Composite structure, method for manufacturing composite structure, molded article, and method for manufacturing molded article

Abstract

An object of the present invention is to provide a composite structure which can control a high degradation rate of a biodegradable polymer and is excellent in toughness.SOLUTION: The composite structure of the present invention is a composite structure comprising a cyclic oligomer which is polyarylene sulfide, and a chain biodegradable polymer passing through an opening of the cyclic oligomer, wherein a mass ratio of the cyclic oligomer to 100% by mass of the composite structure is 0.01 to 10% by mass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a composite structure, a method for manufacturing a composite structure, a molded body, and a method for manufacturing a molded body. [Background technology]

[0002] In recent years, there has been a growing demand for effective utilization and recycling of carbon resources from the viewpoints of preventing environmental pollution and curbing global warming, and there is an increasing need for biodegradable polymers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-110156 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-089737 Summary of the Invention [Problem to be solved by the invention]

[0004] Challenges with biodegradable polymers include the rapid rate of decomposition depending on the usage environment, and the need to maintain physical properties that allow for use throughout their life. It is known to incorporate a specific amount of borate hydrate into a biodegradable polymer in order to adjust the biodegradation rate so as to delay biodegradation without significantly changing the mechanical properties, flexibility, and other properties of the biodegradable polymer (Patent Document 1). It is also known to add one or more additives selected from ultraviolet absorbers and light stabilizers to aliphatic polyester biodegradable resins to inhibit their biodegradation (Patent Document 2). However, when attempting to control the degradation rate by modifying the structure of biodegradable polymers without adding additives, there is a trade-off between the degradation rate and the physical properties, making it difficult to achieve both. In particular, it has been difficult to slow down the degradation rate and control the physical properties.

[0005] Therefore, an object of the present invention is to provide a composite structure that can adjust the rapid decomposition rate of a biodegradable polymer and has excellent toughness. [Means for solving the problem]

[0006] That is, the present invention is as follows. [1] A composite structure comprising a cyclic oligomer that is a polyarylene sulfide and a chain-like biodegradable polymer that penetrates an opening of the cyclic oligomer, The composite structure has a mass ratio of the cyclic oligomer of 0.01 to 10 mass % relative to 100 mass % of the composite structure. [2] The composite structure according to [1], which is a pseudorotaxane. [3] The composite structure according to [1] or [2], which has a crosslinked structure including a coordinate bond between a zinc atom and a sulfur atom in the cyclic oligomer. [4] The composite structure according to [1] or [2], wherein the cyclic oligomer is a 4 to 40-mer. [5] The method includes a polymerization step of polymerizing a chain-like biodegradable polymer from a monomer component, adding a cyclic oligomer which is a polyarylene sulfide during the polymerization; A method for producing the composite structure according to claim 1 or 2. [6] The method for producing a composite structure according to [5], wherein zinc chloride is added after the polymerization step. [7] A molded article comprising the composite structure according to [1] or [2]. [8] A method for producing a molded article, comprising a step of molding the composite structure according to [1] or [2]. [Effects of the Invention]

[0007] The composite structure of the present invention has the above-mentioned configuration, and therefore the rapid decomposition rate of the biodegradable polymer is controlled and the structure has excellent toughness. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating a test piece used in a tensile test. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the embodiments of the present invention will be described in detail. However, the present invention is not limited to the following description, and various modifications can be made within the scope of the present invention.

[0010] [Composite structure] The composite structure of this embodiment is a composite structure comprising a cyclic oligomer that is a polyarylene sulfide and a chain-like biodegradable polymer that penetrates the opening of the cyclic oligomer, and the mass ratio of the cyclic oligomer to 100 mass% of the composite structure is 0.01 to 10 mass%. In this specification, polyarylene sulfide may be referred to as "PAS."

[0011] <Cyclic Oligomer> The cyclic oligomer has a ring of repeating units connected together, and an opening inside the ring. The ring of repeating units may have a side chain. The cyclic oligomer may be used alone or in combination of two or more kinds. In this specification, one structural unit derived from one monomer component that constitutes an oligomer or polymer may be referred to as a “repeating unit.” The repeating unit is not limited to consecutive structural units, and may be a single structural unit.

[0012] The cyclic oligomer preferably contains a repeating unit represented by the following formula (1): The cyclic oligomer may be a homo-oligomer consisting of only the repeating unit represented by the following formula (1), or may be a hetero-oligomer further containing another repeating unit copolymerizable with the repeating unit. -(Ar-Z)- (1) (In formula (1), Ar represents an arylene group, and Z represents S, SO, or SO2.) Examples of the arylene group include divalent aromatic residues containing at least one benzene ring, such as o-phenylene, m-phenylene, p-phenylene, phenylene substituted with an alkyl group having 1 to 6 carbon atoms, phenyl-substituted phenylene, halogen-substituted phenylene, amino-substituted phenylene, and amido-substituted phenylene. Among these, from the viewpoints of being able to adjust the rapid decomposition rate of the biodegradable polymer and achieving even greater toughness, o-phenylene, m-phenylene, and p-phenylene are preferred, and p-phenylene is more preferred. Moreover, the above Z is preferably S (that is, a sulfur atom). The repeating unit represented by the formula (1) in the cyclic oligomer may be of one type or of multiple types.

[0013] The proportion of the repeating units represented by the above formula (1) relative to 100 moles of all repeating units contained in the above cyclic oligomer is preferably 80 mole % or more, more preferably 90 mole % or more, even more preferably 95 mole % or more, and particularly preferably 100 mole %, from the viewpoint of being able to adjust the fast decomposition rate of the biodegradable polymer and achieving even better toughness.

[0014] The other repeating units are preferably repeating units that do not contain an aromatic ring. The proportion of the other repeating units relative to 100 moles of all repeating units contained in the cyclic oligomer is preferably 10 mole % or less, more preferably 5 mole % or less.

