Photodegradable polymer

Abstract

To provide a photodegradable polymer and a method for producing the photodegradable polymer, wherein a polyester is employed as a raw material for the photodegradable polymer, the photodegradable polymer exhibiting excellent photodegradability and being expected to be used as a polymer alternative to polyesters that have been conventionally used.SOLUTION: A photodegradable polymer characterized by having a repeating unit represented by formula (I): (wherein R1 represents an alkylene group having 2 to 18 carbon atoms, which may have a substituent), and a repeating unit based on a polyester-based polymer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photodegradable polymer, and more particularly to a photodegradable polymer that is expected to be used as a substitute for polyesters typified by polyethylene terephthalate. [Background technology]

[0002] Plastics are lightweight yet have high mechanical properties and excellent insulating properties, making them widely used in a variety of applications, from everyday items to industrial products. However, it is generally believed that plastics take a long time to decompose in the natural environment.

[0003] In recent years, the amount of plastic waste flowing into the ocean has been increasing year by year, and there are concerns that marine organisms such as whales and sea turtles will ingest this plastic waste, which could have a negative impact on the ecology of marine organisms and on humanity through the food chain (see, for example, Non-Patent Document 1).

[0004] As a result, international organizations and national governments are considering measures to reduce marine plastic. For example, the National Oceanic and Atmospheric Administration (NOAA) was established in the United States in 2006, and a resolution on marine plastic waste and microplastics was adopted at the Fourth United Nations Environment Assembly (UNEA4) in 2019, attended by approximately 160 countries around the world. Companies are also considering replacing plastic products with paper ones.

[0005] Plastics such as polyesters, typified by polyethylene terephthalate, make up a high proportion of marine litter, but due to their excellent mechanical properties and high heat resistance, they are difficult to decompose in soil or the ocean. Furthermore, plastics fragment over time, becoming microplastics with particles less than 5 mm in size. It is believed that the reason for the creation of microplastics is that plastics themselves are durable and that they are fragmented over time by ultraviolet light in sunlight.

[0006] Therefore, it is believed that the problems caused by plastics and microplastics in the oceans can be solved by developing biodegradable plastics that decompose in the natural environment in a short period of time.

[0007] Polylactide (PLA) is known as a biodegradable plastic currently under development (see, for example, Patent Document 1). Polylactide is decomposed by microorganisms in soil at temperatures above 60°C. However, because soil temperatures rarely reach 60°C or higher in nature, it is not realistic to decompose polylactide in soil using microorganisms. Furthermore, in the ocean, not only do seawater temperatures never reach 60°C or higher, but there are also almost no aerobic microorganisms, making it difficult to decompose polylactide in the ocean (see, for example, Non-Patent Document 2).

[0008] Therefore, polyester is used as a raw material, and there is an urgent need to develop a photodegradable polymer that is highly degradable and can replace conventional polyester. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2023-134406 [Non-patent literature]

[0010] [Non-Patent Document 1] Yamashita Rei et al., "Marine Plastic Pollution: Dynamics of Plastics in Marine Ecosystems and Their Impact on Organisms," Journal of the Ecological Society of Japan, Ecological Society of Japan, 2016, Vol. 66, No. 1, pp. 51-68 [Non-patent document 2] Naoki Hosaka, "Will biodegradable plastics save the Earth from plastic waste pollution?" [online], October 3, 2019, University of Tokyo, [Retrieved March 2024], Internet<https: / / www.oa.u-tokyo.ac.jp / column / trivia / 0024 / index.html> Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in view of the above-mentioned conventional technology, and an object of the present invention is to provide a photodegradable polymer that uses polyester as a raw material, has excellent degradability, and can be a substitute for conventional polyesters, and a method for producing the same. [Means for solving the problem]

[0012] The present invention provides (1) Formula (I):

[0013] [ka]

[0014] (In the formula, R 1 represents an alkylene group having 2 to 18 carbon atoms which may have a substituent. and a repeating unit based on a polyester-based polymer, (2) The photodegradable polymer according to (1), wherein the polyester polymer is a terephthalic acid ester polymer or a polylactide. (3) As a raw material, a compound of formula (II):

[0015] [ka]

[0016] (In the formula, R 1 represents an alkylene group having 2 to 18 carbon atoms which may have a substituent. and a polyester-based polymer, and polymerizing the itaconic acid derivative and the polyester-based polymer; and (4) The method for producing a photodegradable polymer according to (3) above, wherein the polyester polymer used as the raw material is a terephthalic acid ester polymer or a polylactide. Regarding. [Effects of the Invention]

[0017] According to the present invention, a photodegradable polymer is provided which uses polyester as a raw material, has excellent degradability, and can be a substitute for conventional polyesters, and a method for producing the same. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a graph showing the nuclear magnetic resonance ( 1 H-NMR) spectrum of the itaconic acid derivative obtained in Production Example 1. [Figure 2] 1 is a graph showing 1H-NMR spectra of PLA1 to PLA4 obtained in Examples 1 to 4, a polymer (Nylon 6i) having a repeating unit in which R1 in formula (I) is an alkylene group having 10 carbon atoms, and polylactide (polylactic acid). [Figure 3] 1 is a graph showing the results of thermogravimetric analysis (TGA) of PLA1 to PLA4 obtained in Examples 1 to 4 and polylactide (polylactic acid). [Figure 4] 1 is a graph showing infrared absorption spectra of PET1 to PET4 obtained in Examples 5 to 8, an itaconic acid derivative of formula (II) in which R1 is an alkylene group having 10 carbon atoms, and polyethylene terephthalate. [Figure 5]1 is a graph showing the results of thermogravimetric analysis (TGA) of PET1 to PET4 and polyethylene terephthalate. [Figure 6] 1 is a graph showing weight changes when photodegradation of PLA1 to PLA4 and polylactide (PLA) is investigated. [Figure 7] 1 is a graph showing changes in weight when photodegradability of PET1 to PET4 and polyethylene terephthalate (PET) is examined. DETAILED DESCRIPTION OF THE INVENTION

[0019] The photodegradable polymer of the present invention has the formula (I):

[0020] [ka]

[0021] (In the formula, R 1 represents an alkylene group having 2 to 18 carbon atoms which may have a substituent. and a repeating unit based on a polyester polymer.

