Method for producing marine biodegradable polyester and method for producing cross-linked marine biodegradable polyester

Abstract

This invention provides a method for producing polyester compounds that undergo biodegradation in the ocean. [Solution] A method for producing marine biodegradable polyester, comprising the steps of (1) depolymerizing a high molecular weight polyester to obtain an oligomer with a reduced number average molecular weight, and (2) reacting the substituents at the ends of the oligomer obtained in step (1) to introduce acidic groups at the ends.

Description

[Technical Field]

[0001] This invention relates to a method for producing marine biodegradable polyester and a method for producing cross-linked marine biodegradable polyester. [Background technology]

[0002] In recent years, environmental pollution (marine pollution) and adverse effects on ecosystems caused by microplastics have become a serious problem, and various initiatives to reduce the environmental burden have begun. Among these, the development and widespread use of biodegradable resins are attracting attention.

[0003] On the other hand, while general biodegradable resins exhibit high biodegradability in environments with many microorganisms responsible for decomposition, such as soil and sludge, they have the drawback of being difficult to decompose in environments with extremely low microbial concentrations, such as in the ocean (Non-Patent Literature 1). Furthermore, even for resins that have been reported to be biodegradable in the ocean, such as polycaprolactone (PCL) and polyhydroxyalkanoic acid (PHA), it has been found that the rate of decomposition varies greatly depending on the type of seawater. It has been reported that various factors such as the presence and number of decomposing bacteria in the seawater, salt concentration, pH, water temperature, dissolved oxygen concentration, and dissolved organic carbon content are influencing this (Non-Patent Literature 2).

[0004] Furthermore, although starch-based resins have been put into practical use and are on the market as biodegradable resins, single starch materials are significantly inferior in terms of physical properties. Therefore, most are mixed compositions with polyester resins that are difficult to biodegrade in the ocean, such as polybutylene adipate terephthalate (PBAT) or polylactic acid (PLA). As a result, even starch-based resins tend to have significantly reduced biodegradability in the ocean.

[0005] Under these circumstances, there is a need to develop materials that maintain their physical properties, decompose reliably in any type of seawater, act as decomposition accelerators for resins that do not biodegrade easily in seawater, and reduce environmental impact. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Hideki Takada, "Current Status, International Trends, and Countermeasures Regarding Microplastic Pollution," Journal of the Japan Society of Waste Management and Resource Recycling, Vol. 29, No. 4, pp. 261-269, 2018. [Non-Patent Document 2] Akira Ebisu et al., "Decomposition of Biodegradable Plastics in Seawater," *Fisheries Engineering*, Vol. 40, No. 2, pp. 143-149, 2003. [Overview of the project] [Problems that the invention aims to solve]

[0007] This invention has been made in view of the above circumstances, and aims to provide a method for producing a polyester compound that undergoes biodegradation in the ocean. [Means for solving the problem]

[0008] As a result of diligent research to solve the above problems, the present inventors have found that a polyester obtained by introducing an acidic group to the end of an oligomer with a reduced number-average molecular weight obtained by depolymerizing a high molecular weight polyester, and a crosslinked polyester obtained by crosslinking a polymer-type polyvalent anion in which some or all of the protons of the terminal acidic group obtained by neutralizing the polyester are replaced with monovalent cations other than protons, via a divalent or higher cation, exhibits marine biodegradability.

[0009] Furthermore, by using the aforementioned marine biodegradable polyester or cross-linked marine biodegradable polyester in combination with resin, particularly biodegradable resin, we discovered that the material undergoes primary decomposition in seawater, resulting in (1) the formation of pores in the resin material, increasing the specific surface area of ​​the resin and promoting the growth of microorganisms responsible for decomposition, and (2) the primary decomposition, which in turn promotes secondary decomposition, i.e., biodegradation by microorganisms. As a result, we found that the biodegradation of the resin material in the ocean can be accelerated, thus completing the present invention.

[0010] That is, the present invention provides a method for producing the following marine biodegradable polyester and a method for producing a crosslinked marine biodegradable polyester. 1. (1) A step of depolymerizing a high molecular weight polyester to obtain an oligomer with a reduced number average molecular weight, and (2) A step of reacting a substituent at the terminal of the oligomer obtained in step (1) to introduce an acidic group at the terminal A method for producing a marine biodegradable polyester comprising the above steps. 2. The method for producing a marine biodegradable polyester according to 1, wherein the number average molecular weight of the oligomer is 200 to 20,000. 3. The method for producing a marine biodegradable polyester according to 1 or 2, wherein in step (1), depolymerization is carried out using a polyhydric alcohol. 4. When the value obtained by multiplying the amount of substance of the polyhydric alcohol by 0.85 and dividing the result by the amount of substance of the high molecular weight polyester, and then adding 1 is defined as n, and the number average degree of polymerization of the high molecular weight polyester is defined as N, the method for producing a marine biodegradable polyester according to 3, wherein N / n is 2 to 40. 5. The method for producing a marine biodegradable polyester according to 3 or 4, wherein in step (1), further carboxylic acid or its derivative is added for depolymerization. 6. The method for producing a marine biodegradable polyester according to any one of 1 to 5, wherein the acidic group introduced at the terminal in step (2) is a monovalent acidic group. 7. (3) A step of neutralizing the marine biodegradable polyester obtained by any one of the production methods of 1 to 6, and substituting part or all of the protons of the acidic groups at the terminals with monovalent cations other than protons to form a polymer containing a polymer type polyvalent anion, and (4) A step of crosslinking the polymer type polyvalent anion via a divalent or higher valent cation A method for producing a crosslinked marine biodegradable polyester comprising the above steps. 8. (5) A step of adding a divalent or higher valent base to the marine biodegradable polyester obtained by any one of the production methods of 1 to 6 to simultaneously neutralize part or all of the protons of the acidic groups at the terminals and perform crosslinking via a divalent or higher valent cation A method for producing a crosslinked marine biodegradable polyester comprising the above steps.

Advantages of the Invention

[0011] The production method by depolymerization of the present invention has the characteristics of high continuous operability, such as no need for reduced pressure, less dehydration and de-alcoholization, and no possibility of pipe blockage due to monomer sublimation compared with polycondensation from monomers. In addition, the production method of the present invention also has the advantages of low environmental load due to less de-alcoholization, no need for temperature change and pressure change during the reaction, and high simplicity. It is also possible to improve recyclability by using waste plastics as high molecular weight polyesters of raw materials. The marine biodegradable polyester and crosslinked marine biodegradable polyester obtained by the production method of the present invention exhibit high marine biodegradability and can function as a marine biodegradation promoter, so they can be used either as a single material or as a composite material.

Modes for Carrying Out the Invention

[0012] [Method for Producing Marine Biodegradable Polyester] The production method of the marine biodegradable polyester of the present invention is (1) a step of depolymerizing a high molecular weight polyester to obtain an oligomer with a reduced number average molecular weight, and (2) a step of introducing an acidic group to the terminal of the oligomer obtained in step (1) and includes.

[0013] Step (1) is a step of depolymerizing a high molecular weight polyester to obtain an oligomer with a reduced number average molecular weight.

[0014] The high molecular weight polyester contains polyhydric alcohol residues and polyhydric carboxylic acid residues. The polyhydric alcohol residue may contain only one type or two or more types. From the viewpoint of thermal and mechanical properties and biodegradability, the lower limit of the carbon number is preferably 2, 3, 4, 5, and 6 in that order, and the upper limit is preferably 20, 18, 16, and 14 in that order. The polyhydric carboxylic acid residue may contain only one type or two or more types. If only one type of polyhydric carboxylic acid residue is contained, it is preferably an aliphatic carboxylic acid residue. If two or more types of polyhydric carboxylic acid residues are contained, it is preferable that at least one of the polyhydric carboxylic acid residues is an aliphatic carboxylic acid residue.

[0015] Examples of polyhydric alcohols that become the aforementioned polyhydric alcohol residues include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2-butene-1,4-diol, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,5-pentanediol, 2,4-pentanediol, 2-hydroxy-2-ethyl-1,3-propanol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4- Cyclohexanediol, 1,3,5-cyclohexanetriol, 1,6-hexanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, 1,7-heptanediol, 1,4-benzenedimethanol, 3,6-diazaoctane-1,8-diol, 2,6-dihydroxynaphthalene, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,14-tetradecanediol Examples include ol, 1,16-hexadecanediol, 1,18-octadecanediol, phloroglucinol, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenyl ether, polyethylene glycol, glycerol, trimethylolpropane, pentaerythritol, 1,2,5-pentanetriol, pyrogallol, 1,2,4-benzenetriol, etc. It is particularly preferable to include at least one selected from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, glycerol, and pentaerythritol, more preferably at least one selected from ethylene glycol, 1,4-butanediol, 3-methyl-1,5-pentanediol, and glycerol, and even more preferably one selected from 1,4-butanediol and 3-methyl-1,5-pentanediol.

[0016] Examples of polycarboxylic acids that become the aforementioned polycarboxylic acid residues include linear dicarboxylic acids having 2 to 20 carbon atoms such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid; naphthalenedicarboxylic acids such as fumaric acid, maleic acid, malic acid, 1,2,3-propanetricarboxylic acid, aconitic acid, citric acid, phthalic acid, isophthalic acid, terephthalic acid, frangic acid, 5-sulfoisophthalic acid, 2,3-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid; 1,3,5-benzenetricarboxylic acid, biphenyldicarboxylic acid, trimetic acid, pyromellitic acid, etc. At least one selected from succinic acid, adipic acid, sebacic acid, terephthalic acid, frangic acid, 5-sulfoisophthalic acid, and 2,6-naphthalenedicarboxylic acid is particularly preferred, and at least one selected from succinic acid, adipic acid, terephthalic acid, and frangic acid is more preferred.

[0017] The aforementioned high molecular weight polyester is preferably one whose number average molecular weight is 1,000,000 to 10,000, more preferably 500,000 to 20,000, and even more preferably 200,000 to 50,000.

[0018] Specific examples of the aforementioned high molecular weight polyesters include polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene terephthalate (PBT), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), polybutylene azelate terephthalate (PBAzT), polybutylene succinate terephthalate (PBST), polybutylene succinate adipate terephthalate (PBSAT), polyethylene terephthalate (PET), and polyethylene Examples include succinate (PES), polyethylene adipate (PEA), polyethylene succinate adipate (PESA), polyethylene adipate terephthalate (PEAT), polyethylene succinate terephthalate (PEST), etc., and from the viewpoint of cost, strength, physical properties, and biodegradability, PBS, PBT, PBSA, PBAT, PBSAT, PET, PES, and PEAT are particularly preferred, PBS, PBT, PBSA, PBAT, PBSAT, and PET are more preferred, and PBS, PBSA, and PBAT are even more preferred.

