Polyester resins containing amine groups and cross-linked polyester resins containing amine groups

Abstract

The object of this invention is to provide a crosslinked polyester resin that retains its bond exchange activity and exhibits rapid bond exchange even when immersed in water, organic solvents, etc. Another object of this invention is to provide a polyester resin with rapid bond exchange. This invention relates to a crosslinked polyester resin obtained by crosslinking a polyester resin having multiple side chains with carboxyl groups and multiple side chains with tertiary amine groups with an epoxy crosslinking agent having multiple epoxy groups.

Description

[Technical Field]

[0001] The present invention relates to polyester resin and polyester resin obtained by crosslinking (hereinafter referred to as crosslinked polyester resin). [Previous Technology]

[0002] Polymer elastomers obtained by covalent crosslinking are generally not re-shaped or reused. This is due to the irreversible nature of covalent crosslinking points. Recently, bond-exchange type dynamically covalently crosslinked resins have attracted attention regarding this issue.

[0003] In the aforementioned bond-exchange type dynamic covalent crosslinking resin, a bond-exchange active catalyst needs to be added. For example, in Non-Patent Literature 1, zinc acetate (Zn(OAc)2) was added as a bond-exchange active catalyst to a resin obtained by crosslinking a polyester resin with carboxyl groups (COOH) on the side chain with an epoxy crosslinking agent. However, in examples using bond-exchange active catalysts, the catalyst may leak out due to immersion (or contact) with water, organic solvents, etc., thus raising concerns about the possibility of losing bond-exchange activity. Furthermore, there are also concerns about the reduction of catalyst activity over a long period of time.

[0004] Regarding this issue, molecular designs that do not require the addition of bond exchange activating catalysts have also been reported. For example, Non-Patent Literature 2 discloses a resin obtained by crosslinking a polyester resin with COOH side chains using 4,4'-methylenebis(N,N-diepoxypropylaniline). Since the network structure contains amine groups of aniline with catalytic activity, bond exchange can be activated at high temperatures without the need for externally added bond exchange catalysts. [Prior Art Documents] [Non-Patent Literature]

[0005] [Non-Patent Literature 1] Mikihiro Hayashi, et al., Polymer Chemistry. 2019, 10(16), 2047-2056. [Non-Patent Literature 2] Mikihiro Hayashi, ACS Applied Polymer Materials, 2020, 2(12), 5365-5370. [Summary of the Invention]

[0006] [The problem the invention aims to solve]

[0007] However, in cases such as Non-Patent Document 2, amine groups are present at the crosslinking points, resulting in a high degree of constraint on molecular mobility around these points. Therefore, while bond exchange can occur without the addition of a catalyst, the bond exchange timescale is significantly slow. Therefore, the object of the present invention is to provide a crosslinked polyester resin that retains its bond exchange activity even when immersed in water, organic solvents, etc., and exhibits rapid bond exchange. Furthermore, another object of the present invention is to provide a polyester resin with rapid bond exchange. [Means for Solving the Problem]

[0008] The present invention, which solves the aforementioned problems, is structured as follows. [1] A crosslinked polyester resin is obtained by crosslinking a polyester resin having a plurality of side chains with carboxyl groups and a plurality of side chains with tertiary amine groups with an epoxy crosslinking agent having a plurality of epoxy groups. [2] The crosslinked polyester resin of [1], wherein the number of carboxyl groups in the side chains of the aforementioned polyester resin is 3 to 80 per molecule of the aforementioned polyester resin. [3] The crosslinked polyester resin of [1] or [2], wherein the ratio (amine:carboxyl) of the number of tertiary amine groups in the side chains of the aforementioned polyester resin to the number of carboxyl groups in the side chains of the aforementioned polyester resin is 20:80 to 90:10. [4] A crosslinked polyester resin as described in any of [1] to [3], wherein the aforementioned polyester resin is a polycondensation of a polycarboxylic acid component (A) and a polyol component (B); the aforementioned polycarboxylic acid component (A3) containing a nucleophilic reactive group is the aforementioned polycarboxylic acid component (A), and the aforementioned polycarboxylic acid component (A3) containing a nucleophilic reactive group is 50 mol% or more in 100 mol% of the aforementioned polycarboxylic acid component (A); a portion of the aforementioned polycarboxylic acid component (A3) containing a nucleophilic reactive group is added by Michael addition to α,β-unsaturated carboxylic acid (C3C), and the remaining portion or all of the polycarboxylic acid component (A3) containing a nucleophilic reactive group is added by Michael addition to a side chain compound (C3N) having a tertiary amine group. [5] A crosslinked polyester resin as described in [4], wherein the aforementioned polyol component (B) is selected from at least one of aliphatic diols and aromatic polyester diols. [6] A crosslinked polyester resin of any one of [1] to [5], wherein the aforementioned epoxy crosslinking agent having a plurality of epoxy groups is an aliphatic diol diglycidyl ether. [7] A crosslinked polyester resin of any one of [1] to [6], wherein the peak of the temperature change of the loss tangent tanδ is in the range of 0 to 100°C. [8] A crosslinked polyester resin of any one of [1] to [7], wherein the relaxation time at 160°C obtained from the stress relaxation curve is 1 to 2000 seconds. [9] A crosslinked polyester resin of any one of [1] to [8], wherein the ester exchange catalyst is less than 1 part by mass relative to 100 parts by mass of the aforementioned polyester resin; and the epoxy crosslinking agent having tertiary amine groups is less than 30 moles relative to 100 moles of the aforementioned epoxy crosslinking agent having a plurality of epoxy groups.

[10] A polyester resin having: a plurality of side chains having carboxyl groups and a plurality of side chains having tertiary amine groups. [Effects of the Invention]

[0009] According to the present invention, a cross-linked polyester resin that does not lose its bond exchange activity and has fast bond exchange even when immersed in water, organic solvents, etc., can be obtained. Furthermore, according to the present invention, a polyester resin with fast bond exchange can be obtained.

Implementation Method

[0011] 1. Polyester Resin The crosslinked polyester resin of the present invention has the following structure: a structure obtained by crosslinking a polyester resin having a plurality of side chains having carboxyl groups and a plurality of side chains having tertiary amine groups (hereinafter, sometimes referred to as pre-crosslinking polyester resin) with an epoxy crosslinking agent having a plurality of epoxy groups. The pre-crosslinking polyester resin may also be any aliphatic polyester or aromatic polyester. From the viewpoint of improving adhesion, aliphatic polyester is preferred, and from the viewpoint of improving heat resistance, aromatic polyester is preferred. Aliphatic polyester and aromatic polyester may also be used together. As for the tertiary amine group, it is preferred to be a diC1-4 alkylamine such as dimethylamino, methylethylamino, or diethylamino.

[0012] 2. Ordinary polycarboxylic acid component (A1) The aforementioned pre-crosslinking polyester resin has a polycondensation structure of a polycarboxylic acid component (A) and a polyol component (B), and a predetermined side chain can be formed by making at least a portion of the aforementioned polycarboxylic acid component a side chain forming polycarboxylic acid component. The aforementioned polycarboxylic acid component (A) is divided into: a non-side chain forming polycarboxylic acid component (A1) (in this specification, it is sometimes referred to as ordinary polycarboxylic acid component (A1)) and a side chain forming polycarboxylic acid component. As for the polycarboxylic acid constituting the ordinary polycarboxylic acid component (A1), it includes, for example, dicarboxylic acid, tetracarboxylic acid, etc., and is preferably dicarboxylic acid. Examples of dicarboxylic acids include: aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, phthalic acid, and 2,6-naphthalenedicarboxylic acid; aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, and dimer acids; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, tetrahydrophthalic acid, hexahydroisophthalic acid, and 1,2-cyclohexenedicarboxylic acid; and dicarboxylic acids containing unsaturated groups, such as terpene-maleic acid adducts. Examples of tetracarboxylic acids include: 1,2,4,5-phenyltetracarboxylic acid, 3,3',4,4'-diphenylketonetetracarboxylic acid, and their anhydrides. Generally, the polycarboxylic acid component (A1) can be one or more selected from these.

