Polyester resin and its manufacturing method

Abstract

To provide a polyester resin with decomposition regulated, and a production method thereof.SOLUTION: A polyester resin contains a repeating unit of formula (1)-2 and a repeating unit of formula (2) and has an introduction ratio of α-(hydroxymethyl) acrylic acid alkyl ester with a decomposable structure of 10 mol% or more. A production method of the polyester resin includes a step for reacting a diol and / or a derivative thereof, a dicarboxylic acid and / or a derivative thereof, or oligomers thereof and α-(hydroxymethyl) acrylic acid alkyl ester as a monomer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polyester resin and a method for producing the same. [Background technology]

[0002] The chemical decomposition of polymer compounds is being applied to cutting-edge functional materials such as dismantlable adhesive materials, resist materials, and self-repairing materials, which utilize the changes in physical properties before and after decomposition, as well as medical materials such as biocompatible materials and drug delivery systems. Furthermore, in recent years, there has been a demand for the use of chemical decomposition of polymer compounds to achieve highly efficient chemical recycling and promote decomposition in nature, and they are expected to become environmentally friendly materials.

[0003] Against this background, molecular design is being considered to introduce weak covalent bonds into the main chain of polymer compounds that break in response to specific stimuli such as light, heat, acid, and base. The present inventors have reported that bis[α-(halomethyl)acrylate] undergoes a conjugate substitution reaction with dicarboxylic acid, bisphenol, or thiol in the presence of a base to give polyconjugated esters (Non-Patent Document 1). This reaction proceeds even at room temperature, is completed within a few hours to a day, and does not require a special reaction field such as an inert gas atmosphere. Furthermore, the product, polyconjugated ester, can be quantitatively decomposed by the conjugate substitution reaction with thiol without side reactions. The conjugate substitution reaction can be reversible or irreversible depending on the leaving component and nucleophile (Non-Patent Document 2). Therefore, in the decomposition of polyconjugated ester described in Non-Patent Document 1, when the leaving component is bisphenol and the nucleophile is thiol, the acidity of both is about the same, so the conjugate substitution reaction is reversible, resulting in incomplete main chain cleavage and decomposition. Patent Document 1 describes a polymer obtained by condensation polymerization of polyester-forming substances such as diols and dicarboxylic acids with lower alkyl α-methylene-β-hydroxypropionate. This polymer is considered to be a novel insoluble polyester resin with pendant unsaturated bonds. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Y.Kohsaka,T.Miyazaki,K.Hagiwara,Polym.Chem.2018,9,1610-1617 [Non-patent document 2] Y.Kohsaka,Polym.J.2020,52,1175-1183. [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 3,321,552 Summary of the Invention [Problem to be solved by the invention]

[0006] Part of the chemical structure of polyester resin is modified by conjugation substitution reaction (S N By substituting 10 mol % or more of the conjugated ester structure capable of accepting the reaction (2'), that is, the degradable structure represented by the following general formula (1), degradability can be imparted to the polyester resin. [ka] That is, an object of the present invention is to provide a polyester resin with controlled decomposition properties and a method for producing the same. [Means for solving the problem]

[0007] The means for solving the above problems are as follows. 1. A polymer having a repeating unit represented by the following general formula (1)-2 and a repeating unit represented by the following general formula (2), A polyester resin characterized in that the introduction rate of a degradable structure represented by the following general formula (1) is 10 mol % or more. [ka] [In the formula, n represents the number of repeating units.] [ka] [In the formula, R 1 is a divalent linking group obtained by removing a hydroxy group from a diol, and R 2 is a divalent linking group formed by removing a carboxy group from a dicarboxylic acid. m represents the number of repeating units. [ka] 2. The polyester resin according to 1., characterized in that it contains 10 mol % or more and 50 mol % or less of the repeating units represented by the general formula (1)-2 based on all repeating units. 3. A method comprising the step of reacting a diol and / or a derivative thereof with a dicarboxylic acid and / or a derivative thereof, or an oligomer thereof, and an α-(hydroxymethyl)acrylic acid alkyl ester as a monomer, A method for producing a polyester resin, characterized in that it has a repeating unit represented by the following general formula (1)-2 and a repeating unit represented by the following general formula (2), and the introduction rate of the degradable structure represented by the following general formula (1) is 10 mol % or more. [ka] [In the formula, n represents the number of repeating units.] [ka] [In the formula, R 1 is a divalent linking group obtained by removing a hydroxy group from the diol, and R 2 is a divalent linking group obtained by removing a carboxy group from the dicarboxylic acid; and m represents the number of repeating units. [ka] 4. The method for producing a polyester resin according to 3., wherein the repeating unit represented by the general formula (1)-2 is contained in an amount of 10 mol % to 50 mol % based on all repeating units. [Effects of the Invention]

[0008] The polyester resin of the present invention contains a specific degradable structure, and chemical properties such as degradability (stability) and physical properties such as melting point, crystallinity, glass transition point, and elastic modulus can be controlled by the amount of degradable structure introduced. This degradable structure can be easily introduced into the polyester main chain, and the structure of the polyester into which this degradable structure is introduced is not limited, so degradability can be imparted to polyesters with desired physical properties. By introducing a degradable structure into commonly used polyester resins such as PET, PBT, PEN, and PBS, degradability can be easily imparted and their physical properties can also be adjusted. [Brief explanation of the drawings]

[0009] [Figure 1] 1H NMR spectra before solid-phase decomposition (Example 4) and after solid-phase decomposition in Example 8. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described below. Note that the following description is merely an example of the present invention and does not limit the present invention in any way. The present invention is not limited to the embodiments described below, but may include various modifications, changes, and improvements to each disclosed element (including elements described in the claims, specification, and drawings) within the scope of the present invention and based on the technical idea of the present invention. Furthermore, various combinations, substitutions, and selections of each disclosed element are possible within the scope of the claims of the present invention.