[0019] One example of the depolymerization method is to add a polyhydric alcohol to a high molecular weight polyester and heat it to perform alcohol decomposition. This allows us to obtain an oligomer having a hydroxyl group at the end. The amount of polyhydric alcohol used in this case is preferably such that N / n is 2 to 40, more preferably 3 to 20, and even more preferably 4 to 10, when N / n is the number average degree of polymerization of the high molecular weight polyester, and n is the value obtained by multiplying the amount of polyhydric alcohol by 0.85 and dividing by the amount of high molecular weight polyester, and N is the number average degree of polymerization of the high molecular weight polyester. Adjusting N / n to fall within the above range is important in controlling the molecular weight of the oligomer obtained by depolymerization.

[0020] The polyhydric alcohol used in the alcohol decomposition is preferably a polyhydric alcohol derived from a polyhydric alcohol residue constituting the high molecular weight polyester. The amount of the polyhydric alcohol depends on the number-average molecular weight of the oligomer required, if no carboxylic acid or its derivative is added, but it is preferably adjusted to be 0.1 to 25% by mass of the high molecular weight polyester used in step (1), more preferably 1.0 to 20% by mass, and even more preferably 5.0 to 15% by mass.

[0021] In depolymerization, two or more of the high molecular weight polyester compounds may be used. Furthermore, a polycarboxylic acid or its derivative may be added simultaneously to adjust the constituent components of the resulting oligomer. The amount of carboxylic acid or its derivative added to adjust the constituent components is preferably 40%, 30%, and 20% by mass of the high molecular weight polyester as the upper limit, and 1%, 5%, and 10% by mass as the lower limit. In this case, assuming that the polycarboxylic acid or its derivative forms an ester with the coexisting polyhydric alcohol, the aforementioned n is defined as the value obtained by dividing 0.85n1-n2(v2-1) by the amount of substance of the high molecular weight polyester and adding 1, where n1 is the amount of substance of the polyhydric alcohol, v1 is the valence of the alcohol, and n2 is the amount of substance of the polycarboxylic acid and v2 is its valence. However, if 0.85n1-n2(v-1) is negative, n is defined as the value obtained by dividing n1-0.85n1(v1-1) by the amount of substance of the high molecular weight polyester and adding 1.

[0022] When a carboxylic acid or its derivative is added in the alcohol decomposition described above, the amount of substance of the carboxylic acid or its derivative added is preferably less than the amount of substance of the polyhydric alcohol used in the alcohol decomposition described above, and the amount of substance of the carboxylic acid or its derivative is preferably 0.01 to 0.99 times the amount of substance of the polyhydric alcohol, more preferably 0.05 to 0.90 times, and even more preferably 0.10 to 0.80 times.

[0023] In step (1), metal catalysts such as titanium, antimony tin, and zirconium may be used to efficiently advance the reaction. Examples of such catalysts include titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, titanium tetraisobutoxide, antimony trioxide, antimony triacetate, triphenylantimony, tributylantimony, tin formate, potassium titanium oxalate, tin oxalate, tetraphenyltin, dibutyltin dichloride, and dibutyltin dichloride. Examples of catalysts include oxides, diphenyltin oxide, dibutyltin dilaurate, zirconium tetraethoxide, zirconium tetrapropoxide, zirconium tetraisopropoxide, zirconium tetrabutoxide, zirconium tetraisobutoxide, zirconium tetraacetylacetonate, zirconium octylate, and zirconium stearate. It is particularly preferable to use titanium catalysts having alkoxy groups, such as titanium tetraisopropoxide, titanium tetrapropoxide, and titanium tetrabutoxide. From the viewpoint of reactivity and environmental impact, the amount of catalyst used is preferably 0.001 to 2.0% by mass of the high molecular weight polyester, and more preferably 0.005 to 1.0% by mass.

[0024] The number-average molecular weight of the resulting oligomers is preferably in the order of lower limit 200, 500, 1000, and 2000, and in the order of upper limit 20000, 10000, 5000, and 3000. A particularly preferred range is 500 to 5000, and a more preferred range is 1000 to 3000.

[0025] Step (1) is preferably carried out by heating to an appropriate temperature so that the reaction proceeds efficiently. The upper limit of the temperature is preferably 230°C, 220°C, and 210°C in that order, and the lower limit of the temperature is preferably 100°C, 120°C, and 140°C in that order. The particularly preferred range is 120°C to 220°C, and the more preferred range is 140°C to 210°C.

[0026] Step (1) is preferably carried out over an appropriate reaction time, which is preferably 1 to 12 hours, more preferably 2 to 10 hours, and even more preferably 3 to 8 hours.

[0027] Step (2) is a step in which an acidic group is introduced to the end of the oligomer obtained in step (1).

[0028] As a method for introducing an acidic group to the terminal of a polyester having a hydroxyl group at its terminal, for example, when introducing a carboxyl group, one method is to react the polyester having a hydroxyl group at its terminal with a carboxylic acid anhydride. The introduced acidic group is preferably a monovalent acidic group, and more preferably a monovalent carboxyl group. It is preferable to react a divalent carboxylic acid anhydride to introduce a monovalent carboxyl group, and examples of such divalent carboxylic acid anhydrides include succinic anhydride, glutaric anhydride, maleic anhydride, phthalic anhydride, O-acetyl-L-malic acid anhydride, cyclohexanedicarboxylic acid anhydride, tetrahydrophthalic acid anhydride, 1-cyclohexene-1,2-dicarboxylic acid anhydride, diglycolic acid anhydride, and 1,2-naphthalic acid anhydride. Of these, succinic anhydride, glutaric anhydride, maleic anhydride and phthalic anhydride are preferred, and succinic anhydride, glutaric acid anhydride and maleic anhydride are more preferred when considering biodegradability. The reaction between a polyester having a hydroxyl group at its terminus and an acid anhydride can be carried out using known methods commonly used for reactions between acid anhydrides and alcohols, such as heating and mixing the two.

[0029] As a method for introducing an acidic group to the end of a polyester having a hydroxyl group at its terminus, for example, when introducing a sulfuric acid ester group, one method is to react the polyester having hydroxyl groups at both ends with sulfur trioxide or a complex of sulfur trioxide and a Lewis base. Preferred Lewis bases constituting the complex of sulfur trioxide and a Lewis base include tertiary amines, pyridine, dimethylformamide, and dioxane. This can be carried out by referring to known methods, such as using a solvent as needed.

[0030] The marine biodegradable polyester obtained by the above method (hereinafter also referred to as marine biodegradable polyester A) may have a linear, branched, cyclic, or a combination thereof structure, but from the viewpoint of biodegradability and physical properties, it is preferable to be linear or branched, and more preferably linear.

[0031] From the viewpoint of balancing thermal and mechanical properties and biodegradability, the number-average molecular weight of marine biodegradable polyester A is preferably in the order of lower limit 200, 500, 1000, and 2000, and in the order of upper limit 20000, 10000, 5000, and 3000. A particularly preferred range is 500 to 5000, and a more preferred range is 1000 to 3000.

[0032] Furthermore, it is preferable that marine biodegradable polyester A has a relative biodegradation rate of 40% or higher. In this invention, relative biodegradation rate of cellulose refers to the maximum degree of degradation relative to the maximum degree of cellulose degradation within two years after immersion in seawater. It is more preferable that marine biodegradable polyester A has a relative biodegradation rate of 50% or higher, even more preferably 60% or higher, and most preferably 80% or higher. The relative biodegradation rate of cellulose can be measured by ASTM D6691, known marine biodegradation test methods, etc., or BOD modified based on these, and if the sample to be measured is solid, it should be powdered before measurement.

[0033] [Method for producing cross-linked marine biodegradable polyester] The present invention provides a method for producing crosslinked marine biodegradable polyester. (3) A step of neutralizing marine biodegradable polyester A and replacing some or all of the protons of the terminal acidic groups with monovalent cations other than protons to form a polymer containing polymer-type polyvalent anions, and (4) A step of crosslinking the polymer-type polyvalent anion via a divalent or higher cation. This includes the following. Hereinafter, marine biodegradable polyester crosslinked via divalent or higher cations obtained in step (4) and step (5) described later will also be called marine biodegradable polyester C.

[0034] Step (3) is a step in which marine biodegradable polyester A is neutralized and some or all of the protons of the terminal acidic groups are replaced with monovalent cations other than protons to form a polymer containing polymer-type polyvalent anions (hereinafter also referred to as marine biodegradable polyester B).

[0035] The monovalent cation is preferably a monovalent metal cation or a monovalent organic cation. The monovalent metal cation is preferably lithium ion, sodium ion, potassium ion, rubidium ion, cesium ion, francium ion, etc. The monovalent organic cation is preferably ammonium ion, methylammonium ion, ethylammonium ion, anilinium ion, pyridinium ion, dimethylammonium ion, diethylammonium ion, trimethylammonium ion, triethylammonium ion, etc. Of these, sodium ion, potassium ion, and ammonium ion are preferred as monovalent cations contained in marine biodegradable polyester B from the viewpoint of safety, environmental impact, and ease of handling, and sodium ion and potassium ion are more preferred.

[0036] The properties of marine biodegradable polyester B can be adjusted by controlling the content of monovalent cations other than protons. When used as a precursor for a crosslinked product with divalent cations in step (4) described later, the content of monovalent cations other than protons is preferably 80 mol% or more, 90 mol% or more, and 95 mol% or more of the total monovalent cations, in that order. Marine biodegradable polyester B can also be used as a raw material for a marine biodegradation accelerator, in which case the content of monovalent cations other than protons is preferably 30 mol% or less, 20 mol% or less, and 10 mol% or less of the total monovalent cations, in that order.

[0037] The neutralization reaction can be carried out using a base by a known acid-base reaction commonly used for neutralization. Examples of the base include lithium hydroxide, sodium hydroxide, potassium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, trisodium phosphate, tripotassium phosphate, lithium methoxide, sodium methoxide, potassium methoxide, lithium tert-butoxide, sodium tert-butoxide, potassium tert-butoxide, ammonia, methylamine, ethylamine, triethylamine, diazabicycloundecene, etc. Lithium hydroxide, sodium hydroxide, potassium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, and ammonia are preferred, and sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate are particularly preferred considering safety and environmental impact.

