Marine biodegradable polyester

Abstract

To develop a technique for controlling the marine biodegradability of a polyester such as poly(n-alkylene n-alkylene dicarboxylate), and a marine biodegradable polyester using the technique.SOLUTION: The present invention provides a marine biodegradable polyester comprising a structure represented by the general formula (I) in the figure, where x represents an integer equal to or greater than 1, y represents an integer equal to or greater than 0, and m represents an integer equal to or greater than 2.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for producing a polyester, such as poly(n-alkylene-n-alkylene dicarboxylate). The present invention relates to a method for controlling marine biodegradability and marine biodegradable polyesters, etc. [Background technology]

[0002] In recent years, from the perspective of the SDGs, biodegradable polymers with low environmental impact, especially marine biodegradable polymers that decompose in the ocean, have been attracting increasing attention. This is because the ocean is the final destination of polymeric materials that are discharged, so it is important for biodegradable polymers to exhibit biodegradability in the ocean. However, the biodegradability of biodegradable polymers is highly dependent on the environment. Even if a polymer shows biodegradability in soil, there are few polymers that show biodegradability in the ocean. This is thought to be due to the fact that there are few microorganisms in the ocean, and the microbial flora is different from that in soil, making it difficult for microorganisms to attach and grow, and for enzymes to decompose the polymers to be produced.

[0003] Hydroxycarboxylic acid-based aliphatic polyesters are well known as biodegradable polymers. Among them, polyesters with long methylene chains show properties comparable to those of polyethylene (PE), and are therefore expected to be a substitute for PE (Non-Patent Document 1). The number of methylene chains affects not only physical properties but also biodegradability. Regarding the relationship between the number of methylene chains and biodegradability, the present inventors have previously investigated the relationship between the number of methylene chains in poly(n-alkylene-n-alkylene dicarboxylate) (PAAD), an aliphatic polyester. It was revealed that the longer the exposure time, the lower the biodegradability in the soil environment (Non-Patent Document 2). On the other hand, little research has been done on the marine biodegradation of PAAD. However, even polybutylene succinate (PBSu), which is commercially available as a biodegradable polymer, is known not to degrade in the ocean.

[0004] On the other hand, the relationship between enzymatic hydrolysis and molecular weight has been reported for polylactic acid (PLA), It is known that the enzymatic hydrolysis increases with increasing molecular weight (Non-Patent Document 3). However, no systematic study has been conducted on the marine biodegradability and molecular weight of PAAD. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Ortmann, P.; Mecking, S. Long-Spaced Aliphatic Polyesters. Macromolecules 2013, 46 (18), 7213-7218. [Non-Patent Document 2] Baba, T.; Tachibana, Y.; Suda, S.; Kasuya, K. Evaluation of Environmental Degradability Based on the Number of Methylene Units in Poly(Butylene n-Alkylenedionate). Polym. Degrad. Stab. 2017, 138, 18-26. [Non-Patent Document 3] Tsuji, H.; Miyauchi, S. Enzymatic Hydrolysis of Poly(Lactide)s: Effects of Molecular Weight, l -Lactide Content, and Enantiomeric and Diastereoisomeric Polymer Blending. Biomacromolecules 2001, 2 (2), 597-604. Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, there is a high demand for marine biodegradable polymers, but the technology for controlling marine biodegradability has not been fully established. In view of the above circumstances, the present invention provides a technology for controlling the marine biodegradability of polyesters such as poly(n-alkylene-n-alkylene dicarboxylate) (PAAD) and a method for controlling the marine biodegradability of polyesters using the technology. The objective is to develop polyester. [Means for solving the problem]

[0007] The present inventors have conducted intensive research to solve the above problems. Specifically, in order to develop PAAD that can exhibit biodegradability in the ocean, PAADs with different molecular weights were prepared according to the methylene chain length, and their marine biodegradability was systematically evaluated by a microbial oxygen demand (BOD) biodegradability test. This study clarified the "dependence of PAAD biodegradation in the ocean on the number of methylene chains and molecular weight," making it possible to create marine biodegradable polyesters. Based on this knowledge, the present invention was completed. That is, the gist of the present invention relates to the following.

[0008] [1] A marine biodegradable polyester comprising a structure represented by the following general formula (I):

[0009] [ka]

[0010] (In the formula, x represents an integer of 1 or more, y is an integer equal to or greater than 0; m represents an integer of 2 or more. [2] The marine biodegradable polyester according to [1], wherein x and y are each independently an integer of 2 to 100. [3] The marine biocide according to [1], wherein x and y are each independently an integer between 2 and 45. Degradable polyester. [4] The marine biocide according to [1], wherein x and y are each independently an integer between 2 and 14. Degradable polyester. [5] The marine biodegradable polyester according to [1], wherein m is an integer of 2 to 100. [6] The marine biodegradable polyester according to any one of [1] to [5], having a number average molecular weight (Mn) of 10,000 or less. [7] A marine biodegradable resin composition comprising the marine biodegradable polyester according to any one of [1] to [6]. [8] A molded article formed from the marine biodegradable resin composition described in [7]. [9] A method for producing a marine biodegradable polyester comprising the structure represented by the following general formula (I): So, A method of manufacturing comprising controlling x, y and m.