[0011] Polyester resin The polyester of the present invention can be obtained by an ester formation reaction and an ester exchange reaction using diol and / or its derivative (hereinafter also referred to as a diol component), dicarboxylic acid and / or its derivative (hereinafter also referred to as a dicarboxylic acid component), and an α-(hydroxymethyl)acrylic acid alkyl ester (hereinafter also referred to as an acrylic component) as monomers. Note that an oligomer obtained by reacting these may be used instead of the diol component and the dicarboxylic acid component. The polyester of the present invention has a repeating unit represented by the following general formula (1)-2 and a repeating unit represented by the following general formula (2), and has an introduction rate of the degradable structure represented by the following general formula (1) of 10 mol % or more. [ka] [In the formula, n represents the number of repeating units.] [ka] [In the formula, R 1 is a divalent linking group obtained by removing a hydroxy group from a diol, and R 2 is a divalent linking group formed by removing a carboxy group from a dicarboxylic acid. m represents the number of repeating units. [ka]

[0012] As the diol component and dicarboxylic acid component, those used as polyester monomers can be used without any particular limitation. As the diol component, for example, an aliphatic diol, an alicyclic diol, or an aromatic diol can be used. 1Examples of the alkylene group include alkylene groups having 2 to 24 carbon atoms, cycloalkylene groups having 5 to 12 carbon atoms, and arylene groups having 6 to 20 carbon atoms, in which a carbon atom may be substituted with a heteroatom, and a hydrogen atom may be substituted with a functional group that does not participate in the reaction, such as a halogen atom, an alkyl group, an alkoxy group, an acyl group, or a cyano group. Specific examples include aliphatic diols such as ethylene glycol, diethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, dibutylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, and 1,8-octanediol; 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethanol, Alicyclic diols such as 1,4-cyclohexanedimethanol and tricyclo[5.2.1.0(2,6)]decanedimethanol; and aromatic diols such as 1,4-benzenedimethanol, 1,3-benzenedimethanol, xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane, bis(4-hydroxyphenyl)sulfone, and bis[4-(2-hydroxyethoxy)phenyl]sulfone can be used. Biomass-derived diols such as ethylene glycol, 1,3-propanediol, and 1,4-butanediol can also be used. Diol components can be used alone or in combination.

[0013] As the dicarboxylic acid component, for example, an aromatic dicarboxylic acid, an alicyclic dicarboxylic acid, or an aliphatic dicarboxylic acid can be used. 2Examples of the alkylene group include an arylene group having 6 to 20 carbon atoms, a cycloalkylene group having 5 to 12 carbon atoms, and an alkylene group having 2 to 24 carbon atoms, in which a carbon atom may be substituted with a heteroatom, and a hydrogen atom may be substituted with a functional group that does not participate in the reaction, such as a halogen atom, an alkyl group, an alkoxy group, an acyl group, or a cyano group. Specific examples include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and 2,3-norbornenedicarboxylic acid; and aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid, as well as acid anhydrides thereof (e.g., phthalic anhydride, succinic anhydride), (di)alkyl esters (e.g., dimethyl terephthalate, diethyl terephthalate, dimethyl succinate), and (di)halides (e.g., terephthalic acid dichloride, succinic acid dichloride). The dicarboxylic acid component can be used alone or in combination of two or more.

[0014] The diol component and dicarboxylic acid component can be appropriately selected depending on the properties desired for the polyester obtained from only the diol component and the dicarboxylic acid component. For example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), etc. are widely used as thermoplastic resins due to their various excellent physical properties, and these raw material monomers can be suitably used in combination. Furthermore, a combination of raw material monomers such as polybutylene succinate (PBS) and polybutylene adipate (PBA) can be biodegradable.

[0015] The polyester of the present invention contains, in addition to a diol component and a dicarboxylic acid component, an α-(hydroxymethyl)acrylic acid alkyl ester represented by the following chemical formula (3) as an acrylic component monomer. [ka] [In the formula, R is an alkyl group.]

[0016] When the number of carbon atoms in the alkyl group of the acrylic component is large, alkyl alcohol, a by-product generated during the polymerization reaction, may inhibit the polymerization reaction. Therefore, it is preferable to remove the alkyl alcohol from the reaction system during polymerization. There are no particular restrictions on the method for removing the alkyl alcohol from the reaction system, but a method using vacuum heating is easy. From this perspective, it is preferable that the alkyl alcohol has a low boiling point, and the number of carbon atoms in the alkyl group represented by R in chemical formula (3) is preferably 8 or less, more preferably 4 or less, and even more preferably 2 or less.

[0017] When synthesizing the polyester of the present invention, other monomers besides the diol component, dicarboxylic acid component, and acrylic component can also be copolymerized. The other monomers that can be copolymerized are not particularly limited as long as they are compounds having a hydroxy group or a carboxy group that can be inserted into the polyester main chain. Examples include trifunctional or higher polyhydric alcohols such as trimethylolmethane, trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, and dipentaerythritol; trifunctional or higher polycarboxylic acids such as trimellitic acid and pyromellitic acid; hydroxycarboxylic acids such as lactic acid, glycolic acid, hydroxybutyric acid, malic acid, fumaric acid, maleic acid, citric acid, and fumaric acid, and derivatives of these hydroxycarboxylic acids, such as esters.

[0018] The diol component and the dicarboxylic acid component form a repeating unit represented by general formula (2). [ka] [In the formula, R1 is a divalent linking group obtained by removing a hydroxy group from the diol, and R 2 is a divalent linking group obtained by removing a carboxy group from the dicarboxylic acid; and m represents the number of repeating units.

[0019] The acrylic component forms a repeating unit represented by general formula (1)-2. [ka] [In the formula, n represents the number of repeating units.] Therefore, the polyester of the present invention has a repeating unit represented by general formula (1)-2 and a repeating unit represented by general formula (2).