[0013] 3. Tricarboxylic acid component (A2) As for the polycarboxylic acid component for side chain formation, examples include tricarboxylic acid component (A2), polycarboxylic acid component (A3) containing nucleophilic reactive groups (thiol groups, etc.) (in this specification, it is sometimes referred to as nucleophilic polycarboxylic acid component (A3)), and polycarboxylic acid component (A4) containing α,β-unsaturated carbonyl groups (in this specification, it is sometimes referred to as unsaturated polycarboxylic acid component (A4)).

[0014] The tricarboxylic acid component (A2) forms a carboxyl group on its side chain through polycondensation with the polyol component (B). Examples of tricarboxylic acids (A2) include: aliphatic tricarboxylic acids such as 1,3,5-pentanetricarboxylic acid; alicyclic tricarboxylic acids such as 1,3,5-cyclohexanetricarboxylic acid; and aromatic tricarboxylic acids such as trimellitic acid and pyromellitic acid. These tricarboxylic acids (A2) can also be acid anhydrides. The tricarboxylic acid (A2) can be selected from one or more of these.

[0015] 4. Nucleophilic polycarboxylic acid component (A3) The nucleophilic polycarboxylic acid component (A3) is capable of introducing a carboxyl group to the side chain via Michael addition to an α,β-unsaturated carboxylic acid (C3C), and can also introduce a tertiary amino group to the side chain via Michael addition to a compound (C3N) having an α,β-unsaturated carbonyl group and a tertiary amino group (sometimes referred to as an unsaturated amine in this specification). For the nucleophilic polycarboxylic acid component (A3), compounds formed by replacing the hydrogen atoms of the aforementioned common polycarboxylic acid component (A1) with nucleophilic groups (thiol groups, hydroxyl groups, etc.) can be listed. Preferably, aliphatic dicarboxylic acids having a thiol group and approximately 4 to 10 carbon atoms, such as thiomalic acid, can be listed. The nucleophilic polycarboxylic acid component (A3) can use one or more selected from these. Examples of α,β-unsaturated carboxylic acids (C3C) used to introduce carboxyl groups into the side chain include aliphatic α,β-unsaturated monocarboxylic acids with approximately 3 to 10 carbon atoms, such as acrylic acid, methacrylic acid, crotonic acid, and isocrotonic acid. One or more of these α,β-unsaturated carboxylic acids (C3C) can be used. Examples of unsaturated amines (C3N) used to introduce tertiary amino groups into the side chain include N-[3-(dimethylamino)propyl]acrylamide, such as N-[(diC1-4 alkylamino)C1-10 alkyl](meth)acrylamide; and (meth)acrylates (diC1-4 alkylamino)C1-10 alkyl esters, such as 2-(dimethylamino)ethyl acrylate, 2-(diethylamino)ethyl acrylate, 3-(dimethylamino)propyl acrylate, and 3-(diethylamino)propyl acrylate. Unsaturated amines (C3N) can be selected from one or more of these.

[0016] 5. Unsaturated polycarboxylic acid component (A4) The unsaturated polycarboxylic acid component (A4) can be introduced into the side chain by Michael addition of a compound (C4C) having a nucleophilic group and a carboxyl group (sometimes referred to as a nucleophilic carboxylic acid in this specification), and can be introduced into the side chain by Michael addition of a compound (C4N) having a nucleophilic group and a tertiary amino group (sometimes referred to as a nucleophilic amine in this specification). Examples of unsaturated polycarboxylic acid components (A4) include, for example, aliphatic α,β-unsaturated dicarboxylic acids with approximately 4 to 10 carbon atoms, such as maleic acid and fumaric acid. One or more of these compounds can be used as the unsaturated polycarboxylic acid component (A4). Examples of nucleophilic carboxylic acids (C4C) used to introduce a carboxyl group into the side chain include, for example, aliphatic monocarboxylic acids having a thiol group and approximately 2 to 10 carbon atoms, such as thioglycolic acid and mercaptopropionic acid. One or more nucleophilic carboxylic acids (C4C) selected from these can be used. Examples of nucleophilic amines (C4N) used to introduce a tertiary amino group into the side chain include, for example, C2-10 alkyl groups having a thiol group and a diC1-4 alkylamino group, such as 2-(dimethylamino)ethanethiol. One or more nucleophilic amines (C4N) selected from these can be used.

[0017] 6. Polyol Component (B) Regarding polyol component (B), examples include the following monomeric diols: ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (also known as neopentyl glycol), 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, and 1,6-hexanediol. Aliphatic diols such as 3-methyl-1,6-hexanediol, 4-methyl-1,7-heptanediol, 2-methyl-1,8-octanediol, 3-methyl-1,8-octanediol, 4-methyl-1,8-octanediol, 4-propyl-1,8-octanediol, and 1,9-nonanediol; alicyclic polyols such as 1,4-cyclohexanediol, 1,2-cyclohexanediethanol, 1,3-cyclohexanediethanol, 1,4-cyclohexanediethanol, tricyclodecanediols, and hydrogenated bisphenols; and aromatic diols such as bisphenol A. For monomeric diols, aliphatic diols are preferred. Polyol component (B) may also be the following polyether polyols (polyether diols): diethylene glycol, triethylene glycol, polyethylene glycol, polyolefin diols, polytetramethylene glycol, and other polyether diols. Furthermore, the polyol component (B) may also be one of the following polyester polyols: ethylene glycol modified terephthalic acid (e.g., bis-2-hydroxyethyl terephthalate (BHET)), propylene glycol modified terephthalic acid, ethylene glycol modified isophthalic acid, propylene glycol modified isophthalic acid, ethylene glycol modified phthalic acid, propylene glycol modified phthalic acid, etc., and glycol modified aromatic dicarboxylic acids; preferably, it may also be an aromatic polyester diol. The polyol component (B) can be one or more selected from these. With regard to the polyol component (B), it is preferable to include at least one selected from monomeric polyols (especially aliphatic diols) and polyester polyols (especially aromatic polyester diols), more preferably, it includes at least monomeric polyols (especially aliphatic diols) and, as needed, polyester polyols (especially aromatic polyester diols).

[0018] 7. The side chain having a carboxyl group may also be any of the following three: (1) a carboxylic acid derived from the tricarboxylic acid component (A2) (side chain C1) (2) a side chain formed by the Michael addition of a nucleophilic polycarboxylic acid component (A3) to an unsaturated carboxylic acid (C3C) (side chain C2) (3) a side chain formed by the Michael addition of a nucleophilic carboxylic acid (C4C) to an unsaturated polycarboxylic acid component (A4) (side chain C3) The side chain having a carboxyl group is preferably side chain C2. The side chain C2 relative to the total of side chain C1, side chain C2 and side chain C3 of 100 mol is, for example, 50 mol or more, preferably 70 mol or more, more preferably 90 mol or more, and may also be 100 mol.