[0011] [ka]

[0012] (In the formula, x represents an integer of 1 or more, y is an integer equal to or greater than 0; m represents an integer of 2 or more.

[10] A method for controlling marine biodegradability of a polyester containing a structure represented by the following general formula (I): And, A method of control comprising controlling x, y and m.

[0013] [ka]

[0014] (In the formula, x represents an integer of 1 or more, y is an integer equal to or greater than 0; m represents an integer of 2 or more.

[0015] The present invention can also employ the following configuration.

[11] Use of the marine biodegradable polyester according to any one of [1] to [6] in the production of a marine biodegradable resin composition.

[12] A method for producing a marine biodegradable resin composition, comprising blending the marine biodegradable polyester according to any one of [1] to [6]. Effect of the Invention

[0016] According to the method of the present invention, it is possible to control the marine biodegradability of polyesters such as PAAD. Furthermore, the marine biodegradability control technique of the present invention makes it possible to produce marine biodegradable polyesters. [Brief description of the drawings]

[0017] [Figure 1] Figure 1 shows the BOD biodegradation curves (30 °C, 10 days) of the hydrolysates of PAAD inoculated with seawater collected in Yokosuka City. Figure 1a to e show the BOD biodegradation curves of each PAAD hydrolysate. [Diagram 2] Figure 2 shows the BOD biodegradation curves (30°C, 60 days) of PAAD inoculated with seawater collected in Yokosuka City. Figure 2 a to o are graphs of the BOD biodegradation curves of each PAAD. [Diagram 3] Fig. 3 is a graph showing the BOD biodegradation rate and the BOD biodegradability of PAAD. Fig. 3 a to n are graphs showing the BOD biodegradation rate and the BOD biodegradability of each PAAD. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention will now be described. <Marine biodegradable polyester> One aspect of the present invention is a marine biodegradable polyester comprising a structure represented by the following general formula (I): (hereinafter, sometimes referred to as "the marine biodegradable polyester of the present invention").

[0019] [ka]

[0020] (In the formula, x represents an integer of 1 or more, y is an integer equal to or greater than 0; m represents an integer of 2 or more.

[0021] Here, the marine biodegradability of the marine biodegradable polyester of the present invention means the property of the biodegradable resin being cut and fragmented into low molecular weight molecules under marine conditions by the action of hydrolases and the like of biodegradable polymer-degrading bacteria. Preferably, the marine biodegradability of the biodegradable resin may be the property of the biodegradable resin being cut and fragmented into low molecular weight molecules and mineralized under marine conditions. Marine biodegradability can be confirmed, for example, by immersing a sample in seawater and checking whether the weight of the sample after the seawater immersion test is reduced from the initial weight. More specifically, marine biodegradability can be confirmed, for example, by a test method specified in the marine biodegradability test (ASTM D6691-17). can. As an index of marine biodegradability, the marine biodegradable polyester of the present invention means that the biodegradability in the marine biodegradability test (ASTM D6691-17) is, for example, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more. The method used in the examples can be used.

[0022] In the present invention, we conducted extensive research to develop a marine biodegradable polymer, and succeeded in creating a marine biodegradable PAAD by controlling the number of methylene chains and molecular weight of PAAD.

[0023] The biodegradation of PAAD proceeds in two steps: (First step) PAAD undergoes hydrolysis of the ester bond by enzyme to give low molecular weight compounds (maximum Ultimately, this produces diols and dicarboxylic acids. (Second stage) The low molecular weight compounds are taken up and metabolized by microorganisms, resulting in biodegradation. .

[0024] As shown in the examples below, the production rate and biodegradability of the low molecular weight compounds in the first stage are affected by the initial molecular weight of the PAAD. Therefore, it is predicted that biodegradability will be promoted by using a low molecular weight PAAD. In addition, in enzymatic hydrolysis, the enzyme needs to be adsorbed to the polymer, but in high molecular weight substances, the hydrophobicity increases, preventing adsorption and reducing hydrolysis. In this respect, the use of a low molecular weight PAAD is important for imparting biodegradability.

[0025] As shown in the Examples below, the rate at which the compounds degraded in the second step are metabolized by microorganisms is strongly affected by the number of methylene chains in PAAD.

[0026] Thus, according to the present invention, the mesophase of PAAD, which is a compound having a structure represented by general formula (I), By controlling the number of methylene chains x and y, and the molecular weight (which can be controlled by controlling the number of methylene chains x and y in general formula (I) and the degree of polymerization m), a marine biodegradable polyester can be created. In the marine biodegradable polyester of the present invention, by adjusting x, y, and m, This makes it possible to produce a marine biodegradable polyester having the desired marine biodegradability depending on the purpose of use.