[0022] Although the photodegradable polymer of the present invention uses polyester as a raw material, it has excellent photodegradability due to the repeating unit represented by formula (I), and is therefore expected to be used as a replacement for conventional polyesters.

[0023] The photodegradable polymer of the present invention has the formula (II):

[0024] [ka]

[0025] (In the formula, R 1 is the same as above) and a polyester polymer.

[0026] [Itaconic acid derivatives] The itaconic acid derivative is used as a raw material for the photodegradable polymer of the present invention. The itaconic acid derivative can be prepared by reacting itaconic acid and a diamine as raw materials.

[0027] In the reaction between itaconic acid and diamine, 1 mole of itaconic acid reacts with 1 mole of diamine stoichiometrically. However, when itaconic acid and diamine are reacted, either the itaconic acid or the diamine may be in excess.

[0028] Itaconic acid is readily available commercially from, for example, Fuso Chemical Co., Ltd., Iwata Chemical Co., Ltd., Cargill, and others. Itaconic acid may be produced using fungi such as Aspergillus terreus, or may be synthesized using petroleum as a raw material. Among these, itaconic acid produced using fungi such as Aspergillus terreus has the advantage of being more environmentally friendly than itaconic acid synthesized using petroleum as a raw material.

[0029] The diamine may, for example, be a diamine represented by the formula (III): H2N-R 1 -NH2(III) (In the formula, R 1 is the same as above) In the dialkyldiamine represented by formula (III), R 1 represents an alkylene group having 2 to 18 carbon atoms which may have a substituent. Examples of the substituent include a hydroxyl group and a halogen atom, but the present invention is not limited to these examples.

[0030] R 1is an alkylene group having 2 to 18 carbon atoms, preferably an alkylene group having 3 to 16 carbon atoms, more preferably an alkylene group having 3 to 12 carbon atoms, and even more preferably an alkylene group having 3 to 10 carbon atoms, from the viewpoint of obtaining a photodegradable polymer having excellent photodegradability, extensibility, and toughness.

[0031] Examples of dialkyldiamines represented by formula (III) include dimethylene diamine, trimethylene diamine, tetramethylene diamine, pentamethylene diamine, hexamethylene amine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, decamethylene diamine, undecamethylene diamine, and tetradecamethylene diamine, but the present invention is not limited to these examples. These diamines may be used alone or in combination of two or more. Among these diamines, decamethylene diamine is preferred because of its excellent photodegradability.

[0032] The reaction of itaconic acid with the diamine represented by formula (III) can be carried out in a solvent. Examples of the solvent include water, aliphatic alcohols having 1 to 4 carbon atoms such as methanol, ethanol, propanol, and butanol, ketones such as acetone and methyl ethyl ketone, ethyl acetate, tetrahydrofuran, dioxane, chloroform, dichloromethane, chlorobenzene, phenol, and cresol, but the present invention is not limited to these examples.

[0033] The amount of the solvent is not particularly limited, but is usually about 15 to 30 parts by mass per 100 parts by mass of the total amount of itaconic acid and diamine.

[0034] The reaction temperature when reacting itaconic acid with diamine is not particularly limited, but is preferably about 60 to 120°C from the viewpoint of increasing reaction efficiency. The reaction time when reacting itaconic acid with diamine cannot be determined in general because it varies depending on the amount of solvent used, the reaction temperature, etc., but is usually about 10 to 30 hours. The atmosphere when reacting itaconic acid with diamine is not particularly limited, and may be air or an inert gas such as nitrogen gas or argon gas. However, an inert gas is preferred from the viewpoint of avoiding the influence of oxygen contained in air. When reacting itaconic acid with diamine, other compounds such as carboxylic acids and amines may be used within the scope of the present invention, as long as the object of the present invention is not impaired.

[0035] By reacting itaconic acid with a diamine in the manner described above, a reaction mixture containing an itaconic acid derivative represented by formula (II) is obtained.

[0036] After the reaction of itaconic acid with the diamine is completed, the itaconic acid derivative represented by formula (II) may be recovered from the resulting reaction mixture, dissolved in a lower alcohol such as metalloxol, and the lower alcohol may be evaporated from the resulting solution to recover the itaconic acid derivative represented by formula (II).

[0037] [Polyester-based polymer] In the present invention, polyester polymers are used as raw materials for the photodegradable polymer of the present invention. A polyester polymer refers to a polymer polymerized through ester bonds. For example, although polylactide (polylactic acid) contains the word "acid" in its name, it is a type of polyester polymer because it is a polymer in which lactic acid is polymerized through ester bonds.

[0038] Examples of polyester polymers include polyesters obtained by condensing polyhydric alcohols such as ethylene glycol, propylene glycol, and butanediol with dicarboxylic acids such as terephthalic acid, isophthalic acid, sebacic acid, succinic acid, phthalic acid, and adipic acid, and polylactides, but the present invention is not limited to these examples. These polyester polymers may be used alone or in combination of two or more.

[0039] Specific examples of polyester-based polymers include aromatic polyesters such as terephthalic acid ester polymers, polyethylene naphthalate (PEN), and hydroxybenzoic acid-hydroxynaphthoic acid copolymers (LCP), and polylactides (polylactic acids). These polyester-based polymers may be used alone or in combination.

[0040] Examples of terephthalic acid ester polymers include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polybutylene adipate terephthalate (PBAT), and polybutylene succinate terephthalate (PBST), but the present invention is not limited to these examples. These terephthalic acid ester polymers may be used alone or in combination of two or more. All of these polyester-based polymers can be suitably used from the viewpoint of obtaining photodegradable polymers with excellent photodegradability. Among polyester-based polymers, polyethylene terephthalate (PET) and polylactide are more preferred because they are easily available.

[0041] The terminal group of the polyester polymer is not particularly limited. For example, when the polyester polymer is a terephthalic acid ester polymer, the terminal group of the terephthalic acid ester polymer is usually a group derived from the glycol used as a raw material for the terephthalic acid ester polymer. For example, when ethylene glycol is used as a raw material for the terephthalic acid ester polymer, the terminal group of the terephthalic acid ester polymer is a hydroxyethyl group or an ethyl group, but may be other groups. Furthermore, when the polyester polymer is a polylactide, the terminal group of the polylactide is usually a hydroxyl group or a carboxyl group, but may be other groups.