[0020] Here, the acrylic component, α-(hydroxymethyl)acrylic acid alkyl ester, bonds with the dicarboxylic acid component through an ester-forming reaction. Specifically, as shown in the reaction formula below, the carboxyl group derived from the dicarboxylic acid component is attacked by the hydroxyl group of the α-(hydroxymethyl)acrylic acid alkyl ester, initiating an acyl substitution reaction and forming an ester bond between the dicarboxylic acid component and the acrylic component. [ka]

[0021] Furthermore, the alkyl ester moiety (-OR) of the α-(hydroxymethyl)acrylic acid alkyl ester is bonded to the diol component by transesterification. Then, the alkyl component is incorporated into the polyester main chain through an ester formation reaction and an ester exchange reaction, forming a degradable structure represented by general formula (1). [ka] Therefore, the polyester of the present invention has a degradable structure represented by general formula (1).

[0022] (Degradable structure introduction rate) In the present invention, the introduction rate of a degradable structure (hereinafter also referred to as the introduction rate of a degradable structure, unit mol %) means the ratio obtained by dividing the number of conjugated ester (acrylic acid ester) units located inside the main chain by the total number of repeating units. The introduction rate of a degradable structure can be, for example, 1 It can be calculated from the H NMR spectrum by a standard method, by comparing the integrated intensity of one or more hydrogen atoms of each repeating unit with the integrated intensity of the signal of vinylidene hydrogen of the degradable structure. When the polyester of the present invention is composed only of a diol component, a dicarboxylic acid component, and an acrylic component, it can be calculated by comparing the integrated intensity of the signal of O-methylene hydrogen of the saturated ester group with the integrated intensity of the signal of vinylidene hydrogen of the degradable structure. In the examples, 1 H NMR spectra were measured at 25°C using a nuclear magnetic resonance (NMR) apparatus (AVANCE NEO manufactured by Bruker Corporation) with deuterated chloroform as the measurement solvent and tetramethylsilane as the internal standard, but the apparatus and solvent are not limited to these. If the resulting polymer is insoluble in deuterated chloroform used as the solvent, it can be measured after reducing the molecular weight by solid-phase decomposition or the like to increase solubility.

[0023] When the polyester of the present invention is composed only of a diol component, a dicarboxylic acid component, and an acrylic component, 1 The rate of introduction of degradable structures in H NMR spectra can be evaluated using the following formula (1) based on the integrated intensity of the signal from the O-methylene hydrogen of the saturated ester group and the integrated intensity of the signal from one vinylidene hydrogen of the degradable structure (conjugated ester inserted inside the main chain). These signals can be selected appropriately depending on the monomer, the resulting polymer, etc. (Degradable structure introduction rate) = (integrated signal intensity of vinylidene hydrogen) / {(integrated signal intensity of O-methylene hydrogen of saturated ester group) / 4 + (integrated signal intensity of vinylidene hydrogen)} × 100% (1) In addition, although the signal of the α-(hydroxymethyl)acrylic acid alkyl ester group introduced at the terminal is observed in the vinylidene hydrogen peak, the acrylic component at the terminal does not have the decomposable structure represented by general formula (1), and therefore is not a decomposable structure.

[0024] The polyester of the present invention preferably contains 10 mol% or more and 50 mol% or less of the repeating units represented by general formula (1)-2 relative to all repeating units. The content of the repeating units represented by general formula (1)-2 relative to all repeating units can control the introduction rate (10 mol% or more) of the degradable structure represented by general formula (1) in the polyester, thereby adjusting the degradability and physical properties of the polyester. This content is more preferably 13 mol% or more. It is more preferably 40 mol% or less, and even more preferably 30 mol% or less. In the polyester of the present invention, the number average molecular weight is not particularly limited, but in order to exhibit the properties of a polymer, it is preferably 1500 or more, and more preferably 3000 or more.If the number average molecular weight is too large, the solubility decreases, the viscosity increases, and the handleability decreases, so the number average molecular weight is preferably 100,000 or less, more preferably 50,000 or less, and even more preferably 30,000 or less.

[0025] Polyester manufacturing method The method for producing a polyester of the present invention includes a step of reacting a diol component, a dicarboxylic acid component, or an oligomer thereof, with an acrylic component as a monomer. Apart from this step, conventionally known methods can be used for producing the polyester of the present invention. In this process, the introduction rate of a degradable structure and the content of the repeating unit represented by general formula (1)-2 in the polyester can be controlled by adjusting the charging ratio of the acrylic component to the total monomers. The acrylic component can be added as a raw material from the beginning along with the diol and dicarboxylic acid components, or it can be added after the diol and dicarboxylic acid components have been polymerized to a certain extent to form an oligomer. For example, oligobutylene succinate can be used instead of 1,4-butanediol, the diol component, and succinic acid, the dicarboxylic acid component. When the acrylic component is added later, it can be added all at once or in small amounts.

[0026] Decomposition reaction The decomposable structure represented by general formula (1) is a conjugated ester in which a leaving group is substituted at the allylic position. Simply mixing it with a decomposition initiator having nucleophilicity in a homogeneous solution, suspension, or solid state can cause a conjugate substitution reaction (S N Quantitative decomposition occurs by reaction 2'. Specifically, as shown in the following reaction formula, a decomposition initiator (: Nu) attacks the β carbon of the vinylidene group in the decomposable structure represented by general formula (1) to initiate a conjugate substitution reaction (S N The main chain is cleaved by reaction 2'. This decomposition reaction is clearly distinguishable from simple pulverization, since the main chain of the polymer compound is cleaved at the decomposable structure represented by general formula (1).

[0027] [ka]

[0028] The polyester resin of the present invention has a degradable structure represented by general formula (1), and by setting the introduction rate of this degradable structure to 10 mol% or more, the degradability can be effectively utilized. The introduction rate of the degradable structure is preferably 13 mol% or more. Furthermore, it is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 30 mol% or less.

