Amino group-containing polyester resin and amino group-containing crosslinked polyester resin

Abstract

Provided is a crosslinked polyester resin which, even when immersed in water, an organic solvent, etc., retains intact bond-exchange activity and undergoes bond-exchange rapidly. Also provided is a polyester resin which undergoes bond-exchange rapidly.　The crosslinked polyester resin is one in which a polyester resin having a plurality of side chains each having a carboxy group and a plurality of side chains each having a tertiary amino group has been crosslinked with an epoxy crosslinking agent having a plurality of epoxy groups.

Description

[Technical Field]

[0001] The present invention relates to a polyester resin and a crosslinked polyester resin (hereinafter referred to as a crosslinked polyester resin). [Background technology]

[0002] Covalently crosslinked polymeric elastomers cannot usually be reshaped or recycled due to the irreversibility of the covalent crosslinking points. To address this issue, bond-exchange type dynamic covalent crosslinking resins have recently been attracting attention.

[0003] The bond-exchange-type dynamic covalent bond-crosslinking resin requires the addition of a bond-exchange active catalyst. For example, in Non-Patent Document 1, zinc acetate (Zn(OAc)2) is added as a bond-exchange active catalyst to a resin obtained by crosslinking a polyester resin having a carboxy group (COOH) in the side chain with an epoxy crosslinking agent. However, in examples using a bond-exchange active catalyst, there is a concern that the catalyst may be washed out by immersion in (or contact with) water or an organic solvent, resulting in a loss of bond-exchange activity. There is also a concern that the catalytic activity may decrease over a long period of time.

[0004] To address this issue, molecular designs that do not require the addition of bond exchange activation catalysts have also been reported. For example, Non-Patent Document 2 discloses a resin in which a polyester resin having COOH in its side chain is crosslinked with 4,4'-methylenebis(N,N-diglycidylaniline). Because the catalytically active amino groups of the aniline are contained in the network structure, bond exchange is activated at high temperatures without the external addition of a bond exchange catalyst. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Mikihiro Hayashi,et al.,Polymer Chemistry.2019,10(16),2047-2056. [Non-patent document 2] Mikihiro Hayashi,ACS Applied Polymer Materials,2020,2(12),5365-5370. Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the case of Non-Patent Document 2, amino groups are present at the crosslinking points, which results in a high degree of restriction of molecular mobility around the crosslinking points. Therefore, although bond exchange is possible without the addition of a catalyst, the time scale for bond exchange is extremely slow. Therefore, an object of the present invention is to provide a crosslinked polyester resin that does not lose its bond exchange activity even when immersed in water, an organic solvent, etc. and that exhibits fast bond exchange. Another object of the present invention is to provide a polyester resin that exhibits fast bond exchange. [Means for solving the problem]

[0007] The configuration according to the present invention that can solve the above problems is as follows. [1] A crosslinked polyester resin in which a polyester resin having multiple side chains containing carboxy groups and multiple side chains containing tertiary amino groups is crosslinked with an epoxy-based crosslinking agent having multiple epoxy groups. [2] The crosslinked polyester resin according to [1], wherein the number of carboxy groups in the side chains of the polyester resin is 3 to 80 per molecule of the polyester resin. [3] The crosslinked polyester resin according to [1] or [2], wherein the ratio of the number of tertiary amino groups in the side chains of the polyester resin to the number of carboxy groups in the side chains of the polyester resin (amino groups:carboxy groups) is 20:80 to 90:10. [4] The crosslinked polyester resin according to any one of [1] to [3], wherein the polyester resin is a polycondensate of a polycarboxylic acid component (A) and a polyhydric alcohol component (B), and the polycarboxylic acid component (A) contains a nucleophilic reactive group-containing polycarboxylic acid component (A3) in an amount of 50 mol % or more relative to 100 mol % of the polycarboxylic acid component (A), and a part of the nucleophilic reactive group-containing polycarboxylic acid component (A3) undergoes Michael addition to an α,β-unsaturated carboxylic acid (C3C), and a part or all of the remaining nucleophilic reactive group-containing polycarboxylic acid component (A3) undergoes Michael addition to a side chain compound (C3N) having a tertiary amino group. [5] The crosslinked polyester resin according to [4], wherein the polyhydric alcohol component (B) is at least one selected from the group consisting of an aliphatic diol and an aromatic polyester diol. [6] The crosslinked polyester resin according to any one of [1] to [5], wherein the epoxy-based crosslinking agent having a plurality of epoxy groups is an aliphatic diol diglycidyl ether. [7] The crosslinked polyester resin according to any one of [1] to [6], wherein the peak of the temperature change of the loss tangent tan δ is in the range of 0 to 100°C. [8] The crosslinked polyester resin according to any one of [1] to [7], wherein the relaxation time at a temperature of 160°C determined from a stress relaxation curve is 1 to 2000 seconds. [9] The crosslinked polyester resin according to any one of [1] to [8], wherein the transesterification catalyst is less than 1 part by mass per 100 parts by mass of the polyester resin, and the epoxy-based crosslinking agent having a tertiary amino group is less than 30 parts by mole per 100 parts by mole of the epoxy-based crosslinking agent having multiple epoxy groups.

[10] A polyester resin having a plurality of side chains containing carboxy groups and a plurality of side chains containing tertiary amino groups. [Effects of the Invention]

[0008] According to the present invention, a crosslinked polyester resin having fast bond exchange can be obtained without losing its bond exchange activity even when immersed in water, an organic solvent, etc. Furthermore, according to the present invention, a polyester resin having fast bond exchange can be obtained. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a photograph showing the appearance of the film obtained in Example 1. [Figure 2] FIG. 2 is a graph showing the temperature dependence of the storage modulus (G') and loss tangent tan δ of the crosslinked products obtained in Example 1, Example 2 and Comparative Example 1. [Figure 3] FIG. 3 is a graph showing stress-strain curves of the cross-linked products obtained in Example 1, Example 2 and Comparative Example 1. [Figure 4] FIG. 4 is a graph showing the results of a linear expansion test of the crosslinked products obtained in Examples 1 and 2. [Figure 5] FIG. 5 is a graph showing the temperature dependence of the stress relaxation curve of the crosslinked product obtained in Example 1. [Figure 6] FIG. 6 is a graph showing the temperature dependence of the stress relaxation curves of the cross-linked products obtained in Example 1 and Comparative Example 1. [Figure 7] FIG. 7 is a graph showing the temperature dependence of the stress relaxation curves of the crosslinked products obtained in Examples 1 and 2. [Figure 8] FIG. 8 is a photograph showing the recyclability of the crosslinked product obtained in Example 1. [Figure 9] FIG. 9 is a graph showing the temperature dependence of the storage modulus (G') and loss tangent tan δ of the crosslinked products obtained in Examples 3 and 4. [Figure 10] FIG. 10 is a graph showing the results of a linear expansion test of the crosslinked product obtained in Example 3. [Figure 11] FIG. 11 is a graph showing the results of a linear expansion test of the crosslinked product obtained in Example 4. [Figure 12] FIG. 12 is a graph showing the temperature dependence of the stress relaxation curve of the cross-linked product obtained in Example 3. [Figure 13] FIG. 13 is a graph showing the temperature dependence of the stress relaxation curve of the cross-linked product obtained in Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1. Polyester resin The crosslinked polyester resin of the present invention has a structure in which a polyester resin having a plurality of side chains containing carboxy groups and a plurality of side chains containing tertiary amino groups (hereinafter, sometimes referred to as pre-crosslinked polyester resin) is crosslinked with an epoxy-based crosslinking agent having a plurality of epoxy groups. The pre-crosslinked polyester resin may be either an aliphatic polyester or an aromatic polyester. From the viewpoint of improving adhesiveness, an aliphatic polyester is more preferred, and from the viewpoint of improving heat resistance, an aromatic polyester is more preferred, and an aliphatic polyester and an aromatic polyester may be used in combination. The tertiary amino group may be a di-C group such as a dimethylamino group, a methylethylamino group, or a diethylamino group. 1-4 Alkylamino groups are preferred.