[0027] In the general formula (I), x is an integer of 1 or more, and y is an integer of 0 or more. If the values ​​of x and y are too small, If the values ​​of x and y are too large, the polyester may not have the desired physical properties, and if the values ​​of x and y are too large, the polyester may not have the desired marine biodegradability. Depending on the purpose of use, x and y are adjusted to achieve the desired marine biodegradability. The values ​​of x and y can be set independently. As long as the effects of the present invention are achieved, the present invention is not limited to the above. The value of x may be, for example, an integer of 1 or more, an integer of 2 or more, or an integer of 4 or more, an integer of 100 or less, an integer of 45 or less, an integer of 14 or less, or an integer of 4 or less, or a combination of these that is not contradictory. The number may be an integer from 2 to 45, an integer from 2 to 14, or an integer from 2 to 4. The value of y may be, for example, an integer of 0 or more, an integer of 2 or more, or an integer of 4 or more, an integer of 100 or less, an integer of 45 or less, or an integer of 14 or less, provided that these are not inconsistent. The value of y may be, for example, an integer from 0 to 100, an integer from 2 to 100, an integer from 2 to 45, an integer from 2 to 14, or an integer from 4 to 14.

[0028] In the general formula (I), m represents an integer of 2 or more. If the value of m is too small, the desired physical properties of the polyester may not be obtained, whereas if the value of m is too large, the desired sea-state of the polyester may not be obtained. Depending on the purpose of use, m is adjusted so as to exhibit the desired marine biodegradability. As long as the effects of the present invention are achieved, there is no limitation, but the value of m may be, for example, an integer of 2 or more, an integer of 3 or more, or an integer of 4 or more, an integer of 100 or less, an integer of 20 or less, an integer of 10 or less, or an integer of 7 or less, and any combination of these that is not contradictory. The value of m may be, for example, an integer from 2 to 100, an integer from 3 to 20, an integer from 4 to 10, Or it may be an integer from 4 to 7. The values ​​of x, y, and m can be set independently.

[0029] In a preferred embodiment of the marine biodegradable polyester of the present invention, from the viewpoint of being particularly excellent in marine biodegradability, usability, etc., the value of x is an integer of 2 to 4, the value of y is an integer of 2 to 14, and the value of m is an integer of 2 to 20. Marine biodegradable polyesters that are integers are included.

[0030] The molecular weight of the marine biodegradable polyester of the present invention is not limited as long as the effects of the present invention are exhibited, but from the viewpoint of marine biodegradability, for example, the number average molecular weight (Mn) may be 300 to 30,000, 3,000 to 20,000, or 5,000 to 10,000. The weight average molecular weight (Mw) may be 300 to 30,000, 3,000 to 20,000, or 5,000 to 10,000. The molecular weight can be measured by size exclusion chromatography or the like.

[0031] A preferred embodiment of the marine biodegradable polyester of the present invention is a marine biodegradable polyester having a number average molecular weight (Mn) of 10,000 or less, from the viewpoint of particularly excellent marine biodegradability.

[0032] Specific examples of PAAD, which is a compound containing a structure represented by general formula (I), include, but are not limited to, For example, PEAd: poly(ethylene adipate) (general formula (I) in which x = 2, y = 4) compound), PBSu: poly(butylene succinate) (general formula (I) where x = 4 and y = 2) compound), PBGl: poly(butylene glutarate) (compound represented by the general formula (I) where x = 4 and y = 3) PBAd: poly(butylene adipate) (compound represented by general formula (I) where x = 4 and y = 4) PBPi: poly(butylene pimelate) (compound of general formula (I) where x = 4 and y = 5) PBSb: poly(butylene suberate) (compound of general formula (I) where x = 4 and y = 6) ), PBAz: poly(butylene azelate) (compound of general formula (I) where x = 4, y = 7) , PBSe: poly(butylene sebacate) (compound of general formula (I) where x = 4, y = 8), PBUd: poly(butylene undecanedioate) (compound of general formula (I) where x = 4, y = 9), PBDd: poly(butylene dodecanedioate) (compound of general formula (I) where x = 4, y = 10), PBTrd: poly(butylene tridecanedioate) (compound of general formula (I) where x = 4, y = 11), PBTed: poly(butylene tetradecanedioate) (compound of general formula (I) where x = 4, y = 12), where x = 4, y = 12), PBPd: poly(butylene pentadecanedioate) ( PBHd: poly(butylene hexadecanedioate) (a compound represented by the general formula (I) in which x = 4, y = 13), and PBHd: poly(butylene hexadecanedioate) (a compound represented by the general formula (I) in which x = 4, y = 14).

[0033] <Manufacturing method for marine biodegradable polyester> A further aspect of the present invention is a marine biodegradable polyester having a structure represented by the above general formula (I). A method for producing a steer, comprising controlling x, y, and m (hereinafter, "the present method"). The above items explained in the section on <Marine biodegradable polyester> also apply to the explanation of the manufacturing method of the present invention.

[0034] The production method of the present invention is characterized in that the number of methylene chains and the molecular weight of the polyester are controlled by controlling the number of methylene chains x and y and the degree of polymerization m in the general formula (I). The number of methylene chains and the molecular weight of the polyester, as well as x, y and m, are determined depending on the purpose of use. Accordingly, the amount of the polyester may be adjusted so as to obtain a polyester having the desired marine biodegradability. The specific ranges of the values ​​of x, y, and m are described in the above section on <Marine biodegradable polyester>. This is similar to that described in.