[0015] The proportion of repeating units having an aromatic ring relative to 100 moles of all repeating units contained in the cyclic oligomer is preferably 80 mole % or more, more preferably 90 mole % or more, even more preferably 95 mole % or more, and particularly preferably 100 mole %. The repeating unit having an aromatic ring is preferably only the repeating unit represented by the formula (1).

[0016] From the viewpoint of being able to adjust the rapid decomposition rate of the biodegradable polymer and achieving even greater toughness, the cyclic oligomer is preferably a 40-40mer, more preferably a 5-25mer, even more preferably a 6-17mer, even more preferably an 8-15mer, and particularly preferably a 10-13mer.

[0017] The mass proportion of the cyclic oligomer relative to 100% by mass of the composite structure of this embodiment is 0.01 to 10% by mass, preferably 0.05 to 10% by mass, more preferably 0.1 to 10% by mass, and particularly preferably 0.5 to 10% by mass, from the viewpoint of being able to adjust the fast decomposition rate of the biodegradable polymer and achieving even better toughness.

[0018] The molecular weight of the cyclic oligomer is preferably 200 to 3,000, more preferably 400 to 2,500, and even more preferably 600 to 1,700, from the viewpoint of achieving even better toughness. The molecular weight can be measured by matrix-assisted laser desorption / ionization time-of-flight mass spectrometry.

[0019] (Method of Producing Cyclic Oligomers) The cyclic oligomer can be produced, for example, by a method comprising the steps of: (1) reacting a polyhaloaromatic compound with (i) an alkali metal sulfide or (ii) an alkali metal hydrosulfide and an alkali metal hydroxide in an organic polar solvent to obtain a crude reaction mixture containing at least a PAS resin, a cyclic PAS oligomer, a linear PAS oligomer, an alkali metal halide, and an organic polar solvent; (2) removing solid components from the crude reaction mixture by solid-liquid separation to obtain a liquid phase component (A) containing at least a cyclic PAS oligomer; and (3) obtaining the cyclic PAS oligomer from the liquid phase component (A).

[0020] -Process (1)- Step (1) is a step of reacting a polyhaloaromatic compound with (i) an alkali metal sulfide or (ii) an alkali metal hydrosulfide and an alkali metal hydroxide in an organic polar solvent to obtain a crude reaction mixture containing at least a PAS resin, a cyclic PAS oligomer, a linear PAS oligomer, an alkali metal halide, and an organic polar solvent.

[0021] The polyhalogenated aromatic compound can be, for example, a halogenated aromatic compound having two or more halogen atoms directly bonded to aromatic ring, specifically, p-dichlorobenzene, o-dichlorobenzene, m-dichlorobenzene, trichlorobenzene, tetrachlorobenzene, dibromobenzene, diiodobenzene, tribromobenzene, dibromonaphthalene, triiodobenzene, dichlorodiphenylbenzene, dibromodiphenylbenzene, dichlorobenzophenone, dibromobenzophenone, dichlorodiphenyl ether, dibromodiphenyl ether, dichlorodiphenyl sulfide, dibromodiphenyl sulfide, dichlorobiphenyl, dibromobiphenyl and other dihalogenated aromatic compounds and their mixtures, and these compounds can be block copolymerized.Among these, dihalogenated benzenes are preferred, and particularly preferred is that containing more than 80 mol% of p-dichlorobenzene.

[0022] Examples of polyhaloaromatic compounds having a nitro group include mono- or dihalonitrobenzenes such as 2,4-dinitrochlorobenzene and 2,5-dichloronitrobenzene; dihalonitrodiphenyl ethers such as 2-nitro-4,4'-dichlorodiphenyl ether; dihalonitrodiphenyl sulfones such as 3,3'-dinitro-4,4'-dichlorodiphenyl sulfone; mono- or dihalonitropyridines such as 2,5-dichloro-3-nitropyridine and 2-chloro-3,5-dinitropyridine; and various dihalonitronaphthalenes.

[0023] In the above production method, an alkali metal sulfide or an alkali metal hydrosulfide and an alkali metal hydroxide (hereinafter sometimes referred to as a sulfidizing agent) are used as raw materials.

[0024] The alkali metal sulfides include lithium sulfide, sodium sulfide, rubidium sulfide, cesium sulfide, and mixtures thereof. The alkali metal sulfides can be used as hydrates, aqueous mixtures, or anhydrides. The alkali metal sulfides can also be derived by reacting an alkali metal hydrosulfide with an alkali metal hydroxide. A small amount of alkali metal hydroxide may be added to react with the alkali metal hydrosulfide and alkali metal thiosulfate, which are usually present in trace amounts in the alkali metal sulfide.

[0025] The alkali metal hydrosulfides include lithium hydrogen sulfide, sodium hydrogen sulfide, rubidium hydrogen sulfide, cesium hydrogen sulfide, and mixtures thereof. Such alkali metal hydrosulfides can be used as hydrates, aqueous mixtures, or anhydrous forms.

[0026] The alkali metal hydrosulfide is used together with the alkali metal hydroxide. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide. These may be used alone or in combination of two or more. Among these, lithium hydroxide, sodium hydroxide, and potassium hydroxide are preferred because of their easy availability, and sodium hydroxide is particularly preferred.

[0027] In the above-mentioned production method, a hydrous sulfidizing agent can also be used as a raw material, and in this case, it is preferable to subject the hydrous sulfidizing agent to a polymerization reaction for the PAS resin after a step of dehydrating the agent in the presence of at least an aprotic polar solvent. Furthermore, when the amount of the aprotic polar solvent charged is small, for example, less than 1 mole per mole of sulfur atoms in the sulfidizing agent, it is preferable to dehydrate the hydrous sulfidizing agent and the aprotic polar solvent in the presence of a polyhaloaromatic compound.