[0011] 2. Ordinary polycarboxylic acid component (A1) The pre-crosslinked polyester resin has a polycondensation structure of a polycarboxylic acid component (A) and a polyhydric alcohol component (B), and a predetermined side chain can be formed by converting at least a part of the polycarboxylic acid component into a polycarboxylic acid component for forming a side chain. The polycarboxylic acid component (A) is divided into a side chain non-forming polycarboxylic acid component (A1) (sometimes referred to as a polycarboxylic acid component (A1) in this specification) and a side chain-forming polycarboxylic acid component. Examples of polycarboxylic acids constituting the polycarboxylic acid component (A1) include dicarboxylic acids and tetracarboxylic acids, with dicarboxylic acids being preferred. Examples of dicarboxylic acids include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, phenylenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid; aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, and dimer acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, tetrahydrophthalic acid, hexahydroisophthalic acid, and 1,2-cyclohexenedicarboxylic acid; and unsaturated group-containing dicarboxylic acids such as terpene-maleic acid adducts. Examples of tetracarboxylic acids include 1,2,4,5-benzenetetracarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, and the like, or their acid anhydrides. The polycarboxylic acid component (A1) can generally be composed of one or more of these.

[0012] 3. Tricarboxylic acid component (A2) Examples of the polycarboxylic acid component for forming a side chain include a tricarboxylic acid component (A2), a polycarboxylic acid component (A3) containing a nucleophilic reactive group (such as a thiol group) (sometimes referred to as a nucleophilic polycarboxylic acid component (A3) in this specification), and an α,β-unsaturated carbonyl group-containing polycarboxylic acid component (A4) (sometimes referred to as an unsaturated polycarboxylic acid component (A4) in this specification).

[0013] The tricarboxylic acid component (A2) undergoes polycondensation with the polyhydric alcohol component (B) to form a carboxy group on the side chain. Examples of the tricarboxylic acid (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 trimesic acid. These tricarboxylic acids (A2) may also be acid anhydrides. One or more of these tricarboxylic acids (A2) may be used.

[0014] 4. Nucleophilic polycarboxylic acid component (A3) The nucleophilic polycarboxylic acid component (A3) can introduce a carboxy group into the side chain by Michael addition to an α,β-unsaturated carboxylic acid (C3C), and can introduce a tertiary amino group into the side chain by Michael addition to a side chain compound (C3N) (sometimes referred to as an unsaturated amine in this specification) having an α,β-unsaturated carbonyl group and a tertiary amino group. Examples of the nucleophilic polycarboxylic acid component (A3) include compounds in which the hydrogen atoms of the ordinary polycarboxylic acid component (A1) are replaced with nucleophilic groups (thiol groups, hydroxyl groups, etc.), and preferred examples include aliphatic dicarboxylic acids having thiol groups and about 4 to 10 carbon atoms, such as thiomalic acid. One or more of these can be used as the nucleophilic polycarboxylic acid component (A3). Examples of the α,β-unsaturated carboxylic acid (C3C) for introducing a carboxy group into a side chain include aliphatic α,β-unsaturated monocarboxylic acids having about 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 the unsaturated amine (CN) for introducing a tertiary amino group into a side chain include N-[(diC)-(N-dimethylamino)propyl]acrylamide, etc. 1-4 Alkylamino)C 1-10 Alkyl] (meth)acrylic acid amide; (meth)acrylic acid (di-C) such as 2-(dimethylamino)ethyl acrylate, 2-(diethylamino)ethyl acrylate, 3-(dimethylamino)propyl acrylate, 3-(diethylamino)propyl acrylate 1-4 Alkylamino)C 1-10 Alkyl esters, etc. As the unsaturated amine (CN), one or more of these can be used.

[0015] 5. Unsaturated polycarboxylic acid component (A4) A carboxy group can be introduced into the side chain by Michael addition of a side chain compound (C4C) having a nucleophilic group and a carboxy group (sometimes referred to as a nucleophilic carboxylic acid in this specification) to the unsaturated polycarboxylic acid component (A4), and a tertiary amino group can be introduced into the side chain by Michael addition of a side chain compound (C4N) having a nucleophilic group and a tertiary amino group (sometimes referred to as a nucleophilic amine in this specification). Examples of the unsaturated polycarboxylic acid component (A4) include aliphatic α,β-unsaturated dicarboxylic acids having about 4 to 10 carbon atoms, such as maleic acid and fumaric acid. One or more of these can be used as the unsaturated polycarboxylic acid component (A4). Examples of the nucleophilic carboxylic acid (C4C) for introducing a carboxy group into a side chain include aliphatic monocarboxylic acids having a thiol group and about 2 to 10 carbon atoms, such as thioglycolic acid and mercaptopropionic acid. One or more of these nucleophilic carboxylic acids (C4C) can be used. Examples of the nucleophilic amine (CN) for introducing a tertiary amino group into a side chain include a thiol group such as 2-(dimethylamino)ethanethiol and a di-C 1-4 C with alkylamino group 2-10 Alkanes can be used as the nucleophilic amine (CN), and one or more of these can be used.

[0016] 6. Polyhydric alcohol component (B) Examples of the polyhydric alcohol component (B) include ethylene glycol, 1,2-propylene glycol, 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, 1,6-hexanediol, and 3-methyl-1,6-hexanediol. Examples of monomeric diols include aliphatic diols such as 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecane glycols, and hydrated bisphenols; and aromatic diols such as bisphenol A. As the monomeric diol, an aliphatic diol is preferred. The polyhydric alcohol component (B) may be a polyether polyol (polyether glycol) such as polyether glycols such as diethylene glycol, triethylene glycol, polyethylene glycol, polyolefin glycol, and polytetramethylene glycol. The polyhydric alcohol component (B) may also be a polyester polyol, preferably an aromatic polyester diol, such as a glycol-modified aromatic dicarboxylic acid, such as an ethylene glycol-modified terephthalic acid (e.g., bis-2-hydroxyethyl terephthalate (BHET)), a propylene glycol-modified terephthalic acid, an ethylene glycol-modified isophthalic acid, a propylene glycol-modified isophthalic acid, an ethylene glycol-modified orthophthalic acid, or a propylene glycol-modified orthophthalic acid. The polyhydric alcohol component (B) can be one or more of these. The polyhydric alcohol component (B) preferably contains at least one selected from a monomeric polyol (particularly an aliphatic diol) and a polyester polyol (particularly an aromatic polyester diol), and more preferably contains at least a monomeric polyol (particularly an aliphatic diol) and, if necessary, a polyester polyol (particularly an aromatic polyester diol).