[0042] [Photodegradable polymer] The photodegradable polymer of the present invention can be produced by polymerizing the itaconic acid derivative represented by formula (II) with a polyester polymer.

[0043] Examples of methods for polymerizing the itaconic acid derivative represented by formula (II) with a polyester polymer include bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization, but the present invention is not limited to these examples. Among these polymerization methods, bulk polymerization and solution polymerization are preferred, and bulk polymerization is more preferred, from the viewpoint of efficiently preparing a photodegradable polymer with a small amount of impurities.

[0044] When preparing a photodegradable polymer by bulk polymerization, the itaconic acid derivative represented by formula (II) and a polyester polymer are polymerized by heating at a polymerization temperature of about 150 to 250°C to obtain the photodegradable polymer.

[0045] The atmosphere in which the itaconic acid derivative represented by formula (II) and the polyester polymer are polymerized is not particularly limited, and may be air or an inert gas such as nitrogen gas or argon gas, but is preferably an inert gas from the viewpoint of avoiding the influence of oxygen contained in the air. The polymerization time of the itaconic acid derivative represented by formula (II) and the polyester polymer is not particularly limited, but is usually about 10 to 30 hours.

[0046] When polymerizing the itaconic acid derivative represented by formula (II) with a polyester polymer, it is preferable to use an appropriate amount of catalyst from the viewpoint of efficiently preparing a photodegradable polymer. Examples of catalysts include antimony trioxide, barium oxide, zinc acetate, manganese acetate, cobalt acetate, zinc succinate, zinc borate, cadmium formate, dibutyltin dioxide, and tetraisooctyl orthotitanate, but the present invention is not limited to these examples. Among the catalysts, antimony trioxide is preferred.

[0047] When the itaconic acid derivative represented by formula (II) is polymerized with a polyester polymer, the aminolysis reaction and the acidolysis reaction proceed simultaneously, and a photodegradable polymer can be obtained.

[0048] The photodegradable polymer obtained as described above may be purified, if necessary, by dissolving it in a solvent such as a lower alcohol such as methanol, removing the unreacted solid polyester polymer, and then distilling off the solvent under reduced pressure, although this may vary depending on the type of polyester polymer used as a raw material for the photodegradable polymer.

[0049] The photodegradable polymer obtained as described above has the formula (I):

[0050] [ka]

[0051] (In the formula, R 1is the same as above) and a repeating unit based on a polyester polymer.

[0052] When polylactide is used as the polyester polymer, which is the raw material of the photodegradable polymer, the photodegradable polymer has a repeating unit represented by formula (I) and a repeating unit represented by formula (IV):

[0053] [ka]

[0054] When polyethylene terephthalate is used as the polyester raw material, the photodegradable polymer has a repeating unit represented by formula (I) and a repeating unit represented by formula (V):

[0055] [ka]

[0056] The repeating unit has the following structure:

[0057] The photodegradable polymer of the present invention may have a crosslinked structure that may be inevitably formed by polymerizing the itaconic acid derivative represented by formula (II) with a polyester-based polymer. Furthermore, the photodegradable polymer of the present invention may contain repeating units other than the repeating unit represented by formula (I) and the repeating unit based on the polyester-based polymer, as long as the object of the present invention is not impaired.

[0058] The photodegradable polymer of the present invention has a repeating unit represented by formula (I) and a repeating unit based on a polyester-based polymer, and therefore has the properties based on the polyester-based polymer as well as excellent photodegradability.

[0059] The molar ratio of the repeating units based on the polyester polymer to the repeating units represented by formula (I) [repeating units based on the polyester polymer / repeating units represented by formula (I)] is preferably 0.5 / 1 to 8 / 1, more preferably 1 / 1 to 5 / 1, from the viewpoint of imparting sufficient photodegradability to the photodegradable polymer while fully exhibiting the properties of the polyester polymer.

[0060] In the photodegradable polymer of the present invention, the repeating units represented by formula (I) and the repeating units based on the polyester polymer are usually present randomly, but may also be present alternately or in a block form.

[0061] The number-average molecular weight of the photodegradable polymer of the present invention varies depending on the type of polyester polymer used as the raw material for the photodegradable polymer, and therefore cannot be determined in general terms. For example, when polylactide is used as the polyester polymer, the number-average molecular weight of the photodegradable polymer is preferably 5,000 to 200,000, more preferably 6,000 to 100,000, from the viewpoint of fully expressing the properties inherent to polylactide and improving the photodegradability of the photodegradable polymer. Furthermore, for example, when polyethylene terephthalate is used as the polyester polymer, the number-average molecular weight of the photodegradable polymer is preferably 100,000 to 600,000, more preferably 150,000 to 550,000, from the viewpoint of fully expressing the properties inherent to polyethylene terephthalate and improving the photodegradability of the photodegradable polymer. The number-average molecular weight of the photodegradable polymer is a value measured according to the method described in the following examples.

[0062] When the photodegradable polymer of the present invention has solubility in a solvent, a spinning dope can be prepared by dissolving the photodegradable polymer in a solvent.

[0063] Furthermore, the photodegradable polymer of the present invention has thermoplastic properties and melts when heated, and therefore can be used as a molding material for injection molding, blow molding, and the like.

[0064] The photodegradable polymer of the present invention may contain an appropriate amount of additives depending on the intended use, as necessary. Examples of additives include colorants such as pigments and dyes, UV absorbers, UV stabilizers, antioxidants, rust inhibitors, antibacterial agents, plasticizers, algae inhibitors, mildew inhibitors, flame retardants, and foaming agents, but the present invention is not limited to these examples. These additives may be used alone or in combination of two or more. The amount of additive varies depending on the type of additive, so it cannot be determined in general. Therefore, it is preferable to determine the amount appropriately depending on the type of additive.

[0065] The photodegradable polymer of the present invention uses a polyester polymer as a raw material, and therefore has excellent photodegradability while retaining the properties inherent to the polyester polymer. Therefore, it is expected to be used in a wide range of applications, from daily necessities to industrial products, as an alternative polymer to conventional polyesters. [Example]

[0066] EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. The physical properties of each polymer were examined according to the following methods.