[0028] The dehydration step of the hydrous sulfidizing agent is carried out by charging at least an aprotic polar solvent and a hydrous alkali metal sulfide or a hydrous alkali hydrosulfide and an alkali metal hydroxide as the hydrous sulfidizing agent into a reaction vessel equipped with a distillation apparatus, heating to a temperature at which water is removed azeotropically, specifically, in the range of 300°C or less, preferably 80 to 220°C, more preferably 100 to 200°C, and discharging water by distillation to the outside of the system. In the dehydration step, dehydration is preferably carried out until the amount of water in the polymerization system is 5 moles or less, more preferably 0.01 to 2.0 moles per mole of sulfur atoms in the sulfidizing agent.

[0029] Examples of the organic polar solvent include amides, ureas, and lactams such as formamide, acetamide, N-methylformamide, N,N-dimethylacetamide, tetramethylurea, N-methyl-2-pyrrolidone, 2-pyrrolidone, N-methyl-ε-caprolactam, ε-caprolactam, hexamethylphosphoramide, N-dimethylpropyleneurea, and 1,3-dimethyl-2-imidazolidinoic acid; sulfolanes such as sulfolane and dimethylsulfolane; nitriles such as benzonitrile; ketones such as methyl phenyl ketone; and mixtures thereof. Among these, amides having an aliphatic cyclic structure, such as N-methyl-2-pyrrolidone, 2-pyrrolidone, N-methyl-ε-caprolactam, ε-caprolactam, hexamethylphosphoramide, N-dimethylpropyleneurea, and 1,3-dimethyl-2-imidazolidinoic acid, are preferred, and N-methyl-2-pyrrolidone is more preferred.

[0030] The polymerization reaction in the PAS polymerization step involves reacting the above-mentioned alkali metal sulfide as a sulfidizing agent with a polyhaloaromatic compound in the presence of these organic polar solvents. Alternatively, the polymerization reaction involves reacting the above-mentioned alkali metal hydrosulfide and alkali metal hydroxide as sulfidizing agents with a polyhaloaromatic compound in the presence of these organic polar solvents. Polymerization conditions generally involve a temperature in the range of 200 to 330°C, and a pressure in a range that maintains the polymerization solvent and the polyhaloaromatic compound (polymerizable monomer) substantially in liquid phase, generally selected from the range of 0.1 to 20 MPa, preferably 0.1 to 2 MPa. The amount of polyhaloaromatic compound charged is adjusted to 0.2 to 5.0 moles, preferably 0.8 to 1.3 moles, and more preferably 0.9 to 1.1 moles per mole of sulfur atom in the sulfidizing agent. The amount of aprotic polar solvent used is adjusted to 1.0 to 6.0 moles, preferably 2.5 to 4.5 moles, per mole of sulfur atom in the sulfidizing agent. The polymerization reaction is preferably carried out in the presence of a small amount of water, the proportion of which is preferably adjusted appropriately depending on the polymerization method, the molecular weight of the resulting polymer, and productivity. Specifically, the dehydration operation is carried out so that the amount of water is 2.0 moles or less, preferably 1.6 moles or less, per mole of sulfur atom in the sulfidizing agent. Furthermore, when the dehydration operation is carried out in the presence of a polyhaloaromatic compound (for example, method "5") in the specific embodiment below), the amount of water is 0.9 moles or less, preferably 0.05 to 0.3 moles, and more preferably 0.01 to 0.02 moles.

[0031] Specific embodiments of polymerizing a sulfidizing agent and a polyhaloaromatic compound in the presence of the above-mentioned aprotic polar solvent include, for example, 1) A method using a polymerization aid such as an alkali metal carboxylate or a lithium halide, 2) A method using a branching agent such as an aromatic polyhalogen compound, 3) A method in which the polymerization reaction is carried out in the presence of a small amount of water, and then water is added to carry out further polymerization. 4) A method in which the gas phase portion of the reaction vessel is cooled during the reaction of the alkali metal sulfide with the aromatic dihalogen compound, and a part of the gas phase in the reaction vessel is condensed and refluxed to the liquid phase; 5) a production method comprising, as essential production steps, a step of reacting an alkali metal sulfide or a hydrous alkali metal hydrosulfide and an alkali metal hydroxide with an amide, urea or lactam having an aliphatic cyclic structure in the presence of a polyhalo-aromatic compound while dehydrating to produce a slurry containing a solid alkali metal sulfide; a step of adding a polar organic solvent such as NMP after producing the slurry and distilling off water to dehydrate it; and a step of reacting the polyhalo-aromatic compound, the alkali metal hydrosulfide, and the alkali metal salt of a hydrolyzate of the amide, urea or lactam having an aliphatic cyclic structure in the slurry obtained through the dehydration step, at a concentration of 0.02 mol or less of water present in the reaction system per 1 mol of the polar organic solvent such as NMP to polymerize it.

[0032] Thus, by polymerizing a dihaloaromatic compound with (i) an alkali metal sulfide or (ii) an alkali metal hydrosulfide and an alkali metal hydroxide in an organic polar solvent, a mixture of PAS resin, cyclic PAS oligomer, linear PAS oligomer, etc. Other substances remaining after the reaction may include by-products such as alkali metal-containing inorganic salts, carboxyalkylamino group-containing compounds, and terminal SH group-containing compounds, as well as unreacted raw materials and water.

[0033] -Process (2)- Step (2) is a step in which solid phase components are removed from the crude reaction mixture by solid-liquid separation to obtain at least a liquid phase component (A) containing cyclic PAS oligomers.

[0034] The solid-liquid separation is broadly divided into two types: a flash method and a quench method, which will be described later, with the quench method being preferred.

