelerator, etc. 1. A biodegradable resin decomposition accelerator that is an amide ester having an amino alcohol and one or more dicarboxylic acids selected from the group consisting of aliphatic dicarboxylic acids and aromatic dicarboxylic acids as reaction components. 2. The biodegradable resin decomposition accelerator according to 1, wherein the amino alcohol is a compound represented by the following general formula (N): (In the general formula (N), R Ｎ 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 dicarboxylic acid is a compound represented by the following general formula (A): (In the general formula (A), 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. 4. The biodegradable resin degradation accelerator according to any one of 1 to 3, wherein the amide ester has a number average molecular weight of less than 2,000. 5. The biodegradable resin degradation accelerator according to any one of 1 to 4, wherein the amide ester does not contain an amino group. 6. A biodegradable resin composition containing a biodegradable resin and the biodegradable resin degradation accelerator according to any one of 1 to 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 degradation accelerator] The biodegradable resin degradation accelerator of the present invention is an amide ester having as reaction components an amino alcohol (N) and one or more dicarboxylic acids (A) selected from the group consisting of aliphatic dicarboxylic acids and aromatic dicarboxylic acids. The above "reaction components" mean components that constitute the amide ester, which is the biodegradable resin degradation accelerator of the present invention, and do not include solvents or catalysts that do not constitute the amide ester.

[0013] The amide ester, which is the biodegradable resin decomposition accelerator of the present invention (hereinafter sometimes referred to as the "amide ester of the present invention"), contains a nitrogen atom in its structure, which is known as a nutrient source for microorganisms, and is therefore presumed to attract and proliferate microorganisms, thereby promoting the decomposition of biodegradable resins.

[0014] Amino acids are compounds containing nitrogen atoms in their structure, but because amino acids generally have high polarity and high melting points, they have the problem of poor compatibility with biodegradable resins, which will be described later. In the present invention, amino acids are derived into amide esters using amino alcohols (N) and dicarboxylic acids (A) as reaction components, which lower the melting point and polarity and increase the compatibility with biodegradable resins.

[0015] The amide ester of the present invention is an amide ester in which an amino alcohol and a dicarboxylic acid are reactants, and does not use a component such as glycol as a reactant, so that the amide bond concentration (nitrogen concentration) is high and a higher effect of promoting the degradation of biodegradable resins can be expected. Each reactant of the amide ester is explained below.

[0016] (Aminoalcohol (N)) The aminoalcohol (N) is a compound having a hydroxy group and an amino group, and is preferably a compound represented by the following general formula (N).

[0017] (In the general formula (N), R Ｎ is an alkylene group having 1 to 12 carbon atoms or a heteroalkylene group having 1 to 12 carbon atoms.

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

[0019] R Ｎ 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 formula (N), R Ｎ 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—). ＮThe 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] Specific examples of the amino alcohol (N) 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 amino alcohol (N) used may be one type alone, or two or more types may be used in combination.

[0022] (Dicarboxylic Acid (A)) The dicarboxylic acid (A) is a compound having two carboxyl groups, and is preferably a compound represented by the following general formula (A).

[0023] (In the general formula (A), 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.

[0024] The alkylene group having 1 to 12 carbon atoms and the heteroalkylene group having 1 to 12 carbon atoms in the general formula (A) are the same as the alkylene group having 1 to 12 carbon atoms and the heteroalkylene group having 1 to 12 carbon atoms in the general formula (N), respectively.

[0025] R Ａ The alkylene group having 1 to 12 carbon atoms is preferably an alkylene group having 2 to 12 carbon atoms.

[0026] R ＡSpecific 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.

[0027] R Ａ Examples of the aryl group having 5 to 15 carbon atoms include a phenylene group and a naphthalenylene group.

[0028] R Ａ 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.

[0029] R Ａ 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.

[0030] Specific examples of the dicarboxylic acid (A) include oxalic acid, succinic acid, adipic acid, maleic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, cyclohexanedicarboxylic acid, dodecanedicarboxylic acid, hexahydrophthalic acid, phthalic acid, furandicarboxylic acid, etc., and preferred are succinic acid, sebacic acid, maleic acid, adipic acid, etc. The dicarboxylic acid used may be one type alone or two or more types may be used in combination.