[0017] 7. Side Chain The side chain having a carboxy group may be any of the following three types: (1) Carboxylic acid (side chain C1) derived from tricarboxylic acid component (A2) (2) A side chain (side chain C2) formed by Michael addition of a nucleophilic polycarboxylic acid component (A3) to an unsaturated carboxylic acid (C3C). (3) A side chain (side chain C3) formed by Michael addition of a nucleophilic carboxylic acid (C4C) to an unsaturated polycarboxylic acid component (A4). The side chain having a carboxy group is preferably side chain C2. The amount of side chain C2 is, for example, 50 moles or more, preferably 70 moles or more, more preferably 90 moles or more, and may be 100 moles, relative to 100 moles in total of side chains C1, C2, and C3.

[0018] The side chain having a tertiary amino group may be either of the following two: (1) Side chain (side chain N1) formed by Michael addition of nucleophilic polycarboxylic acid component (A3) to unsaturated amine (CN) (2) Side chain (side chain N2) formed by Michael addition of nucleophilic amine (CN) to unsaturated polycarboxylic acid component (A4) The side chain having a tertiary amino group is preferably the side chain N1. The amount of the side chain N1 is, for example, 50 moles or more, preferably 70 moles or more, more preferably 90 moles or more, and may be 100 moles, relative to 100 moles in total of the side chains N1 and N2.

[0019] The pre-crosslinked polyester resin preferably contains a nucleophilic polycarboxylic acid component (A3) as the polycarboxylic acid component (A), in which a portion of the nucleophilic polycarboxylic acid component (A3) undergoes Michael addition to an unsaturated carboxylic acid (C3C), and a portion or all (preferably all) of the remaining nucleophilic polycarboxylic acid component (A3) adds to an unsaturated amine (C3N). The nucleophilic polycarboxylic acid component (A3) accounts for, for example, 50 mol % or more, preferably 70 mol % or more, more preferably 90 mol % or more, and may be 100 mol % of the total polycarboxylic acid component (A).

[0020] The number of carboxy groups in the side chains per molecule of the polyester resin before crosslinking is, for example, about 3 to 80, preferably about 10 to 60, and more preferably about 20 to 50. The greater the number of carboxy groups, the greater the number of crosslinking points and the improved heat resistance. Furthermore, if the number of carboxy groups is not too large, the toughness or elasticity will be good.

[0021] The number of tertiary amino groups in the side chains is, for example, about 5 to 100, preferably about 20 to 85, and more preferably about 30 to 70 per molecule of the polyester resin before crosslinking. The ratio of tertiary amino groups in the side chains to carboxy groups in the side chains (amino groups:carboxy groups) is, for example, 20:80 to 90:10, preferably 25:75 to 70:30, and more preferably 30:70 to 50:50. By adjusting the ratio of tertiary amino groups appropriately, bond exchange at crosslinking points can be accelerated.

[0022] The acid value of the polyester resin before crosslinking is, for example, 5 to 250 mgKOH / g, preferably 30 to 200 mgKOH / g, and more preferably 50 to 150 mgKOH / g. The higher the acid value, the more crosslinking points there are, and the better the heat resistance. Furthermore, if the acid value is not too high, the toughness or elasticity will be good.

[0023] The number average molecular weight (Mn) of the polyester resin before crosslinking is, for example, 4,000 to 90,000. When the number average molecular weight (Mn) of the polyester resin before crosslinking is 4,000 or more, heat resistance can be improved. The number average molecular weight (Mn) is more preferably 4,200 or more, and even more preferably 10,000 or more. However, if the number average molecular weight (Mn) of the polyester resin having carboxy groups in the side chains becomes too large, the polyester resin becomes too hard and brittle. Therefore, the number average molecular weight (Mn) is preferably 90,000 or less, more preferably 60,000 or less, and even more preferably 40,000 or less.

[0024] The molecular weight dispersity (PDI) of the polyester resin having a carboxy group in the side chain is preferably 1.3 to 1.8. The molecular weight dispersity can be calculated using the following formula based on the weight average molecular weight (Mw) and the number average molecular weight (Mn). PDI value = Mw / Mn

[0025] 8. Epoxy-based crosslinking agents The epoxy-based crosslinking agent bonds with the carboxyl groups on the side chains of the polyester resin before crosslinking to crosslink the polyester resin. The epoxy-based crosslinking agent is not particularly limited as long as it has two or more epoxy groups in the molecule. Examples include diol diglycidyl ether, glycidyl ether of an alcohol having three or more hydroxyl groups, epoxy resin, epoxy amine compound having two or more epoxy groups and two or more tertiary amino groups in the molecule, and compound having two or more epoxy groups and one tertiary amino group in the molecule. One or more of these epoxy-based crosslinking agents can be used.

[0026] Examples of diol diglycidyl ethers include compounds in which a glycidyl group is ether-bonded to the hydroxyl group of a diol listed as the polyhydric alcohol component (B), and preferred are ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,5-pentanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, aliphatic diol diglycidyl ethers such as hydrogenated bisphenol A diglycidyl ether, and aromatic diol diglycidyl ethers such as bisphenol A diglycidyl ether, with aliphatic diol diglycidyl ethers being more preferred. One or more of these compounds in which a diglycidyl group is ether-bonded to the hydroxyl group of the polyhydric alcohol can be used.

[0027] Examples of glycidyl ethers of alcohols having three or more hydroxyl groups include diglycidyl ethers of aliphatic polyols such as glycerin diglycidyl ether and trimethylolpropane diglycidyl ether. One or more of these glycidyl ethers of alcohols having three or more hydroxyl groups can be used.

[0028] Examples of epoxy resins include cresol novolac epoxy resins, phenol novolac epoxy resins, and epoxy resins having a dicyclopentadiene skeleton. One or more of these epoxy resins can be used. Commercially available cresol novolac epoxy resins include YDCN-700 manufactured by DIC Corporation. Commercially available phenol novolac epoxy resins include EPICLON N-700A manufactured by DIC Corporation. Commercially available epoxy resins having a dicyclopentadiene skeleton include HP7200 series manufactured by DIC Corporation.

[0029] Examples of epoxy amine compounds having two or more epoxy groups and two or more tertiary amino groups in the molecule include compounds having two diglycidylamino groups and a benzene ring, such as N,N,N',N'-tetraglycidyl-m-xylylenediamine and 4,4'-methylenebis(N,N-diglycidylaniline). N,N,N',N'-tetraglycidyl-m-xylylenediamine is commercially available from Mitsubishi Gas Chemical Company, Inc. as the multifunctional epoxy compound "TETRAD-X." 4,4'-methylenebis(N,N-diglycidylaniline) is available from Tokyo Chemical Industry Co., Ltd. (TCI).