[0038] From the viewpoint of thermal and mechanical properties, biodegradability, and reactivity, marine biodegradable polyester B has a preferred lower limit of number average molecular weight in the order of 200, 500, 1000, and 2000, and a preferred upper limit in the order of 20000, 10000, 5000, and 3000. A particularly preferred range is 500 to 5000, and a more preferred range is 1000 to 3000.

[0039] Furthermore, it is preferable that marine biodegradable polyester B has a relative biodegradation rate of 40% or higher. In this invention, relative biodegradation rate of cellulose refers to the maximum degree of degradation relative to the maximum degree of cellulose degradation within two years after immersion in seawater. It is more preferable that marine biodegradable polyester B has a relative biodegradation rate of 50% or higher, even more preferably 60% or higher, and most preferably 80% or higher. The relative biodegradation rate of cellulose can be measured by ASTM D6691, known marine biodegradation test methods, etc., and BOD modified based on these. If the sample to be measured is solid, it should be powdered before measurement.

[0040] Step (4) is a step of crosslinking the polymer-type polyvalent anions contained in the marine biodegradable polyester B via divalent or greater cations.

[0041] The aforementioned cations with a valency of 2 or higher are not particularly limited, but include ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-butanediamine, 1,5-diaminopentane, 1,6-diaminohexane (hexamethylenediamine), 1,7-diaminoheptane, 1,8-diaminooctane, 1,10-diaminodecane, 1,12-diaminododecane, 3,3-diaminodipropylamine, tris(3-aminopropyl)amine, 3,3'-diaminobenzidine, 1,4-cyclohexanediamine, spermine, spermidine, triethylenetetramine, 1,4- Examples include polyvalent ammonium cations obtained from divalent or higher amines such as phenylenediamine, 1,2-diphenylethylenediamine, and orthotolidine, as well as calcium ions, beryllium ions, magnesium ions, strontium ions, barium ions, zinc ions, aluminum ions, iron ions, copper ions, platinum ions, gold ions, titanium ions, nickel ions, cobalt ions, manganese ions, zirconium ions, ruthenium ions, rhodium ions, palladium ions, scandium ions, gallium ions, indium ions, and radium ions. Of these, ethylenediammonium, calcium ions, beryllium ions, magnesium ions, strontium ions, barium ions, zinc ions, and aluminum ions are preferred, and calcium ions, magnesium ions, and aluminum ions are more preferred. The divalent or higher cations may be used individually or in combination of two or more.

[0042] The aforementioned crosslinking treatment methods include a method in which a powder or solution of polyvalent salt is dropped onto a medium in which marine biodegradable polyester B is dissolved or dispersed, and precipitates or settles while performing a bonding treatment; a method in which a powder or solution of polyvalent salt is dropped onto a molten marine biodegradable polyester B and performs a bonding treatment; and a method in which a solution in which marine biodegradable polyester B is dissolved is dropped onto a solution in which a powder of polyvalent salt or a polyvalent metal salt is dissolved, and precipitates or settles while performing a bonding treatment.

[0043] As a preferred example, a solution is prepared by dissolving or dispersing marine biodegradable polyester B in water, an organic solvent, or a mixture thereof, or by heating marine biodegradable polyester B to dissolve or disperse it. At this time, heating may be done as necessary to improve solubility and dispersibility, or to reduce the viscosity of the molten liquid. Next, a solution containing a divalent or higher salt is added to the obtained solution, dispersion, or molten liquid and stirred. Alternatively, a solution, dispersion, or molten liquid in which marine biodegradable polyester B is dissolved may be added to a solution containing a divalent or higher salt and stirred.

[0044] Examples of the polyvalent salts include organic salts such as the salts of the polyvalent amines, and metallic salts such as calcium salts, strontium salts, magnesium salts, barium salts, radium salts, lead salts, zinc salts, nickel salts, iron salts, copper salts, cadmium salts, cobalt salts, manganese salts, aluminum salts, gallium salts, indium salts, and thallium salts. However, from the standpoint of environmental impact, safety, and versatility, ethylenediammonium salts, calcium salts, magnesium salts, strontium salts, and aluminum salts are preferred, and calcium salts and magnesium salts are more preferred when considering the environment of seawater. Specific examples of the polyvalent salts include ethylenediamine hydrochloride, ethylenediamine sulfate, calcium chloride, calcium sulfate, calcium carbonate, calcium hydroxide, calcium oxide, magnesium chloride, magnesium sulfate, magnesium carbonate, magnesium hydroxide, magnesium oxide, aluminum sulfate, sodium aluminum sulfate (sodium alum), potassium aluminum sulfate (potassium alum), etc. However, from the viewpoint of solubility in water, ease of handling, and cost, ethylenediamine hydrochloride, calcium chloride, magnesium chloride, strontium chloride, and aluminum sulfate are preferred, and calcium chloride and magnesium chloride are more preferred.

[0045] Furthermore, the cross-linked marine biodegradable polyester is (5) A process in which a divalent or higher base is added to marine biodegradable polyester A to simultaneously neutralize some or all of the protons of the terminal acidic groups and crosslink via divalent or higher cations. It can also be manufactured by methods that include [a specific component].

[0046] As a preferred example of the method in step (5), a solution is prepared by dissolving or dispersing marine biodegradable polyester A in water, an organic solvent, or a mixture thereof, or by heating and dissolving marine biodegradable polyester A to prepare a molten solution. At this time, heating may be done as necessary to improve solubility or to reduce the viscosity of the molten solution. Next, a solution of a divalent or higher base is added to the obtained solution, dispersion, or molten solution and stirred. Alternatively, a solution, dispersion, or molten solution of marine biodegradable polyester A may be added to a solution of a divalent or higher base and stirred.

[0047] Examples of the aforementioned bases with a valency of 2 or more include the aforementioned polyvalent amines as organic bases, and magnesium hydride, strontium hydride, calcium hydride, barium hydride, magnesium methoxide, calcium methoxide, strontium methoxide, barium methoxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, magnesium oxide, strontium oxide, calcium oxide, barium oxide, magnesium carbonate, strontium carbonate, calcium carbonate, barium carbonate, magnesium bicarbonate, strontium bicarbonate, calcium bicarbonate, and barium bicarbonate, among others. However, ethylenediamine, calcium hydride, calcium methoxide, calcium hydroxide, barium hydroxide, and strontium hydroxide are preferred in terms of solubility in water, reactivity, cost, etc., and calcium hydroxide is more preferred.

[0048] The concentration of the polyvalent salt in the solution containing the polyvalent salt, or the concentration of the base in the solution containing a base of 2 or more valents, is preferably 1 to 40% by mass, and more preferably 10 to 30% by mass. The solvent of the solution is preferably a lower alcohol solvent such as water, methanol, ethanol, 1-propanol, 2-propanol, amphiphilic solvents such as acetone, acetonitrile, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, or a mixture thereof. However, a mixture of other organic solvents is also acceptable as long as the salt can be dissolved to the desired concentration without dissolving the particles.

[0049] Furthermore, if the polyvalent salt or divalent or more base is highly reactive and reacts even in a solid state, it may be used in powder form without a medium, or dispersed in a small amount of a medium.

[0050] In this way, the polyester-type polyvalent anions contained in marine biodegradable polyester A or B can be bonded via divalent or higher cations, and the target marine biodegradable polyester C, which has gradually become insoluble, can be obtained as precipitate, sediment, or bulk. The treatment time is preferably 0.5 to 24 hours, and more preferably 1 to 12 hours.

[0051] In this case, for the purpose of controlling the particle size and shape (such as spherical) of the precipitate or sediment, a surfactant or polymer stabilizer may be dissolved in at least one of a solution containing marine biodegradable polyester A or B, and a solution containing a divalent or polyvalent base or polyvalent salt.

[0052] Heating may be performed when precipitating or precipitation the target marine biodegradable polyester C. Heating may be performed when mixing a solution containing a dissolved or dispersed marine biodegradable polyester A or B, or a molten marine biodegradable polyester A or B, with a solution containing a polyvalent salt or a base of two or more progenitors, or when stirring after mixing, or both. The heating temperature is preferably 15 to 150°C, more preferably 20 to 100°C, and more preferably 40 to 80°C.

[0053] After processing, marine biodegradable polyester C can be obtained by washing the resin as needed. Washing can be carried out by conventional methods, such as removing the solvent after bonding and adding water, followed by centrifugation or decantation.

[0054] After washing, marine biodegradable polyester C can be obtained by drying as needed. Drying can be carried out by conventional methods, such as spray drying, vacuum drying, or freeze-drying. The drying process may also involve stirring or heating, and if heating is used, a temperature of 30 to 200°C is preferred, 40 to 190°C is more preferred, and 60 to 180°C is even more preferred.

[0055] After drying, heating may be performed to improve fluidity when extracting marine biodegradable polyester C, in which case a temperature of 20 to 180°C is preferred, 30 to 160°C is more preferred, and 40 to 140°C is even more preferred.

[0056] Furthermore, the obtained marine biodegradable polyester C may be subjected to surface treatment or pulverization to adjust its particle size using known equipment, if necessary.

[0057] The marine biodegradable polyester C may have at least one of its ends that are not bonded to other polyester-type polyvalent anions via a divalent cation sealed with a sealing segment group.

[0058] By selecting the appropriate sealing segment group, multiple effects can be incorporated in single materials and composite materials (marine biodegradable compositions) using this material, such as adjustment of melt temperature and melt viscosity, adjustment of crystallinity, adjustment of microbial adhesion and biodegradability, adjustment of physical properties such as resin tensile strength, flexural strength, and elasticity, improvement of compatibility with resins, adjustment of hydrophobicity, adjustment of water repellency, adjustment of adhesion, and adjustment of plasticity. This allows for improvements in both the biodegradability and physical properties of marine biodegradable compositions. Since the organic anion that forms the sealing segment is desirable to have a structure that is biodegradable in the ocean, it is desirable to select a sealing segment group with a molecular weight of 5000 or less that is biodegradable in the ocean. For example, when prioritizing the biodegradation rate in the ocean and maintaining average physical properties, a molecular weight of 2500 or less is preferred, and a molecular weight of 1000 or less is more preferred.

[0059] Specifically, the sealing segment group is preferably one having a monovalent hydrocarbon group with 3 or more carbon atoms, more preferably one having a monovalent hydrocarbon group with 6 or more carbon atoms, even more preferably one having a monovalent hydrocarbon group with 10 or more carbon atoms, and most preferably one having a monovalent hydrocarbon group with 12 or more carbon atoms. The upper limit of the number of carbon atoms in the monovalent hydrocarbon group is not particularly limited, but is preferably 30 or less, more preferably 25 or less, and even more preferably 20 or less.