[0035] The quenching method separates particulate cyclic PAS oligomers by slowly cooling a crude reaction mixture. Typically, the crude reaction mixture is gradually cooled from a high-temperature, high-pressure state to crystallize the PAS resin in the reaction system, followed by solid-liquid separation (e.g., filtration) to separate the solids containing the PAS resin as granules and recover the liquid. Generally, as the molecular weight of a polymer increases, the interactions between the polymers become stronger, resulting in poorer solubility in the solvent. Therefore, in this process, the PAS resin precipitates as a solid, while the cyclic PAS oligomers remain dissolved in the solvent. While there are no particular limitations on the cooling time during the quenching process, a rate of 0.1°C / min to 3°C / min is typically preferred. Furthermore, the cooling rate does not need to be constant throughout the entire quenching process; for example, a rate of 0.1°C / min to 1°C / min is preferred until the PAS resin granules crystallize, followed by a rate of 1°C / min or faster is also preferred. Finally, it is preferable to cool the mixture to 70°C or higher, preferably 100°C or higher and 200°C or lower, and then remove the solid content including the PAS resin by solid-liquid separation. Examples of solid-liquid separation in the quench method include a method in which separation is performed by filtration or using a centrifuge such as a screw decanter, followed by adding water directly to the resulting filtration residue to form a slurry and then repeatedly performing solid-liquid separation, and a method in which the resulting filtration residue is heated in a non-oxidizing atmosphere to remove the remaining solvent.

[0036] In this case, if necessary, a step of removing a part or most of the organic polar solvent in the crude reaction mixture by distillation may be included, and after performing this step, the crude reaction mixture may be subjected to solid-liquid separation by filtration to remove solid phase components.Furthermore, a step of washing the crude reaction mixture, or preferably the solid fraction (slurry) obtained after solid-liquid separation, by contacting it with water or an organic polar solvent may be included.

[0037] -Process (3)- Step (3) is a step of obtaining a cyclic PAS oligomer from the liquid phase component (A). The method for obtaining the cyclic PAS oligomer from the liquid phase component (A) is not particularly limited, and any known method can be used as long as it does not impair the effects of the present invention. Examples include a method in which the organic polar solvent is removed by heating, the residue is washed with an organic solvent or water, and the cyclic PAS oligomer is extracted and purified using an organic solvent (see JP 2020-007490 A), and a method in which the organic polar solvent is removed using a membrane, the residue is washed with an organic solvent or water, and the cyclic PAS oligomer is extracted and purified using an organic solvent.

[0038] When removing the organic polar solvent, it is desirable to remove the solvent so that the nonvolatile content is in the range of 20 to 100% by mass, preferably 20 to 99.99% by mass, and more preferably 30 to 90% by mass. The temperature when removing the solvent by heating cannot be uniquely limited because it depends on the properties of the solvent used, but it can usually be selected from the range of 20 to 150°C, preferably 40 to 120°C. In addition, the pressure at which the solvent is removed is preferably atmospheric pressure or less, which allows the solvent to be removed at a lower temperature.

[0039] The purity of the cyclic PAS oligomer thus obtained is preferably 90% by mass or more, more preferably 96% by mass or more, and even more preferably 98% by mass or more, and is preferably 100% by mass or less, more preferably 99.99% by mass or less. Within this range, excellent mechanical properties can be exhibited while reducing gas generation during melt molding of a composite structure.

[0040] <Biodegradable polymer> The biodegradable polymer is chain-shaped. The chain-shaped biodegradable polymer may be linear or branched. Among these, a linear structure is preferred from the viewpoints of being able to adjust the rapid decomposition rate of the biodegradable polymer and achieving even greater toughness.

[0041] The biodegradable polymers include polylactic acid (PLA), polyethylene succinate (PES), polyethylene terephthalate succinate (PETS), polybutylene succinate (PBS), polybutylene adipate, polybutylene adipate terephthalate (PBAT), polybutylene adipate isonylate, polyethylene adipate terephthalate (PEAT), polybutylene succinate terephthalate (PBST), and polyethylene succinate terephthalate. (PEST), polybutylene succinate-adipate (PBSA), polybutylene succinate-carbonate (PEC), polybutylene succinate-adipate-terephthalate (PBSAT), polyethylene succinate-adipate-terephthalate (PESAT), polytetramethylene adipate-terephthalate (PTMAT), polyhydroxybutyrate (PHB), polyhydroxybutyrate-hydroxyhexanoate (PHBH), polycaprolactone (PCL), polycaprolactone Polybutene-butylene succinate (PCLBS), cellulose acetate, polyglycolic acid, polyhydroxyalkanoate, polybutylene succinate lactate, aliphatic polyamide resins (polyamide 6, polyamide 66, polyamide 610, polyamide 11, polyamide 12, polyamide 612, etc.), alicyclic polyamide resins (polymers of bis(aminomethyl)cyclohexane and adipic acid, etc.), aromatic polyamide resins (polyamide MXD (polymers of xylylenediamine and adipic acid), Examples of the polyamide resin include polymers of trimethylhexamethylenediamine and terephthalic acid, the aliphatic polyamide resins, the alicyclic polyamide resins, and copolyamides of the aromatic polyamide resins (copolyamides in which homopolyamide components are copolymerized, for example, copolyamide 6 / 66, copolyamide 6 / 11, copolyamide 66 / 12, etc.), polyester resins, polyesteramide resins, polyestercarbonate resins, polycarbonate resins, and those made from bio-derived raw materials such as polyaspartic acid. The above biodegradable polymers may be used alone or in combination of two or more.

[0042] The biodegradable polymer preferably contains an amorphous region, and may have an amorphous region and a crystalline region. In the composite structure of this embodiment, from the viewpoint of being able to adjust the rapid decomposition rate of the biodegradable polymer, it is preferable that cyclic oligomers are present in the amorphous region of the biodegradable polymer, and it is more preferable that cyclic oligomers are present in the amorphous region of the biodegradable polymer and that the biodegradable polymer has a pseudorotaxane structure.

[0043] The mass proportion of the biodegradable polymer relative to 100% by mass of the composite structure of this embodiment is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 92% by mass or more, and particularly preferably 94% by mass or more, and is preferably 99.99% by mass or less, more preferably 99.9% by mass or less, and even more preferably 99.5% by mass or less.