[0029] Furthermore, since this decomposition reaction proceeds as long as the polymer compound has a decomposable structure represented by general formula (1), any polymer compound having a decomposable structure represented by general formula (1) can be decomposed, without being limited to the polyester of the present invention. However, the decomposable structure represented by general formula (1) has an ester bond and a carbonyl group at both ends. Therefore, from the viewpoint of efficiently introducing the decomposable structure represented by general formula (1), the polymer compound preferably contains, as its main component, polyurethane or polycarbonate in addition to polyester, and more preferably polycarbonate. Examples of polycarbonates include polycarbonate resins that use diols such as bisphenol, phosgene and / or its derivatives, and alkyl α-(hydroxymethyl)acrylate as monomers, and have a repeating unit represented by general formula (1)-2 and a repeating unit represented by general formula (2).

[0030] The decomposition initiator can be any one that functions as a nucleophile for the β-carbon of the vinylidene group of the decomposable structure, that is, a base that is at least as strong as the carboxylate ion that is eliminated. In this specification, the decomposition initiator is defined as a compound that converts the decomposable structure represented by general formula (1) into a nucleophile by a conjugate substitution reaction (S N 2' reaction) of a degradable structure represented by general formula (1), which has nucleophilic ability but is an impurity, a residue, or an additive for imparting other functions. N This does not include compounds that are not intended for cleavage by reaction 2'. Specific examples of the decomposition initiator include compounds having at least one of an amino group, a carboxy group, a mercapto group (sulfanyl group), a hydroxy group, and salts thereof, and may also be compounds having two or more of the above-mentioned functional groups within the compound, such as amino acids. Examples of compounds having an amino group include diethylamine and n-propylamine. Examples of compounds having a carboxy group include acetic acid, sodium acetate, ammonium acetate, tetrabutylammonium acetate, benzoic acid, and sodium benzoate. Examples of compounds having a mercapto group include benzyl mercaptan, 1-dodecanethiol, and thioglycerol. Examples of compounds having a hydroxy group include methanol, ethanol, and phenol. Among these, a compound may be selected taking into consideration the acidity, electron density, steric hindrance, and energy level difference between the highest occupied molecular orbital (HOMO) of the compound or its conjugate acid and the lowest unoccupied molecular orbital (LUMO) of the β carbon of the vinylidene group in general formula (1) of the highest occupied molecular orbital (HOMO), etc. Specifically, compounds having an amino group, a mercapto group, or a hydroxy group are preferred because the decomposition reaction is irreversible, and compounds having an amino group are more preferred because a base is not required as described below.

[0031] The decomposition method in a homogeneous solution is not limited by the type of solvent or temperature as long as the polymer compound and decomposition initiator are dissolved, and organic solvents such as dichloromethane, chloroform, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, acetone, acetonitrile, dioxane, ethyl acetate, methanol, ethanol, tetrahydrofuran, 2-butanone, and N-methyl-2-pyrrolidone, as well as water, can be used. The decomposition method in a homogeneous solution is excellent in decomposition ability, but the polymer compounds to be decomposed are limited to those that can be dissolved in the solvent. The decomposition method in a suspension state is a method in which the polymer compound and / or the decomposition initiator are suspended in a liquid and contact is promoted between the polymer compound and the decomposition initiator by methods such as immersion, stirring, convection, shaking, dispersion, emulsification, etc. The liquid is not limited as long as it has the property of not completely dissolving the polymer compound and / or the decomposition initiator, and water, alcohols, ethers, hexane, cyclohexane, and other hydrocarbons can be used. In the decomposition method in a suspension state, the polymer compound to be decomposed is not limited, but if the decomposition product does not dissolve in the liquid, the decomposition will plateau. This is presumably because if the decomposition product does not dissolve, the solid decomposition product will adhere to the surface and the decomposable structure will not be exposed. Decomposition methods in a solid state (solid-phase decomposition) are methods in which decomposition is promoted by applying a physical stimulus to a mixture of a polymer compound and a decomposition initiator. Solid-phase decomposition also includes cases in which the decomposition initiator is liquid. Known stirring or grinding devices such as a mortar, ball mill, bead mill, sand mill, or paint shaker can be used for the physical stimulus. Solid-phase decomposition is not limited to polymer compounds to be decomposed, so even polymer compounds with poor solubility can be decomposed. Furthermore, the physical stimulus exposes the decomposable structure, resulting in a high reaction rate for the decomposition reaction.

[0032] The amount of the decomposition initiator used is not particularly limited as long as the polymer decomposes smoothly, but if it is too little, polymer chains are likely to remain without any main chain scission, and if it is too much, the atomic efficiency decreases and a large amount of unreacted decomposition initiator remains. Therefore, the amount of the decomposition initiator used is preferably 0.10 molar equivalents or more and 5.0 molar equivalents or less, more preferably 0.15 molar equivalents or more and 2.0 molar equivalents or less, and even more preferably 0.20 molar equivalents or more and 1.5 molar equivalents or less, relative to the decomposable structure represented by general formula (1). The temperature during decomposition is not particularly limited, but can be from 5° C. to 80° C. Since this decomposition reaction proceeds even at low temperatures, from the viewpoints of energy costs and preventing radical polymerization of the acrylic component due to heat, the temperature is preferably 60° C. or less, more preferably 40° C. or less, and even more preferably 30° C. or less.