[0060] The sealing segment group is preferably a monovalent organic anion selected from a carboxylic acid anion having 3 or more C3 monovalent hydrocarbon groups, a sulfonic acid anion having 3 or more C3 monovalent hydrocarbon groups, a sulfate ester anion having 3 or more C3 monovalent hydrocarbon groups, and a phosphate ester anion having 3 or more C3 monovalent hydrocarbon groups. Of these, it is preferably a monovalent organic anion derived from a carboxylic acid having 3 or more C3 monovalent hydrocarbon groups, and more preferably a monovalent organic anion derived from a fatty acid having 3 or more C3 monovalent hydrocarbon groups or an amino acid derivative having 3 or more C3 monovalent hydrocarbon groups.

[0061] End encapsulation can be performed using at least one end encapsulant selected from carboxylic acids having three or more C3 or more monovalent hydrocarbon groups, salts of the carboxylic acid, sulfonic acids having three or more C3 or more monovalent hydrocarbon groups, salts of the sulfonic acid, sulfate esters having three or more C3 or more monovalent hydrocarbon groups, salts of the sulfate esters, phosphate esters having three or more C3 or more monovalent hydrocarbon groups, and salts of the phosphate esters. End encapsulation can be performed by adding the end encapsulant to a solution containing marine biodegradable polyester A or B, and then binding it with polyvalent metal ions.

[0062] As the end-capturing agent, acid compounds or salt compounds described in paragraphs

[0029] to

[0044] of Japanese Patent Application Publication No. 2021-191810 are preferred.

[0063] The polyvalent ion equivalents in the aforementioned marine biodegradable polyester C are set to an upper limit of 100, 80, and 50 eq / 10 from the viewpoint of thermal, mechanical properties, and biodegradability. 5 The order of preference is g, with 1, 2, 5 and 10 eq / 10 as the lower limit. 5 The order of preference is g. If the ion equivalent is within the above range, it is preferable because it has good biodegradability and its mechanical properties are not impaired. The ion equivalent is measured by inductively coupled plasma mass spectrometry (ICP-MS) when the ion is a metal, and by liquid chromatography-mass spectrometry (LC-MS) when the ion is an organic cation.

[0064] The polyvalent ion equivalent is the theoretical value when all polyester-type polyvalent anions and all polyvalent cations are stoichiometrically consumed by the infinite connection of polyfunctional polyester-type polyvalent anions through polyvalent cations or by the connection of the linked polymer compound itself with polyvalent cations within the molecule. Let this value be k ideal Then, k ideal =nf / nv·1 / Mn·10 5 eq / 10 5 g. Here, nf is the number of anionic functional groups of the polyester-type polyvalent anion, nv is the valence of the polyvalent cation, and Mn is the number-average molecular weight of the polyester-type polyvalent anion. As combinations of the polyfunctional polyester-type polyvalent anion constituting the marine biodegradable polyester C with polyvalent cations, the values of k ideal are preferably 100, 80, and 50 eq / 10 5 g in this order as the upper limit, and preferably 1, 2, 5, and 10 eq / 10 5 g in this order as the lower limit. If the value of k ideal is within the above range, it has good biodegradability and does not impair the mechanical properties, so it is preferable.

[0065] Taking the polyvalent ion equivalent in the marine biodegradable polyester C as k, when the ratio of k to the above k ideal is q = k / k ideal the value of q is preferably in the range of 0.70 to 1.30, more preferably in the range of 0.80 to 1.20, and even more preferably in the range of 0.90 to 1.10. If the value of q is within the above range, the polyvalent anion and the polyvalent cation are sufficiently linked, and there are also few excess ions, which is a good state.

[0066] Marine biodegradable polyester C is a material in which the polyester-type polyvalent anions contained in the aforementioned marine biodegradable polyesters A or B are bonded via metal cations. In marine biodegradable polyester C, only one type of polyester-type polyvalent anion may be present, or multiple different types may be present. Marine biodegradable polyester C may also simultaneously contain anionic compounds other than the polyester-type polyvalent anions. Examples of such anionic compounds include polymer compounds with anionic groups at their terminals and a number average molecular weight of 500 to 10000, carboxylic acid anions with a molecular weight of 1000 or less, amino acid anions with a molecular weight of 1000 or less, amino acid derivative anions with a molecular weight of 1000 or less, and sulfonic acid anions with a molecular weight of 1000 or less.

[0067] An example of a polymer compound having an anionic group at its terminus and a number-average molecular weight of 500 to 10000 is a compound obtained by introducing an acidic group to a polymer compound having an active hydrogen group such as a hydroxyl group, amino group, or thiol group at its terminus, and then neutralizing it. A method for introducing the acidic group is to introduce an acidic group to the aforementioned polyester having a hydroxyl group at its terminus by a modification reaction. As for the polymer compound having an anionic group at its terminus and a number-average molecular weight of 500 to 10000, a compound obtained by reacting a polymer compound having an active hydrogen group such as a hydroxyl group or amino group at its terminus with succinic anhydride, maleic anhydride, or phthalic anhydride and then neutralizing it is preferred, and a compound obtained by reacting a polymer compound having a hydroxyl group at its terminus with succinic anhydride or maleic anhydride and then neutralizing it is more preferred.

[0068] The polymer compound having a hydroxyl group at the terminus or the polymer compound having an amino group at the terminus may be a commercially available product or a synthesized product. Examples of the commercially available products include Kuraray Polyol P-1010, P-2010, P-2011, P-2012, P-2020, P-2050, P-520, C-590, C-1090, F-510, F-1010 (manufactured by Kuraray Co., Ltd.), Praxel 210B, 220N, 308 (manufactured by Daicel Corporation), polypropylene glycol, diol type 1000, polypropylene glycol, triol type 300 (manufactured by Fujifilm Wako Pure Chemical Industries Ltd.), poly(propylene glycol) bis(2-aminopropyl ether) 400, poly(propylene glycol) bis(2-aminopropyl ether) 2000 (manufactured by Sigma-Aldrich). One example of synthesis is a method in which two or more appropriate raw materials are selected from the aforementioned divalent or higher carboxylic acids, divalent or higher alcohols and divalent or higher amines, as well as the divalent or higher isocyanates, lactones, lactams, etc., described later, and polycondensation or polyaddition reactions are carried out. For example, polyester polyols can be obtained by polycondensation of a divalent or higher carboxylic acid and a divalent or higher alcohol, polyamide polyamines by polycondensation of a divalent or higher carboxylic acid and a divalent or higher amine, polyurethane polyols by polyaddition of a divalent or higher isocyanate and a divalent or higher alcohol, ring-opening polymerization type polyester polyols by ring-opening polymerization of a divalent or higher alcohol and a lactone, and ring-opening polymerization type polyamide polyamines by ring-opening polymerization of a divalent or higher amine and a lactam. However, the combinations are not limited to these, and three or more raw materials with different functional groups, or two or more different raw materials having the same functional group, may be used simultaneously. The aforementioned divalent or higher carboxylic acids, divalent or higher alcohols, divalent or higher amines, divalent or higher isocyanates, lactones / lactides, and lactams may be derivatized, for example, by acid halides, esters, or halides, in order to enhance reactivity. Known methods can be used for the polycondensation and polyaddition reactions, and metal catalysts or organic catalysts may be used to enhance reactivity as needed.

[0069] The aforementioned amines with a valency of 2 or higher include ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-butanediamine, 1,5-diaminopentane, 1,6-diaminohexane (hexamethylenediamine), 1,7-diaminoheptane, 1,8-diaminooctane, 1,10-diaminodecane, 1,12-diaminododecane, 3,3-diaminodipropylamine, tris(3-aminopropyl)amine, 3,3'-diaminobenzidine, 1, Examples include 4-cyclohexadiamine, spermine, spermidine, triethylenetetramine, 1,4-phenylenediamine, 1,2-diphenylethylenediamine, and orthotolidine. Ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-butanediamine, hexamethylenediamine, and 1,4-phenylenediamine are particularly preferred, with ethylenediamine, 1,4-butanediamine, and hexamethylenediamine being more preferred.

[0070] Examples of the divalent or higher isocyanates include hexamethylene diisocyanate (HDI), pentamethylene diisocyanate (PDI), isophorone diisocyanate (IPDI), cyclohexane-1,4-diisocyanate, methylenebis(4-cyclohexyl isocyanate), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric MDI, xylene diisocyanate, 1,4-phenylene diisocyanate, and others, with HDI, PDI, MDI, and TDI being particularly preferred.

[0071] Examples of the aforementioned lactones and lactides include β-propiolactone, γ-butyrolactone, ε-caprolactone, δ-hexanolactone, mevalonate lactone, 1,3-dioxan-2-one, 1,4-dioxan-2-one, 1,4-dioxan-2,5-dione, γ-heptanolactone, γ-hexanolactone, glycolide, lactide, and 1,6-dioxacyclodecane-2,7-dione, with ε-caprolactone, glycolide, and lactide being particularly preferred.

[0072] Examples of the aforementioned lactams include β-propiolactam, ε-caprolactam, ω-heptalactam, ω-octalactam, and ω-laurinlactam, with β-propiolactam and ε-caprolactam being particularly preferred.

[0073] Carboxylate anions with a molecular weight of 1000 or less that may be included in the aforementioned marine biodegradable polyester C include 1,5-naphthalenedisulfonic acid, ethanedisulfonic acid, monoethyl phosphate, malic acid, aspartic acid, glutamic acid, succinic acid, adipic acid, sebacic acid, terephthalic acid, isophthalic acid, caproic acid, enanthic acid, caprylic acid, octic acid, pelargonic acid, capric acid, undecylenic acid, lauric acid, myristic acid, pentadecyl acid, palmitic acid, palmitoleic acid, margaric acid, stearyl acid Examples of anions include linic acid, isostearic acid, oleic acid, vaccenic acid, ricinoleic acid, linoleic acid, linolenic acid, eleostearic acid, oxystearic acid, arachidic acid, meadic acid, arachidonic acid, eicosapentaenoic acid, behenic acid, docosahexaenoic acid, lignoceric acid, nervonic acid, cerotic acid, montanic acid, melissic acid, coconut oil fatty acid, palm oil fatty acid, etc., with lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, oleic acid, and linoleic acid anions being particularly preferred.