[0031] The reaction components of the amide ester of the present invention may contain an amino alcohol (N) and a dicarboxylic acid (A), and may contain other components. The reaction components of the amide ester of the present invention preferably contain 90 mass % or more of the amino alcohol (N) and the dicarboxylic acid (A) relative to the total amount of the reaction components, more preferably 95 mass % or more of the amino alcohol (N) and the dicarboxylic acid (A), and even more preferably consist of only the amino alcohol (N) and the dicarboxylic acid (A). The amide ester of the present invention preferably does not contain glycol as a reaction component.

[0032] In the reaction components, the contents of the amino alcohol (N) and the dicarboxylic acid (A) may be set, for example, so that the equivalent of the carboxyl group derived from the dicarboxylic acid (A) contained in the reaction components is the same as or less than the total equivalent of the amino group and the hydroxyl group derived from the amino alcohol (N).

[0033] The reaction of the amino alcohol (N) with the dicarboxylic acid (A) is not particularly limited and may be carried out by a known method, for example, by carrying out an amide esterification reaction in the presence of a catalyst as needed at a temperature of 180 to 250° C. for 10 to 25 hours. The conditions for the amide esterification reaction, such as the temperature and time, are not particularly limited and may be set appropriately.

[0034] Examples of the 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.

[0035] The amount of the 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.

[0036] For example, in the reaction between an amino acid and a dicarboxylic acid, the amino acid undergoes a self-condensation reaction preferentially, which makes it difficult to react with the dicarboxylic acid. However, in the present invention, an amino alcohol is used as the reactive component, so the self-condensation reaction does not occur, and the reaction can proceed more smoothly.

[0037] The amide ester of the present invention preferably does not contain an amino group. The absence of an amino group in the amide ester ensures dispersibility in the biodegradable resin, for example, when mixed with a biodegradable resin. The absence of an amino group in the amide ester is confirmed by the method described in the Examples. Since amides are structurally more stable than esters and amides are preferentially formed during the reaction, an amide ester not containing an amino group can be obtained, for example, by setting the equivalent of carboxyl groups derived from the dicarboxylic acid (A) contained in the reaction components to be greater than the equivalent of amino groups derived from the amino alcohol (N).

[0038] The upper limit of the number average molecular weight (Mn) of the amide ester of the present invention is preferably less than 2,000, more preferably not more than 1,800, and even more preferably not more than 1,500. The lower limit of the number average molecular weight (Mn) of the amide ester of the present invention is preferably not less than 200, more preferably not less than 300, and even more preferably not less than 500. 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.

[0039] The acid value of the amide ester 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 amide ester 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, in that order. The acid value of the amide ester is confirmed by the method described in the Examples.

[0040] The hydroxyl value of the amide ester 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 amide ester is confirmed by the method described in the Examples.

[0041] The properties of the amide ester 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).

[0042] [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. By containing the biodegradable resin composition with the biodegradable resin degradation accelerator of the present invention, the decomposition of the biodegradable resin can be further accelerated.

[0043] 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.

[0044] 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.

[0045] The polyhydroxyalkanoic acid includes polyhydroxybutyric acid (PHB), polyhydroxybutyric acid-hydroxyhexanoic acid (PHBH), and the like.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] The biodegradable resin composition of the present invention may further contain a plasticizer. 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] [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.

[0056] [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.

[0057] 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.).

[0058] 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.

[0059] [Uses of Molded Articles] Molded articles obtained from the biodegradable resin composition of the present invention are suitable for a wide range of uses, such as packaging materials for packaging liquids, powders, and solids, agricultural materials, construction materials, etc. Specific uses 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.), blown-molded articles (bottles, etc.), etc.

[0060] It can also be used in 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 for medical purposes, surgical threads, sutures, artificial bones, artificial skin, microcapsules, wound dressings, etc.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] [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.

[0072] 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.

[0073] 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).

[0074] 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.

[0075] 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.

[0076] In the examples of the present application, the acid value, hydroxyl value, and molecular weight 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.

[0077] In the examples of the present application, the number average molecular weight 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".

[0078] (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

[0079] Synthesis Example 1: Synthesis of Decomposition Accelerator A 283 g of sebacic acid and 147 g of 2-(2-aminoethoxy)ethanol were placed in a 1 L four-neck flask equipped with a thermometer, a stirrer, and a reflux condenser, and the temperature was raised stepwise while stirring under a nitrogen stream. The temperature was raised to 220°C, and the mixture was stirred for 2 hours, with the generated water being continuously removed. This yielded Decomposition Accelerator A (white paste, number average molecular weight: 940, acid value: 49 mg KOH / g, hydroxyl value: 47 mg KOH / g, ninhydrin reaction: negative), which was an amide ester of sebacic acid and ethylene glycol in which all amino groups had been converted to amide groups.