[0019] The side chain having a tertiary amino group may also be any of the following two: (1) a side chain formed by the addition of a nucleophilic polycarboxylic acid component (A3) to an unsaturated amine (C3N) (side chain N1) (2) a side chain formed by the addition of a nucleophilic amine (C4N) to an unsaturated polycarboxylic acid component (A4) (side chain N2) The side chain having a tertiary amino group is preferably side chain N1. The side chain N1 relative to the total of side chain N1 and side chain N2 of 100 mol is, for example, 50 mol or more, preferably 70 mol or more, more preferably 90 mol or more, and may also be 100 mol.

[0020] The pre-crosslinking polyester resin preferably has the following form: it contains a nucleophilic polycarboxylic acid component (A3) as a polycarboxylic acid component (A), and a portion of this nucleophilic polycarboxylic acid component (A3) is added to an unsaturated carboxylic acid (C3C) via Michael addition, and the remaining portion or all (preferably all) of the nucleophilic polycarboxylic acid component (A3) is added to an unsaturated amine (C3N). The nucleophilic polycarboxylic acid component (A3) is, for example, 50 mol% or more, preferably 70 mol% or more, more preferably 90 mol% or more, or may be 100 mol% of the total 100 mol% of the polycarboxylic acid component (A).

[0021] The number of carboxyl groups in the side chain is approximately 3 to 80 per molecule of polyester resin before crosslinking, preferably 10 to 60, and even more preferably 20 to 50. The more carboxyl groups, the more crosslinking points there are, and the better the heat resistance. Furthermore, by keeping the number of carboxyl groups moderate, the toughness or elasticity becomes good.

[0022] The number of tertiary amine groups in the side chains is, for example, about 5 to 100 per molecule of polyester resin before crosslinking, preferably about 20 to 85, and more preferably about 30 to 70. The ratio of tertiary amine groups to carboxyl groups in the side chains (amine:carboxyl groups) is, for example, 20:80 to 90:10, preferably 25:75 to 70:30, and more preferably 30:70 to 50:50. By making the ratio of tertiary amine groups appropriate, the bond exchange at the crosslinking points can be accelerated.

[0023] The acid value of the polyester resin before crosslinking is, for example, 5~250 mgKOH / g, preferably 30~200 mgKOH / g, and even more preferably 50~150 mgKOH / g. The higher the acid value, the more crosslinking points there are and the better the heat resistance. Furthermore, by keeping the acid value not too high, the toughness or elasticity becomes good.

[0024] The number average molecular weight (Mn) of the polyester resin before crosslinking is, for example, 4,000 to 90,000. By having a number average molecular weight (Mn) of 4,000 or more before crosslinking, heat resistance can be improved. A number average molecular weight (Mn) of 4,200 or more is preferred, and even more preferably 10,000 or more. However, when the number average molecular weight (Mn) of the polyester resin with carboxyl groups on the side chains becomes too large, it becomes too hard and brittle. Therefore, a number average molecular weight (Mn) of 90,000 or less is preferred, more preferably 60,000 or less, and even more preferably 40,000 or less.

[0025] The molecular weight dispersion (PDI) of polyester resins with carboxyl groups on the side chains is preferably 1.3 to 1.8. The molecular weight dispersion can be calculated based on the weight average molecular weight (Mw) and the number average molecular weight (Mn) using the following formula: PDI value = Mw / Mn

[0026] 8. Epoxy Crosslinking Agent An epoxy crosslinking agent crosslinks the polyester resin by bonding with the carboxyl groups of the side chains of the polyester resin before crosslinking. There are no particular limitations on the epoxy crosslinking agent as long as it has two or more epoxy groups within its molecule. Examples include glycol diglycidyl ether, glycidyl ether of an alcohol having three or more hydroxyl groups, epoxy resin, epoxy amine compounds having two or more epoxy groups and two or more tertiary amine groups within their molecule, and compounds containing two or more epoxy groups and one tertiary amine group within their molecule. One or more epoxy crosslinking agents selected from these can be used.

[0027] Examples of diol diepoxypropyl ethers include compounds formed by ether bonding of an epoxypropyl group with the hydroxyl group of a diol listed as a polyol component (B); preferably, they are ethylene glycol diepoxypropyl ether, diethylene glycol diepoxypropyl ether, polyethylene glycol diepoxypropyl ether, propylene glycol diepoxypropyl ether, dipropylene glycol diepoxypropyl ether, tripropylene glycol diepoxypropyl ether, polypropylene glycol diepoxypropyl ether, 1,4-butanediol diepoxypropyl ether, 1,5-pentanediol diepoxypropyl ether, neopentanediol diepoxypropyl ether, 1,6-hexanediol diepoxypropyl ether, hydrogenated bisphenol A diepoxypropyl ether, etc., aliphatic diol diepoxypropyl ethers, bisphenol A diepoxypropyl ether, etc., aromatic diol diepoxypropyl ethers, etc., and more preferably, aliphatic diol diepoxypropyl ethers. The compounds formed by the ether bonding of the aforementioned diglycidyl group with the hydroxyl group of a polyol can use one or more of the aforementioned compounds.

[0028] Examples of glycidyl ethers of alcohols having three or more hydroxyl groups include diglycidyl ethers of aliphatic polyols such as glycerol diglycidyl ether and trimethylolpropane diglycidyl ether. Glycidyl ethers of alcohols having three or more hydroxyl groups can use one or more selected from these.

[0029] Examples of epoxy resins include cresol-phenolic varnish-type epoxy resins, phenolic phenolic varnish-type epoxy resins, and epoxy resins having a dicyclopentadiene backbone. One or more of these types of epoxy resins can be used. For commercially available cresol-phenolic varnish-type epoxy resins, YDCN-700 manufactured by DIC Corporation can be used, for example. For commercially available phenolic phenolic varnish-type epoxy resins, EPICLON N-700A manufactured by DIC Corporation can be used, for example. For commercially available epoxy resins having a dicyclopentadiene backbone, the HP7200 series manufactured by DIC Corporation can be used, for example.

[0030] Examples of epoxide amine compounds having two or more epoxy groups and two or more tertiary amino groups within their molecules include N,N,N',N'-tetracyclooxypropyl-m-phenylenediamine and 4,4'-methylenebis(N,N-dicyclooxypropylaniline), which have two dicyclooxypropylamine groups and a benzene ring. N,N,N',N'-tetracyclooxypropyl-m-phenylenediamine is sold by Mitsubishi Gas Chemical Co., Ltd. in the form of the multifunctional epoxide compound "TETRAD-X". 4,4'-methylenebis(N,N-dicyclooxypropylaniline) is available from Tokyo Chemical Industry Co., Ltd. (TCI).

[0031] For compounds containing two or more epoxy groups and one tertiary amino group within their molecule, examples include triglycidyl para-aminophenol (also known as N,N-diepoxypropyl-4-(epoxypropyloxy)aniline), which has one diepoxypropylamino group, an epoxypropyloxy group, and a benzene ring. For commercially available triepoxypropyl para-aminophenol, for example, JER630 manufactured by Mitsubishi Chemical Corporation can be used.

[0032] In terms of epoxy crosslinking agents having multiple epoxy groups, epoxy crosslinking agents without tertiary amine groups (diol diglycidyl ether, epoxy propyl ether of alcohols having 3 or more hydroxyl groups, epoxy resin, etc.) are preferred, and diol diglycidyl ether (especially aliphatic diol diglycidyl ether) is even more preferred.

[0033] The content of the epoxy crosslinking agent having multiple epoxy groups is, for example, 1 to 50 parts by weight, more preferably 5 to 40 parts by weight, and even more preferably 10 to 30 parts by weight, relative to 100 parts by weight of the polyester resin before crosslinking.