[0074] The amino acid anions or amino acid derivative anions with a molecular weight of 1000 or less that may be contained in the aforementioned marine biodegradable polyester C include anions of amino acids such as alanine, leucine, arginine, lysine, asparagine, methionine, aspartic acid, phenylalanine, cysteine, proline, glutamine, serine, glutamic acid, threonine, glycine, tryptophan, histidine, tyrosine, and isoleucine, as well as sarcosine derivatives (caproyl sarcosine, lauroyl sarcosine, myristoyl sarcosine, palmitoyl sarcosine). Cosine, coconut oil fatty acid sarcosine, etc.), glutamic acid derivatives (caproyl glutamic acid, lauroyl glutamic acid, myristoyl glutamic acid, palmitoyl glutamic acid, stearoyl glutamic acid, coconut oil fatty acid acyl glutamic acid, cocoyl glutamic acid, acyl glutamic acid, dilauroyl glutamic acid, etc.), glycine derivatives (lauroyl glycine, myristoyl glycine, palmitoyl glycine, palmitoyl methylglycine, coconut oil fatty acid acylglycine, cocoyl glycine, etc.), alanine derivatives (lauryl methyl a Lanine, myristoyl methylalanine, cocoyl alanine, coconut oil fatty acid methylalanine, etc., lysine derivatives (lauroyl lysine, myristoyl lysine, palmitoyl lysine, stearoyl lysine, oleyl lysine, acylated lysine, etc.), aspartic acid derivatives (lauroyl aspartic acid, myristoyl aspartic acid, palmitoyl aspartic acid, stearoyl aspartic acid, etc.), taurine derivatives (lauroyl taurine, lauroyl methyl taurine, myristoyl taurine, myristoyl methyl taurine, palmitoyl Examples include anions of amino acid derivatives having hydrocarbon groups, such as taurine, palmitoylmethyltaurine, stearoyltaurine, stearoylmethyltaurine, etc., and proline derivatives (lauroylproline, myristoylproline, palmitoylproline, etc.). Particularly preferred are anions of caproyl sarcosine, lauroyl sarcosine, myristoyl sarcosine, palmitoyl sarcosine, caproyl glutamic acid, lauroyl glutamic acid, myristoyl glutamic acid, palmitoyl glutamic acid, and stearoyl glutamic acid.

[0075] Examples of sulfonic acid anions with a molecular weight of 1000 or less that may be contained in the marine biodegradable polyester C include alkyl sulfonic acids (lauryl sulfonic acid, myristyl sulfonic acid, cetyl sulfonic acid, stearyl sulfonic acid, oleyl sulfonic acid, etc.), dodecylbenzene sulfonic acid, dialkyl succinate sulfonic acid, monoalkyl succinate sulfonic acid, naphthalene sulfonic acid, olefin sulfonic acid, alkyl isethionic acid (lauroyl isethionic acid, myristoyl isethionic acid, palmitoyl isethionic acid, stearoyl isethionic acid, etc.), and dialkyl sulfosuccinic acid (dihexyl sulfosuccinic acid, dioctyl sulfosuccinic acid, didecyl sulfosuccinic acid, diisobutyl sulfosuccinic acid, etc.), with lauryl sulfonic acid, myristyl sulfonic acid, cetyl sulfonic acid, and stearyl sulfonic acid being particularly preferred.

[0076] Furthermore, marine biodegradable polyester C containing anions derived from other anionic compounds can be produced by using a medium in which the aforementioned marine biodegradable polyester A or B is dissolved or dispersed, or by adding anionic compounds to the molten marine biodegradable polyester A or B.

[0077] When marine biodegradable polyester C is mixed with other resins, it is preferable that it has a softening point or melting point suitable for the melting temperature of the other resins. The polymer compound is solid at room temperature, and more specifically, the lower limit of the softening point or melting point is preferably 40°C, 50°C, and 60°C in that order, and the upper limit is preferably 250°C, 180°C, 160°C, and 140°C in that order. If the other resin is a biodegradable resin, it is preferable that the softening point or melting point is in the range of 40 to 200°C, more preferably 50 to 160°C, and even more preferably 60 to 140°C.

[0078] Marine biodegradable polyester C preferably has a relative biodegradation rate of 40% or higher relative to cellulose. In this invention, relative biodegradation rate of cellulose refers to the degree of decomposition of cellulose after 60 days of immersion in seawater. Marine biodegradable polyester C is more preferably 50% or higher relative to cellulose, even more preferably 60% or higher, and most preferably 80% or higher. Relative biodegradation rate of cellulose can be measured by ASTM D6691, known marine biodegradation test methods, or BOD modified based on these, and if the sample to be measured is solid, it should be powdered before measurement.

[0079] Steps (1) to (5) may be carried out under reduced pressure or increased pressure as necessary, but from the viewpoint of manufacturing efficiency and simplicity, it is preferable to carry out one or more of steps (1) to (5) under normal pressure, more preferably three or more steps under normal pressure, and even more preferably all steps under normal pressure. Normal pressure refers to atmospheric pressure.

[0080] The marine biodegradable polyesters A, B, and C obtained by the method of the present invention (hereinafter collectively referred to as marine biodegradable polyesters) can be suitably used as raw materials for marine biodegradable compositions containing them.

[0081] The marine biodegradable polyester may be used as the main raw material, or it may be used as an additive in combination with other resins. The other resins are not particularly limited, but are preferably biodegradable resins. In this case, the composite resin will be a composition that promotes biodegradation in the ocean. Furthermore, in order to adjust the physical properties and handling characteristics of the composition, multiple types of resins may be used in combination as the other resins.

[0082] Other resins include polyethylene, polyester, polypropylene, polyethylene terephthalate, polystyrene, polyurethane, epoxy resin, chlorinated polyethylene resin, chlorinated polypropylene resin, modified nylon resin, phenolic resin, silicone resin, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, styrene-maleic acid resin, styrene-butadiene resin, butadiene resin, acrylonitrile-butadiene resin, poly(meth)acrylonitrile resin, (meth)acrylamide resin, bioPET, biopolyamide, biopolycarbonate, biopolyurethane, polyvinyl alcohol, polybutylene adipate terephthalate, polyethylene terephthalate succinate, biopolybutylene succinate, polylactic acid blend, starch blend polyester resin, polybutylene terephthalate succinate, polylactic acid, polyhydroxyalkanoic acid, etc. However, considering the reduction of environmental impact and the effect of promoting marine biodegradability, resins with high biodegradability are particularly preferred.

[0083] Furthermore, the biodegradable resins include polycaprolactone, poly(caprolactone / butylene succinate), polybutylene succinate (PBS), poly(butylene succinate / adipate) (PBSA), poly(butylene adipate / terephthalate) (PBAT), poly(butylene succinate / carbonate), polyethylene terephthalate copolymer, poly(ethylene terephthalate / succinate), poly(tetramethylene adipate / terephthalate), polyethylene succinate, polyvinyl alcohol, polyglycolic acid, glycolic acid / caprolactone copolymer, glycolic acid / trimethylene carbonate copolymer, etc., which are resins derived from petroleum; (polylactic acid / polybutylene succinate-based) block copolymer, (polylactic acid / polycaprolactone) copolymer, (polylactic acid / polyether) copolymer, Examples of resins include those made from partially biomass-derived raw materials such as polylactic acid blend PBAT, lactic acid / glycolic acid copolymer, biopolybutylene succinate, poly(butylene succinate / adipate), starch blend polyester resin, and poly(butylene succinate terephthalate) (PBST); resins made from 100% biomass-derived raw materials such as polyhydroxyalkanoates like polyhydroxybutyric acid, polyhydroxyvaleric acid, polyhydroxycaprylic acid, poly(hydroxybutyrate / hydroxyhexanoate) (PHBH), poly(3-hydroxybutyrate / 4-hydroxybutyrate) (P3HB4HB), and poly(hydroxybutyrate / hydroxyvaleric acid) (PHBV), and polylactic acid (PLA); and resins made from natural polymers such as cellulose, cellulose acetate, cellulose ester resin, starch, esterified starch, and chitosan. These may be used individually or in combination of two or more types.

[0084] Of these, it is preferable to combine a biodegradable resin, selected from resins that are biodegradable in soil or compost but have poor biodegradability in the ocean, such as polycaprolactone, PBS, PBSA, PBAT, PBST, poly(tetramethylene adipate / terephthalate), poly(butylene succinate / carbonate), polyhydroxyalkanoates such as PHBH, PHBV, PLA, cellulose, starch, polylactic acid blend PBAT, chitosan, and other resins derived from natural polymers, with the marine biodegradable polyester. Among these, resins derived from PBSA, PBS, PBAT, PBST, PLA, starch, and polylactic acid blend PBAT are particularly preferred as the biodegradable resin.

[0085] From the viewpoint of thermal and mechanical properties and biodegradability, a preferred combination of the biodegradable resin and the marine biodegradable polyester is, if all polycarboxylic acid residues of the marine biodegradable polyester are aliphatic carboxylic acid residues, then the biodegradable resin is preferably PBSA, PBS, PLA, PHBV, or PHBH, and more preferably PBSA or PBS. Furthermore, if the polycarboxylic acid residues of the marine biodegradable polyester include both aliphatic and aromatic carboxylic acid residues, then the biodegradable resin is preferably PBAT, PBST, PLA, starch, or polylactic acid blend PBAT, and more preferably PBAT, starch, or polylactic acid blend PBAT. With the above combinations, there is little change in the physical properties of the biodegradable resin due to compounding, and the effect of promoting biodegradation is significant.

[0086] Furthermore, considering the reduction of environmental impact, the raw materials for the resin to be combined are preferably 20% or more biomass-derived, more preferably 50% or more biomass-derived, and most preferably 100% biomass-derived.

[0087] The marine biodegradable composition may contain a solvent. The solvent may dissolve the resin matrix while leaving the marine biodegradable polyester as particles, or it may dissolve both the resin and the marine biodegradable polyester. By adjusting these as appropriate, the composition can be used as a molded product formed into a film by casting, or as a paint, ink, surface treatment agent, etc. Preferred solvents include, for example, water, formic acid, hexane, heptane, acetonitrile, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dimethyl sulfone, acetone, methyl ethyl ketone, diethyl ketone, acetophenone, dimethyl ether, dipropyl ether, tetrahydrofuran, chloroform, methylene chloride (dichloromethane), trichloroethylene, dichloroethylene, tetrachloroethane, chlorobenzene, methanol, ethanol, n-propanol, isopropanol, butanol, pentanol, hexafluoroisopropanol, methyl glycol, methyl triglyceride, hexyl glycol, phenyl glycol, ethylene glycol, propylene glycol, phenol, cresol, polyethylene glycol, benzene, toluene, and xylene. These may be used individually or in combination of two or more.