[0067] [Polymer structure] (1) Nuclear magnetic resonance ( 1 H-NMR spectrum Polymer Nuclear Magnetic Resonance ( 1H-NMR spectra were measured using a nuclear magnetic resonance spectrometer (Bruker, trade name: DRX500, 400 MHz) by dissolving 5 mg of sample (polymer) in 0.5 mL of heavy water (DO) (Kanto Chemical Co., Ltd.) or 0.5 mL of dimethyl sulfoxide-d6 (DMSO-d6) (Kanto Chemical Co., Ltd.), transferring the resulting solution to a glass sample tube, and measuring at 25°C with 16 accumulations.

[0068] (2) Infrared absorption spectrum (FT-IR spectrum) The infrared absorption spectrum of the polymer was measured using a Perkin Elmer Spectrum 100 (ATR method) at 400-4000 cm -1 Measurement was performed at a measurement wave number of 4 times.

[0069] [Number average molecular weight of polymer] The number-average molecular weight of the polymer was measured by gel permeation chromatography (GPC). More specifically, the measurement was performed using a GPC measurement device (pump: JASCO Corporation, product number PU-20800 Plus; detector: JASCO Corporation, product number RI-2031 Plus; column oven: GL Sciences Inc., product number CO631A) equipped with two columns (Showa Denko K.K., product name: Shodex KD-806). The number-average molecular weight of the polymer was measured using a 0.01 mol / L lithium bromide dimethylformamide (DMF) solution as the solvent for dissolving the polymer, at a measurement temperature of 40°C and a flow rate of 1 mL / min.

[0070] [Properties of Polymer] (1) Thermogravimetric analysis (TGA) Thermogravimetric analysis was performed using a thermogravimetric analyzer (Hitachi High-Tech Science Corporation, product number: STA7200) and a platinum oven-type sample container (diameter: 5.2 mm, height: 5 mm) as the test container (sample container). The analysis was performed at a temperature range of 25 to 800°C with a nitrogen gas flow rate of 250 mL / min and a heating rate of 5°C / min.

[0071] Manufacturing Example 1 Itaconic acid 2.5 x 10 -2 mol and 1,10-decamethylenediamine 2.5 x 10 -2 The moles were mixed, the resulting mixture was dissolved in 1.5 mL of pure water, and the resulting solution was refluxed at a liquid temperature of 110° C. for 24 hours under stirring in a nitrogen gas atmosphere to obtain a mixed solution.

[0072] The resulting mixed solution was cooled to 25° C. to precipitate a white solid reaction product. The mixed solution was filtered to recover the reaction product, which was then washed with ethanol at about 10° C. and dried in a vacuum dryer at 40° C. for 12 hours to obtain the compound represented by the formula (II), R 1 The itaconic acid derivative [N-(10-aminodecyl)-2-pyrrolidone-4-carboxylic acid] in which the carboxyl group is a decylene group was obtained. 1 H-NMR (solvent: DO) is shown in Figure 1.

[0073] As shown in FIG. 1, it is clear that the itaconic acid derivative obtained above does not contain vinyl groups derived from itaconic acid in the concentration range of 5 to 6 ppm.

[0074] Furthermore, it can be seen that the itaconic acid derivative obtained above has peaks at concentrations of 3.10 to 3.20 ppm (a in Figure 1), 3.50 to 3.80 ppm (b in Figure 1), and 3.00 ppm (c in Figure 1) derived from pyrrolidone rings formed by ring closure of itaconic acid.

[0075] From the above results, it is clear that the itaconic acid derivative obtained above is a compound represented by the formula (II): 1 It can be seen that the compound is an itaconic acid derivative having a decylene group.

[0076] Manufacturing Example 2 Itaconic acid 2.5 x 10 -2 moles and hexamethylenediamine 2.5 x 10 -2The resulting mixture was dissolved in 1.5 mL of pure water, and the resulting solution was refluxed at a liquid temperature of 110°C for 24 hours under stirring in a nitrogen gas atmosphere to obtain a mixed solution.

[0077] The resulting mixed solution was cooled to 25° C. to precipitate a white solid reaction product. The mixed solution was filtered to recover the reaction product, which was then washed with ethanol at about 10° C. and dried in a vacuum dryer at 40° C. for 12 hours to obtain the compound represented by the formula (II), R 1 The itaconic acid derivative, N-(6-aminohexyl)-2-pyrrolidone-4-carboxylic acid, in which the hydroxyl group is a hexamethylene group, was obtained.

[0078] Manufacturing Example 3 Itaconic acid 2.5 x 10 -2 2.5 x 10 moles of pentamethylenediamine -2 The moles were mixed, the resulting mixture was dissolved in 1.5 mL of pure water, and the resulting solution was refluxed at a liquid temperature of 110° C. for 24 hours under stirring in a nitrogen gas atmosphere to obtain a mixed solution.

[0079] The resulting mixed solution was cooled to 25° C. to precipitate a white solid reaction product. The mixed solution was filtered to recover the reaction product, which was then washed with ethanol at about 10° C. and dried in a vacuum dryer at 40° C. for 12 hours to obtain the compound represented by the formula (II), R 1 The itaconic acid derivative, N-(5-aminopentyl)-2-pyrrolidone-4-carboxylic acid, in which the hydroxyl group is a pentamethylene group, was obtained.

[0080] Manufacturing Example 4 Itaconic acid 2.5 x 10 -2 2.5 x 10 moles of octamethylenediamine -2 The moles were mixed, the resulting mixture was dissolved in 1.5 mL of pure water, and the resulting solution was refluxed at a liquid temperature of 110° C. for 24 hours under stirring in a nitrogen gas atmosphere to obtain a mixed solution.

[0081] The resulting mixed solution was cooled to 25° C. to precipitate a white solid reaction product. The mixed solution was filtered to recover the reaction product, which was then washed with ethanol at about 10° C. and dried in a vacuum dryer at 40° C. for 12 hours to obtain the compound represented by the formula (II), R 1 The itaconic acid derivative, N-(8-aminooctyl)-2-pyrrolidone-4-carboxylic acid, in which the octamethylene group is the hydroxyl group, was obtained.