[0035] As a method for controlling the numbers of methylene chains x and y and the degree of polymerization m in general formula (I) and adjusting the number of methylene chains and molecular weight of the polyester, x and y can be adjusted, for example, by selecting and using a dicarboxylic acid having the desired numbers of methylene chains x and y as a dicarboxylic acid that is a raw material of PAAD. Regarding m, it is necessary to adjust the polymerization conditions of PAAD (e.g., polymerization time, temperature, catalyst amount, etc.). The polymerization conditions can be adjusted based on a known method. Alternatively, commercially available PAAD may be hydrolyzed to a desired degree of polymerization m. The PAAD with a given degree of polymerization n may be adjusted by the polymerization.

[0036] The production method of the present invention can be carried out in the same manner as a conventional polymer production method, except for adjusting the number of methylene chains and the molecular weight of the polyester. The polymer production method may be a method using a microorganism or a method using chemical synthesis. More specifically, for example, as shown in the examples below, a marine biodegradable polyester containing a structure represented by general formula (I) can be synthesized by dehydration polycondensation of a diol having a desired methylene chain number x and a dicarboxylic acid having y, which serve as monomer raw materials, using a catalyst such as a titanic acid catalyst under conditions that can achieve a desired degree of polymerization m. The dehydration polycondensation reaction conditions are not limited, but examples include reaction conditions of 200 to 280° C. and 1 to 10 hours. The dicarboxylic acid and 1,4-butanediol, which are the raw materials for the marine biodegradable polyester, can be either commercially available or chemically synthesized.

[0037] <Method of controlling marine biodegradability of polyester> A further aspect of the present invention is a method for producing a polyester having a structure represented by the above general formula (I). A method for controlling biodegradability, comprising controlling x, y, and m (hereinafter, " The above-mentioned items explained in the sections "Marine biodegradable polyester" and "Production method of marine biodegradable polyester" all apply to the explanation of the control method of the present invention.

[0038] The control method of the present invention is characterized in that the number of methylene chains x and y, and the degree of polymerization m in the general formula (I) are controlled to control the number of methylene chains and the molecular weight of the polyester. The method of controlling x, y, and m to adjust the molecular weight of the polyester is the same as that of the above-mentioned <Marine Biodegradable Polyester>. That is, x, y and m are each a marine biodegradable polyester having a desired marine biodegradability depending on the purpose of use. can be adjusted so as to obtain

[0039] <Marine biodegradable resin composition> A further aspect of the present invention relates to a marine biodegradable resin composition containing the marine biodegradable polyester of the present invention (hereinafter, may be referred to as the "marine biodegradable resin composition of the present invention"). Note that the matters explained in the above sections "Marine biodegradable polyester", "Method for producing marine biodegradable polyester", and "Method for controlling marine biodegradability of polyester" all apply to the explanation of the marine biodegradable resin composition of the present invention.

[0040] The marine biodegradable resin composition of the present invention is a composition that contains the marine biodegradable polyester of the present invention and has marine biodegradability. The marine biodegradable resin composition of the present invention may contain one or more marine biodegradable polyesters.

[0041] The marine biodegradable resin composition of the present invention may consist only of the marine biodegradable polyester, but may also contain, if necessary, various additives that are usually used in biodegradable resin compositions, such as plasticizers for biodegradable resins, stabilizers (antioxidants, heat stabilizers, light resistance stabilizers, etc.), surfactants, lubricants, colorants, fillers, antistatic agents, silane coupling agents, dispersants, dispersion aids, release agents, etc. The additives may be used alone or in combination of two or more.

[0042] The blend ratio of the marine biodegradable polyester in the marine biodegradable resin composition of the present invention is not limited, but may be, for example, 0.1 to 100% by weight, 1 to 99.9% by weight, or 10 to 100% by weight based on the total amount of the composition. It can be about 50% by weight.

[0043] The marine biodegradable polyester in the marine biodegradable resin composition of the present invention may also link multiple marine biodegradable polyesters with easily degradable bonds, and the blend ratio of the marine biodegradable polyester in such an embodiment is not limited, but may be, for example, about 0.1 to 100% by weight, 1 to 99.9% by weight, or 10 to 50% by weight relative to the total amount of the composition.

[0044] The form of the marine biodegradable resin composition of the present invention is not particularly limited, and it may be in the form of a powder, pellet, film-like solid, or dissolved or dispersed in a hydrophilic or lipophilic liquid, sol, or gel. The marine biodegradable resin composition can be produced according to a conventional method.

[0045] <Molded products> Another aspect of the present invention relates to a molded article formed from the marine biodegradable resin composition of the present invention (hereinafter, may be referred to as "molded article of the present invention"). Note that the matters explained in the above sections "Marine biodegradable polyester", "Method for producing marine biodegradable polyester", "Method for controlling marine biodegradability of polyester", and "Marine biodegradable resin composition" all apply to the explanation of the molded article of the present invention.