[0034] When the total amount of epoxy crosslinking agents having multiple epoxy groups is 100 moles, the epoxy crosslinking agent without tertiary amine groups (especially the aforementioned compound formed by ether bonding of diglycidyl group and hydroxyl group of polyol) is preferably 30 moles or more, more preferably 50 moles or more, and even more preferably 80 moles or more, or may be 100 moles. On the other hand, when the total amount of epoxy crosslinking agents having multiple epoxy groups is 100 moles, the epoxy crosslinking agent with tertiary amine groups in the molecule is preferably less than 30 moles.

[0035] 9. Ester Exchange Catalyst The crosslinked polyester resin of the present invention may not contain an ester exchange catalyst, but may contain an ester exchange catalyst within the scope that does not impair the effect of the present invention. Furthermore, in this specification, "not containing an ester exchange catalyst" means less than 1 part by weight relative to 100 parts by weight of polyester resin. Examples of metal-containing catalysts for transesterification include: titanium compounds (tetrabutyl titanate, tetraisopropyl titanate, acetyl acetone oxytitanium, etc.), antimony compounds (tributoxyantimony, antimony trioxide, etc.), germanium compounds (tetrabutoxygermanium, germanium oxide, etc.), scandium compounds (scandium trifluoromethanesulfonate, etc.), zinc compounds (zinc acetate, zinc octanoate, etc.), and aluminum compounds (aluminum acetate, aluminum acetyl acetate, etc.); amines such as trimethylamine, triethylamine, and benzyldimethylamine; quaternary ammonium salts such as tetramethylammonium chloride and triethylbenzylammonium chloride; imidazoles and amides such as 2-ethyl-4-imidazolium; pyridines such as 4-dimethylaminopyridine; phosphines such as triphenylphosphine; and phosphonium salts such as tetraphenylphosphonium bromide. Metal-containing catalysts such as scandium compounds and zinc compounds are preferred. One type of transesterification catalyst can be used, or two or more types can be used.

[0036] In the case of blending ester exchange catalyst, the amount of crosslinked polyester resin is, for example, 1 to 30 parts by weight, more preferably 3 to 20 parts by weight, and even more preferably 5 to 10 parts by weight, relative to 100 parts by weight of crosslinked polyester resin.

[0037] 10. The peak of the temperature change of the loss tangent tanδ of the cross-linked polyester resin (α-gradient peak) is, for example, in the range of 0~100℃, preferably in the range of 10~70℃, and more preferably in the range of 20~50℃. The higher the temperature of the α-gradient peak, the higher the heat resistance. The peak of the temperature change of the loss tangent tanδ is the value obtained by measuring with the measurement frequency set to 1Hz and the strain set to 0.1%.

[0038] The Young's coefficient (measurement temperature: room temperature, e.g., 25°C) of the crosslinked polyester resin is, for example, 0.1 MPa to 5000 MPa, preferably 0.5 MPa to 2500 MPa, and even more preferably 2 MPa to 1000 MPa.

[0039] Crosslinked polyester resins lose linearity in the temperature range above the glass transition temperature when plotting the temperature change of elongation. That is, crosslinked polyester resins possess the property that the bond exchange at the crosslinking points is activated. Therefore, they exhibit high strength at room temperature and can be reprocessed and bonded between films above the ester bond exchange activation temperature. Furthermore, due to their reformability, crosslinked polyester resins can be molded and filmized after the crosslinking reaction, and can repair damage through self-healing properties, thus allowing for semi-permanent use. The ester bond exchange activation temperature of crosslinked polyester resins can be determined based on the inversion point of the linear expansion coefficient and is used as the softening temperature.

[0040] The stress relief time of the crosslinked polyester resin at 160°C, obtained from the stress relief curve, is, for example, 1 to 2000 seconds, preferably 50 to 1500 seconds, and more preferably 100 to 1000 seconds. Although it exhibits a high Young's coefficient and high elastic strength, its rapid relief time results in excellent heat distortion above the predetermined temperature. Furthermore, in this specification, the relief time is defined as the time required for the stress relief test to be performed and for the elastic modulus to become 1 / e (=0.37) times the initial elastic modulus.

[0041] Cross-linked polyester resins possess self-adhesive properties. By overlapping and layering cross-linked polyester resins and applying heat and pressure, transesterification occurs at the interfaces of the cross-linked polyester resins, allowing them to bond together even without the use of an adhesive. Because of its self-adhesive properties, cross-linked polyester resins can be used as a main component of self-adhesives. Cross-linked polyester resins also possess reshaping properties. After being deformed into a predetermined shape, heating it in its deformed state causes transesterification and reshaping, maintaining the predetermined shape even after cooling. Furthermore, cross-linked polyester resins possess damage-repairing properties. Even if the surface is damaged by a cutting tool, it can still self-repair through bond exchange caused by the transesterification reaction when heated. Therefore, cross-linked polyester resins can be used as a main component of self-healing materials.

[0042] Crosslinked polyester resin can be used, for example, as a main component (or molding material) of adhesive sheets or molding materials. When used as an adhesive sheet, it is sandwiched between the components to be bonded by the crosslinked polyester resin of the present invention and heated. Due to heating, bond exchange occurs due to ester exchange reaction, and the components to be bonded can be bonded to each other. Examples of the components to be bonded include resin films and metal foils, and it is possible to bond, for example, resin films to each other, metal foils to each other, and resin films and metal foils. Examples of resin films include polyimide films, polyester films, and PET films. Examples of metal foils include copper foil, silver foil, and gold foil. Crosslinked polyester resin becomes bond exchangeable by heating to above the ester exchange activation temperature, so when crosslinked polyester resin is used as an adhesive material, it becomes easy to peel off by heating the adhesive to above the ester exchange activation temperature. Therefore, crosslinked polyester resin can be used as an adhesive for repair purposes that is adhesive and peelable. Cross-linked polyester resin can be used as a laminating material. Due to its heat resistance, cross-linked polyester resin can improve the heat resistance of resin molded bodies and metal molded bodies by laminating films made of cross-linked polyester resin onto their surfaces. Cross-linked polyester resin is also useful as a molding material due to its good processability and extrusion properties; for example, it can be used as a material for 3D printers and for linear molded bodies. Cross-linked polyester resin can also be used as a material for mesh structures. A mesh structure refers to a structure in which parts of a linear molded body are interconnected. Mesh structures can be manufactured by melting cross-linked polyester resin, expelling the molten material from a nozzle, and simultaneously fusing and solidifying the extruded material.

[0043] 11. Method for manufacturing crosslinked polyester resin. Crosslinked polyester resin can be manufactured by conventional methods. For example, a method in which the above-mentioned pre-crosslinked polyester resin and the above-mentioned epoxy crosslinking agent having multiple epoxy groups are dissolved in a solvent, the solvent is removed, and crosslinking is achieved by heating under reduced pressure. Examples of solvents include: aromatic hydrocarbons such as toluene; ketones such as methyl ethyl ketone and cyclohexanone; nitrogen-containing solvents such as dimethyl acetamide, dimethylformamide, and N-methylpyrrolidone; and ethers such as tetrahydrofuran, 1,4-dimethylethane, 1,3-dimethylethane, and 1,3-dioxolane. Nitrogen-containing solvents such as dimethylformamide are preferred. The pre-crosslinked polyester resin can be manufactured by reacting a side-chain compound after polycondensation of a polycarboxylic acid component (A) and a polyol component (B) using conventional methods. The polycondensation and reaction with the side-chain compound can also be carried out using a solvent. Furthermore, polycondensation reactions can also be carried out without the use of solvents. In addition, conventional catalysts such as the transesterification catalysts mentioned above can also be used in polycondensation.