[0082] Manufacturing Example 5 Itaconic acid 2.5 x 10 -2 2.5 x 10 moles of heptamethylenediamine -2 The moles were mixed, the resulting mixture was dissolved in 1.5 mL of pure water, and the resulting solution was refluxed at a liquid temperature of 110° C. for 24 hours under stirring in a nitrogen gas atmosphere to obtain a mixed solution.

[0083] The resulting mixed solution was cooled to 25° C. to precipitate a white solid reaction product. The mixed solution was filtered to recover the reaction product, which was then washed with ethanol at about 10° C. and dried in a vacuum dryer at 40° C. for 12 hours to obtain the compound represented by the formula (II), R 1 The itaconic acid derivative, N-(7-aminoheptyl)-2-pyrrolidone-4-carboxylic acid, in which the hydroxyl group is a heptamethylene group, was obtained.

[0084] Manufacturing Example 6 Itaconic acid 2.5 x 10 -2 2.5 x 10 moles of nonamethylenediamine -2 The moles were mixed, the resulting mixture was dissolved in 1.5 mL of pure water, and the resulting solution was refluxed at a liquid temperature of 110° C. for 24 hours under stirring in a nitrogen gas atmosphere to obtain a mixed solution.

[0085] The resulting mixed solution was cooled to 25° C. to precipitate a white solid reaction product. The mixed solution was filtered to recover the reaction product, which was then washed with ethanol at about 10° C. and dried in a vacuum dryer at 40° C. for 12 hours to obtain the compound represented by the formula (II), R 1The itaconic acid derivative, N-(9-aminononyl)-2-pyrrolidone-4-carboxylic acid, in which the hydroxyl group is a nonamethylene group, was obtained.

[0086] Manufacturing Example 7 Itaconic acid 2.5 x 10 -2 mol and dodecamethylenediamine 2.5 x 10 -2 The moles were mixed, the resulting mixture was dissolved in 1.5 mL of pure water, and the resulting solution was refluxed at a liquid temperature of 110° C. for 24 hours under stirring in a nitrogen gas atmosphere to obtain a mixed solution.

[0087] The resulting mixed solution was cooled to 25° C. to precipitate a white solid reaction product. The mixed solution was filtered to recover the reaction product, which was then washed with ethanol at about 10° C. and dried in a vacuum dryer at 40° C. for 12 hours to obtain the compound represented by the formula (II), R 1 The itaconic acid derivative, N-(12-aminododecyl)-2-pyrrolidone-4-carboxylic acid, in which the hydroxyl group is a dodecamethylene group, was obtained.

[0088] Manufacturing Example 8 Itaconic acid 2.5 x 10 -2 2.5 x 10 moles of undecamethylenediamine -2 The moles were mixed, the resulting mixture was dissolved in 1.5 mL of pure water, and the resulting solution was refluxed at a liquid temperature of 110° C. for 24 hours under stirring in a nitrogen gas atmosphere to obtain a mixed solution.

[0089] The resulting mixed solution was cooled to 25° C. to precipitate a white solid reaction product. The mixed solution was filtered to recover the reaction product, which was then washed with ethanol at about 10° C. and dried in a vacuum dryer at 40° C. for 12 hours to obtain the compound represented by the formula (II), R 1 The itaconic acid derivative, N-(11-aminoundecyl)-2-pyrrolidone-4-carboxylic acid, in which the undecamethylene group is the hydroxyl group, was obtained.

[0090] Manufacturing Example 9 Itaconic acid 2.5 x 10 -22.5 x 10 moles of tetramethylenediamine -2 The moles were mixed, the resulting mixture was dissolved in 1.5 mL of pure water, and the resulting solution was refluxed at a liquid temperature of 110° C. for 24 hours under stirring in a nitrogen gas atmosphere to obtain a mixed solution.

[0091] The resulting mixed solution was cooled to 25° C. to precipitate a white solid reaction product. The mixed solution was filtered to recover the reaction product, which was then washed with ethanol at about 10° C. and dried in a vacuum dryer at 40° C. for 12 hours to obtain the compound represented by the formula (II), R 1 The itaconic acid derivative [N-(4-aminobutyl)-2-pyrrolidone-4-carboxylic acid] was obtained, in which the tetramethylene group was

[0092] Manufacturing Example 10 Itaconic acid 2.5 x 10 -2 2.5 x 10 moles of trimethylenediamine -2 The moles were mixed, the resulting mixture was dissolved in 1.5 mL of pure water, and the resulting solution was refluxed at a liquid temperature of 110° C. for 24 hours under stirring in a nitrogen gas atmosphere to obtain a mixed solution.

[0093] The resulting mixed solution was cooled to 25° C. to precipitate a white solid reaction product. The mixed solution was filtered to recover the reaction product, which was then washed with ethanol at about 10° C. and dried in a vacuum dryer at 40° C. for 12 hours to obtain the compound represented by the formula (II), R 1 The itaconic acid derivative [N-(3-aminopropyl)-2-pyrrolidone-4-carboxylic acid] was obtained, in which the hydroxyl group is a trimethylene group.

[0094] Manufacturing Example 11 Itaconic acid 2.5 x 10 -2 2.5 x 10 moles of dimethylene diamine -2 The moles were mixed, the resulting mixture was dissolved in 1.5 mL of pure water, and the resulting solution was refluxed at a liquid temperature of 110° C. for 24 hours under stirring in a nitrogen gas atmosphere to obtain a mixed solution.

[0095] The resulting mixed solution was cooled to 25° C. to precipitate a white solid reaction product. The mixed solution was filtered to recover the reaction product, which was then washed with ethanol at about 10° C. and dried in a vacuum dryer at 40° C. for 12 hours to obtain the compound represented by the formula (II), R 1 The itaconic acid derivative [N-(2-aminoethyl)-2-pyrrolidone-4-carboxylic acid] was obtained, in which the dimethylene group was present.