[0044] The total mass proportion of the cyclic oligomer and the biodegradable polymer relative to 100% by mass of the composite structure of this embodiment is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 80% by mass or more, and particularly preferably 100% by mass.

[0045] The composite structure of this embodiment is a structure in which the chain-like biodegradable polymer penetrates the opening of the cyclic oligomer. Examples of the structure in which the chain-like biodegradable polymer penetrates the opening of the cyclic oligomer include a rotaxane in which at least one end (preferably both ends) of the chain-like biodegradable polymer is blocked with a blocking group, and a pseudorotaxane in which the ends are not blocked with a blocking group. Among these, pseudorotaxanes are preferred from the viewpoint of ease of synthesis.

[0046] The number of cyclic oligomers threading through the chain-like biodegradable polymer is not particularly limited and may be 1 or more, but from the viewpoint of uniform dispersion of the polyarylene sulfide, it is preferable that the number is 2 or more.

[0047] Examples of the blocking group include dinitrophenyl groups, cyclodextrins, adamantane groups, trityl groups, fluoresceins, silsesquioxanes, pyrenes, substituted benzenes (substituents include, but are not limited to, alkyl, alkyloxy, hydroxy, halogen, cyano, sulfonyl, carboxyl, amino, phenyl, etc.; one or more substituents may be present), optionally substituted polynuclear aromatics (substituents include the same as those described above; one or more substituents may be present), and steroids.

[0048] The composite structure of the present embodiment preferably has a crosslinked structure, and from the viewpoint of achieving even greater toughness, it is more preferable that the sulfur atom in the cyclic oligomer has a crosslinked structure including a coordinate bond. The coordinate bond with the sulfur atom in the cyclic oligomer is preferably a coordinate bond between a certain atom and the sulfur atom in the cyclic oligomer. The certain atom may be a metal atom present in the matrix, for example, a metal atom contained in zinc chloride added in the production method described below. Examples of the certain atom that forms a coordinate bond with the sulfur atom in the cyclic oligomer include a zinc atom, an aluminum atom, an iron atom, a silver atom, a copper atom, and a gold atom. Among these, a zinc atom is preferred from the viewpoint of being able to adjust the rapid decomposition rate of the biodegradable polymer and achieving even greater toughness. That is, the composite structure of this embodiment preferably has a crosslinked structure including a coordinate bond between a zinc atom and a sulfur atom in the cyclic oligomer.

[0049] The number of days required for 20% decomposition in the decomposition test of the composite structure of this embodiment is preferably 2 days or more, and more preferably 4 days or more. The number of days required for 50% decomposition is preferably 6 days or more, more preferably 8 days or more, and even more preferably 10 days or more. The number of days required for decomposition in the above decomposition test can be measured by the method described in the Examples below.

[0050] The toughness of the composite structure of this embodiment is 80MJ / m3 It is preferable that the concentration is equal to or higher than 100MJ / m 3 That's all. The toughness can be measured by the method described in the Examples below.

[0051] <Manufacturing method> Examples of a method for producing the composite structure of this embodiment include a method of polymerizing a biodegradable polymer from a monomer component under conditions in which the cyclic oligomer, which is polyarylene sulfide, is present.

[0052] Although a method of mixing a cyclic oligomer with a biodegradable polymer has been known in the past, this method has not been able to obtain a chain-like biodegradable polymer structure that penetrates the opening of the cyclic oligomer. Furthermore, because polyarylene sulfide has a high tendency to aggregate, the cyclic oligomer (polyarylene sulfide) is not uniformly dispersed in a mixture of a cyclic oligomer and a biodegradable polymer, and the degradation rate of the biodegradable polymer cannot be sufficiently suppressed. Furthermore, adding a large amount of cyclic oligomer causes aggregation and reduces physical properties such as toughness, so there has been a need to improve physical properties while adjusting the degradation rate. In the manufacturing method of this embodiment, by adding a cyclic oligomer during polymerization of the biodegradable polymer, a composite structure can be obtained in which the cyclic oligomer, which is polyarylene sulfide, penetrates the linear biodegradable polymer. In the composite structure of this embodiment, the cyclic oligomer, which is polyarylene sulfide, can be uniformly dispersed near the biodegradable polymer, reducing the surface area where the biodegradable polymer is exposed, thereby suppressing enzymatic degradation. Furthermore, aggregation of the cyclic oligomer can be suppressed, resulting in excellent physical properties such as toughness. Furthermore, the presence of a crosslinked structure (preferably a mobile crosslinked structure) in the composite structure can adjust the rapid degradation rate of the biodegradable polymer, resulting in even better toughness.

[0053] The method for producing a composite structure of this embodiment preferably includes a polymerization step of polymerizing a chain-like biodegradable polymer from monomer components, and is a method in which a cyclic oligomer that is polyarylene sulfide is added during the polymerization.

[0054] The polymerization step may be a step of mixing the monomer components, the cyclic oligomer, and, if necessary, a catalyst, and polymerizing the mixture. Alternatively, a prepolymer of the monomer components may be used as an initiator.

[0055] The monomer component may be selected depending on the desired biodegradable polymer. For example, when the biodegradable polymer is polycaprolactone, the monomer component preferably contains at least ε-caprolactone, and more preferably is a monomer component consisting of only ε-caprolactone. When the biodegradable polymer contains multiple types of repeating units, it may contain multiple types of monomer components corresponding to the respective repeating units.

[0056] Examples of the catalyst used in the polymerization include organic tin acids such as tin 2-ethylhexanoate, tin halides such as tin chloride, diethylzinc, zinc lactate, iron lactate, dimethylaluminum, calcium hydride, organic alkali metal compounds such as butyllithium and t-butoxypotassium, metal porphyrin complexes, and metal alkoxides such as diethylaluminum methoxide.