[0044] This application claims priority based on Japanese Patent Application No. 2021-079856, filed on May 10, 2021. The entire contents of the description in the aforementioned Japanese Patent Application No. 2021-079856 are incorporated herein by reference. [Example]

[0045] Hereinafter, embodiments are listed to illustrate the present invention in more detail, but the present invention is of course not limited to the following embodiments, and can of course be implemented by appropriate modifications within the scope that can meet the foregoing and the following intent, all of which are included in the technical scope of the present invention.

[0046] Manufacturing Example 1: Melt polycondensation (80°C, 14 hours) was carried out using 9.00 g (86.4 mmol) of 1,5-pentanediol, 12.87 g (85.7 mmol) of thiomalic acid and 0.42 g (0.86 mmol) of scandium trifluoromethanesulfonate to obtain a polyester (PE-SH1) containing thiol side chains.

[0047] [Chemical 1]

[0048] Manufacturing Example 2: 3.00 g of PE-SH1 was dissolved in 30 ml of dimethylformamide (DMF). 5.37 g of N-[3-(dimethylamino)propyl]acrylamide (DAPAM) and 0.47 g of acrylic acid (AA) were added to the obtained DMF solution, and the mixture was stirred at room temperature for 24 hours to allow the thiol group of PE-SH1 to add to DAPAM and AA. The ratio of DAPAM to 2.5 mol and AA to 1 mol of thiol group in PE-SH1 was 1 mol. The reaction solution was concentrated using a rotary evaporator and then added dropwise to a large excess of tetrahydrofuran while stirring. The resulting precipitate was filtered off (re-precipitation purification). This re-precipitation purification process was repeated twice using DMF as the dissolving solvent (good solvent) and tetrahydrofuran as the precipitating solvent (poor solvent), followed by vacuum drying to obtain the target compound (PE-COOH-Amine-1). The number average molecular weight (Mn) of PE-COOH-Amine-1 is 30533 g / mol, the number of carboxyl groups per molecule is 46, and the number of tertiary amine groups per molecule is 46 (carboxyl:tertiary amine = 50:50, acid value 86 mg KOH / g).

[0049] [Chemical 2]

[0050] Furthermore, the number average molecular weight (Mn), the number of carboxyl groups per molecule, the number of tertiary amine groups per molecule, and the acid value are obtained as follows (unless otherwise specified, the same measurement method is used in the examples section below).

[0051] (Number Average Molecular Weight (Mn)) The pre-crosslinked polyester resin was dissolved in DMF at a concentration of approximately 0.5% by mass, and the resulting sample was filtered through a polytetrafluoroethylene membrane filter with a pore size of 0.5 μm. The number average molecular weight (Mn) was measured using gel permeation chromatography with DMF containing 0.05% LiBr as the mobile phase and a differential refractometer as the detector. The flow rate was set to 0.5 mL / min, and the column temperature was set to 40°C. Showa Denko KF-803, KF-804L, and KF-805L columns were used. Monodisperse polymethyl methacrylate was used as the standard material (molecular weight standard). Low molecular weight compounds (oligomers, etc.) with a number average molecular weight (Mn) less than 1000 were omitted from the count.

[0052] (Number of carboxyl groups and tertiary amine groups per molecule) The number of carboxyl groups and tertiary amine groups (in this example, the number of dimethylamine groups) per molecule were determined using proton nuclear magnetic resonance (1H NMR). The measuring apparatus was a Bruker Analytik DPX400 spectrometer (400MHz), the measuring solvent was deuterated DMSO, and the measuring temperature was set to 25°C.

[0053] (Acid Value) The acid value is calculated based on the number of carboxyl groups per molecule and the number average molecular weight (Mn). When the acid value is X (mgKOH / g), the acid value X can be obtained using the following formula: X / 56.10 = (1 / Mn) × number of carboxyl groups per molecule × 1000

[0054] Example 1: PE-COOH-Amine-1 (1.0 g) and 1,4-butanediol diglycidyl ether (BDE) (0.16 g) were dissolved separately in dimethylformamide (DMF), and the solutions were mixed in a polytetrafluoroethylene container. The amount of BDE added was such that the carboxyl and epoxy groups were in equal molar amounts. The DMF solution was placed on a heater at 60°C for about 40 hours to allow the solvent to evaporate. It was then vacuum dried at 60°C for 7 hours to allow the solvent to evaporate completely and to achieve dryness. The resulting dried sample was heated at 120°C under vacuum for 14 hours to obtain a thermally crosslinked product.

[0055] [Chemical 3]

[0056] The already adhesive, dried sample was heated for 14 hours to become a highly self-supporting elastomer film. To confirm the progress of the crosslinking reaction, a swelling test was performed using DMF. 0.049 g of the crosslinked sample was immersed in DMF. After 24 hours, the extracted sol solution was transferred to another sample bottle. The remaining gel component was then immersed in DMF again, and this process was repeated three times. Comparing the initial weight with the residual weight of the gel component, the result showed that the gel component of the sample after heating for 14 hours was approximately 85%. This result confirms that a sufficient crosslinking reaction has occurred.

[0057] For samples of the mixture of PE-COOH-Amine-1 and BDE before and after thermal crosslinking, the glass transition temperature (Tg) was determined by measuring the heat flow rate at a rate of 10°C / min in a N2 atmosphere within a range of -50°C to 200°C. The Tg of the sample before thermal crosslinking was 6.7°C, and the Tg of the sample after thermal crosslinking was 18.3°C. This temperature increase was due to the formation of the crosslinked structure.

[0058] Example 2 Except for changing the amounts of acrylic acid (AA) and N-[3-(dimethylamino)propyl]acrylamide (DAPAM), the process was carried out in the same manner as in Example 2, with the thiol groups of PE-SH1 added to AA and DAPAM to obtain the target product (PE-COOH-Amine-2). The number average molecular weight (Mn) of PE-COOH-Amine-2 was 28800 g / mol, the number of carboxyl groups per molecule was 27, and the number of tertiary amino groups was 64 (carboxyl:tertiary amino = 30:70, acid value was 52.6 mg KOH / g). Except for using the obtained PE-COOH-Amine-2, the process was carried out in the same manner as in Example 1 to obtain a thermally crosslinked product. Furthermore, the DMF swelling test of the thermally crosslinked product of Example 2 was carried out in the same manner as in Example 1. The results showed that the gel content was approximately 85%, and it was confirmed that a sufficient crosslinking reaction had been carried out.

[0059] Comparative Example 1: Except for the absence of DAPAM, a polyester (PE-COOH-1) with carboxyl groups on the side chains was manufactured in the same manner as in Manufacturing Example 2 to produce a polyester (PE-COOH-1). The number average molecular weight (Mn) of PE-COOH-1 was 20100 g / mol, the number of carboxyl groups per molecule was 25, and the acid value was 70 mg KOH / g. Except for the use of 4,4'-methylenebis(N,N-diepoxypropylaniline) as the crosslinking agent and THF as the solvent, the process was the same as in Example 1 to obtain a thermally crosslinked product.

[0060] [Chemical 4]

[0061] For the crosslinked products obtained in Example 1, Example 2 and Comparative Example 1, (1) the formability was evaluated, (2) the temperature dispersion viscoelasticity was measured, (3) a tensile test was performed, (4) the coefficient of linear expansion was measured, (5) a stress relief test was performed, and (6) the reusability was evaluated.

[0062] (1) Formability: The crosslinked products of Examples 1 and 2 were pressed in a hot press at 150°C for 1 hour and formed into a film. The appearance of the formed product of the crosslinked product of Example 1 is shown in Figure 1.