[0096] Manufacturing Example 12 Itaconic acid 2.5 x 10 -2 2.5 x 10 moles of tridecamethylenediamine -2 The moles were mixed, the resulting mixture was dissolved in 1.5 mL of pure water, and the resulting solution was refluxed at a liquid temperature of 110° C. for 24 hours under stirring in a nitrogen gas atmosphere to obtain a mixed solution.

[0097] The resulting mixed solution was cooled to 25° C. to precipitate a white solid reaction product. The mixed solution was filtered to recover the reaction product, which was then washed with ethanol at about 10° C. and dried in a vacuum dryer at 40° C. for 12 hours to obtain the compound represented by the formula (II), R 1 The itaconic acid derivative, N-(13-aminotridecyl)-2-pyrrolidone-4-carboxylic acid, in which the hydroxyl group is a tridecamethylene group, was obtained.

[0098] The itaconic acid derivatives obtained in Production Examples 1 to 12 differ only in the number of carbon atoms in the dialkylamines used as raw materials, and are therefore considered to have similar properties. Therefore, the itaconic acid derivative obtained in Production Example 1 was used in the following Examples as a representative dialkylamine of the itaconic acid derivatives obtained in Production Examples 1 to 12.

[0099] Example 1 0.016 mol of polylactide (PLA) having a number average molecular weight of 12,000 was heated to 200°C in a nitrogen gas atmosphere to melt it, and then 0.016 mol of the itaconic acid derivative obtained in Production Example 1 and 5.60 g of antimony trioxide as a catalyst were added to and mixed with the molten polylactide, followed by heating at a temperature of 180°C for 24 hours with stirring to obtain a reaction mixture.

[0100] The reaction mixture obtained above is dissolved in methanol, and the precipitated unreacted polylactide is removed by suction filtration. The filtrate obtained is then evaporated under reduced pressure and dried under reduced pressure to obtain a compound represented by the formula (I), 1 A photodegradable polymer (hereinafter referred to as PLA1) having a repeating unit in which R is an alkylene group having 10 carbon atoms and a repeating unit represented by formula (IV) was obtained. The number average molecular weight of the obtained PLA1 was 8,000.

[0101] Example 2 0.026 mol of polylactide (PLA) having a number average molecular weight of 12,000 was heated to 200°C in a nitrogen gas atmosphere to melt it, and then 0.013 mol of the itaconic acid derivative obtained in Production Example 1 and 5.60 g of antimony trioxide as a catalyst were added to and mixed with the molten polylactide, followed by heating at a temperature of 180°C for 24 hours with stirring to obtain a reaction mixture.

[0102] The reaction mixture obtained above is dissolved in methanol, and the precipitated unreacted polylactide is removed by suction filtration. The filtrate obtained is then evaporated under reduced pressure and dried under reduced pressure to obtain a compound represented by the formula (I), 1 A photodegradable polymer (hereinafter referred to as PLA2) having a repeating unit in which R is an alkylene group having 10 carbon atoms and a repeating unit represented by formula (IV) was obtained. The number average molecular weight of the PLA2 obtained above was 7,000.

[0103] Example 3 0.033 mol of polylactide (PLA) having a number average molecular weight of 12,000 was heated to 200°C in a nitrogen gas atmosphere to melt it, and then 0.011 mol of the itaconic acid derivative obtained in Production Example 1 and 5.60 g of antimony trioxide as a catalyst were added to and mixed with the molten polylactide, followed by heating with stirring at a temperature of 180°C for 24 hours to obtain a reaction mixture.

[0104] The reaction mixture obtained above is dissolved in methanol, and the precipitated unreacted polylactide is removed by suction filtration. The filtrate obtained is then evaporated under reduced pressure and dried under reduced pressure to obtain a compound represented by the formula (I), 1 A photodegradable polymer (hereinafter referred to as PLA3) having a repeating unit in which R is an alkylene group having 10 carbon atoms and a repeating unit represented by formula (IV) was obtained. The number average molecular weight of the PLA3 obtained above was 9,000.

[0105] Example 4 0.04 mol of polylactide (PLA) having a number average molecular weight of 12,000 was heated to 200°C in a nitrogen gas atmosphere to melt it, and then 0.01 mol of the itaconic acid derivative obtained in Production Example 1 and 5.60 g of antimony trioxide as a catalyst were added to and mixed with the molten polylactide. The resulting mixture was heated at a temperature of 180°C for 24 hours with stirring to obtain a reaction mixture.

[0106] The reaction mixture obtained above is dissolved in methanol, and the precipitated unreacted polylactide is removed by suction filtration. The filtrate obtained is then evaporated under reduced pressure and dried under reduced pressure to obtain a compound represented by the formula (I), 1 A photodegradable polymer (hereinafter referred to as PLA4) having a repeating unit in which R is an alkylene group having 10 carbon atoms and a repeating unit represented by formula (IV) was obtained.

[0107] Comparative Example 1 Polylactide (polylactic acid) with a number average molecular weight of 12,000 was used as a polymer for comparison with the photodegradable polymer.

[0108] Comparative Example 2 In contrast to photodegradable polymers, polymers having R 1 A polymer having a repeating unit in which is an alkylene group having 10 carbon atoms was used.

[0109] PLA1 to PLA4 obtained above, in formula (I), R 1 Polymers and polylactides (polylactic acids) having a repeating unit in which the repeating unit is an alkylene group having 10 carbon atoms 1 The H-NMR spectrum (solvent: DMSO-d6) is shown in Figure 2. In Figure 2, PLA represents polylactide (polylactic acid), and Nylon 6i represents the R 1 represents a polymer having a repeating unit in which is an alkylene group having 10 carbon atoms.

[0110] The results shown in FIG. 2 show that PLA1 to PLA4 contain peaks at concentrations of around 3.40 ppm and 2.40 ppm that are derived from pyrrolidone rings, indicating that polylactide is incorporated therein.

[0111] The results of thermogravimetric analysis (TGA) of the above-obtained PLA1 to PLA4 and polylactide (polylactic acid) are shown in Figure 3. In Figure 3, PLA represents polylactide (polylactic acid).

[0112] From the results shown in Figure 3, Td5 of polylactide (PLA) is 295°C, and Td 10 It can be seen that the temperature is 310℃.