[0080] 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.

[0081] (Example 1 and Reference Example 1: Biodegradability test of decomposition accelerator) 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 equipped with a pressure sensor ("Oxitop-IDS" manufactured by WTW Co., Ltd.) with a stirrer. ２ Granular sodium hydroxide was placed as an absorbent, and the glass container was sealed and stirred continuously for 4 weeks in a thermostatic chamber at 30°C. During the stirring, the decomposition accelerator was decomposed using the oxygen in the container, releasing carbon dioxide. The released carbon dioxide was CO ２ The absorbent absorbs the water, and the internal pressure decreases accordingly. This decrease in internal pressure is measured by a pressure sensor, and the biochemical oxygen demand (BOD, [mg L －１] was calculated. The BOD of seawater containing no decomposition accelerator was also measured in the same manner as above, and the BOD due to biodegradation of the decomposition accelerator (BOD (with decomposition accelerator) - BOD (without decomposition accelerator)) was calculated. The biodegradation rate of the decomposition accelerator was evaluated as (BOD due to biodegradation x seawater volume) / (theoretical oxygen demand x sample volume) x 100. The results are shown in Table 1. Note that biochemical oxygen demand means the amount of oxygen required to decompose organic matter contained in 1 L of soil.

[0082]

[0083] In Table 1, PHB in Reference Example 1 is polyhydroxybutyric acid, which is a biodegradable resin. It can be seen that the decomposition accelerators in the synthesis examples have necessary and sufficient biodegradability.

[0084] (Example 2 and Comparative Example 1: Preparation and Evaluation of PBS Composition) A biodegradable resin composition was prepared by kneading the components shown in Table 2 at 130°C for 5 minutes using a mixer. The obtained biodegradable resin composition was hot-pressed to a thickness of 1 mm and then powdered using a freeze-grinding machine ("JFC-300" manufactured by Japan Analytical Industry Co., Ltd.). 30 g of soil (moisture 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 equipped with a pressure sensor ("Oxitop-IDS" manufactured by WTW Corporation). CO was measured in the glass container. ２ Granular sodium hydroxide was placed as an absorbent, and the glass container was sealed and stirred continuously for 4 weeks in a thermostatic bath at 30°C. The BOD associated with the biodegradation of the biodegradable resin composition was confirmed with a pressure sensor. The BOD of soil not containing the biodegradable resin composition was also measured using the same procedure as above, and the BOD due to the biodegradation of the biodegradable resin composition (BOD (with biodegradable resin composition) - BOD (without biodegradable resin composition)) was calculated. The biodegradation rate of the biodegradable resin composition was then evaluated as (BOD due to biodegradation x seawater volume) / (theoretical oxygen demand x sample amount) x 100. The results are shown in Table 2.

[0085] The "PBS (polybutylene succinate)" used in Table 2 is "BioPBS FZ71PM" manufactured by PTT MCC Biochem.

[0086]

[0087] From the perspective of nitrogen content alone, the amino acid glycine has a higher nitrogen content than the degradation accelerator of the synthesis example, but as shown in the results in Table 2, the degradation accelerator of the synthesis example exhibits a higher biodegradation-promoting property than glycine. This is presumably because the "amide ester" form has high compatibility with polybutylene succinate, resulting in a more effective degradation-promoting effect.

Claims

1. A biodegradable resin decomposition accelerator which is an amide ester having as reaction components an amino alcohol and one or more dicarboxylic acids selected from the group consisting of aliphatic dicarboxylic acids and aromatic dicarboxylic acids.

2. The biodegradable resin decomposition accelerator according to claim 1, wherein the amino alcohol is a compound represented by the following general formula (N): (In the general formula (N), R Ｎ 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 claim 1, wherein the dicarboxylic acid is a compound represented by the following general formula (A): (In the general formula (A), 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.

4. The biodegradable resin decomposition accelerator according to claim 1, wherein the number average molecular weight of the amide ester is less than 2,000.

5. The biodegradable resin decomposition accelerator according to claim 1, wherein the amide ester does not contain an amino group.

6. A biodegradable resin composition containing a biodegradable resin and the biodegradable resin decomposition accelerator according to any one of claims 1 to 5.

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, which contains 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 accelerator described in any one of claims 1 to 5 to the biodegradable resin.

Images