[0030] Examples of compounds containing two or more epoxy groups and one tertiary amino group in the molecule include compounds having one diglycidylamino group, a glycidyloxy group, and a benzene ring, such as triglycidyl paraaminophenol (also known as N,N-diglycidyl-4-(glycidyloxy)aniline). Commercially available triglycidyl paraaminophenols include jER630 manufactured by Mitsubishi Chemical Corporation.

[0031] As the epoxy-based crosslinking agent having multiple epoxy groups, an epoxy-based crosslinking agent having no tertiary amino group (such as diol diglycidyl ether, glycidyl ether of an alcohol having three or more hydroxyl groups, or epoxy resin) is preferred, and diol diglycidyl ether (particularly aliphatic diol diglycidyl ether) is more preferred.

[0032] The amount of the epoxy-based crosslinking agent having multiple epoxy groups is, for example, 1 to 50 parts by mass, preferably 5 to 40 parts by mass, and more preferably 10 to 30 parts by mass relative to 100 parts by mass of the polyester resin before crosslinking.

[0033] When the total amount of the epoxy crosslinking agent having multiple epoxy groups is taken as 100 parts by mole, the amount of the epoxy crosslinking agent not having a tertiary amino group (particularly the compound in which a diglycidyl group is ether-bonded to the hydroxyl group of the polyhydric alcohol) is preferably 30 parts by mole or more, more preferably 50 parts by mole or more, even more preferably 80 parts by mole or more, and may be 100 parts by mole. On the other hand, when the total amount of the epoxy crosslinking agent having multiple epoxy groups is taken as 100 parts by mole, the amount of the epoxy crosslinking agent having a tertiary amino group in the molecule is preferably less than 30 parts by mole.

[0034] 9. Transesterification catalyst The crosslinked polyester resin of the present invention may not contain a transesterification catalyst, but may contain a transesterification catalyst within a range that does not impair the effects of the present invention. In this specification, "not containing a transesterification catalyst" means that the amount of the transesterification catalyst is less than 1 part by mass per 100 parts by mass of the polyester resin. Examples of transesterification catalysts include metal-containing catalysts such as titanium compounds (tetra-n-butyl titanate, tetraisopropyl titanate, titanium oxyacetylacetonate, etc.), antimony compounds (tributoxyantimony, antimony trioxide, etc.), germanium compounds (tetra-n-butoxygermanium, germanium oxide, etc.), scandium compounds (scandium triflate, etc.), zinc compounds (zinc acetate, zinc octoate, etc.), and aluminum compounds (aluminum acetate, aluminum acetylacetate, etc.); amines such as trimethylamine, triethylamine, and benzyldimethylamine; quaternary ammonium salts such as tetramethylammonium chloride and triethylbenzylammonium chloride; imidazoles such as 2-ethyl-4-imidazole; amides; pyridines such as 4-dimethylaminopyridine; phosphines such as triphenylphosphine; and phosphonium salts such as tetraphenylphosphonium bromide. Preferred are metal-containing catalysts such as scandium compounds and zinc compounds. The transesterification catalyst may be used alone or in combination of two or more.

[0035] When a transesterification catalyst is added, the amount is, for example, 1 to 30 parts by mass, preferably 3 to 20 parts by mass, and more preferably 5 to 10 parts by mass relative to 100 parts by mass of the crosslinked polyester resin.

[0036] 10. Cross-linked polyester resin The crosslinked polyester resin has a peak (α relaxation peak) of the temperature change of loss tangent tanδ within a range of, for example, 0 to 100°C, preferably 10 to 70°C, and more preferably 20 to 50°C. The higher the α relaxation peak temperature, the higher the heat resistance. The peak of the temperature change of loss tangent tanδ is a value measured at a measurement frequency of 1 Hz and a strain of 0.1%.

[0037] The Young's modulus of the crosslinked polyester resin (measurement temperature: room temperature, for example, 25° C.) is, for example, 0.1 MPa to 5000 MPa, preferably 0.5 MPa to 2500 MPa, and more preferably 2 MPa to 1000 MPa.

[0038] In graphs showing the temperature change in elongation of crosslinked polyester resins, linearity is lost above the glass transition temperature. This means that bond exchange at crosslinking points is activated. This results in high strength at room temperature, and above the ester bond exchange activation temperature, reprocessing and film adhesion become possible. Furthermore, the remoldability of crosslinked polyester resins allows them to be molded and thinned after the crosslinking reaction, and their self-healing properties allow them to repair scratches, making them semi-permanent. The ester bond exchange activation temperature of crosslinked polyester resins can be calculated as the softening temperature based on the inflection point of the change in linear expansion coefficient.

[0039] The relaxation time at 160°C, as determined from the stress relaxation curve of the crosslinked polyester resin, is, for example, 1 to 2000 seconds, preferably 50 to 1500 seconds, and more preferably 100 to 1000 seconds. Despite exhibiting a high Young's modulus and high elastic strength, the relaxation time is fast, resulting in excellent thermal deformation resistance at temperatures above a predetermined temperature. In this specification, the relaxation time is defined as the time, in a stress relaxation test, at which the elastic modulus becomes 1 / e (= 0.37) times the initial elastic modulus.

[0040] Crosslinked polyester resins have self-adhesive properties, and when crosslinked polyester resins are stacked on top of each other and heated and pressurized, transesterification occurs at the interface of the crosslinked polyester resins, allowing the crosslinked polyester resins to bond to each other without the use of an adhesive. Because crosslinked polyester resins have self-adhesive properties, they can be used as the main component of self-adhesives. Crosslinked polyester resins are remoldable; after being deformed into a desired shape, they are heated in that deformed state, causing transesterification, resulting in remolding, and they retain the desired shape even after cooling. Cross-linked polyester resins have scratch-repairing properties, and even if their surface is scratched with a cutter knife or similar, they undergo a bond exchange through an ester exchange reaction when heated, allowing them to self-repair. Because of their scratch-repairing properties, cross-linked polyester resins can be used as the main component of self-repairing materials.