[0057] The mass proportion of the cyclic oligomer relative to 100% by mass of the monomer component is preferably 0.001 to 25% by mass, more preferably 0.01 to 20% by mass, and even more preferably 0.1 to 10% by mass, from the viewpoint of being able to adjust the fast decomposition rate of the biodegradable polymer and achieving even better toughness.

[0058] The molar ratio of the catalyst added to 100 moles of the monomer component is preferably 0.00001 to 1 mole, and more preferably 0.001 to 0.05 mole.

[0059] In the method for producing a composite structure of this embodiment, it is preferable to add zinc chloride. Zinc chloride may be added before or after the polymerization step. Among these, adding zinc chloride after the polymerization step is preferable from the viewpoint of obtaining a composite structure with even greater toughness. In particular, it is preferable to polymerize a biodegradable polymer from monomer components under conditions containing the cyclic oligomer, which is polyarylene sulfide, to obtain a composite structure containing the cyclic oligomer, which is polyarylene sulfide, and a chain-like biodegradable polymer penetrating the opening of the cyclic oligomer, and then add zinc chloride continuously. Adding zinc chloride after the polymerization step can form a crosslinked structure containing a coordinate bond between a zinc atom and a sulfur atom in the cyclic oligomer, thereby improving toughness. The molar ratio of the zinc chloride added relative to 100 mol % of the cyclic oligomer may be 0.1 to 10 mol %.

[0060] The temperature in the polymerization step may be 10 to 200°C. The polymerization step may take from 10 minutes to 48 hours.

[0061] After the polymerization, unreacted monomers may be removed by purification, for example, by vacuum drying.

[0062] [Molded body] The molded article of this embodiment includes the composite structure of this embodiment described above. The molded article of this embodiment may consist of only the composite structure, or may further contain other components such as a mold release agent, a colorant, a heat stabilizer, an ultraviolet stabilizer, a foaming agent, a rust inhibitor, a flame retardant, a lubricant, a coupling agent, and a filler. The molded article may be a molded article obtained by melt-molding a composite structure. The method for producing a molded article according to the present embodiment includes a step of melt-molding the composite structure.

[0063] Examples of fillers include inorganic fillers of various shapes, such as fibrous ones and non-fibrous ones such as granular or plate-like ones. Specifically, fibrous fillers such as glass fiber, carbon fiber, silane glass fiber, ceramic fiber, aramid fiber, metal fiber, potassium titanate, silicon carbide, calcium silicate, wollastonite, and natural fibers can be used, as well as non-fibrous fillers such as glass beads, glass flakes, barium sulfate, clay, pyrophyllite, bentonite, sericite, mica, talc, attapulgite, ferrite, calcium silicate, calcium carbonate, glass beads, zeolite, milled fiber, and calcium sulfate.

[0064] The molded article may further contain a synthetic resin other than the cyclic oligomer and the biodegradable polymer, and an elastomer. Examples of the synthetic resin include polyester, polyamide, polyimide, polyetherimide, polycarbonate, polyphenylene ether, polysulfone, polyethersulfone, polyetheretherketone, polyetherketone, polyarylene, polyethylene, polypropylene, polytetrafluoroethylene, polydifluoroethylene, polystyrene, ABS resin, epoxy resin, silicone resin, phenolic resin, urethane resin, and liquid crystal polymer. Examples of the elastomer include polyolefin rubber, fluororubber, and silicone rubber.

[0065] The composite structure can be subjected to various molding processes, such as injection molding, compression molding, extrusion molding of composites, sheets, pipes, etc., pultrusion molding, blow molding, and transfer molding, but is particularly suitable for injection molding. When molding by injection molding, the molding conditions are not particularly limited, and molding can be performed using a typical method. For example, the composite structure can be melted in an injection molding machine at a resin temperature in a range equal to or higher than the melting point of the composite structure, preferably at a temperature equal to or higher than the melting point +10°C, more preferably at a temperature between the melting point +10°C and the melting point +100°C, and even more preferably at a temperature between the melting point +20°C and the melting point +50°C, and then injected into a mold through a resin outlet. The mold temperature can also be set within a known temperature range, for example, from room temperature (23°C) to 300°C, preferably 130°C to 190°C.

[0066] The method for producing a molded article according to this embodiment may include a step of annealing the molded article. The optimal conditions for the annealing treatment are selected depending on the application or shape of the molded article. The annealing temperature is preferably in a range equal to or higher than the glass transition temperature of the composite structure, preferably in a range equal to or higher than the glass transition temperature +10°C, and more preferably in a range equal to or higher than the glass transition temperature +30°C. The annealing time is preferably in a range equal to or lower than 260°C, and more preferably in a range equal to or lower than 240°C. The annealing time is not particularly limited, but is preferably in a range equal to or higher than 0.5 hours, and more preferably in a range equal to or higher than 1 hour. The annealing time is preferably in a range equal to or lower than 10 hours, and more preferably in a range equal to or lower than 8 hours. This range is preferable because it reduces distortion in the resulting molded article, improves the crystallinity of the resin, and further improves chemical resistance. The annealing treatment may be performed in air, but is preferably performed in an inert gas such as nitrogen gas.

[0067] <Application> The composite structure and molded article of this embodiment can be suitably used for design applications such as implants, DDS, wound dressings, and regenerative medicine systems, as well as agricultural applications such as multi-compost films. [Example]

[0068] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0069] The composite structure was fabricated in the following manner.