[0046] The marine biodegradable resin composition of the present invention can be molded into films, sheets, and other molded articles such as tools, containers, nonwoven fabrics, and the like having shapes suitable for the intended use.

[0047] There is no particular limitation on the method for obtaining a film or sheet made of the marine biodegradable resin composition of the present invention, and the composition can be molded into a film or sheet by a known molding method. For example, the composition can be molded into a film or sheet by a T-die molding method, an inflation molding method, a calendar molding method, a hot press molding method, or the like. These films or sheets may be stretched in at least one direction. There is no particular limitation on the stretching method, and examples thereof include a roll stretching method, a tenter method, and an inflation method.

[0048] There are no particular limitations on the method for obtaining a molded article having a shape suitable for the intended use, which is made from the marine biodegradable resin composition of the present invention, and the article can be produced by any known method, such as extrusion molding or injection molding in a mold.

[0049] The thickness of the molded article of the marine biodegradable resin composition of the present invention is preferably thin in order to enhance its water disintegrability and biodegradability, but can be freely adjusted to satisfy strength, flexibility, etc. The preferred thickness of the film is 5 to 300 μm, more preferably 10 to 100 μm. The thickness of the sheet or container-shaped molded product is preferably 0.1 to 5 mm, and more preferably 0.2 to 2. mm.

[0050] There is no particular limitation on the method for obtaining a nonwoven fabric of the marine biodegradable resin composition of the present invention, and it can be produced by a known method, for example, a dry method, a spunbond method, a meltblowing method, a wet method, etc. That is, the nonwoven fabric can be obtained by spinning the marine biodegradable resin composition of the present invention, forming a web, and bonding the web by a known method.

[0051] The uses of the molded article made of the marine biodegradable resin composition of the present invention are not particularly limited, and it can be used, for example, as a member (part) constituting a sanitary product, an agricultural and horticultural material, a civil engineering and construction material, a fishing material, etc. In other words, it is possible to manufacture sanitary products, agricultural and horticultural materials, civil engineering and construction materials, fishing materials, etc. using a material containing the marine biodegradable resin composition of the present invention.

[0052] As for the method of producing sanitary products, agricultural and horticultural materials, civil engineering and construction materials, fishing materials, etc., they can be produced by molding and processing the marine biodegradable resin composition of the present invention into desired shapes, and further by bonding and fixing the molded products to each other by known methods such as hot melt bonding or thermal bonding.

[0053] Examples of the sanitary products include disposable paper diapers, incontinence pads, sanitary napkins, and the like. Examples of the agricultural and horticultural materials include mulch films, seedling pots, gardening tapes, fruit cultivation bags, stakes, fumigation sheets, films for vinyl greenhouses, and fertilizer covering materials. Examples of the civil engineering and construction materials include vegetation nets, vegetation pots, three-dimensional net structures, civil engineering fibers, stakes, and heat insulating materials. Examples of the fishing materials include fishing nets, aquaculture equipment, fishing tackle, mooring ropes, fenders, sea anchors, floats, and the like. EXAMPLES

[0054] The present invention will be described in detail below with reference to examples. However, these are merely illustrative of the present invention and the scope of the present invention is not limited to these examples.

[0055] [material and method] <Reagents> Adipic acid (AdA), azelaic acid (AzA), CaCl2·2H2O, dodecanedioic acid (DdA), FeCl3·6H2O, glutaric acid (GlA), KH2PO4, K2HPO4, NaCl, Na2HPO4·H2O, NH4Cl, MgSO4·7H2O, sebacic acid (SeA), succinic acid (SuA), succinic anhydride, and ethanol were purchased from Fujifilm Wako Pure Chemical Industries, Ltd. HCl, NaOH, Na2SO4, NaHCO3, chloroform, and deuterated chloroform. (CDCl3), deuterium oxide (D2O), deuterated dimethyl sulfoxide (DMSO-d6), ethyl acetate, toluene , p-toluenesulfonic acid monohydrate, hexane, and anhydrous THF were purchased from Kanto Chemical Co., Ltd. L-arginine, dichloromethane, methanol, ethylene glycol, and 1,4-butanediol (BD) were purchased from Kishida Chemical Co., Ltd. Pentadecanedioic acid (PdA), pimelic acid (PiA), suberic acid (SbA), tetradecanedioic acid (TedA), tridecanedioic acid (TrdA), undecanedioic acid (UdA), allylthiourea, 4-dimethylaminopyridine (DMAP), titanium tetraisopropanol, and tetraisopropanol were purchased from Kishida Chemical Co., Ltd. Hexadecanedioic acid (HdA) was purchased from Sigma-Aldrich. The reagents were purchased from Rudrich Japan LLC. BD was purified by vacuum distillation at 90 °C and 240 Pa. The other reagents were used without purification.

[0056] <Instrumental analysis> (Nuclear magnetic resonance (NMR)) For NMR measurements, we used a JNM-ECS400 NMR spectrometer (JEOL Ltd.) and a JNM-ECA600 NMR spectrometer (JEOL Ltd.). A chromatograph (JEOL Ltd.) was used. Samples (1.0-5.0 mg) were dissolved in either CDCl3, DMSO-d6, or D2O (0.6 mL) containing tetramethylsilane as an internal standard. 1 H NMR measurements were carried out.