[0041] The crosslinked polyester resin can be used, for example, as the main component (or molding material) of an adhesive sheet or a molding material. When used as an adhesive sheet, the crosslinked polyester resin of the present invention can be sandwiched between the bonded members to be bonded and heated. Heating causes a bond exchange due to an ester exchange reaction, bonding the bonded members together. Examples of bonded members include resin films and metal foils. For example, resin films can be bonded to each other, metal foils can be bonded to each other, or resin films and metal foils can be bonded together. Examples of resin films include polyimide films, polyester films, and PET films. Examples of metal foils include copper foil, silver foil, and gold foil. Since crosslinked polyester resins can undergo bond exchange by heating above their ester bond exchange activation temperature, when crosslinked polyester resins are used as adhesive materials, the adhesives can be easily peeled off by heating them above their ester bond exchange activation temperature, and therefore crosslinked polyester resins can be used as adhesives for repair applications that can be applied and removed. The crosslinked polyester resin can be used as a laminating material. Because the crosslinked polyester resin has heat resistance, for example, by laminating a film using the crosslinked polyester resin onto the surface of a resin molded body or a metal molded body, the heat resistance of the resin molded body or the metal molded body can be improved. Crosslinked polyester resins have good moldability and extrusion moldability, making them useful as molding materials. For example, they can be used as materials for 3D printers and filamentous moldings. The crosslinked polyester resin can be used as a material for a network structure. A network structure is a structure in which parts of filamentous molded bodies are connected to each other. The network structure can be produced by melting the crosslinked polyester resin, discharging the molten material from a nozzle, and solidifying the discharged material while welding it together.

[0042] 11. Manufacturing method of cross-linked polyester resin The crosslinked polyester resin can be produced by a known method, for example, a method in which the pre-crosslinked polyester resin and the epoxy-based crosslinking agent having a plurality of epoxy groups are dissolved in a solvent, the solvent is removed, and the mixture is heated under reduced pressure to crosslink the polyester resin. Examples of the solvent include aromatic hydrocarbons such as toluene, ketones such as methyl ethyl ketone and cyclohexanone, nitrogen-containing solvents such as dimethylacetamide, dimethylformamide and N-methylpyrrolidone, and ethers such as tetrahydrofuran, 1,4-dioxane, 1,3-dioxane and 1,3-dioxolane. Of these, nitrogen-containing solvents such as dimethylformamide are preferred. The pre-crosslinked polyester resin can be produced by polycondensing a polycarboxylic acid component (A) with a polyhydric alcohol component (B) by a known method, followed by reaction with a side chain compound. A solvent may be used for the polycondensation and the reaction with the side chain compound. The polycondensation reaction may also be performed without a solvent. Furthermore, a known catalyst, such as the above-mentioned transesterification catalyst, may be used in the polycondensation.

[0043] This application claims the benefit of priority based on Japanese Patent Application No. 2021-079856, filed on May 10, 2021. The entire contents of the specification of said Japanese Patent Application No. 2021-079856 are incorporated herein by reference. [Example]

[0044] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and it is possible to carry out the invention by making appropriate modifications within the scope of the above and below-described aims, and all such modifications are included in the technical scope of the present invention.

[0045] Manufacturing Example 1 Melt polycondensation was carried out (80°C, 14 hours) using 9.00 g (86.4 mmol) of 1,5-pentanediol and 12.87 g (85.7 mmol) of thiomalic acid in the presence of 0.42 g (0.86 mmol) of scandium triflate to obtain a polyester (PE-SH1) containing thiol group side chains.

[0046] [ka]

[0047] 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 resulting DMF solution and stirred at room temperature for 24 hours, resulting in a Michael addition reaction of the thiol groups of PE-SH1 to DAPAM and AA. Per mole of thiol group in PE-SH1, 2.5 moles of DAPAM and 1 mole of AA were used. The reaction solution was concentrated using a rotary evaporator and then added dropwise to a large excess of tetrahydrofuran with stirring. The resulting precipitate was collected by filtration (reprecipitation purification). This reprecipitation purification process was repeated twice using DMF as a dissolution solvent (good solvent) and tetrahydrofuran as a precipitation solvent (poor solvent), followed by vacuum drying to obtain the desired product (PE-COOH-Amine-1). The number-average molecular weight (Mn) of PE-COOH-Amine-1 was 30,533 g / mol, and the number of carboxyl groups and tertiary amino groups per molecule was 46 (carboxyl group:tertiary amino group = 50:50, acid value 86 mg KOH / g).

[0048] [ka]

[0049] The number average molecular weight (Mn), the number of carboxy groups per molecule, the number of tertiary amino groups per molecule, and the acid value were determined as follows (unless otherwise specified, the same measurement methods were used in the Examples section below).

[0050] (Number average molecular weight (Mn)) The uncrosslinked polyester resin was dissolved in DMF to a concentration of approximately 0.5% by mass and filtered through a 0.5 μm pore size polytetrafluoroethylene membrane filter to prepare a sample. The number-average molecular weight (Mn) was measured by gel permeation chromatography using a differential refractometer as a detector and DMF supplemented with 0.05% by mass of LiBr as the mobile phase. The flow rate was 0.5 mL / min and the column temperature was 40°C. The columns used were Showa Denko KF-803, KF-804L, and KF-805L. Monodisperse polymethyl methacrylate was used as the standard (molecular weight standard). Low-molecular-weight compounds (oligomers, etc.) with a number-average molecular weight (Mn) of less than 1000 were not counted and were omitted.

[0051] (Number of carboxyl groups and tertiary amino groups per molecule) The number of carboxyl groups and tertiary amino groups (in this example, the number of dimethylamino groups) per molecule was determined by proton nuclear magnetic resonance (H NMR) using a BrukerAnalytik DPX400 spectrometer (400 MHz) at 25°C using deuterated DMSO as the solvent.

[0052] (acid number) The acid value was calculated based on the number of carboxyl groups per molecule and the number average molecular weight (Mn). If the acid value is X (mgKOH / g), the acid value X can be calculated using the following formula: X / 56.10 = (1 / Mn) × number of carboxyl groups per molecule × 1000

[0053] Example 1 PE-COOH-Amine-1 (1.0 g) and 1,4-butanediol diglycidyl ether (BDE) (0.16 g) were dissolved in dimethylformamide (DMF), and the resulting solutions were mixed in a polytetrafluoroethylene container. BDE was added in an amount that resulted in equimolar amounts of carboxyl and epoxy groups. The DMF solution was left on a heater at 60°C for approximately 40 hours to evaporate the solvent. The solvent was completely evaporated and the mixture was dried in vacuum at 60°C for 7 hours. The resulting dried sample was then heated under vacuum at 120°C for 14 hours to obtain a thermally crosslinked product.

[0054] [ka]

[0055] The sticky dried sample became a highly self-supporting elastomer film after 14 hours of heating. 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 immersed in DMF again, and the same procedure was repeated three times. Comparing the initial weight with the remaining weight of the gel component, the gel component of the sample heated for 14 hours was approximately 85%. This result confirmed that the crosslinking reaction had progressed sufficiently.

[0056] The glass transition temperature (Tg) of each sample of the PE-COOH-Amine-1 and BDE mixture before and after thermal crosslinking was determined by measuring the heat flow rate at 10°C / min in a N2 gas atmosphere over the range of -50°C to 200°C using a DSC7020 (Hitachi HighTech). 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 is due to the formation of a crosslinked structure.