[0070] Example 1 10 g of ε-caprolactone and 50 μL of tin(II) 2-ethylhexanoate were mixed and heated to 60°C to remove water. Ethylene glycol was added and the mixture was allowed to react at 180°C for 30 minutes. After returning to room temperature, the mixture was dissolved in 50 mL of THF and added dropwise to methanol to remove unreacted monomers and catalyst. The mixture was then dried overnight in a windy oven at 50°C and then for 24 hours in a vacuum dryer at 60°C to remove the solvent, yielding a PCL-Diol prepolymer. 0.1g of PCL-Diol prepolymer, 2g of ε-caprolactone, 0.1g of PAS cyclic oligomer (cPPS), and 10μL of tin(II) 2-ethylhexanoate were mixed and heated to 60°C to remove water. Ethylene glycol was added and the mixture was reacted at 180°C for 30 minutes. After returning to room temperature, the mixture was dissolved in 20mL of THF. The mixture was dried overnight in a windy oven at 60°C and then in a vacuum dryer at 60°C for 24 hours to remove the solvent, yielding a composite structure. The cPPS used in the examples and comparative examples was produced by the following method. <Method of manufacturing cyclic PPS oligomer> A 150-liter autoclave equipped with a stirrer, a bottom valve, a pressure gauge, a thermometer, and a condenser was charged with 19.413 kg (150 mol) of flaky sodium sulfide (60.3 wt % NaS) and 45.0 kg (454 mol) of N-methyl-2-pyrrolidone (NMP). The mixture was heated to 209°C with stirring under a nitrogen stream, and 4.644 kg of water was distilled off (the remaining water content was 1.13 mol per mole of sodium sulfide). The autoclave was then sealed and cooled to 180°C. 21.631 kg (147 mol) of p-dichlorobenzene and 18.0 kg (182 mol) of NMP were then charged. At a liquid temperature of 150°C, the mixture was pressurized to 0.1 MPa using nitrogen gas, and the temperature was increased. The liquid temperature was raised to 240°C over 135 minutes and maintained at that temperature for 30 minutes. The liquid temperature was then raised to 250°C over 40 minutes and maintained at this temperature for 73 minutes to complete the reaction. The autoclave was then cooled. The bottom valve of the autoclave was opened at 100°C, and the reaction slurry was transferred to a 150-liter plate filter and pressure filtered at 120°C. 48.0 kg of NMP was added, and the cake was again pressure washed and filtered. The weight of the recovered NMP filtrate was 80.0 kg. Water was added to the resulting NMP filtrate to form a water slurry, which was then subjected to solid-liquid separation and water washing twice, followed by drying in a 120°C hot air dryer for 4 hours to obtain a powder. Chloroform was added to the resulting powder, and the mixture was stirred at 65°C for 1 hour. After cooling to room temperature, the mixture was filtered, and the residue was washed with 25°C chloroform. After removing the filtrate, the solid was dried in a 120°C hot air dryer for 4 hours to obtain 0.763 kg of cyclic PPS oligomer. Analysis of the resulting composite structure revealed that the openings of the cyclic oligomer were penetrated by chain polycaprolactone, and the mass ratio of the cyclic oligomer to 100 mass% was 5 mass%.

[0071] Example 2 A composite structure was obtained in the same manner as in Example 1, except that the amount of cPPS added was 0.2 g. Analysis of the obtained composite structure revealed that the openings of the cyclic oligomer were penetrated by linear polycaprolactone, and the mass ratio of the cyclic oligomer to 100 mass% was 10 mass%.

[0072] Example 3 A composite structure was obtained in the same manner as in Example 1, except that 0.66 mg of zinc chloride (0.5 mol % relative to the cyclic oligomer) was added when dissolving in 20 mL of THF. The composite structure of Example 3 had crosslinks involving coordinate bonds between zinc atoms and sulfur atoms in the cyclic oligomers. Analysis of the resulting composite structure revealed that the openings of the cyclic oligomer were penetrated by chain polycaprolactone, and the mass ratio of the cyclic oligomer to 100 mass% was 5 mass%.

[0073] Example 4 A composite structure was obtained in the same manner as in Example 1, except that 1.32 mg of zinc chloride (1 mol % relative to the cyclic oligomer) was added when dissolving in 20 mL of THF. The composite structure of Example 4 had crosslinks involving coordinate bonds between zinc atoms and sulfur atoms in the cyclic oligomers. Analysis of the resulting composite structure revealed that the openings of the cyclic oligomer were penetrated by chain polycaprolactone, and the mass ratio of the cyclic oligomer to 100 mass% was 5 mass%.

[0074] Example 5 A composite structure was obtained in the same manner as in Example 2, except that 0.66 mg of zinc chloride (0.25 mol % relative to the cyclic oligomer) was added when dissolving in 20 mL of THF. The composite structure of Example 5 had crosslinks involving coordinate bonds between zinc atoms and sulfur atoms in the cyclic oligomers. Analysis of the obtained composite structure revealed that the openings of the cyclic oligomer were penetrated by linear polycaprolactone, and the mass ratio of the cyclic oligomer to 100 mass% was 10 mass%.

[0075] Example 6 A composite structure was obtained in the same manner as in Example 2, except that 1.32 mg of zinc chloride (0.5 mol % relative to the cyclic oligomer) was added when dissolving in 20 mL of THF. The composite structure of Example 6 had crosslinks involving coordinate bonds between zinc atoms and sulfur atoms in the cyclic oligomers. Analysis of the obtained composite structure revealed that the openings of the cyclic oligomer were penetrated by linear polycaprolactone, and the mass ratio of the cyclic oligomer to 100 mass% was 10 mass%.