[0063] (2) Temperature-dispersed viscoelasticity was measured using an MCR302 (manufactured by Anton Paar) in a cooling mode within a temperature range of 190°C to -50°C. The measurement was performed in an N2 gas environment at a temperature change rate of 5°C / min. The measurement frequency was 1 Hz, and the strain coefficient was 0.1%. The test specimen used was a disk with a diameter of 8 mm and a thickness of 0.5 mm. Figure 2 shows the temperature dependence of the storage elastic modulus (G') and loss tangent tanδ of the crosslinks obtained in Examples 1, 2, or Comparative Example 1. In Figure 2, the solid line represents the temperature dependence of the storage elastic modulus (G'), and the dashed line represents the temperature dependence of the loss tangent tanδ. In Examples 1 and 2, a tanδ peak originating from segment easing (α-easing peak) was observed in the region of approximately 30°C. At lower temperatures compared to this peak region, the specimen was in a glassy state, while at higher temperatures it was in a rubbery state. The rubbery, flat region remained stable within the measured temperature range, indicating that the crosslinking density did not change. On the other hand, in Comparative Example 1, a moderate α-peak was observed at approximately -30°C. In conclusion, compared to Comparative Example 1, Examples 1 and 2 exhibited higher elastic moduli near room temperature. Furthermore, the rubbery, flat elastic moduli values ​​of Examples 1 and 2 were also higher than those of Comparative Example 1. Therefore, it can be concluded that Examples 1 and 2 possess higher material strength than Comparative Example 1 near room temperature and in high-temperature regions.

[0064] (3) Tensile test measurement conditions: Tensile tests were conducted at room temperature using an AGS-500NX (manufactured by SHIMADZU). The tensile test speed was 10 mm / min. The specimen used was a dumbbell-shaped test piece with a thickness of 0.3 mm, a gauge width of 4 mm, and a gauge length of 13 mm. Figure 3 shows the stress-strain curves of the crosslinked products of Example 1, Example 2, and Comparative Example 1. The Young's coefficient of Example 1 was 3.0 MPa, the Young's coefficient of Example 2 was 4.4 MPa, and the Young's coefficient of Comparative Example 1 was 0.5 MPa. Compared with Comparative Example 1, the Young's coefficients of Examples 1 and 2 were significantly larger. This is consistent with the results of the temperature-dispersed viscoelasticity measurement mentioned above.

[0065] (4) The coefficient of linear expansion was measured using a TMA7100 (manufactured by HITACHI HighTech) in the range of room temperature to 240°C. The measurement was performed in an N2 gas environment at a temperature change rate of 10°C / min. The sample used was a strip sample with a width of 4 mm, a thickness of 0.5 mm, and a length of 20 mm. Figure 4 shows the results of the coefficient of linear expansion test for Example 1. The longitudinal axis is the sample length (L) after normalization to the sample length at 100°C (L100°C). At a high temperature of approximately 150°C, a deviation from the straight line extrapolated with a certain elongation was observed, indicating that the sample softened. The results of the DSC measurement showed that the softening did not originate from glass transfer. Furthermore, the thermal decomposition temperature (5% weight loss) was 210°C, as determined by the thermogravimetric analysis. This suggests that the softening was caused by the activation of bond exchange, and that crosslinking bonds would exchange at temperatures above approximately 150°C. Similarly, in Example 2, the sample softened at approximately 150°C. This demonstrates that bond exchange can still be activated even without the addition of a catalyst.

[0066] (5) Stress relief test: An MCR302 (manufactured by Anton Paar) was used to conduct stress relief tests at temperatures of 100°C, 150°C, 160°C, 170°C, or 180°C. The test was conducted in an N2 gas environment. The specimen used was a disc-shaped specimen with a diameter of 8 mm and a thickness of 0.5 mm. Figure 5 shows the results of stress relief measurement for the crosslinked product of Example 1. The vertical axis represents the stress (σ) after normalization with the initial stress (σ0), and the horizontal axis represents the time elapsed. Significant stress relief was observed at 150°C to 180°C, and it can be seen that the relief rate increases with increasing temperature. This is because the bond exchange rate is accelerated with increasing temperature. On the other hand, in the stress relief curve of the crosslinked product of Example 1 at 100°C shown in Figure 5, stress relief did not occur. The linear expansion coefficient test indicates that bond exchange is activated at temperatures above approximately 150°C, and that bond exchange pauses at 100°C. Figure 6 shows a comparison of stress relief measurement data between Example 1 and Comparative Example 1. Furthermore, the measurement temperatures for comparison were 160°C, 170°C, and 180°C. When the relief time is defined as the elastic modulus becoming 1 / e (=0.37) times the initial elastic modulus, the relief time of Example 1 at 180°C was approximately 60 seconds, and the relief time of Comparative Example 1 at 180°C was approximately 3400 seconds. That is, in the bond exchange resin obtained by introducing tertiary amine groups into the side chain (Example 1), an approximately 50-fold increase in bond exchange rate was achieved compared to the case where tertiary amine groups were introduced at the crosslinking points (Comparative Example 1). Comparisons at other temperatures are summarized in Table 1.

[0067] Figure 7 shows a comparison of stress relief measurement data between Example 1 and Example 2. Furthermore, the measurement temperature for comparison was 180°C. Similar to Example 1, significant stress relief was observed in the crosslinked material of Example 2, and bond exchange was confirmed. The relief rate of the crosslinked material of Example 2 was almost the same as that of Example 1, and the exchange rate was significantly higher than that of Comparative Example 1. Table 1 summarizes the relief time of the crosslinked material of Example 2 at various temperatures. From this, it can be seen that even without the addition of a catalyst, bond exchange occurs sufficiently quickly.

[0068] [Table 1]

[0069] (6) Reusability The crosslinked material of Example 1 was shredded using a cutter. The shredded sample was placed into a disc-shaped Teflon (registered trademark) mold and hot-pressed (150°C, 1 h). By hot pressing, a disc-shaped sample formed by fusing the shredded sample was obtained (Fig. 8). This result suggests that the bond exchange between the surfaces of the shredded sample and the molecular penetration into the surface have been sufficiently carried out. On the other hand, Comparative Example 1, which has a slow bond exchange, did not produce a fused sample under the same conditions. Thus, it can be seen that the sample with a fast bond exchange has an advantage in terms of reusability.

[0070] Manufacturing Example 3: 25.42 g (100.0 mmol) of bis-2-hydroxyethyl terephthalate, 10.42 g (100.0 mmol) of 1,5-pentanediol, 30.03 g (200.0 mmol) of thiomalic acid, and scandium trifluoromethanesulfonate were melt-polymerized (100 °C, 8 hours) to obtain a polyester (PE-SH2) containing thiol side chains.

[0071] [Chemical 5]

[0072] Manufacturing Example 4: 3.00 g of PE-SH2 was dissolved in 30 ml of dimethylformamide (DMF). 3.05 g of N-[3-(dimethylamino)propyl]acrylamide (DAPAM) and 0.28 g of acrylic acid (AA) were added to the resulting DMF solution, and the mixture was stirred at room temperature for 24 hours to allow the thiol groups of PE-SH2 to add to DAPAM and AA. The ratio of DAPAM to 2.5 mol of thiol groups in PE-SH2 was 1 mol, and the ratio of AA to 0.5 mol. The reaction solution was concentrated using a rotary evaporator and then added dropwise to a large excess of tetrahydrofuran while stirring. The resulting precipitate was filtered off (re-precipitation purification). This re-precipitation purification process was repeated twice using DMF as the dissolving solvent (good solvent) and tetrahydrofuran as the precipitating solvent (poor solvent), followed by vacuum drying to obtain the target compound (PE-COOH-Amine-3). The number average molecular weight (Mn) of PE-COOH-Amine-3 is 4324 g / mol, the ratio of carboxyl groups to tertiary amino groups is 30:70, and the acid value is 75 mg KOH / g.