[0057] Example 2 The thiol group of PE-SH1 was added to AA and DAPAM in the same manner as in Preparation Example 2, except for changing the amounts of acrylic acid (AA) and N-[3-(dimethylamino)propyl]acrylamide (DAPAM) used, to obtain the target product (PE-COOH-Amine-2). PE-COOH-Amine-2 had a number-average molecular weight (Mn) of 28,800 g / mol, 27 carboxy groups per molecule, and 64 tertiary amino groups (carboxy group:tertiary amino group = 30:70, acid value 52.6 mg KOH / g). A thermally crosslinked product was obtained in the same manner as in Example 1, except for using the obtained PE-COOH-Amine-2. A DMF swelling test of the thermally crosslinked product of Example 2 was performed in the same manner as in Example 1. The gel content was approximately 85%, confirming that the crosslinking reaction had progressed sufficiently.

[0058] Comparative Example 1 A polyester (PE-COOH-1) having a carboxy group in the side chain was produced in the same manner as in Production Example 2, except that DAPAM was not used. PE-COOH-1 had a number average molecular weight (Mn) of 20,100 g / mol, 25 carboxy groups per molecule, and an acid value of 70 mg KOH / g. A thermally crosslinked product was obtained in the same manner as in Example 1, except that 4,4'-methylenebis(N,N-diglycidylaniline) was used as the crosslinking agent and THF was used as the solvent.

[0059] [ka]

[0060] For the crosslinked products obtained in Example 1, Example 2, and Comparative Example 1, (1) moldability was evaluated, (2) temperature dispersion viscoelasticity was measured, (3) a tensile test was conducted, (4) the linear expansion coefficient was measured, (5) a stress relaxation test was conducted, and (6) recyclability was evaluated.

[0061] (1) Formability The crosslinked products of Examples 1 and 2 could be molded into a film when pressed for 1 hour in a heat press at 150° C. The appearance of the molded crosslinked product of Example 1 is shown in FIG.

[0062] (2) Temperature-dispersive viscoelasticity Using an MCR302 (manufactured by Anton Paar), temperature dispersion viscoelasticity was measured in the temperature decreasing mode over a temperature range of 190°C to -50°C. The measurements were carried out in a N2 gas atmosphere at a temperature change rate of 5°C / min. The measurement frequency was 1 Hz and the strain was 0.1%. The measurement sample used was a disk with a diameter of 8 mm and a thickness of 0.5 mm. FIG. 2 shows the temperature dependence of the storage modulus (G') and loss tangent tanδ for the crosslinked products obtained in Example 1, Example 2, and Comparative Example 1. In FIG. 2, the solid line shows the temperature dependence of the storage modulus (G'), and the dashed line shows the temperature dependence of the loss tangent tanδ. In Examples 1 and 2, a tanδ peak (α-relaxation peak) due to segmental relaxation is observed in the region of approximately 30°C. Below this peak, the sample is in a glassy state, while above this peak, it is in a rubbery state. The rubbery plateau region is stable within the measurement temperature range, indicating that the crosslink density remains unchanged. On the other hand, in Comparative Example 1, an α-relaxation peak is observed at approximately -30°C. As a result, Examples 1 and 2 have higher moduli near room temperature than Comparative Example 1. Furthermore, the rubbery plateau modulus values ​​of Examples 1 and 2 are also higher than Comparative Example 1. From these findings, it can be said that Examples 1 and 2 have higher material strength than Comparative Example 1 near room temperature and in the high-temperature region.

[0063] (3) Tensile test Measurement conditions: The tensile test was performed at room temperature using an AGS-500NX (Shimadzu Corporation). The tensile test speed was 10 mm / min. The specimen used was a dumbbell 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 modulus of Example 1 was 3.0 MPa, that of Example 2 was 4.4 MPa, and that of Comparative Example 1 was 0.5 MPa. The Young's moduli of Examples 1 and 2 were significantly larger than that of Comparative Example 1. This is consistent with the results of the temperature dispersion viscoelasticity measurement described above.

[0064] (4) Linear expansion coefficient The linear expansion coefficient was measured in the range of room temperature to 240°C using a TMA7100 (manufactured by Hitachi HighTech Corporation). The measurements were carried out in a N2 gas atmosphere at a temperature change rate of 10°C / min. The samples used were strips measuring 4 mm wide, 0.5 mm thick, and 20 mm long. FIG. 4 shows the results of the linear expansion coefficient test measurement for Example 1. The vertical axis represents the sample length (L 100℃ ) is the sample length (L) normalized by . Deviation from the linear extrapolation assuming constant elongation was observed above approximately 150°C, indicating that the sample softened. DSC measurements showed that this softening was not due to glass transition, and thermal weight loss measurements revealed that the thermal decomposition temperature (5% weight loss) was 210°C. In other words, this softening was due to the activation of bond exchange, suggesting that cross-linking bonds were constantly being exchanged above approximately 150°C. Similarly, in Example 2, the sample softened at approximately 150°C. These results demonstrate that bond exchange was activated even without the addition of a catalyst.

[0065] (5) Stress relaxation test Stress relaxation tests were performed using an MCR302 (manufactured by Anton Paar) at temperatures of 100°C, 150°C, 160°C, 170°C, or 180°C in a N2 gas atmosphere. The samples used were disk-shaped samples with a diameter of 8 mm and a thickness of 0.5 mm. Figure 5 shows the results of stress relaxation measurements on the cross-linked product of Example 1. The vertical axis shows stress (σ) normalized by the initial stress (σ0), and the horizontal axis shows elapsed time. Significant stress relaxation was observed between 150°C and 180°C, and it can be seen that the relaxation rate increased with increasing temperature. This is because the bond exchange rate accelerates with increasing temperature. On the other hand, the stress relaxation curve at 100°C for the cross-linked product of Example 1 shown in Fig. 5 shows that stress relaxation does not progress. The linear expansion coefficient test suggests that bond exchange is activated at temperatures of approximately 150°C or higher, and it was found that bond exchange is frozen at 100°C. Figure 6 shows a comparison of stress relaxation measurement data between Example 1 and Comparative Example 1. The measurement temperatures used for the comparison were 160°C, 170°C, and 180°C. If the relaxation time is defined as the point at which the elastic modulus becomes 1 / e (=0.37) times the initial elastic modulus, the relaxation time at 180°C for Example 1 was approximately 60 seconds, while the relaxation time at 180°C for Comparative Example 1 was approximately 3,400 seconds. In other words, the bond exchange resin with tertiary amino groups introduced into the side chains (Example 1) achieved an approximately 50-fold increase in bond exchange rate compared to the case where tertiary amino groups were introduced into the crosslinking points (Comparative Example 1). Comparisons at other temperatures are summarized in Table 1.

[0066] FIG. 7 shows a comparison of stress relaxation measurement data between Example 1 and Example 2. The measurement temperature used for the comparison was 180°C. As with Example 1, the crosslinked product of Example 2 also showed significant stress relaxation, confirming the progress of bond exchange. The relaxation rate of the crosslinked product of Example 2 was almost the same as that of Example 1, and was significantly higher than that of Comparative Example 1. Table 1 summarizes the relaxation times at each temperature for the crosslinked product of Example 2. These results demonstrate that bond exchange proceeds sufficiently quickly even without the addition of a catalyst.