[0113] In contrast, Td5 of PLA1 is 220℃, Td 10 is 285℃, Td5 of PLA2 is 250℃, Td 10 is 290℃, Td5 of PLA3 is 260℃, Td 10 Td5 of PLA4 is 280℃, Td 10 Since the Td5 is 305°C, it can be seen that PLA1 to PLA4 all have the same thermal properties as polylactide. 10is the 10% weight loss temperature (the same applies below).

[0114] Furthermore, although it is difficult to see in PLA1, PLA1 to PLA4 all have two concave inflection points, which suggests that the amide bond in PLA is decomposed after the ester bond is decomposed.

[0115] Example 5 0.016 mol of polyethylene terephthalate (PET) having a number average molecular weight of 27,000 was dissolved in 15 mL of dimethyl sulfoxide, and the resulting solution was heated at 200°C to volatilize the dimethyl sulfoxide and obtain a residual molten product. To the resulting molten product, 0.016 mol of the itaconic acid derivative obtained in Production Example 1 and 7.50 g of antimony trioxide as a catalyst were added and mixed, and the resulting mixture was heated at 180°C for 24 hours with stirring to obtain a reaction mixture.

[0116] The reaction mixture obtained above is dropped into acetone to precipitate a polymer, and the resulting polymer is recovered by suction filtration and dried under reduced pressure to obtain a compound represented by the formula (I), wherein R 1 A photodegradable polymer (hereinafter referred to as PET1) having a repeating unit in which R is an alkylene group having 10 carbon atoms and a repeating unit represented by formula (V) was obtained. The number average molecular weight of the obtained PET1 was 190,000.

[0117] Example 6 0.022 mol of polyethylene terephthalate (PET) with a number average molecular weight of 27,000 was dissolved in dimethyl sulfoxide. The resulting solution was heated at 200°C to volatilize the dimethyl sulfoxide and obtain a residual molten product. To the resulting molten product, 0.011 mol of the itaconic acid derivative obtained in Production Example 1 and 7.50 g of antimony trioxide as a catalyst were added and mixed. The resulting mixture was heated at 180°C for 24 hours with stirring to obtain a reaction mixture.

[0118] The reaction mixture obtained above is dropped into acetone to precipitate a polymer, and the resulting polymer is recovered by suction filtration and dried under reduced pressure to obtain a compound represented by the formula (I), wherein R 1 A photodegradable polymer (hereinafter referred to as PET2) having a repeating unit in which R is an alkylene group having 10 carbon atoms and a repeating unit represented by formula (V) was obtained. The number average molecular weight of the obtained PET2 was 250,000.

[0119] Example 7 0.027 mol of polyethylene terephthalate (PET) with a number average molecular weight of 27,000 was dissolved in dimethyl sulfoxide. The resulting solution was heated at 200°C to volatilize the dimethyl sulfoxide and obtain a residual molten product. To the resulting molten product, 0.009 mol of the itaconic acid derivative obtained in Production Example 1 and 7.50 g of antimony trioxide as a catalyst were added and mixed. The resulting mixture was heated at 180°C for 24 hours with stirring to obtain a reaction mixture.

[0120] The reaction mixture obtained above is dropped into acetone to precipitate a polymer, and the resulting polymer is recovered by suction filtration and dried under reduced pressure to obtain a compound represented by the formula (I), wherein R 1 A photodegradable polymer (hereinafter referred to as PET3) having a repeating unit in which R is an alkylene group having 10 carbon atoms and a repeating unit represented by formula (V) was obtained. The number average molecular weight of the obtained PET3 was 170,000.

[0121] Example 8 0.028 mol of polyethylene terephthalate (PET) with a number average molecular weight of 27,000 was dissolved in dimethyl sulfoxide. The resulting solution was heated at 200°C to volatilize the dimethyl sulfoxide and obtain a residual molten product. To the resulting molten product, 0.007 mol of the itaconic acid derivative obtained in Production Example 1 and 7.50 g of antimony trioxide as a catalyst were added and mixed. The resulting mixture was heated at 180°C for 24 hours with stirring to obtain a reaction mixture.

[0122] The reaction mixture obtained above is dropped into acetone to precipitate a polymer, and the resulting polymer is recovered by suction filtration and dried under reduced pressure to obtain a compound represented by the formula (I), wherein R 1 A photodegradable polymer (hereinafter referred to as PET4) having a repeating unit in which R is an alkylene group having 10 carbon atoms and a repeating unit represented by formula (V) was obtained. The number average molecular weight of the obtained PET4 was 540,000.

[0123] The PET1 to PET4 obtained above are 1 Due to its low solubility in solvents used for H-NMR measurements, 1 Structural analysis by H-NMR was not possible.

[0124] Comparative Example 3 Polyethylene terephthalate with a number average molecular weight of 27,000 was used as a polymer to compare with the photodegradable polymer.

[0125] PET1 to PET4 obtained above, R 1 The infrared absorption spectra (FT-IR spectra) of an itaconic acid derivative (ID) in which R is an alkylene group having 10 carbon atoms and polyethylene terephthalate are shown in FIG. 4. In FIG. 4, ID is represented by the formula (II) 1 is an itaconic acid derivative with an alkylene group having 10 carbon atoms, and PET is polyethylene terephthalate.

[0126] From the results shown in Figure 4, the wavenumbers of PET1 to PET4 are 3000 to 3400 cm -1The absorption peak around this point is attributed to the N-H stretching.

[0127] In addition, in all of PET1 to PET4, the wavenumber is 3000 to 3400 cm -1 The presence of an absorption peak due to the NH stretching of the itaconic acid derivative obtained in Production Example 1 in the vicinity indicates that the pyrrolidone ring derived from the itaconic acid derivative obtained in Production Example 1 is incorporated into the polyethylene terephthalate.

[0128] In addition, in Figure 4, the wave number 1730 cm -1 and 1680 cm -1 The absorption peaks at 1260 cm are due to esters and amides, and the absorption of esters (-C=OC) derived from polyethylene terephthalate occurs at a wavenumber of 1260 cm. -1 It exists in.

[0129] The above results show that the itaconic acid derivative obtained in Production Example 1 was incorporated into PET1 to PET4.