[0073] [Chemical 6]

[0074] Example 3 PE-COOH-Amine-3 (0.8 g) and 1,4-butanediol diglycidyl ether (BDE) (0.11 g) were dissolved separately in N-methylpyrrolidone (NMP), and the solutions were mixed in a polytetrafluoroethylene container. The amount of BDE added was such that the carboxyl and epoxy groups were in equal molar amounts. The NMP solution was placed on a heater at 100°C for about 24 hours to allow the solvent to evaporate. It was then vacuum dried at 100°C for 7 hours to allow the solvent to evaporate completely and to achieve dryness. The resulting dried sample was heated under vacuum at 130°C for 1 hour, then at 140°C for 1 hour, and then at 150°C for 3 hours to obtain a thermally crosslinked product.

[0075] Example 4 Except for changing the amounts of acrylic acid (AA) and N-[3-(dimethylamino)propyl]acrylamide (DAPAM), the process was carried out in the same manner as in Example 4, by adding the thiol groups of PE-SH2 to AA and DAPAM to obtain the target product (PE-COOH-Amine-4). The number average molecular weight (Mn) of PE-COOH-Amine-4 was 4269 g / mol, the carboxyl:tertiary amino group ratio was 50:50, and the acid value was 97.2 mgKOH / g. Except for using the obtained PE-COOH-Amine-4, the process was carried out in the same manner as in Example 3 to obtain a thermally crosslinked product.

[0076] For the crosslinked products obtained in Examples 3 and 4, (2) the temperature dispersion viscoelasticity was measured, (4) the coefficient of linear expansion was measured, and (5) a stress relief test was conducted.

[0077] (2) Temperature-dispersive viscoelasticity was measured using an MCR302 (manufactured by Anton Paar) in a cooling mode within a temperature range of 190°C to 20°C. The measurement was performed in an N2 gas environment at a temperature change rate of 5°C / min. The measurement frequency was 1 Hz, and the strain coefficient was 0.1%. The measurement specimen used was a disk-shaped specimen with a diameter of 8 mm and a thickness of 0.5 mm. Figure 9 shows the temperature dependence of the storage elastic modulus (G') and loss tangent tanδ of the crosslinks obtained in Examples 3 and 4. In Figure 9, the solid line represents the temperature dependence of the storage elastic modulus (G'), and the dashed line represents the temperature dependence of the loss tangent tanδ. In Examples 3 and 4, a tanδ peak originating from segment easing (α-easing peak) was observed in the region of approximately 50°C. At lower temperatures compared to this peak region, the specimen was in a glassy state, while at higher temperatures it was in a rubbery state. The rubbery, flat region remained stable within the measured temperature range, indicating that the crosslinking density did not change.

[0078] (4) The coefficient of linear expansion was measured using a TMA7100 (manufactured by HITACHI HighTech) within the range of room temperature to 200°C. The measurement was performed in an N2 gas environment at a temperature change rate of 10°C / min. The sample used was a strip sample with a width of 4 mm, a thickness of 0.5 mm, and a length of 20 mm. Figure 10 shows the results of the coefficient of linear expansion test for Example 3. The longitudinal axis is the sample length (L) after normalization to the sample length at 100°C (L100°C). At a high temperature of approximately 160°C, a deviation from the straight line extrapolation assuming a certain elongation was observed, indicating that the sample softened. Figure 11 shows the results of the coefficient of linear expansion test for Example 4. The longitudinal axis is the sample length (L) after normalization to the sample length at 130°C (L130°C). At a high temperature of approximately 160°C, a deviation from the straight line extrapolation assuming a certain elongation was observed, indicating that the sample softened. This shows that bond exchange will still be activated even without the addition of a catalyst.

[0079] (5) Stress relief test: An MCR302 (manufactured by Anton Paar) was used to conduct stress relief tests at temperatures of 100°C, 160°C, 170°C, or 180°C. The tests were conducted in an N2 gas environment. The specimens used were disc-shaped specimens with a diameter of 8 mm and a thickness of 0.5 mm. Figure 12 shows the results of stress relief measurements for the crosslinked product of Example 3. The vertical axis represents the stress (σ) after normalization with the initial stress (σ0), and the horizontal axis represents the time elapsed. Significant stress relief was observed at 160°C to 180°C, and it can be seen that the relief rate increases with increasing temperature. This is because the bond exchange rate is accelerated with increasing temperature. On the other hand, in the stress relief curve of the crosslinked product of Example 3 at 100°C shown in Figure 12, stress relief did not occur. The linear expansion coefficient test indicates that bond exchange is activated at temperatures above approximately 160°C, and that bond exchange pauses at 100°C. Figure 13 shows the results of stress relief measurements for the crosslinked product of Example 4. The vertical axis represents the stress (σ) normalized to the initial stress (σ0), and the horizontal axis represents the elapsed time. Significant stress relief was observed between 160°C and 180°C, and the relief rate increased with increasing temperature. This is due to the accelerated bond exchange rate with increasing temperature. On the other hand, in the stress relief curve of the crosslinked product of Example 4 at 100°C shown in Figure 13, stress relief did not occur. The linear expansion coefficient test indicates that bond exchange is activated at temperatures above approximately 160°C, and that bond exchange pauses at 100°C.

[0080] The easing times of the crosslinks of Examples 3 and 4 at various temperatures are summarized in Table 2 below. This shows that even without the addition of a catalyst, sufficiently fast bond exchange still occurs.

[0081] [Table 2]

[0082] For the crosslinked products obtained in Examples 1-4 and Comparative Example 1, (7) softening temperature was measured, (8) damage repair properties were evaluated, (9) molding processability was evaluated, and (10) extrusion molding properties were evaluated. The evaluation results of softening temperature, damage repair properties, molding processability, and extrusion molding properties are shown in Table 3 below.

[0083] (7) Softening Temperature The softening temperature was determined using a HITACHI "TMA7100" measuring instrument, and was obtained from the inflection point of the change in the coefficient of linear expansion of the sample from room temperature to 300°C. The measurement was performed in a nitrogen atmosphere with a slight tension (30 mN) applied to prevent the sample from deflecting. Furthermore, the initial distance between the clamps was 15 mm. The temperature at which the inflection point could be observed was recorded.

[0084] (8) Damage Repair: A cross-linked polyester resin film with dimensions of 1.5 cm in length, 1.5 cm in width, and 0.7 mm in thickness was manufactured using the cross-linked material. Damage (approximately 0.1 mm deep) was applied to the surface of the obtained cross-linked polyester resin film using a cutter. Subsequently, a heat treatment step was performed on the cross-linked polyester resin film. For the heat treatment step, the film was placed at a high temperature (softening temperature + approximately 20°C) for 10 minutes and then cooled to room temperature. The case where the cross-linked aromatic polyester resin film after the heat treatment step has no damage and no surface damage is evaluated as having good damage repair (self-healing) (evaluation 0), and the case where residual damage is evaluated as having poor damage repair (self-healing) (evaluation ×).