[0088] When a solvent is used, the total concentration of the resin and marine biodegradable polyester in the composition is preferably 0.5 to 90% by mass, more preferably 1 to 80% by mass, even more preferably 5 to 60% by mass, and most preferably 10 to 50% by mass. Furthermore, the ratio of marine biodegradable polyester to the resin is preferably 99:1 to 10:90 by mass, more preferably 97:3 to 40:60, even more preferably 95:5 to 50:50, and most preferably 90:10 to 60:40.

[0089] The lower limit of the softening point of the composition is preferably 50°C, 60°C, and 70°C, in that order, and the upper limit is preferably 250°C, 200°C, and 180°C, in that order. Preferably, the softening point is in the range of 50 to 250°C, more preferably 60 to 200°C, and even more preferably 70 to 180°C.

[0090] Furthermore, the marine biodegradable composition does not need to contain a solvent. In this case, the resin may be heated and melted, and a non-melting marine biodegradable polyester may be added and mixed thereto, or the resin and the marine biodegradable polyester may be melted together and mixed.

[0091] In the marine biodegradable composition, the content of marine biodegradable polyester is preferably 1 to 60% by mass, more preferably 3 to 50% by mass, even more preferably 5 to 45% by mass, still more preferably 7 to 40% by mass, and most preferably 10 to 35% by mass. By including marine biodegradable polyester within the above range, the marine biodegradable composition can be used as a marine biodegradation accelerator that promotes biodegradation in seawater while maintaining the physical properties of the biodegradable resin. The marine biodegradable polyester may be used alone or in combination of two or more types.

[0092] The tensile strength of the test specimen obtained from the composition is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more, compared to a blank resin test specimen that does not contain marine biodegradable polyester, when the marine biodegradable polyester content in the composition is 10% by mass. Furthermore, when the marine biodegradable polyester content in the composition is 30% by mass, the tensile strength is preferably 65% ​​or more, more preferably 70% or more, and even more preferably 80% or more.

[0093] The marine biodegradable composition may optionally contain additives such as antioxidants, mold release agents, release agents, surface modifiers, hydrophobic agents, water-repellent agents, hydrophilic agents, dyes and pigments, colorants, heat stabilizers, light stabilizers, weather resistance improvers, antistatic agents, antifogging agents, lubricants, antiblocking agents, hardening agents, softening agents, compatibilizers, flame retardants, flow improvers, plasticizers, dispersants, antibacterial agents, fillers, and metal deactivators. The content of these additives is not particularly limited as long as it does not impair the effects of the present invention, but is preferably about 0.1 to 50 parts by mass per 100 parts by mass of resin.

[0094] If the marine biodegradable composition contains a solvent, it can be prepared, for example, by adding the resin, the marine biodegradable polyester, and the additives as needed to the solvent simultaneously or in any order and mixing them. If the marine biodegradable composition does not contain a solvent, for example, the resin may be melted, and the marine biodegradable polyester and the additives as needed may be added simultaneously or in any order and mixed; or the resin and marine biodegradable polyester may be heated to melt them together and mixed, and the additives as needed may be added and mixed.

[0095] By molding using the aforementioned marine biodegradable composition, a molded article can be obtained in which marine biodegradable polyester is dispersed or dissolved in the resin. If the composition contains a solvent, the composition can be used as is for molding; if the composition does not contain a solvent, the resin in the composition, or the resin and marine biodegradable polyester, can be melted by heat before molding.

[0096] Examples of the shape of the molded article include film-like, fibrous, plate-like, foamed molded article-like, and other shapes depending on the application. The molding method is not particularly limited, and various conventionally known molding methods can be used. Specific examples include blow molding, injection molding, extrusion molding, compression molding, melt extrusion molding, solution casting molding, and calendering.

[0097] The aforementioned marine biodegradable polyester and marine biodegradable composition can be used as a raw material for plastic molded products, and as various additives to molded products such as liquids, coatings, films, plates, and paper. When used as a raw material for plastic molded products, it can be used as a raw material for general-purpose applications such as films, packaging, containers, trays, laminates, adhesives, coatings, medical and clothing fibers, shoes, belts, tires, tubes, shock absorbers, fishing lines, and fishing nets, as well as marine application materials, and is particularly suitable for use as a raw material for marine application materials. Furthermore, when used as an additive, it can be widely used as an additive for various applications, such as light scattering agents, optical filter materials, colorants, cosmetics, absorbents, adsorbents, inks, adhesives, electromagnetic shielding materials, fluorescent sensors, biomarkers, recording materials, recording elements, polarizing materials, drug holders for drug delivery systems (DDS), biosensors, DNA chips, diagnostic reagents, calcined porous molded products, antiblocking agents, additives for printing inks used in screen printing, offset printing, process printing, gravure printing, pad printing, coaters, inkjet printers, etc., additives for writing instrument inks such as marking pens, ballpoint pens, fountain pens, brush pens, and markers, additives for stationery such as crayons, paints, and erasers, and additives for paints used in brush painting, spray painting, electrostatic painting, electrodeposition painting, pouring, roller painting, and dipping painting, particularly as an additive for paints used in marine applications such as ship hull paints. [Examples]

[0098] The present invention will be described more specifically below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples and comparative examples, the metal ion equivalent was measured by emission analysis using ICP-MS (ICPE-9820, Shimadzu Corporation) after heating and decomposing the target substance with nitric acid or aqua regia. The organic cation equivalent was measured using LC-MS / MS (Triple Quad 3500, AB Sci-X Corporation) after decrosslinking the target substance by immersion in brine or a solution containing a chelating agent. The number-average molecular weight and the composition ratio of carboxylic acid residues in the polyester were measured using a nuclear magnetic resonance spectrometer (JNM-ECZ400S, JEOL Ltd.). 1The softening temperature was calculated from the integrated peak values ​​in 1H-NMR. The softening temperature was determined using a thermomechanical analyzer (NETZSCH Japan Co., Ltd. TMA4000SE).

[0099] [1] Synthesis of marine biodegradable polyester A

[0100] [Example 1-1] Synthesis of marine biodegradable polyester A-1 Depolymerization was carried out by adding 500g of polybutylene succinate (PBS) pellets with a number-average molecular weight of 110,000, 27.3g of 1,4-butanediol, and 2.50g of titanium tetraisopropoxide to a 1L flask and heating and stirring at 160°C for 6 hours. After cooling to room temperature, 10mg was taken from the contents of the flask. 1 ¹H-NMR analysis revealed the presence of hydroxyl groups at the terminals, and the number-average molecular weight determined by terminal determination was 2000. Subsequently, 52.5 g of acetonitrile and 54.0 g of maleic anhydride were added, and the mixture was heated and stirred at 130°C for 4 hours. After that, the contents were removed from the mixture into a stainless steel tray with a Teflon® sheet to obtain marine biodegradable polyester A-1 as a solid resin. 10 mg was taken from the obtained resin, 1 ¹H-NMR analysis revealed that all terminal hydroxyl groups had reacted.

[0101] [Examples 1-2] Synthesis of marine biodegradable polyester A-2 Depolymerization was carried out by adding 500g of polybutylene adipate terephthalate (PBAT) pellets, which have an adipic acid residue to terephthalic acid residue ratio of 49:51 and a number-average molecular weight of 98,000, 116g of 1,4-butanediol, 109g of dimethyl adipate, and 2.50g of titanium tetraisopropoxide to a 1L flask and heating and stirring at 160°C for 6 hours. After cooling to room temperature, 10mg was taken from the contents of the flask. 1¹H-NMR analysis revealed that the compound had hydroxyl groups at its termini, and its number-average molecular weight by terminology was 1200. The ratio of adipic acid residues to terephthalic acid residues was 60:40. Next, 67.3 g of acetonitrile and 117 g of succinic anhydride were added, and the mixture was heated and stirred at 130°C for 4 hours. The contents were then transferred to a stainless steel tray with a Teflon® sheet to obtain marine biodegradable polyester A-2 as a solid resin. 10 mg was taken from the obtained resin. 1 ¹H-NMR analysis revealed that all terminal hydroxyl groups had reacted.

[0102] [Examples 1-3] Synthesis of marine biodegradable polyester A-3 Depolymerization was carried out by adding 500g of polybutylene succinate adipate (PBSA) pellets with a succinic acid residue to adipic acid residue ratio of 80:20 and a number-average molecular weight of 100,000, 6.50g of 1,2-ethanediol, 7.50g of 1,4-butanediol, and 2.50g of titanium tetraisopropoxide to a 1L flask and heating and stirring at 160°C for 6 hours. After cooling to room temperature, 10mg was taken from the contents of the flask, 1 ¹H-NMR analysis revealed that the compound had hydroxyl groups at its termini, and its number-average molecular weight by terminology was 3000. The ratio of succinic acid residues to adipic acid residues was 80:20, and the ratio of 1,2-ethanediol residues to 1,4-butanediol residues was 45:55. Subsequently, 51.3 g of toluene and 53.2 g of phthalic anhydride were added, and the mixture was heated and stirred at 130°C for 4 hours. After that, the contents were removed from the mixture into a stainless steel tray with a Teflon® sheet to obtain marine biodegradable polyester A-3 as a solid resin. 10 mg was taken from the obtained resin, 1 ¹H-NMR analysis revealed that all terminal hydroxyl groups had reacted.

[0103] [Examples 1-4] Synthesis of marine biodegradable polyester A-4 In a 1L flask, 300g of polybutylene succinate (PBS) pellets with a number-average molecular weight of 110,000, 200g of polybutylene adipate terephthalate (PBAT) pellets with an adipic acid residue to terephthalic acid residue ratio of 49:51 and a number-average molecular weight of 98,000, 27.3g of 1,4-butanediol, and 2.50g of titanium tetraisopropoxide were added and depolymerized by heating and stirring at 160°C for 6 hours. After cooling to room temperature, 10mg was taken from the contents of the flask. 1 ¹H-NMR analysis revealed that the compound had hydroxyl groups at its ends, and its number-average molecular weight by terminal determination was 2000. The ratio of succinic acid residues, adipic acid residues, and terephthalic acid residues was 63:18:19. Subsequently, 52.5 g of acetonitrile and 55.1 g of succinic anhydride were added, and the mixture was heated and stirred at 130°C for 4 hours. After that, the contents were removed from the mixture into a stainless steel tray with a Teflon® sheet to obtain marine biodegradable polyester A-4 as a solid resin. 10 mg was taken from the obtained resin, 1 ¹H-NMR analysis revealed that all terminal hydroxyl groups had reacted.