[0033] Conjugate substitution reaction (S N A base can be used to efficiently carry out the conjugate substitution reaction (S N The base can be freely selected within the range in which reaction 2' proceeds, or it may not be used at all. When generating carboxylate ions, thiolate ions, amide ions, alkoxide ions, or phenolate ions from carboxylic acids, thiols, amines, alcohols, or phenols, respectively, in the reaction system, it is preferable to use tertiary amines such as triethylamine, pyridine, N,N-diisopropylethylamine, and imidazole; alkali carbonates such as potassium carbonate, sodium carbonate, and sodium bicarbonate; or alkali hydroxides such as sodium hydroxide and potassium hydroxide. Furthermore, when the nucleophile also has basic properties, such as compounds having an amino group such as n-propylamine and diethylamine, the addition of a base is not necessary. The amount of the base used is preferably 0.05 to 2.0 molar equivalents, more preferably 0.10 to 1.5 molar equivalents, and even more preferably 0.20 to 1.2 molar equivalents, relative to the decomposable structure represented by general formula (1). [Example]

[0034] <Analytical equipment> ( 1 H NMR spectrum) Measurement was carried out using a nuclear magnetic resonance (NMR) apparatus (AVANCE NEO manufactured by Bruker Corporation) at 25° C. Deuterated chloroform was used as the measurement solvent, and tetramethylsilane was used as the internal standard.

[0035] (Degradable structure introduction rate: when the resulting polymer is soluble in deuterated chloroform) If the resulting polyester is soluble in deuterated chloroform, 1The introduction rate of the degradable structure was evaluated using H NMR spectra. Specifically, signals from four O-methylene hydrogens of the saturated ester group were observed at 4.4-3.8 ppm, and a signal from one vinylidene hydrogen of the degradable structure (conjugated ester inserted inside the main chain) was observed at 6.36 ppm. Based on these integrated intensities, the introduction rate of the degradable structure was evaluated using the following formula (2). (Degradable structure introduction rate) = (integrated signal intensity at 6.36 ppm) / {(4.4-3.8 ppm signal integral intensity) / 4+(6.36 ppm signal integral intensity)}×100% (2) Although a signal from the α-(hydroxymethyl)acrylic acid alkyl ester group introduced at the terminal was observed at 6.26 ppm, the acrylic component at the terminal does not have the degradable structure represented by general formula (1), and therefore is not a degradable structure. In other words, the introduction rate of degradable structures means the ratio of the number of conjugated ester (acrylic acid ester) units located within the main chain divided by the total number of repeating units.

[0036] (molecular weight) The molecular weight (number average molecular weight Mn) and molecular weight dispersity D (Mw / Mn) were measured by loading two size exclusion columns "Shodex GPC HK-404L" (Showa Denko K.K.) heated to 40°C in series into an EXTREMA chromatograph (JASCO). Chloroform (for high-performance liquid chromatography, Wako Pure Chemical Industries) was used as the eluent at 0.3 mL / min. The chromatogram was detected with an ultraviolet absorption spectrometer "UV-4070" (detected at 254 nm, JASCO) and a differential refractometer (RI-4035, JASCO). The chromatogram was then analyzed by standard polystyrene (Tosoh, TSK Gel Oligomer Kit, Mn: 6.03 × 10 5 , 2.522×10 5 , 1.416×10 5 , 2.912×10 4 , 8.59 x 10 3 , 4.25×10 3 , 1.46×10 3 , 8.30×10 2 ) and evaluated by calibration with a cubic curve.

[0037] (Melting Point) The melting point was measured using a thermogravimetric differential scanning calorimeter (TG-DTA, manufactured by Rigaku, differential thermobalance Thermo plus EVO2 sample observation TG-DTA) in a nitrogen atmosphere at a heating rate of 10°C / min from 50 to 500°C.

[0038] (Comparative Example 1) Synthesis of polybutylene succinate Succinic anhydride (1.64 g, 16.4 mmol) and 1,4-butanediol (3.06 g, 33.9 mmol) were heated at 160 °C for 3 hours under an argon atmosphere. The mixture was then vacuumed (<1 Torr) for 3 hours. After returning to room temperature, tetraisopropyl orthotitanate (16 μL, 55 μmol) was added and the mixture was heated at 180 °C under a vacuum of 0.075 Torr for 7 hours. The product was dissolved in chloroform (12 mL) and reprecipitated using methanol (240 mL). The precipitate was filtered and dried under vacuum to yield polybutylene succinate (1.74 g, 62.0%) as a white solid. The number average molecular weight was 8580 and the molecular weight dispersity was 2.00.

[0039] (Synthesis of oligobutylene succinate (oligomer)) Succinic anhydride (6.67 g, 66.6 mmol) and 1,4-butanediol (9.00 g, 99.9 mmol) were heated at 160° C. for 3 hours under an argon atmosphere to obtain oligobutylene succinate (13.7 g) as a white solid. The number average molecular weight was outside the range of the calibration curve, but the molecular weight at the peak in the size exclusion chromatogram was 340. The chemical structures of the resulting oligomers are shown in chemical formulas (4) and (5). Although there are oligomers in which the terminal structures are alcohol and carboxylic acid, for simplicity, these are included in chemical formulas (4) and (5). [ka] [ka]

[0040] For the above chemical structure, 1 In the H NMR spectrum, signal A of the succinate ester moiety inside the main chain was observed at 2.62 ppm, along with signal A' of the methylene group derived from the carboxylic acid terminal. In addition, signal B of the O-methylene hydrogen of the ester group was observed at 4.13 ppm, and signal B' derived from the alcohol terminal was observed at 3.67 ppm. The signal intensity A of the succinate ester moiety inside the main chain should match the signal intensity B of the O-methylene hydrogen of the ester group at 4.13 ppm. Therefore, the integrated intensity of signal A' of the methylene group derived from the carboxylic acid terminal is (Integrated intensity of signal A') = (integrated intensity of signals A and A') - (integrated intensity of signal B) (3) It is estimated as. Therefore, the number average degree of polymerization, n, is n = (integrated intensity of signal B) / [{(integral intensity of signal A') + (integral intensity of signal B')} / 2] (4) It is estimated as. The proportions of carboxylic acid terminals and alcohol terminals in all terminals can be estimated by the following formulas (5) and (6), respectively. (Proportion of carboxylic acid terminals) = (integral intensity of signal A') / {(integral intensity of signal A') + (integral intensity of signal B')} (5) (proportion of alcohol terminals) = (integral intensity of signal B') / {(integral intensity of signal A')+(integral intensity of signal B')} (6) In this case, the number average molecular weight Mn of the whole oligomer is Mn = (molecular weight of repeating unit) × n + (molecular weight of succinic acid) × (percentage of carboxylic acid terminals) + (molecular weight of 1,4-butanediol) × (percentage of alcohol terminals) (7) It can be calculated as follows. As a result of the measurement, the number average molecular weight Mn of the oligobutylene succinate was determined to be 317.5.