[0057] (molecular weight measurement) The molecular weight of the synthesized polymer was calculated by size exclusion chromatography. GPC measurement The LC-4000 system (JASCO Corporation) was used for the measurement at a flow rate of 1.0 mL / min and a temperature of 40 °C. The calibration curve was prepared using TSK standard polystyrene (number average molecular weight = 2890000, 706000, 355000, 96400, 3.79 × 10 4 , 10200, 2630, 433) was used. The column used was a combination of a TSKgel guardcolumnMP (XL) and a TSKgel MultiporeHXL-M, and detection was performed using an RI detector. The sample solution was prepared by dissolving the polymer (1.0-5.0 mg) in chloroform (1.0 mL).

[0058] (Molecular weight fractionation by preparative GPC) The polymer was fractionated at a flow rate of 3.5 mL / min using a Multiple Preparative HPLC LC-Forte / R (YMC Hikari Co., Ltd.). The column consisted of GPC K-2001 Column No. A601021, GPC K-2002 Column No. A601022, and GPC K-2004 Column No. A702010. The sample solution was prepared by dissolving the sample (0.15-0.25 g) in chloroform (6.0 mL) and filtering through a membrane filter with a pore size of 0.45 μm.

[0059] <Method> (Marine BOD biodegradability test) Seawater collected in Yokosuka, Kanagawa Prefecture, was filtered using a membrane filter. Potassium dihydrogen phosphate (0.10 g / L) and ammonium chloride (0.5 g / L) were added to the filtered seawater. Meanwhile, the filtered seawater was suction filtered through a membrane filter, the filter was removed and suspended in seawater to which inorganic salts had been added to prepare 100-fold concentrated seawater. 100-fold concentrated seawater (1.0 mL) and 5.0 g / L N-allylthiourea (200 μL) were added to a medium bottle, and the filtered seawater was diluted to 200 mL with seawater to which potassium dihydrogen phosphate (0.10 g / L) and ammonium chloride (0.5 g / L) had been added using a graduated scale. As blanks, prepare two medium bottles without adding any carbon source sample. An appropriate amount of Yabashiri lime was added to the carbon dioxide absorbent container and attached to the top of the medium bottle. The prepared medium bottle was placed in a BOD TESTER and stirred in a dark room at 30 °C, and the pressure was periodically adjusted. The variation was measured. <Synthesis of polyester> (Synthesis of PAAD) [Reference 1] Baba, T.; Tachibana, Y.; Suda, S.; Kasuya, K. Evaluation of Environmental Degradability Based on the Number of Methylene Units in Poly(Butylene n-Alkylenedionate). Polym. Degrad. Stab. 2017, 138, 18-26. [Reference 2] Tachibana, Y.; Tsutsuba, T.; Kageyama, K.; Kasuya, K. Biodegradability of Poly(Butylene n-Alkylenedionate)s Composed of Long-Methylene Chains as Alternative Polymers to Polyethylene. Polym. Degrad. Stab. 2021, 190, 109650.

[0060] In a two-necked flask, 1,4-butanediol (BD) (1.1 eq.) and dicarboxylic acid (DCA) were added. Titanium tetraisopropoxide (50 × 10 -2 mol%) is added The mixture was stirred at 200 °C for 1-2 hours. After the reaction, titanium tetraisopropoxide (50 × 10 -2 mol%) was added again and the pressure was reduced (10 -1 The mixture was stirred at 200-240 °C for 1-5 hours while maintaining a constant pressure of 1 Pa. After the reaction, the solid was dissolved in chloroform and precipitated by dropping it into methanol. The precipitate was filtered by suction and dried under reduced pressure to obtain PAAD. Then, if necessary, titanium tetraisopropoxide was further added to the PAAD for repolymerization to obtain PAAD with a higher molecular weight. In order to obtain PAAD with different molecular weights, PAAD was fractionated at a predetermined flow time by preparative GPC.

[0061] PEAd 1 H NMR (400 MHz, CDCl3) δ 4.28 (d, J = 4.4 Hz, 4H, -O-CH2-), 2.42-2.32 (m, 4H, -(C=O)-CH2-), 1.72-1.63 (m, 4H, -(C=O)-CH2-CH2-) ppm.

[0062] PBSu 1 H NMR (400 MHz, CDCl3) δ 4.18-4.07 (m, 4H, -O-CH2-), 2.63 (s, 4H, -(C=O)-CH2-), 1.77-1.67 (m, 4H, -O-CH2-CH2-) ppm.

[0063] P.B.G.l 1H NMR (400 MHz, CDCl3) δ 4.13-4.04 (m, 4H, -O-CH2-), 2.38 (t, J= 7.6 Hz, 4H, -(C=O)-CH2-), 1.95 (q, J = 7.4 Hz, 2H, -(C=O)-CH2-CH2-), 1.74-1.68 (m, 4H, -O-CH2-CH2-) ppm.