[0104] [Examples 1-5] Synthesis of marine biodegradable polyester A-5 Depolymerization was carried out by adding 400g of polybutylene succinate (PBS) pellets with a number-average molecular weight of 110,000, 111g of 1,4-butanediol, 157g of dimethyl adipate, and 2.00g of titanium tetraisopropoxide to a 1L flask and heating and stirring at 160°C for 6 hours. After cooling to room temperature, 10mg was taken from the contents of the flask. 1 ¹H-NMR analysis revealed that the compound had hydroxyl groups at its ends, and its number-average molecular weight by terminal determination was 4000. The ratio of succinic acid residues to adipic acid residues was 70:30. Subsequently, 59.9 g of acetonitrile and 30.9 g of maleic anhydride were added, and the mixture was heated and stirred at 130°C for 4 hours. After that, the contents were removed from the mixture into a stainless steel tray with a Teflon® sheet to obtain marine biodegradable polyester A-5 as a solid resin. 10 mg was taken from the obtained resin, 1¹H-NMR analysis revealed that all terminal hydroxyl groups had reacted.

[0105] [Comparative Example 1-1] Synthesis of marine biodegradable polyester X-1 In a 1L flask, 210g of dimethyl adipate, 156g of dimethyl terephthalate, 225g of 1,4-butanediol, and 2.85g of titanium tetraisopropoxide were added and heated and stirred at 160°C for 6 hours to obtain a linear polyester having hydroxyl groups at both ends. After cooling to room temperature, 10mg was taken from the contents of the flask. 1 ¹H-NMR analysis revealed the disappearance of methyl esters and the presence of hydroxyl groups at the terminals, with a number-average molecular weight of 1200 determined by terminal determination. The ratio of adipic acid residues to terephthalic acid residues was 60:40. Subsequently, 46.0 g of acetonitrile and 86.0 g of succinic anhydride were added and the mixture was heated and stirred at 130°C for 4 hours. The contents were then transferred to a stainless steel tray with a Teflon® sheet to obtain a solid resin, resulting in marine biodegradable polyester X-1. 10 mg was taken from the obtained resin. 1 ¹H-NMR analysis revealed that all terminal hydroxyl groups had reacted.

[0106] Table 1 below shows all marine biodegradable polyesters A-1 to A-5 and X-1 together.

[0107] [Table 1]

[0108] [2] Synthesis of marine biodegradable polyester B

[0109] [Example 2-1] Synthesis of marine biodegradable polyester B-1 310 g of marine biodegradable polyester A-1 and 308 g of water were added to a 1 L flask and stirred at 80°C for 30 minutes. Subsequently, 21.5 g of potassium carbonate was added and stirred for another 30 minutes at 90°C to obtain marine biodegradable polyester B-1 as a 50% aqueous solution, in which the protons of the acidic groups of marine biodegradable polyester A-1 were replaced with potassium.

[0110] [Example 2-2] Synthesis of marine biodegradable polyester B-2 300 g of marine biodegradable polyester A-2 and 359 g of water were added to a 1 L flask and stirred at 80°C for 30 minutes. Subsequently, 25.0 g of sodium carbonate was added and stirred for another 30 minutes at 90°C to obtain marine biodegradable polyester B-2 as a 45% aqueous solution, in which the protons of the acidic groups of marine biodegradable polyester A-2 were replaced with sodium.

[0111] [Examples 2-3] Synthesis of marine biodegradable polyester B-3 400 g of marine biodegradable polyester A-3 and 254 g of water were added to a 1 L flask and stirred at 80°C for 30 minutes. Subsequently, 16.2 g of 28% aqueous ammonia was added and stirred for another 30 minutes at 90°C to obtain marine biodegradable polyester B-3 as a 60% aqueous solution, in which the protons of the acidic groups of marine biodegradable polyester A-3 were replaced with ammonium ions.

[0112] [Examples 2-4] Synthesis of marine biodegradable polyester B-4 300 g of marine biodegradable polyester A-4 and 300 g of water were added to a 1 L flask and stirred at 80°C for 30 minutes. Subsequently, 16.8 g of potassium hydroxide was added and stirred for another 30 minutes at 90°C to obtain marine biodegradable polyester B-4 as a 50% aqueous solution, in which the protons of the acidic groups of marine biodegradable polyester A-4 were replaced with potassium.

[0113] [Examples 2-5] Synthesis of marine biodegradable polyester B-5 400 g of marine biodegradable polyester A-5 and 264 g of water were added to a 1 L flask and stirred at 80°C for 30 minutes. Subsequently, 14.5 g of potassium carbonate was added and stirred for another 30 minutes at 90°C to obtain marine biodegradable polyester B-5 as a 60% aqueous solution, in which the protons of the acidic groups of marine biodegradable polyester A-5 were replaced with potassium.

[0114] [Comparative Example 2-1] Synthesis of marine biodegradable polyester Y-1 200 g of marine biodegradable polyester X-1 and 304 g of water were added to a 1 L flask and stirred at 80°C for 30 minutes. Subsequently, 16.7 g of sodium carbonate was added and stirred for another 30 minutes at 90°C to obtain marine biodegradable polyester Y-1 as a 40% aqueous solution, in which the protons of the acidic groups of marine biodegradable polyester X-1 were replaced with sodium.

[0115] [3] Synthesis of marine biodegradable polyester C

[0116] [Example 3-1] Synthesis of marine biodegradable polyester C-1 413 g of a 50% by mass aqueous solution of marine biodegradable compound B-1 was added to a 1 L flask and heated to 80°C over 30 minutes while stirring. Then, 67.4 g of a 30% by mass aqueous solution of calcium chloride was added and stirred, causing a precipitate to form. After washing the precipitate with water, it was dried under reduced pressure to obtain marine biodegradable polyester C-1.

[0117] [Example 3-2] Synthesis of marine biodegradable polyester C-2 456 g of a 45% by mass aqueous solution of marine biodegradable compound B-2 was added to a 1 L flask and heated to 80°C over 30 minutes while stirring. Then, 106 g of a 30% by mass aqueous solution of calcium chloride was added and stirred, causing a precipitate to form. After washing the precipitate with water, it was dried under reduced pressure to obtain marine biodegradable polyester C-2.

[0118] [Example 3-3] Synthesis of marine biodegradable polyester C-3 503 g of a 60% by mass aqueous solution of marine biodegradable compound B-3 was added to a 1 L flask and heated to 80°C over 30 minutes while stirring. Then, 86.7 g of a 20% by mass aqueous solution of magnesium chloride was added and stirred, causing a precipitate to form. After washing the precipitate with water, it was dried under reduced pressure to obtain marine biodegradable polyester C-3.

[0119] [Examples 3-4] Synthesis of marine biodegradable polyester C-4 412 g of a 50% by mass aqueous solution of marine biodegradable compound B-4 was added to a 1 L flask and heated to 80°C over 30 minutes while stirring. Then, 207 g of a 10% by mass aqueous solution of aluminum sulfate was added and stirred, causing a precipitate to form. After washing the precipitate with water, it was dried under reduced pressure to obtain marine biodegradable polyester C-4.

[0120] [Examples 3-5] Synthesis of marine biodegradable polyester C-5 505 g of a 60% by mass aqueous solution of marine biodegradable compound B-5 was added to a 1 L flask and heated to 80°C over 30 minutes while stirring. Then, 52.9 g of a 30% by mass aqueous solution of calcium chloride was added and stirred, causing a precipitate to form. After washing the precipitate with water, it was dried under reduced pressure to obtain marine biodegradable polyester C-5.

[0121] [Examples 3-6] Synthesis of marine biodegradable polyester C-6 10 g of marine biodegradable polyester A-2 and 581 g of water were added to a 1 L flask and stirred at 80°C for 30 minutes. Subsequently, 0.58 g of calcium hydroxide was added and stirred for another 30 minutes at 90°C, resulting in the formation of a precipitate. After washing the precipitate with water, it was dried under reduced pressure to obtain marine biodegradable polyester C-6.

[0122] [Comparative Example 3-1] Synthesis of marine biodegradable polyester Z-1 386 g of a 40% by mass aqueous solution of marine biodegradable polyester Y-1 and 55.5 g of water were added to a 1 L flask and stirred at 80°C for 30 minutes. Subsequently, 23.8 g of calcium chloride was added and stirred for another 30 minutes at 90°C, resulting in the formation of a precipitate. After washing the precipitate with water, it was dried under reduced pressure to obtain marine biodegradable polyester Z-1.

[0123] Table 2 below shows a summary of marine biodegradable polyesters C-1 to C-6 and Z-1.

[0124] [Table 2]

[0125] [4] Biodegradability test of marine biodegradable polyester [Examples 4-1 to 4-5, Comparative Example 4-1, Examples 5-1 to 5-5, Comparative Example 5-1, Examples 6-1 to 6-6, Comparative Example 6-1] The marine biodegradable polyesters A-1 to A-5, B-1 to B-5, C-1 to C-6, X-1, Y-1, and Z-1 were subjected to seawater biodegradation tests using the following method. Microcrystalline cellulose (Avicel PH-101, manufactured by Sigma-Aldrich) was used as a control material, and the relative biodegradation rate of the cellulose was evaluated. The results are shown in Tables 3 to 5.

[0126] <Testing methods and conditions> Method for measuring biodegradability: Measurement of oxygen consumption using a closed-loop respirator (refer to ASTM D6691). Test equipment: OxiTop IDS (manufactured by WTW) Culture temperature: 30±1℃, dark place Biodegradation (%)=(BOD O -BOD B ) / ThOD×100 BOD O : Biochemical oxygen demand for testing or confirmation of plant source activity (measured value: mg) BOD B : Average biochemical oxygen demand of a blank test (measured value: mg) ThOD: Required when the test material or control material is completely oxidized. Theoretical oxygen demand (calculated value: mg) Relative biodegradability of cellulose (%) = (Maximum biodegradability of test particles / Maximum biodegradability of cellulose) × 100 Seawater (collected from Tokyo Bay [Chiba Prefecture: Chiba Port]) The collected seawater was filtered to remove impurities using a 10 μm filter, and then aerated at room temperature (25°C). In addition, ammonium chloride (0.05 g / L) and potassium dihydrogen phosphate (0.1 g / L) were added as inorganic nutrients.

[0127] [Table 3]

[0128] [Table 4]

[0129] [Table 5]

[0130] As shown in Tables 3-5, marine biodegradable polyesters A, B, and C achieved biodegradability of 40% or more in relative cellulose degradation by 60 days of cultivation. Furthermore, the compounds obtained by depolymerization showed almost the same performance as those obtained by step polymerization.