[0067] [Table 1]

[0068] (6) Recyclability The crosslinked product of Example 1 was shredded using a cutter. The shredded sample was placed in a disk-shaped Teflon (registered trademark) mold and subjected to a heat press treatment (150°C, 1 hour). A disk-shaped sample was obtained in which the shredded samples were fused together by the heat press (Figure 8). This result suggests that bond exchange between the surfaces of the shredded samples and molecular penetration into the opposing surfaces had progressed sufficiently. On the other hand, in Comparative Example 1, where bond exchange was slow, no fused sample was obtained under the same conditions. Thus, it was found that samples in which bond exchange progressed quickly were superior in terms of expressing recyclability.

[0069] Manufacturing Example 3 Using 25.42 g (100.0 mmol) of bis-2-hydroxyethyl terephthalate, 10.42 g (100.0 mmol) of 1,5-pentanediol, and 30.03 g (200.0 mmol) of thiomalic acid, melt polycondensation was carried out (100°C, 8 hours) in the presence of 0.49 g (1.0 mmol) of scandium triflate to obtain a polyester (PE-SH2) containing thiol group side chains.

[0070] [ka]

[0071] 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 stirred at room temperature for 24 hours, resulting in a Michael addition reaction of the thiol group of PE-SH2 to DAPAM and AA. Per mole of thiol group in PE-SH2, 2.5 moles of DAPAM and 0.5 moles of AA were used. The reaction solution was concentrated using a rotary evaporator and then added dropwise to a large excess of tetrahydrofuran with stirring. The resulting precipitate was collected by filtration (reprecipitation purification). This reprecipitation purification process was repeated twice using DMF as a dissolution solvent (good solvent) and tetrahydrofuran as a precipitation solvent (poor solvent), followed by vacuum drying to obtain the desired product (PE-COOH-Amine-3). The number average molecular weight (Mn) of PE-COOH-Amine-3 was 4324 g / mol, the carboxyl group:tertiary amino group ratio was 30:70, and the acid value was 75 mgKOH / g.

[0072] [ka]

[0073] Example 3 PE-COOH-Amine-3 (0.8 g) and 1,4-butanediol diglycidyl ether (BDE) (0.11 g) were dissolved in N-methylpyrrolidone (NMP), and the resulting solutions were mixed in a polytetrafluoroethylene container. BDE was added in an amount that resulted in equimolar amounts of carboxyl and epoxy groups. The NMP solution was left on a heater at 100°C for approximately 24 hours to evaporate the solvent. The solution was then vacuum dried at 100°C for 7 hours to completely evaporate the solvent and dry it. The resulting dried sample was then 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.

[0074] Example 4 The thiol group of PE-SH2 was added to AA and DAPAM in the same manner as in Production Example 4, except that the amounts of acrylic acid (AA) and N-[3-(dimethylamino)propyl]acrylamide (DAPAM) used were changed, to obtain the target product (PE-COOH-Amine-4). PE-COOH-Amine-4 had a number average molecular weight (Mn) of 4269 g / mol, a carboxy group:tertiary amino group ratio of 50:50, and an acid value of 97.2 mgKOH / g. A thermally crosslinked product was obtained in the same manner as in Example 3, except that the obtained PE-COOH-Amine-4 was used.

[0075] The crosslinked products obtained in Examples 3 and 4 were subjected to (2) temperature dispersion viscoelasticity measurement, (4) linear expansion coefficient measurement, and (5) stress relaxation test.

[0076] (2) Temperature-dispersive viscoelasticity Using an MCR302 (manufactured by Anton Paar), temperature dispersion viscoelasticity was measured in the temperature decreasing mode over a temperature range of 190°C to 20°C. The temperature change rate was 5°C / min in a N2 gas atmosphere. The measurement frequency was 1 Hz, and the strain was 0.1%. The measurement sample used was a disk with a diameter of 8 mm and a thickness of 0.5 mm. Figure 9 shows the temperature dependence of the storage modulus (G') and loss tangent tanδ for the crosslinked products obtained in Examples 3 and 4. In Figure 9, the solid line shows the temperature dependence of the storage modulus (G'), and the dashed line shows the temperature dependence of the loss tangent tanδ. In Examples 3 and 4, a tanδ peak (α relaxation peak) resulting from segmental relaxation is observed in the region of approximately 50°C. Below this peak region, the sample is in a glassy state, and above this peak region, it is in a rubbery state. The rubbery plateau region is stable within the measurement temperature range, indicating that the crosslink density does not change.

[0077] (4) Linear expansion coefficient The linear expansion coefficient was measured in the range of room temperature to 200°C using a TMA7100 (manufactured by Hitachi HighTech Corporation). The measurements were carried out in a N2 gas atmosphere at a temperature change rate of 10°C / min. The samples used were strips measuring 4 mm wide, 0.5 mm thick, and 20 mm long. FIG. 10 shows the results of the linear expansion coefficient test measurement for Example 3. The vertical axis represents the sample length (L 100℃ ) is the sample length (L) normalized by the temperature. At temperatures above approximately 160°C, deviation from the linear extrapolation assuming constant elongation is observed, indicating that the sample is softening. FIG. 11 shows the results of the linear expansion coefficient test measurement for Example 4. The vertical axis represents the sample length (L 130℃ ) is the sample length (L) normalized by the temperature. Deviation from the linear extrapolation assuming constant elongation is observed above approximately 160°C, indicating that the sample is softening. These findings demonstrate that bond exchange is activated even without the addition of a catalyst.

[0078] (5) Stress relaxation test A stress relaxation test was performed using an MCR302 (manufactured by Anton Paar) at temperatures of 100°C, 160°C, 170°C, or 180°C in a N2 gas atmosphere. The samples used were disk-shaped samples with a diameter of 8 mm and a thickness of 0.5 mm. Figure 12 shows the results of stress relaxation measurements on the cross-linked product of Example 3. The vertical axis shows stress (σ) normalized by the initial stress (σ0), and the horizontal axis shows elapsed time. Significant stress relaxation was observed between 160°C and 180°C, and it can be seen that the relaxation rate increased with increasing temperature. This is because the bond exchange rate accelerates with increasing temperature. On the other hand, the stress relaxation curve at 100°C for the cross-linked product of Example 3 shown in Figure 12 does not show any progress in stress relaxation. A linear expansion coefficient test suggested that bond exchange is activated at temperatures above approximately 160°C, and it was found that bond exchange was frozen at 100°C. Figure 13 shows the results of stress relaxation measurements on the cross-linked product of Example 4. The vertical axis shows stress (σ) normalized by the initial stress (σ0), and the horizontal axis shows elapsed time. Significant stress relaxation was observed between 160°C and 180°C, and it can be seen that the relaxation rate increased with increasing temperature. This is because the bond exchange rate accelerates with increasing temperature. On the other hand, the stress relaxation curve at 100°C for the cross-linked product of Example 4 shown in Figure 13 does not show any progress in stress relaxation. A linear expansion coefficient test suggested that bond exchange is activated at temperatures above approximately 160°C, and it was found that bond exchange was frozen at 100°C.