[0041] Example 1: Synthesis of polybutylene succinate copolymer Oligobutylene succinate (1.07 g, 3.37 mmol / chain, 5.15 mmol of succinic acid units including end groups), methyl α-(hydroxymethyl)acrylate (200 mg, 1.72 mmol, 33 mol% relative to succinic acid units), tetraisopropyl orthotitanate (5 μL, 19 μmol), and 4-methoxyphenol (1 mg) were heated at 180 °C under a reduced pressure of 0.20 Torr. During heating, the mixture was cooled once after 1 hour and once after 3 hours, and samples were taken accordingly. After heating for a total of 7 hours, the product was dissolved in chloroform (5 mL) and reprecipitated using methanol (250 mL). The precipitate was filtered and dried under vacuum to obtain a white solid (0.653 g). The product was soluble in chloroform (including deuterated chloroform), had a number-average molecular weight of 9800, a molecular weight dispersity of 1.22, and a degradable structure introduction rate of 15 mol%.

[0042] Example 2: Synthesis of polybutylene succinate copolymer The same procedure as in Example 1 was repeated except that oligobutylene succinate (1.04 g, 3.28 mmol / chain, 5.00 mmol of succinic acid units including terminal groups) and methyl α-(hydroxymethyl)acrylate (254 mg, 2.19 mmol, 44 mol% based on succinic acid units) were used to obtain a white solid (0.528 g). The product was soluble in chloroform (including deuterated chloroform), had a number-average molecular weight of 18,000, a molecular weight dispersity of 1.35, and a degradable structure introduction rate of 16 mol%.

[0043] (Example 3) Synthesis of polybutylene succinate copolymer The same procedure as in Example 1 was repeated except that oligobutylene succinate (1.03 g, 3.25 mmol / chain, 4.97 mmol of succinic acid units including terminal groups) and methyl α-(hydroxymethyl)acrylate (314 mg, 2.71 mmol, 55 mol% based on succinic acid units) were used, to obtain a white solid (0.287 g). The product was soluble in chloroform (including deuterated chloroform), had a number average molecular weight of 8000, a molecular weight dispersity of 1.24, and a degradable structure introduction rate of 22 mol%.

[0044] Example 4: Synthesis of polybutylene succinate copolymer (scale-up) The same procedure as in Example 1 was repeated except that oligobutylene succinate (1.93 g, 6.08 mmol / chain, 9.29 mmol of succinic acid units including terminal groups) and methyl α-(hydroxymethyl)acrylate (363 mg, 3.06 mmol, 33 mol% based on succinic acid units) were used to obtain a white solid (1.32 g). The product was soluble in chloroform (including deuterated chloroform), had a number average molecular weight of 8500, a molecular weight dispersity of 1.59, and a degradable structure introduction rate of 17 mol%.

[0045] (Thermal properties of polybutylene succinate copolymer) Table 1 summarizes the polymerization results of Comparative Example 1 and Examples 1 to 4, as well as the melting points of each polymer. The introduction rate of degradable structures and the content of acrylic units increased depending on the charge ratio of methyl α-(hydroxymethyl)acrylate, and the melting point decreased proportionally. This confirmed that physical properties such as thermal properties can be controlled by the charge ratio of methyl α-(hydroxymethyl)acrylate. [Table 1]

[0046] (Example 5) Decomposition of polybutylene succinate copolymer with benzyl mercaptan in homogeneous solution To a chloroform (0.4 mL) solution of the polybutylene succinate copolymer (58 mg, acrylic unit 0.065 mmol) obtained in Example 4, a chloroform (0.2 mL) solution of benzyl mercaptan (71 μL, 0.89 mmol) and triethylamine (58 μL, 0.067 mmol) was added and stirred for 24 hours. Water (0.6 mL) was added to wash the organic layer, and the aqueous layer was further extracted three times with chloroform (0.6 mL). The organic layers were combined, concentrated, and vacuum dried to obtain a white solid (65 mg). 1 In the H NMR spectrum, the signals of vinylidene hydrogen at 6.36 ppm and 5.87 ppm completely disappeared, confirming main chain cleavage due to a conjugation substitution reaction. On the other hand, the signal of the O-methylene group of the ester group at 4.12 ppm remained unchanged, indicating that main chain cleavage occurred selectively through functional groups in the degradable structure. Since the size exclusion chromatogram fell outside the range of the calibration curve, the precise number average molecular weight could not be evaluated, but the molecular weight at the peak maximum was 1200, a significant decrease from 8500 in Example 4, indicating that a conjugation substitution reaction (S N Main chain cleavage due to the 2' reaction was confirmed.

[0047] (Example 6) Decomposition of polybutylene succinate copolymer in homogeneous solution by diethylamine Diethylamine (25 μL, 0.24 mmol) was added to a chloroform (0.1 mL) solution of the polybutylene succinate copolymer (26 mg, acrylic unit 0.030 mmol) obtained in Example 4, and the mixture was stirred for 24 hours. The mixture was concentrated and dried in vacuo to obtain a white solid (24 mg). 1 In the H NMR spectrum, the signal of the allylic hydrogen at 4.87 ppm completely disappeared, confirming main chain cleavage due to a conjugated substitution reaction. On the other hand, the signal of the O-methylene group of the ester group at 4.12 ppm remained unchanged, indicating that main chain cleavage occurred selectively through functional groups in the degradable structure. The size exclusion chromatogram fell outside the range of the calibration curve, so the precise number-average molecular weight could not be evaluated. However, the molecular weight at the peak maximum was 1000, a significant decrease from 8500 in Example 4, indicating that a conjugated substitution reaction (S NMain chain cleavage due to the 2' reaction was confirmed.