[0131] [5] Preparation of marine biodegradable compositions and confirmation tests in seawater - 1 (1) Surface changes [Examples 7-1 to 7-6, Comparative Examples 7-1 to 7-2] A biodegradable resin, PBSA (FD-92, manufactured by Mitsubishi Chemical Corporation), was pulverized using a pulverizer (Wonder Blender WB-1, manufactured by Osaka Chemical Co., Ltd.), and the resulting marine biodegradable polyesters C-1 to C-6 and polymer compound Z-1 were classified using a stainless steel sieve (mesh size 26 μm). These were then melt-kneaded at 140°C to a concentration of 20% by mass, and press-molded at 150°C to produce a film with a thickness of 200 μm. In addition, PBSA itself (without marine biodegradable polyesters) was press-molded at 150°C to produce a film with a thickness of 200 μm (Comparative Example 7-2). Furthermore, the obtained films were processed into 10 mm squares and placed in 200 mL of deionized water and 200 mL of seawater (collected from Tokyo Bay [Chiba Prefecture: Chiba Port]), respectively. After standing at 25°C for 7 and 30 days, the films were removed and their surfaces and appearance were observed using a scanning electron microscope. The results are shown in Table 6.

[0132] [Table 6]

[0133] The results shown in Table 6 suggest that biodegradation is accelerated by the presence of microorganisms in seawater, in addition to disintegration by seawater. Furthermore, the compounds obtained by depolymerization showed almost the same performance as those obtained by stepwise polymerization.

[0134] (2) Weight reduction of composite resin [Examples 8-1 to 8-6, Comparative Examples 8-1 to 8-2] Using the same method as in (1), films were prepared by adding marine biodegradable polyesters C-1 to C-6 and polymer compound Z-1 to PBSA, respectively, as well as a film of PBSA alone. The obtained films were processed into 20 mm squares, sandwiched between stainless steel nets, and immersed in seawater (collected from Tokyo Bay [Chiba Prefecture: Chiba Port]) in a 15 L tank. The weight loss after immersion was observed after 30, 60, and 90 days. The results are shown in Table 7.

[0135] [Table 7]

[0136] The results shown in Table 7 suggest that biodegradation is accelerated by the presence of microorganisms in seawater, in addition to disintegration by seawater. Furthermore, the compounds obtained by depolymerization showed almost the same performance as those obtained by step polymerization.

[0137] (3) Measurement of tensile strength [Examples 9-1 to 9-6, Comparative Example 9-1] Using the same method as in (1), films were prepared by adding marine biodegradable polyesters C-1 to C-6 and polymer compound Z-1 to PBSA at concentrations of 10% by mass, 20% by mass, or 30% by mass, respectively, as well as a film of PBSA alone. Dumbbells were prepared from each film according to JIS K 7139-A22, and the tensile stress (yield point) was measured using a universal testing machine (MCT-2150, A&D Co., Ltd.). Each sample was measured five times, and the average value was taken as the tensile stress. The results are shown in Table 8.

[0138] [Table 8]

[0139] The results shown in Table 8 clearly demonstrate that the marine biodegradable polyester obtained by the method of the present invention does not significantly alter its mechanical properties even when mixed with other biodegradable resins. Furthermore, the compounds obtained by depolymerization showed almost the same performance as those obtained by step polymerization.

[0140] (4) Softening point measurement [Examples 10-1 to 10-6, Comparative Example 10-1] Using the same method as in (1), films were prepared by adding marine biodegradable polyesters C-1 to C-6 and polymer compound Z-1 to PBSA at concentrations of 10% by mass, 20% by mass, or 30% by mass, respectively, as well as a film of PBSA alone. The softening points were measured using a thermomechanical analyzer (TMA4000SE, manufactured by NETZSCH Japan Co., Ltd.). Specifically, a 1.5 mm thick, 3 mm square test piece was subjected to a 0.5 g load, and the softening point was defined as the temperature at which a 150 μm penetration was observed within a temperature range of 25 to 200 °C (heating rate of 3 °C / min). The results are shown in Table 9.

[0141] [Table 9]

[0142] The results shown in Table 9 clearly demonstrate that the marine biodegradable polyester obtained by the method of the present invention does not undergo significant changes in its thermophysical properties even when mixed with other biodegradable resins. Furthermore, the compounds obtained by depolymerization exhibited almost the same performance as those obtained by step polymerization.

[0143] [6] Preparation of marine biodegradable compositions and confirmation tests in seawater - 2 (1) Surface changes [Examples 11-1 to 11-6, Comparative Examples 11-1 to 11-2] A biodegradable starch-based resin (Mater-Bi EF05B, manufactured by Novamont) was pulverized using a pulverizer (Wonder Blender WB-1, manufactured by Osaka Chemical Co., Ltd.), and marine biodegradable polyesters C-1 to C-6 and Z-1, which were classified using a stainless steel sieve (mesh size 26 μm), were melt-kneaded at 150°C to a concentration of 20% by mass, and then press-molded at 160°C to produce a film with a thickness of 200 μm (Examples 11-1 to 11-6, Comparative Example 11-1). In addition, a film with a thickness of 200 μm was produced by press-molding the starch-based resin itself (without marine biodegradable polyester) at 160°C (Comparative Example 11-2). Furthermore, the obtained films were processed into 10 mm squares and placed in 200 mL of deionized water and 200 mL of seawater (collected from Tokyo Bay [Chiba Prefecture: Chiba Port]), respectively. After standing at 25°C for 7 and 30 days, the films were removed and their surfaces and appearance were observed using a scanning electron microscope. The results are shown in Table 10.

[0144] [Table 10]

[0145] The results shown in Table 10 suggest that biodegradation is accelerated by the presence of microorganisms in seawater, in addition to disintegration by seawater. Furthermore, the compounds obtained by depolymerization showed almost the same performance as those obtained by step polymerization.

[0146] (2) Weight reduction of composite resin [Examples 12-1 to 12-6, Comparative Example 12-1] Using the same method as in (1), films were prepared by adding marine biodegradable polyesters C-1 to C-6 and polymer compound Z-1 to starch resin, respectively, as well as a film of starch resin alone. The obtained films were processed into 20 mm squares, sandwiched between stainless steel nets, and immersed in seawater (collected from Tokyo Bay [Chiba Prefecture: Chiba Port]) in a 15 L tank. The weight loss after immersion was observed after 30, 60, and 90 days. The results are shown in Table 11.

[0147] [Table 11]

[0148] The results shown in Table 11 suggest that biodegradation is accelerated by the presence of microorganisms in seawater, in addition to disintegration by seawater. Furthermore, the compounds obtained by depolymerization showed almost the same performance as those obtained by step polymerization.

[0149] (3) Measurement of tensile strength [Examples 13-1 to 13-6, Comparative Example 13-1] Using the same method as in (1), films were prepared by adding marine biodegradable polyesters C-1 to C-6 and polymer compound Z-1 to a starch-based resin at concentrations of 10% by mass, 20% by mass, or 30% by mass, respectively, as well as films of the starch-based resin alone. Dumbbells were prepared from various films in accordance with JIS K 7139-A22, and the tensile stress (yield point) was measured using a universal testing machine (MCT-2150, manufactured by A&D Co., Ltd.). Each sample was measured five times, and the average value was taken as the tensile stress. The results are shown in Table 12.

[0150] [Table 12]

[0151] The results shown in Table 12 clearly demonstrate that the marine biodegradable polyester obtained by the method of the present invention does not significantly alter its mechanical properties even when mixed with other biodegradable resins. Furthermore, the compounds obtained by depolymerization showed almost the same performance as those obtained by step polymerization.

[0152] (4) Softening point measurement [Examples 14-1 to 14-6, Comparative Example 14-1] Using the same method as in (1), films were prepared by adding marine biodegradable polyesters C-1 to C-6 and polymer compound Z-1 to a starch-based resin at concentrations of 10% by mass, 20% by mass, or 30% by mass, respectively, as well as a film of the starch-based resin alone. The softening points were measured using a thermomechanical analyzer (TMA4000SE, manufactured by NETZSCH Japan Co., Ltd.). Specifically, a 1.5 mm thick, 3 mm square test piece was subjected to a 0.5 g load, and the softening point was defined as the temperature at which a 150 μm penetration was observed within a temperature range of 25 to 200 °C (heating rate of 3 °C / min). The results are shown in Table 13.

[0153] [Table 13]

[0154] The results shown in Table 13 clearly demonstrate that the marine biodegradable polyester obtained by the method of the present invention does not undergo significant changes in its thermophysical properties even when mixed with other biodegradable resins. Furthermore, the compounds obtained by depolymerization exhibited almost the same performance as those obtained by step polymerization.

Claims

1. (1) A step of depolymerizing a high molecular weight polyester to obtain an oligomer with a reduced number average molecular weight, and (2) A step of reacting the substituents at the end of the oligomer obtained in step (1) to introduce an acidic group at the end. A method for producing marine biodegradable polyester containing [the specified substance].

2. A method for producing marine biodegradable polyester according to claim 1, wherein the number average molecular weight of the oligomer is 200 to 20,000.

3. A method for producing marine biodegradable polyester according to claim 1, wherein depolymerization is performed using a polyhydric alcohol in step (1).

4. The method for producing marine biodegradable polyester according to claim 3, wherein when the amount of substance of the polyhydric alcohol multiplied by 0.85 is divided by the amount of substance of the high molecular weight polyester and 1 is added to the result, n is defined as the number average degree of polymerization of the high molecular weight polyester, and N is defined as N / n is 2 to 40.

5. A method for producing marine biodegradable polyester according to claim 3, wherein in step (1), a carboxylic acid or a derivative thereof is further added to carry out depolymerization.

6. A method for producing marine biodegradable polyester according to claim 1, wherein the acidic group introduced at the end in step (2) is a monovalent acidic group.

7. (3) A step of neutralizing a marine biodegradable polyester obtained by the manufacturing method described in any one of claims 1 to 6, and replacing some or all of the protons of the terminal acidic groups with monovalent cations other than protons to form a polymer containing polymer-type polyvalent anions, and (4) A step of crosslinking the polymer-type polyvalent anion via a divalent or higher cation. A method for producing cross-linked marine biodegradable polyester containing [the specified ingredient].

8. (5) A step of adding a divalent or higher base to a marine biodegradable polyester obtained by the manufacturing method described in any one of claims 1 to 6, thereby simultaneously neutralizing some or all of the protons of the terminal acidic groups and crosslinking via divalent or higher cations. A method for producing cross-linked marine biodegradable polyester containing [the specified ingredient].

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