[0079] The relaxation times at each temperature for the crosslinked products of Examples 3 and 4 are summarized in Table 2 below. These show that bond exchange proceeds sufficiently quickly even without the addition of a catalyst.

[0080] [Table 2]

[0081] The crosslinked products obtained in Examples 1 to 4 and Comparative Example 1 were (7) measured for softening temperature, (8) evaluated for scratch repairability, (9) evaluated for molding processability, and (10) evaluated for extrusion moldability. The evaluation results of softening temperature, scratch repairability, molding processability, and extrusion moldability are shown in Table 3 below.

[0082] (7) Softening temperature The softening temperature was determined from the bending point of the change in the linear expansion coefficient of the sample from room temperature to 300°C using a Hitachi "TMA7100." The measurement was carried out in a nitrogen gas atmosphere with a small constant tension (30 mN) applied to prevent sample deflection. The initial jig distance was 15 mm. When a bending point was observed, the corresponding temperature was recorded.

[0083] (8) Scratch repair A cross-linked polyester resin film measuring 1.5 cm long x 1.5 cm wide x 0.7 mm thick was produced from the cross-linked product, and the surface of the resulting cross-linked polyester resin film was scratched (approximately 0.1 mm deep) using a cutter. The cross-linked polyester resin film was then subjected to a heat treatment process. The heat treatment process involved leaving the film at a high temperature (softening temperature + approximately 20°C) for 10 minutes and then allowing it to cool to room temperature. After the heat treatment process, if the scratches disappeared and the crosslinked aromatic polyester resin film had no scratches on the surface, the scratch repair property (self-repair property) was evaluated as good (evaluated as ◯), and if scratches remained, the scratch repair property (self-repair property) was evaluated as poor (evaluated as ×).

[0084] (9) Molding processability A cross-linked polyester resin film (0.7 mm thick) produced from the cross-linked product was cut into a 5 mm wide x 5 mm long sample, and the resulting sample was placed in a mold. The mold was made by cutting an 8 mm diameter circle out of a 1 mm thick Teflon (registered trademark) sheet. The sample was then pressurized and heated in a heat press. The pressure was 4 MPa, and the heating conditions were softening temperature + 30°C for 15 minutes. When the crosslinked polyester resin film piece could be molded into the mold shape, the moldability was evaluated as good (evaluated as ◯), and when it could not be molded, the moldability was evaluated as bad (evaluated as x).

[0085] (10) Extrusion moldability 6 g of cross-linked polyester resin film (thickness 0.7 mm) produced from the cross-linked product was cut into a width of 5 mm and a length of 5 mm. The obtained sample was fed into a twin-screw extruder "MiniLab" manufactured by HAAKE in three batches at a barrel temperature of 170°C and a screw rotation speed of 50 min-1 After the sample was completely charged, the mixture was kneaded for 5 minutes, and then the kneaded mixture was extruded from the barrel. After kneading, if the kneaded material could be discharged and a filamentous molded body was obtained, the extrusion moldability was evaluated as good (evaluated as ○), and if the kneaded material could not be discharged and a filamentous molded body was not obtained, the extrusion moldability was evaluated as poor (evaluated as ×).

[0086] [Table 3]

[0087] As is clear from Table 3, the crosslinked products obtained in Examples 1 to 4 had a low softening temperature and exhibited properties of scratch repairability, molding processability, and extrusion moldability. On the other hand, the crosslinked product obtained in Comparative Example 1 had good molding processability, but had a high softening temperature and poor scratch repairability and extrusion moldability. [Industrial Applicability]

[0088] The crosslinked polyester resin of the present invention can be applied to polymer-based resin materials, film materials, elastomer materials, gel materials, etc. It is particularly advantageous for use in the presence of water and oil, which has previously been considered unsuitable for bond exchange resins (tubes, packing, vehicle components, etc.).

Claims

1. a crosslinked polyester resin in which a polyester resin having a plurality of side chains each having a carboxy group and a plurality of side chains each having a tertiary amino group is crosslinked with an epoxy-based crosslinking agent having a plurality of epoxy groups; The polyester resin is a polycondensate of a polycarboxylic acid component (A) and a polyhydric alcohol component (B), The polycarboxylic acid component (A) contains a side chain-forming polycarboxylic acid component, and the side chain-forming polycarboxylic acid component has a plurality of side chains each having a carboxy group and a plurality of side chains each having a tertiary amino group formed therein.

2. 2. The crosslinked polyester resin according to claim 1, wherein the number of carboxy groups in the side chains of the polyester resin is 3 to 80 per molecule of the polyester resin.

3. 3. The crosslinked polyester resin according to claim 1, wherein the ratio of the number of tertiary amino groups in side chains of the polyester resin to the number of carboxy groups in side chains of the polyester resin (amino groups:carboxy groups) is 20:80 to 90:

10.

4. The polycarboxylic acid component (A) contains a nucleophilic reactive group-containing polycarboxylic acid component (A3) in an amount of 50 mol% or more based on 100 mol% of the polycarboxylic acid component (A), a part of the nucleophilic reactive group-containing polycarboxylic acid component (A3) undergoes Michael addition to an α,β-unsaturated carboxylic acid (C3C), The crosslinked polyester resin according to any one of claims 1 to 3, wherein a part or all of the remaining nucleophilic reactive group-containing polycarboxylic acid component (A3) undergoes Michael addition to a side chain compound (CN) having a tertiary amino group.

5. 5. The crosslinked polyester resin according to claim 1, wherein the polyhydric alcohol component (B) is at least one selected from the group consisting of an aliphatic diol and an aromatic polyester diol.

6. 6. The crosslinked polyester resin according to claim 1, wherein the epoxy-based crosslinking agent having a plurality of epoxy groups is an aliphatic diol diglycidyl ether.

7. 7. The crosslinked polyester resin according to claim 1, wherein the peak of the temperature change of loss tangent tan δ is in the range of 0 to 100°C.

8. 8. The crosslinked polyester resin according to claim 1, wherein the relaxation time at 160° C. determined from a stress relaxation curve is 1 to 2,000 seconds.

9. the transesterification catalyst is less than 1 part by mass per 100 parts by mass of the polyester resin; 9. The crosslinked polyester resin according to claim 1, wherein the epoxy-based crosslinking agent having a tertiary amino group is less than 30 parts by mole per 100 parts by mole of the epoxy-based crosslinking agent having a plurality of epoxy groups.

10. A crosslinked polyester resin described in any of claims 1 to 9, wherein the polycarboxylic acid component for forming the side chain is either 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 each having a carboxy group and a plurality of side chains each having a tertiary amino group, The polyester resin is a polycondensate of a polycarboxylic acid component (A) and a polyhydric alcohol component (B), The polycarboxylic acid component (A) includes a side chain-forming polycarboxylic acid component, and the side chain-forming polycarboxylic acid component has a plurality of side chains each having a carboxy group and a plurality of side chains each having a tertiary amino group formed therein.

12. A polyester resin as described in Claim 11, wherein the polycarboxylic acid component for forming the side chain is either 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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