[0048] (Example 7) Decomposition of polybutylene succinate copolymer in suspension with aqueous ammonia The polybutylene succinate copolymer (16 mg, acrylic unit 0.023 mmol) obtained in Example 4 was suspended in 1 M aqueous ammonia (1 mL) and stirred for 6 hours, followed by freeze-drying to obtain a white solid (24 mg). 1 In the H NMR spectrum, the vinylidene hydrogen signals at 6.36 ppm and 5.87 ppm decreased, and new signals appeared at 6.25 and 5.29 ppm, confirming main chain scission due to a conjugated substitution reaction. The ratio of the integrated intensities at 6.36 ppm and 6.25 ppm indicated that the progress of the conjugated substitution reaction was estimated to be 56%. Meanwhile, the signal from the O-methylene group of the ester group at 4.12 ppm remained unchanged, indicating that main chain scission occurred selectively through functional groups in the degradable structure. Because the size exclusion chromatogram fell outside the range of the calibration curve, an accurate number-average molecular weight could not be evaluated. However, the molecular weight at the peak maximum was 3,000, a decrease from 8,500 in Example 4, confirming main chain scission. These results demonstrate that the conjugated substitution reaction (S) can be carried out even under heterogeneous aqueous conditions. N It was confirmed that the main chain can be cleaved by the 2' reaction.

[0049] (Example 8) Solid-phase decomposition of polybutylene succinate copolymer with N-methyloctadecylamine N-methyloctadecylamine (5.9 mg, 0.021 mmol, solid at room temperature) was added to the polybutylene succinate copolymer (20 mg, acrylic unit 0.029 mmol) obtained in Example 4, and the mixture was mixed and ground in a mixer mill (MM200, Retsch) at a frequency of 30 Hz for 6 hours. The reaction product was then dissolved in trifluoroacetic acid / deuterated chloroform, and the soluble portion was extracted. 1 H NMR spectra were measured. 1 The 1 H NMR spectrum is shown in Figure 1. 1In the H NMR spectrum, the signal of the allylic hydrogen at 4.84 ppm decreased, and a new signal of the allylic hydrogen at 3.30 ppm, which is attributed to the substitution product, appeared, confirming main chain cleavage due to the conjugated substitution reaction. From the ratio of the integrated intensities of the two, the progress of the conjugated substitution reaction was estimated to be 78%. Meanwhile, the signal of the O-methylene group of the ester group at 4.12 ppm remained unchanged, indicating that main chain cleavage had occurred selectively through functional groups in the degradable structure. Since the size exclusion chromatogram fell outside the range of the calibration curve, the precise number average molecular weight could not be evaluated, but the molecular weight at the peak maximum was 760 (reference value, as it was outside the range of the calibration curve), which was a decrease from 8500 in Example 4, confirming main chain cleavage. From these results, it was found that the conjugated substitution reaction (S N It was confirmed that the main chain can be cleaved by the 2' reaction.

[0050] (Comparative Example 2) Synthesis of polybutylene terephthalate Dimethyl terephthalate (7.57 g, 38.6 mmol), 1,4-butanediol (7.22 g, 77.1 mmol), and zinc acetate (36 mg, 0.18 mmol) were added and heated at 190°C for 1 hour under an argon stream. Tetraisopropyl orthotitanate (54 μL, 29 μmol) was added and the mixture was heated again to 265°C. The pressure was immediately reduced to 0.075 Torr and the mixture was heated to 290°C. After 1 hour, the mixture was cooled to 270°C and heated for an additional 3 hours. A brown solid was obtained that adhered to the flask and was insoluble in chloroform.

[0051] (Reference Example 1) Synthesis of polybutylene terephthalate copolymer Dimethyl terephthalate (7.57 g, 38.6 mmol) and 1,4-butanediol (7.37 g, 81.7 mmol) were added and mixed until homogenous. Tetraisopropyl orthotitanate (36 μL, 18 μmol), methyl α-(hydroxymethyl)acrylate (453 mg, 3.86 mmol, 10 mol% relative to the terephthalic acid units), and 4-methoxyphenol (10 mg) were added and heated to 200 °C. The pressure was immediately reduced to 0.075 Torr and the mixture was heated for 1 hour. An orange solid (8.08 g, 98.4%) was obtained that adhered to the flask and was insoluble in chloroform.

[0052] (Reference Example 2) Synthesis of polybutylene terephthalate copolymer Dimethyl terephthalate (7.50 g, 38.6 mmol), 1,4-butanediol (7.39 g, 82.0 mmol), tetraisopropyl orthotitanate (56 μL, 30 μmol), methyl α-(hydroxymethyl)acrylate (914 mg, 7.88 mmol, 20 mol% relative to the terephthalic acid unit), and 4-methoxyphenol (10 mg) were used. Reference example 1 The procedure was carried out in the same manner as in the previous step, and an orange solid which adhered to the flask and was insoluble in chloroform was obtained.

[0053] (Example 9) Synthesis of polybutylene terephthalate copolymer Dimethyl terephthalate (7.58 g, 39.0 mmol), 1,4-butanediol (7.15 g, 79.3 mmol), tetraisopropyl orthotitanate (66 μL, 33 μmol), methyl α-(hydroxymethyl)acrylate (1.81 g, 15.6 mmol, 40 mol% relative to the terephthalic acid unit), and 4-methoxyphenol (20 mg) were used. Reference example 1 The procedure was carried out in the same manner as in the previous step, and an orange solid which adhered to the flask and was insoluble in chloroform was obtained.