[0064] PBAd 1 H NMR (400 MHz, CDCl3) δ 4.13-4.04 (m, 4H, -O-CH2-), 2.33 (t, J= 7.7 Hz, 4H, -(C=O)-CH2-), 1.70 (q, J = 6.0 Hz, 4H, -(C=O)-CH2-CH2-), 1.66 (q, J = 6.0 Hz, 4H, -O-CH2-CH2-) ppm.

[0065] PBPi 1 H NMR (400 MHz, CDCl3) δ 4.14-4.07 (m, 4H, -O-CH2-) 2.31 (t, J= 7.6 Hz, 4H, -(C=O)-CH2-), 1.70 (q, J = 7.4 Hz, 4H, -(C=O)-CH2-CH2-), 1.67-1.59 (m, 4H, -O-CH2-CH2-), 1.42-1.30 (m, 2H, -(C=O)-CH2-CH2-CH2-) ppm.

[0066] PBSb 1 H NMR (400 MHz, CDCl3) δ 4.12-4.06 (m, 4H, -O-CH2-), 2.30 (t, J= 7.7 Hz, 4H, -(C=O)-CH2-), 1.76-1.67 (m, 4H, -(C=O)-CH2-CH2-), 1.67-1.56 (m, 4H, -O-CH2-CH2-), 1.38-1.31 (m, 4H, -(C=O)-CH2-CH2-CH2-) ppm.

[0067] PBAz 1 H NMR (400 MHz, CDCl3) δ 4.12-4.05 (m, 4H, -O-CH2-), 2.30 (t, J= 7.6 Hz, 4H, -(C=O)-CH2-), 1.73-1.65 (m, 4H, -(C=O)-CH2-CH2-), 1.66-1.55 (m, 4H, -O-CH2-CH2-), 1.40-1.24 (m, 6H, -(C=O)-CH2-CH2-(CH2)3-) ppm.

[0068] PBSe 1 H NMR (400 MHz, CDCl3) δ 4.12-4.04 (m, 4H, -O-CH2-), 2.29 (t, J= 7.6 Hz, 4H, -(C=O)-CH2-), 1.74-1.67 (m, 4H, -(C=O)-CH2-CH2-), 1.68-1.52 (m, 4H, -O-CH2-CH2-), 1.40-1.25 (m, 8H, -(C=O)-CH2-CH2-(CH2)4-) ppm.

[0069] PBUd 1 H NMR (400 MHz, CDCl3) δ 4.13-4.05 (m, 4H, -O-CH2-), 2.29 (t, J= 7.6 Hz, 4H, -(C=O)-CH2-), 1.76-1.67 (m, 4H, -(C=O)-CH2-CH2-), 1.67-1.52 (m, 4H, -O-CH2-CH2-), 1.38-1.23 (m, 10H, -(C=O)-CH2-CH2-(CH2)5-) ppm.

[0070] PBDd 1 H NMR (400 MHz, CDCl3) δ 4.13-4.03 (m, 4H, -O-CH2-), 2.29 (t, J= 7.7 Hz, 4H, -(C=O)-CH2-), 1.77-1.66 (m, 4H, -(C=O)-CH2-CH2-), 1.67-1.50 (m, 4H, -O-CH2-CH2-), 1.39-1.22 (m, 12H, -(C=O)-CH2-CH2-(CH2)6-) ppm.

[0071] PBTrd 1 H NMR (400 MHz, CDCl3) δ 4.13-4.03 (m, 4H, -O-CH2-), 2.29 (t, J= 7.7 Hz, 4H, -(C=O)-CH2-), 1.78-1.66 (m, 4H, -(C=O)-CH2-CH2-), 1.66-1.48 (m, 4H, -O-CH2-CH2-), 1.38-1.23 (m, 14H, -(C=O)-CH2-CH2-(CH2)7-) ppm.

[0072] PBTed 1 H NMR (400 MHz, CDCl3) δ 4.12-4.04 (m, 4H, -O-CH2-), 2.29 (t, J= 7.6 Hz, 4H, -(C=O)-CH2-), 1.76-1.67 (m, 4H, -(C=O)-CH2-CH2-), 1.65-1.54 (m, 4H, -O-CH2-CH2-), 1.38-1.20 (m, 16H, -(C=O)-CH2-CH2-(CH2)8-) ppm.

[0073] PBPd 11H NMR (400 MHz, CDCl3) δ 4.13 - 4.04 (m, 4H, -O-CH2-), 2.29 (t, J = 7.6 Hz, 4H, -(C=O)-CH2-), 1.75 - 1.67 (m, 4H, -(C=O)-CH2-CH2-), 1.66 - 1.54 (m, 4H, -O-CH2-CH2-), 1.37 - 1.20 (m, 18H, -(C=O)-CH2-CH2-(CH2)9-) ppm.

[0074] PBHd 1 1H NMR (400 MHz, CDCl3) δ 4.14 - 4.05 (m, 4H, -O-CH2-), 2.29 (t, J = 7.6 Hz, 4H, -(C=O)-CH2-), 1.75 - 1.67 (m, 4H, -(C=O)-CH2-CH2-), 1.68 - 1.55 (m, 4H, -O-CH2-CH2-), 1.37 - 1.20 (m, 20H, -(C=O)-CH2-CH2-(CH2) 10 -) ppm.