[0130] The results of thermogravimetric analysis (TGA) of the above-obtained PET1 to PET4 and polyethylene terephthalate (referred to as PET in FIG. 5) are shown in FIG.

[0131] From the results shown in Figure 5, the Td5 of polyethylene terephthalate (PET) is 390°C, and the Td 10 In contrast, Td5 of PET1 is 370°C, Td 10 is 390℃, Td5 of PET2 is 370℃, Td 10 is 390℃, Td5 of PET3 is 375℃, Td 10 is 400℃, Td5 of PET4 is 360℃, Td 10 It can be seen that the temperature at which the PET1 to PET4 melts is heated is 392° C. Therefore, it can be seen that PET1 to PET4 have thermal properties similar to those of polyethylene terephthalate.

[0132] [Solubility of each polymer in solvent] Five mg of each polymer was weighed out and placed in a 5 mL flat-bottom glass vial, and 2 mL of each solvent shown in Table 1 (liquid temperature: 25°C) was added to the vial. The temperature of the solvent was raised to about 60°C using a hot stirrer heater and stirred with a magnetic stirrer for 24 hours. The appearance of each solution was then visually observed, and the solubility of each polymer in the solvent was evaluated based on the following evaluation criteria. When the solution became cloudy or gelled, it was heated to about 60°C, and after 24 hours, the appearance of each solution was visually observed again, and the solubility of each polymer in the solvent was evaluated based on the following evaluation criteria.

[0133] [Evaluation criteria] ○: The polymer dissolves in the solvent. ×: The polymer does not dissolve in the solvent.

[0134] The abbreviations in Table 1 have the following meanings: DMSO: dimethyl sulfoxide DMF: N,N-dimethylformamide THF: tetrahydrofuran DMAc: N,N-dimethylacetamide PLA: Polylactide (polylactic acid) PET: Polyethylene terephthalate

[0135] [Table 1]

[0136] The results shown in Table 1 indicate that photodegradable polymers that use polylactide as a polyester polymer are soluble in alcohols such as methanol and ethanol, and therefore have better solubility in various solvents than the polylactide used as their raw material, making them suitable for applications in which they are dissolved in a solvent.

[0137] Furthermore, photodegradable polymers that use polyethylene terephthalate as a polyester polymer are not only water resistant but also more insoluble in organic solvents than the polyethylene terephthalate used as the raw material. This means that they are suitable for applications that require water resistance as well as applications that require properties such as solvent resistance and chemical resistance.

[0138] [Photodegradability] An ultraviolet irradiation device (manufactured by LUMEN DYNAMICS, product name: OmniCure® SERIES 1000) was used. 0.30 g of polymer was immersed in 100 mL of seawater, and ultraviolet light was applied from a position 6 cm above the water surface at an illuminance of 80 to 100 mW / cm. 2 The mass of the polymer was measured before UV irradiation and 1, 2, 3, 4, 5, and 6 hours after UV irradiation to examine the change in mass. The results are shown in Figures 6 and 7.

[0139] Figure 6 is a graph showing the weight changes of photodegradable polymers (PLA1 to PLA4) in which polylactide is used as the polyester polymer, and polylactide (PLA). Figure 7 is a graph showing the weight changes of photodegradable polymers (PET1 to PET4) in which polyethylene terephthalate is used as the polyester polymer, and polyethylene terephthalate (PET).

[0140] The results shown in Figure 6 show that polylactide was hardly photodecomposed by UV irradiation, whereas photodegradable polymers that use polylactide as the raw polyester polymer reduced in mass upon UV irradiation, demonstrating their excellent decomposition ability upon UV irradiation.

[0141] FIG. 7 is a graph showing the weight changes of photodegradable polymers (PET1 to PET4) in which polyethylene terephthalate is used as the polyester polymer, and polyethylene terephthalate (PET).

[0142] The results shown in Figure 7 show that polyethylene terephthalate was hardly photodecomposed by ultraviolet light irradiation, whereas the photodegradable polymer that uses polyethylene terephthalate as the raw polyester polymer lost approximately 80% of its mass after 1 hour of exposure to ultraviolet light, demonstrating that it has exceptionally excellent photodegradability when exposed to ultraviolet light.

[0143] [Formability into film] Next, 1 mg of each of the photodegradable polymers PLA1 to PLA4 was dissolved in dimethyl sulfoxide or N,N-dimethylformamide at 50°C, and the resulting solution was cast onto a glass plate to form a film. This indicates that all of PLA1 to PLA4 can be used as molding materials to obtain molded articles such as films.

[0144] [Moldability into fiber] Each of the photodegradable polymers PET1 to PET4 was heated to 220°C and melted to prepare a molten spinning solution. The molten spinning solution obtained above was applied to a glass plate, a glass rod was brought into contact with the surface, and the glass rod was then removed from the glass plate. The molten spinning solution was stretched to a length of 1 m or more, forming filaments, confirming that fibers could be easily produced using the molten spinning solution. [Industrial Applicability]

[0145] Polyesters such as polyethylene terephthalate and polylactide are difficult to decompose in soil and the ocean, whereas the photodegradable polymer of the present invention decomposes easily in a relatively short time when exposed to ultraviolet light. Even if the polymer is released into the ocean, it is decomposed in the ocean where ultraviolet light shines, and is therefore unlikely to become microplastics. Therefore, it is expected that the use of the photodegradable polymer of the present invention as a substitute for conventional plastics such as polyester will help to solve the problem of marine pollution caused by microplastics.

Claims

1. Formula (I): 【Chemistry 1】 (In the formula, R 1 represents an alkylene group having 2 to 18 carbon atoms which may have a substituent. and a repeating unit based on a polyester-based polymer.

2. 2. The photodegradable polymer according to claim 1, wherein the polyester polymer is a terephthalic acid ester polymer or a polylactide.

3. As a raw material, a compound of formula (II): 【Chemistry 2】 (In the formula, R 1 represents an alkylene group having 2 to 18 carbon atoms which may have a substituent. and a polyester-based polymer, and polymerizing the itaconic acid derivative and the polyester-based polymer.

4. 4. The method for producing a photodegradable polymer according to claim 3, wherein the polyester polymer used as the raw material is a terephthalic acid ester polymer or polylactide.

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