[0076] Example 7 10 g of ε-caprolactone and 50 μL of tin(II) 2-ethylhexanoate were mixed and heated to 60°C to remove water. Ethylene glycol was added and the mixture was allowed to react at 180°C for 30 minutes. After returning to room temperature, the mixture was dissolved in 50 mL of THF and added dropwise to methanol to remove unreacted monomers and catalyst. The mixture was then dried overnight in a windy oven at 50°C and then for 24 hours in a vacuum dryer at 60°C to remove the solvent, yielding a PCL-Diol prepolymer. 1.2 g of PCL-Diol prepolymer and 60 mg of PAS cyclic oligomer (cPPS) were dissolved in 20 mg of THF. The THF was removed using an evaporator, and the mixture was then dried under reduced pressure at 90°C for 12 hours to remove moisture. The mixture was then dissolved in 7 mL of dehydrated toluene, followed by the addition of 25 mg of 4,4'-methylenediphenyl diisocyanate and 3 μL of dibutyltin(II) dilaurate. The mixture was then reacted at 90°C for 2 hours under a nitrogen atmosphere. The mixture was then dissolved in 10 mL of THF and dried in a windy oven at 80°C for 3 hours, followed by 12 hours in a vacuum dryer at 80°C to remove the solvent, yielding a composite structure. Analysis of the resulting composite structure revealed that the openings of the cyclic oligomer were penetrated by chain polycaprolactone, and the mass ratio of the cyclic oligomer to 100 mass% was 5 mass%.

[0077] Example 8 A composite structure was obtained in the same manner as in Example 7, except that the amount of cPPS added was 120 mg. Analysis of the obtained composite structure revealed that the openings of the cyclic oligomer were penetrated by linear polycaprolactone, and the mass ratio of the cyclic oligomer to 100 mass% was 10 mass%.

[0078] (Comparative Example 1) A structure was obtained in the same manner as in Example 1, except that cPPS was not added.

[0079] (Comparative Example 2) A structure was obtained in the same manner as in Example 3, except that cPPS was not added.

[0080] (Comparative Example 3) A structure was obtained in the same manner as in Example 4, except that cPPS was not added.

[0081] Comparative Example 4 10 g of ε-caprolactone and 50 μL of tin(II) 2-ethylhexanoate were mixed and heated to 60°C to remove water. Ethylene glycol was added and the mixture was allowed to react at 180°C for 30 minutes. After returning to room temperature, the mixture was dissolved in 50 mL of THF and added dropwise to methanol to remove unreacted monomers and catalyst. The mixture was then dried overnight in a windy oven at 50°C and then for 24 hours in a vacuum dryer at 60°C to remove the solvent, yielding a PCL-Diol prepolymer. 1.2 g of PCL-Diol prepolymer was dissolved in 20 mg of THF, and the THF was removed using an evaporator. The mixture was then dried under reduced pressure at 90°C for 12 hours to remove moisture. After dissolving in 7 mL of dehydrated toluene, 25 mg of 4,4'-methylenediphenyl diisocyanate and 3 μL of dibutyltin(II) dilaurate were added and the reaction was carried out at 90°C for 2 hours under a nitrogen atmosphere. 60 mg of PAS cyclic oligomer (cPPS) was then added and dissolved in 10 mL of THF. The mixture was then dried in a windy oven at 80°C for 3 hours, and then in a vacuum dryer at 80°C for 12 hours to remove the solvent, yielding the structure. Analysis of the obtained structure revealed that no structure in which chain polycaprolactone threaded through the opening of the cyclic oligomer was present, and the mass ratio of the cyclic oligomer to 100 mass% was 5 mass%.

[0082] (Comparative Example 5) A structure was obtained in the same manner as in Comparative Example 4, except that the amount of cPPS added was 120 mg. Analysis of the obtained structure revealed that no structure in which chain polycaprolactone threaded through the opening of the cyclic oligomer was present, and the mass ratio of the cyclic oligomer to 100 mass% was 10 mass%.

[0083] (Comparative Example 6) A structure was obtained in the same manner as in Example 7, except that cPPS was not added.

[0084] The composite structures obtained in the examples and comparative examples were subjected to the following measurements.

[0085] <Evaluation> (1) Decomposition test The composite structures obtained in each example and comparative example were pressed into a dumbbell mold with a thickness of 300 μm, a straight portion of 2 mm × 12 mm, and a test piece length including the grip portion of 35 mm at 90°C under a compressive force of 7 kN for 5 minutes to obtain test pieces (Fig. 1). Lipase (Burkholderia cepacia LP-7, Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in phosphate buffer to prepare a 0.5 mg / L lipase dispersion, to which the test specimens were placed and slowly shaken in an incubator temperature-controlled at 37°C. The test specimens were removed every 0.5 days and weighed to measure the amount of decomposition. Measurements were then taken at the time when the weight had decreased by 20% and 50% from the start of the test.

[0086] (2) Toughness The composite structures obtained in each example and comparative example were pressed into a dumbbell mold with a thickness of 300 μm, a straight portion of 2 mm × 12 mm, and a test piece length including the grip portion of 35 mm at 90°C under a compressive force of 7 kN for 5 minutes to obtain test pieces (Fig. 1). Tensile tests were carried out using a Shimadzu Autograph AG-X at a tensile speed of 1.0 mm / s, and the toughness (MJ / m3 ) was calculated.

[0087] [Table 1]

Claims

1. A composite structure comprising a cyclic oligomer that is a polyarylene sulfide and a chain-like biodegradable polymer that penetrates an opening of the cyclic oligomer, A composite structure in which the mass ratio of the cyclic oligomer to 100 mass% of the composite structure is 0.01 to 10 mass%.

2. The composite structure of claim 1 which is a pseudorotaxane.

3. 3. The composite structure according to claim 1, having a crosslinked structure comprising a coordinate bond between a zinc atom and a sulfur atom in the cyclic oligomer.

4. 3. The composite structure according to claim 1, wherein the cyclic oligomer is a 4- to 40-mer.

5. The method includes a polymerization step of polymerizing a chain-like biodegradable polymer from a monomer component, adding a cyclic oligomer which is a polyarylene sulfide during the polymerization; A method for manufacturing the composite structure according to claim 1 or 2.

6. The method for producing a composite structure according to claim 5 , wherein zinc chloride is added after the polymerization step.

7. A molded article comprising the composite structure according to claim 1 or 2.

8. A method for producing a molded article, comprising the step of molding the composite structure according to claim 1 or 2.

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