[0075] [Results] [Elucidation of the correlation between the molecular weight and biodegradability of PAAD] [Preparation of low-molecular-weight PAAD by molecular weight fractionation of PAAD] To evaluate the molecular weight dependence of the biodegradability of PAAD, PAADs with different molecular weights were prepared. Each PAAD was synthesized by dehydrative polycondensation of DCA and diol using a titania catalyst. The crude product was purified by reprecipitation (good solvent: chloroform, poor solvent: methanol), and samples were repolymerized as needed to synthesize higher molecular weight products. Molecular weight control is difficult in dehydrative polycondensation, especially for low molecular weight components where monomers and the like are mixed in, making it difficult to synthesize with a controlled polydispersity. Therefore, preparative GPC was also used in the preparation of the molecular weight of PAAD . In this study, multiple samples with different molecular weights were prepared, and their sample names are the number average molecular weight (M n) as a suffix to form PAAD (M n / 1000).

[0076] The number average molecular weight, polydispersity, and degree of polymerization of each PAAD whose molecular weight was adjusted are summarized in Table 1. The number average molecular weight of the sample with the largest molecular weight among the samples was about 20,000 to 30,000. The molecular weight of the sample with the lowest molecular weight was about 13,000, which is lower than that of the sample with the highest molecular weight, but the polydispersity was 3.3, and it also contained high molecular weight substances. On the other hand, the sample with the lowest molecular weight was prepared so that the degree of polymerization was less than about 10, and the sample with the next highest molecular weight was prepared so that the degree of polymerization was about 20.

[0077] [Table 1]

[0078] (BOD biodegradability test) The BOD biodegradation curves for DCA and BD, which are hydrolysates of PAAD, are shown in Figure 1. The biodegradation rates calculated from the maximum slope during the biodegradation phase and the BOD biodegradation after 10 days are shown in Figure 3. The induction phase was completed within one day except for HdA and BD, while the induction periods for HdA and BD were 4 and 3 days, respectively. After that, the BOD biodegradation of both substances reached a stationary phase after 6 days.

[0079] A BOD biodegradation test was conducted for 60 days for PAAD with different molecular weights. Figure 2 shows the BOD biodegradation curves for each sample, and Figure 3 shows the biodegradation rate after 60 days and the biodegradation rate calculated from the maximum slope during the biodegradation period. Table 2 shows the BOD biodegradation rate after 60 days. The decomposition rate of PAAD increased with increasing molecular weight overall. The lower the molecular weight, the faster the BOD biodegradation rate. A tendency for the concentration to increase was observed.

[0080] [Table 2]

[0081] As described above, the results of the BOD biodegradation test for PAAD with each methylene chain length and molecular weight showed that It was observed that PAAD tended to be easily biodegraded in the body. It was also observed that the smaller the number of methylene chains, the easier the biodegradation. In other words, biodegradability depended on the number of methylene chains and molecular weight. Based on these findings, it was found that by controlling the number of methylene chains and molecular weight, PAAD with marine biodegradability was successfully created. [Industrial Applicability]

[0082] The PAAD provided by the present invention can be used as an alternative biodegradable polymer to polyethylene, polypropylene, polystyrene, ethylene vinyl acetate resin, ABS resin, AS resin, etc. In view of marine biodegradability, it can be preferably applied to fishing gear and the like. In addition, the PAAD provided by the present invention can also be used as a biodegradable unit of a stimuli-responsive polymer in a copolymer or the like.

Claims

1. A marine biodegradable polyester comprising a structure represented by the following general formula (I): 【Chemistry 1】 (In the formula, x represents an integer of 1 or more, y is an integer equal to or greater than 0; m is an integer of 2 or more.

2. The marine biodegradable polyester according to claim 1, wherein x and y are each independently an integer from 2 to 100.

3. 2. The marine biodegradable composition according to claim 1, wherein x and y are each independently an integer from 2 to 45. polyester.

4. 2. The marine biodegradable composition according to claim 1, wherein x and y are each independently an integer from 2 to 14. polyester.

5. The marine biodegradable polyester according to claim 1, wherein m is an integer from 2 to 100.

6. The marine biodegradable polyester according to claim 1, having a number average molecular weight (Mn) of 10,000 or less.

7. A marine biodegradable resin composition comprising the marine biodegradable polyester according to claim 1.

8. A molded article formed from the marine biodegradable resin composition according to claim 7.

9. A method for producing a marine biodegradable polyester comprising the structure represented by the following general formula (I): A method of manufacturing comprising controlling x, y and m. 【Chemistry 2】 (In the formula, x represents an integer of 1 or more, y is an integer equal to or greater than 0; m is an integer of 2 or more.

10. A method for controlling marine biodegradability of a polyester containing a structure represented by the following general formula (I): 、 A method of control comprising controlling x, y and m. 【Chemistry 3】 (In the formula, x represents an integer of 1 or more, y is an integer equal to or greater than 0; m is an integer of 2 or more.

Images