[0085] (9) Formability: A cross-linked polyester resin film (0.7 mm thick) made of cross-linked material was cut into 5 mm wide x 5 mm long samples, and the obtained samples were placed into a mold. The mold was made by cutting a circle with a diameter of 8 mm from a 1 mm thick Teflon (registered trademark) sheet. Subsequently, pressure and heat were applied using a hot press. The pressure conditions were set to 4 MPa, and the heating conditions were set to softening temperature +30°C for 15 minutes. The case where the cross-linked polyester resin film sheet could be formed into the mold shape was evaluated as good formability (evaluation 0), and the case where it could not be formed was evaluated as poor formability (evaluation ×).

[0086] (10) Extrusion molding performance: 6g of cross-linked polyester resin film (thickness 0.7mm) made from cross-linked material was cut into 5mm wide × 5mm long pieces. The resulting sample was fed into a HAAKE twin-screw extruder "MiniLab" in three batches at a barrel temperature of 170°C. After the sample was fed, it was mixed at a screw speed of 50 min-1 for 5 minutes. Then, the mixture was extruded from the barrel. The case in which the mixture could be discharged after mixing and a linear molded body could be obtained was evaluated as good extrusion molding performance (evaluation ○). The case in which the mixture could not be discharged and a linear molded body could not be obtained was evaluated as poor extrusion molding performance (evaluation ×).

[0087] [Table 3] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Softening temperature (°C) 150 150 160 170 >200 Damage repair 〇 〇 〇 〇 × Formability 〇 〇 〇 〇 〇 Extrusion molding properties 〇 〇 〇 〇 ×

[0088] As can be seen from Table 3, the crosslinked products obtained in Examples 1-4 have low softening temperatures and exhibit good damage repair, processability, and extrusion molding properties. On the other hand, the crosslinked product obtained in Comparative Example 1, while having good processability, has a high softening temperature and poor damage repair and extrusion molding properties. [Industrial Applicability]

[0089] The cross-linked polyester resin of the present invention can be applied to resin materials, film materials, elastomer materials, gel materials, etc., which are obtained by using polymers as constituents. In particular, it has advantages in applications where bond exchange resins have been unsuitable for use in the presence of moisture and oil (pipes, pads, vehicle components, etc.). [Simplified Explanation of the Diagram]

[0010] [Figure 1] Figure 1 is a photograph showing the appearance of the film obtained in Example 1. [Figure 2] Figure 2 is a graph showing the temperature dependence of the storage elastic modulus (G') and loss tangent tanδ of the crosslinked materials obtained in Examples 1, 2 and Comparative Example 1. [Figure 3] Figure 3 is a graph showing the stress-strain curves of the crosslinked materials obtained in Examples 1, 2 and Comparative Example 1. [Figure 4] Figure 4 is a graph showing the results of the linear expansion test of the crosslinked materials obtained in Examples 1 and 2. [Figure 5] Figure 5 is a graph showing the temperature dependence of the stress relief curve of the crosslinked material obtained in Example 1. [Figure 6] Figure 6 is a graph showing the temperature dependence of the stress relief curve of the crosslinked materials obtained in Examples 1 and Comparative Example 1. [Figure 7] Figure 7 is a graph showing the temperature dependence of the stress relief curve of the crosslinked materials obtained in Examples 1 and 2. [Figure 8] Figure 8 is a photograph showing the reusability of the crosslinked material obtained in Example 1. [Figure 9] Figure 9 is a graph showing the temperature dependence of the storage elastic modulus (G') and loss tangent tanδ of the crosslinked products obtained in Examples 3 and 4. [Figure 10] Figure 10 is a graph showing the results of the linear expansion test of the crosslinked product obtained in Example 3. [Figure 11] Figure 11 is a graph showing the results of the linear expansion test of the crosslinked product obtained in Example 4. [Figure 12] Figure 12 is a graph showing the temperature dependence of the stress relief curve of the crosslinked product obtained in Example 3. [Figure 13] Figure 13 is a graph showing the temperature dependence of the stress relief curve of the crosslinked product obtained in Example 4.

Claims

1. A crosslinked polyester resin, obtained by crosslinking a polyester resin having a plurality of side chains with carboxyl groups and a plurality of side chains with tertiary amine groups with an epoxy crosslinking agent having a plurality of epoxy groups, wherein the polyester resin is a polycondensation product of a polycarboxylic acid component (A) and a polyol component (B), wherein the polycarboxylic acid component (A) includes a polycarboxylic acid component for side chain formation, and the plurality of side chains with carboxyl groups and the plurality of side chains with tertiary amine groups are formed in the polycarboxylic acid component for side chain formation.

2. The cross-linked polyester resin as claimed in claim 1, wherein, The number of carboxyl groups in the side chains of this polyester resin is 3 to 80 per molecule of this polyester resin.

3. The cross-linked polyester resin as claimed in claim 1 or 2, wherein, The ratio of the number of tertiary amine groups to the number of carboxyl groups in the side chain of the polyester resin (amine:carboxyl) is 20:80~90:

10.

4. The cross-linked polyester resin as claimed in claim 1 or 2, wherein, The polycarboxylic acid component (A) contains a nucleophilic reactive group (A3) as the polycarboxylic acid component (A), and the nucleophilic reactive group-containing polycarboxylic acid component (A3) accounts for more than 50 mol% of 100 mol% of the polycarboxylic acid component (A); a portion of the nucleophilic reactive group-containing polycarboxylic acid component (A3) is added by Michael addition to α,β-unsaturated carboxylic acid (C3C), and the remaining portion or all of the nucleophilic reactive group-containing polycarboxylic acid component (A3) is added by Michael addition to a side chain compound (C3N) having a tertiary amine group.

5. The cross-linked polyester resin as claimed in claim 1, wherein, The polyol component (B) is selected from at least one of aliphatic diols and aromatic polyester diols.

6. The cross-linked polyester resin as claimed in claim 1 or 2, wherein, The epoxy crosslinking agent having multiple epoxy groups is an aliphatic diol digoxypropyl ether.

7. The cross-linked polyester resin as claimed in claim 1 or 2, wherein, The peak of the temperature change of the loss tangent tanδ is in the range of 0~100℃.

8. The cross-linked polyester resin as claimed in claim 1 or 2, wherein, The relaxation time at 160°C, obtained from the stress relaxation curve, is 1~2000 seconds.

9. The cross-linked polyester resin as claimed in item 1 or 2, wherein, The ester exchange catalyst is less than 1 part by weight of the polyester resin in 100 parts by weight; the epoxy crosslinking agent with tertiary amine groups is less than 30 moles of the epoxy crosslinking agent with multiple epoxy groups in 100 moles.

10. The cross-linked polyester resin as claimed in claim 1 or 2, wherein, The polycarboxylic acid component used for side chain formation is any one of the following: a tricarboxylic acid component (A2), a polycarboxylic acid component containing a nucleophilic reactive group (A3), or a polycarboxylic acid component containing an α,β-unsaturated carbonyl group (A4).

11. A polyester resin having: a plurality of side chains having carboxyl groups and a plurality of side chains having tertiary amino groups, the polyester resin being a polycondensation of a polycarboxylic acid component (A) and a polyol component (B), the polycarboxylic acid component (A) comprising a polycarboxylic acid component for side chain formation, wherein the plurality of side chains having carboxyl groups and the plurality of side chains having tertiary amino groups are formed in the polycarboxylic acid component for side chain formation.

12. The polyester resin as claimed in claim 11, wherein, The polycarboxylic acid component used for side chain formation is any one of the following: a tricarboxylic acid component (A2), a polycarboxylic acid component containing a nucleophilic reactive group (A3), or a polycarboxylic acid component containing an α,β-unsaturated carbonyl group (A4).

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