[0054] (Thermal properties of polybutylene terephthalate copolymer) Table 2 summarizes the polymerization results of Comparative Example 2, Reference Examples 1 and 2, and Example 9, as well as the thermal properties of each polymer. It was found that the content of acrylic units increased depending on the charge ratio of methyl α-(hydroxymethyl)acrylate, and the melting point decreased proportionally. In other words, it was confirmed that physical properties such as thermal properties can be controlled by the charge ratio of methyl α-(hydroxymethyl)acrylate. [Table 2]

[0055] (Reference Example 4) Solid-phase decomposition of polybutylene terephthalate copolymer Diethylamine (3 mg) was added to the polymer (19 mg) obtained in Reference Example 1, and the mixture was mixed and ground in a mixer mill (MM200, Retsch) at a frequency of 30 Hz for 6 hours. The reaction product was then dissolved in trifluoroacetic acid / deuterated chloroform (v / v=1 / 10, 0.3 mL). The polymer obtained in Reference Example 1 was insoluble in chloroform, but it was confirmed that the molecular weight was reduced by solid-phase decomposition, resulting in improved solubility. 1 In the H NMR spectrum, several signals derived from vinylidene hydrogen appeared at 6.88-5.99 ppm. A signal from the aromatic hydrogen of the terephthaloyl skeleton was confirmed at 8.15 ppm, and by comparing the integrated intensity ratio of these to the vinylidene hydrogen, taking into account the number of protons, the content of acrylic components (degradable structures and terminal groups) was estimated to be 4.6 mol%. The introduction rate of degradable structures is expected to be less than 4.6 mol%.

[0056] (Reference Example 5) Solid-phase decomposition of polybutylene terephthalate copolymer The polymer obtained in Reference Example 2 was subjected to the same procedure as in Reference Example 4. The polymer obtained in Reference Example 2 was also insoluble in chloroform, but it was confirmed that the molecular weight was reduced by solid-phase decomposition, improving solubility. The content of acrylic components (degradable structures and terminal groups) was estimated to be 7.8 mol%. The introduction rate of degradable structures is expected to be less than 7.8 mol%.

[0057] (Example 10) Solid-phase decomposition of polybutylene terephthalate copolymer Diethylamine (41 mg) was added to the polymer (21 mg) obtained in Example 9, and the mixture was mixed and ground in a mixer mill (MM200, Retsch) at a frequency of 30 Hz for 6 hours. The reaction product was then dissolved in trifluoroacetic acid / deuterated chloroform (v / v = 1 / 10, 0.3 mL). The polymer obtained in Example 9 was insoluble in chloroform, but it was confirmed that the molecular weight was reduced by solid-phase decomposition, and the solubility was improved. 1 In the H NMR spectrum, several signals derived from vinylidene hydrogen appeared at 6.88-5.99 ppm. A signal from aromatic hydrogen of the terephthaloyl skeleton was confirmed at 8.15 ppm. By comparing the integrated intensity ratio of these to the vinylidene hydrogen, taking into account the number of protons, the content of acrylic components (degradable structures and terminal groups) was estimated to be 13 mol%, and the introduction rate of degradable structures was estimated to be 10 mol% or more.

[0058] (Example 11) Synthesis of polyethylene terephthalate copolymer Dimethyl terephthalate (7.52 g, 38.7 mmol), ethylene glycol (4.93 g, 79.5 mmol), tetraisopropyl orthotitanate (46 μL, 23 μmol), methyl α-(hydroxymethyl)acrylate (1.79 g, 15.4 mmol, 40 mol% relative to the terephthalic acid unit), and 4-methoxyphenol (29 mg) were used. Reference example 1 The procedure was carried out in the same manner as in the above, and an orange solid (6.78 g) which adhered to the flask and was insoluble in chloroform was obtained.

[0059] (Example 12) Solid-phase decomposition of polyethylene terephthalate copolymer To the polymer (25 mg) obtained in Example 11, diethylamine (5 mg) was added, and the same procedure as in Example 10 was carried out. The polymer obtained in Example 11 was insoluble in chloroform, but it was confirmed that the molecular weight was reduced by solid-phase decomposition, improving its solubility. The content of acrylic components (degradable structures and terminal groups) was estimated to be 12 mol%, and the introduction rate of degradable structures was estimated to be 10 mol% or more.

Claims

1. A polyester resin having a repeating unit represented by the following general formula (1)-2 and a repeating unit represented by the following general formula (2), wherein the introduction rate of a degradable structure represented by the following general formula (1) is 10 mol % or more, and the number average molecular weight is 1,500 or more and 100,000 or less. 【Chemical 1】 [In the formula, n represents the number of repeating units.] 【Chemistry 2】 [In the formula, R １ is a divalent linking group obtained by removing a hydroxy group from a diol, and R ２ is a divalent linking group obtained by removing a carboxy group from a dicarboxylic acid, and m represents the number of repeating units. 【Chemistry 3】

2. 2. The polyester resin according to claim 1, wherein the repeating unit represented by the general formula (1)-2 is contained in an amount of 10 mol % to 50 mol % based on all repeating units.

3. The method includes a step of reacting a diol and / or a derivative thereof, a dicarboxylic acid and / or a derivative thereof, or an oligomer thereof, with an α-(hydroxymethyl)acrylic acid alkyl ester as a monomer, A method for producing a polyester resin, characterized in that the polyester resin has a repeating unit represented by the following general formula (1)-2 and a repeating unit represented by the following general formula (2), the introduction rate of a degradable structure represented by the following general formula (1) is 10 mol % or more, and the number average molecular weight is 1,500 or more and 100,000 or less. 【Chemistry 4】 [In the formula, n represents the number of repeating units.] 【Chemistry 5】 [In the formula, R １ is a divalent linking group obtained by removing a hydroxy group from the diol, and R ２ is a divalent linking group obtained by removing a carboxy group from the dicarboxylic acid, and m represents the number of repeating units. 【Chemistry 6】

4. 4. The method for producing a polyester resin according to claim 3, wherein the repeating unit represented by the general formula (1)-2 is contained in an amount of 10 mol % to 50 mol % based on all repeating units.

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