Method for producing crosslinkable polyester composition

Abstract

Provided is a method for producing a crosslinkable polyester composition, which can easily provide a polyester that can have a bond exchange type dynamic covalent bond in the future in a state in which workability is good. A cured product having a dynamic covalent bond of a bond exchange type is provided from the crosslinkable polyester composition having good processability. Also provided is a method for producing the cured product from the crosslinkable polyester composition having good processability. Also provided is a molded article containing the crosslinkable polyester composition having good processability. A method for producing a crosslinkable polyester composition, the method including a step of kneading a polyfunctional epoxy compound having a plurality of epoxy groups, a transesterification catalyst, and a copolyester in a heated molten state. A molded body containing a crosslinkable polyester composition, the molded body containing a copolyester, a polyfunctional epoxy compound having a plurality of epoxy groups, and a transesterification catalyst, the molded body having a gel fraction of less than 30%, the molded body being rod-shaped, strand-shaped, granular or flake-shaped.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for producing a cross-linkable polyester composition, a method for producing a cross-linked polyester composition, and a molded body containing a cross-linkable polyester composition. BACKGROUND

[0002] Polyesters are condensation polymers synthesized by dehydration condensation of polycarboxylic acids and polyhydric alcohols, and examples include high molecular compounds produced from terephthalic acid or an ester-forming derivative thereof and ethylene glycol. Polyesters are excellent in terms of versatility and practicality, and are preferably used as materials for films, sheets, fibers, bottles, and the like. Polyesters are expected to be applied to various uses in the future due to their excellent mechanical properties, weather resistance, and chemical resistance, and examples include electrical insulation uses, solar cell uses, and industrial component uses such as tire cords.

[0003] Such a polyester can also be used as a cross-linked polyester by cross-linking between polyesters using a cross-linking agent. Conventional cross-linked polyesters are cross-linked between polyesters by covalent bonds, and thus cannot be subjected to re-molding. In contrast, cross-linked polyesters cross-linked between polyesters by exchangeable dynamic covalent bonds have recently attracted attention. Cross-linked polyesters cross-linked between polyesters by exchangeable dynamic covalent bonds are further subjected to exchangeable dynamic covalent bond reactions by heating, and thus can be subjected to re-molding.

[0004] As an example of production of a cross-linked polyester cross-linked between polyesters by exchangeable dynamic covalent bonds, for example, Non-Patent Literature 1 describes that a cross-linked polyester is produced by heating, melting, and kneading polyethylene terephthalate (PET), a diglycidyl ether of bisphenol A, and 2,2-bis(hydroxymethyl)-2,2',2"-nitrilotriethanol (BIS-TRIS) at 240 to 270°C using a twin-screw extruder, and that the obtained pellets are subjected to post-curing under vacuum at 205°C for 10 hours. Further, Non-Patent Literature 2 describes that a cross-linked polyester is produced by heating, melting, and kneading polybutylene terephthalate (PBT), a diglycidyl ether of bisphenol A, and zinc acetylacetonate hydrate at 270°C using a twin-screw extruder, and that the obtained melt is injected into a test piece-shaped 200°C mold and held. On the other hand, the present inventors et al. disclose in Non-Patent Literature 3 a method for producing a cross-linkable resin film having a gel fraction of about 100% by mixing a mixture of an amorphous polyester resin, 4,4'-methylenebis(N,N-diglycidylaniline), and 1,8-diazabicyclo[5.4.0]undec-7-ene in the presence of THF, removing THF by casting and vacuum drying, and heating the solid at 200°C for 24 hours.

[0005]

Prior Art Documents

[0006]

Non-Patent Literature

[0007] [Non-patent literature 1] Jianfan Qiu, et al., Macromolecules. 2021, 54(2), 703-712.

[0008] [Non-patent literature 2] L. Farge, et al., Macromolecules. 2021, 54(4), 1838-1849.

[0009] [Non-patent literature 3] Mikihiro Hayashi, et al., Journal of Materials Chemistry A, 2022, 34(10), 17406-17414. SUMMARY

[0010]

[0011] The polyethylene terephthalate described in Non-patent literature 1 and the polybutylene terephthalate described in Non-patent literature 2 both have crystallinity, and thus the temperature during heating, melting, and kneading using a twin-screw extruder increases, and the extrudate is already crosslinked at the point of extrusion from the twin-screw extruder. Thus, the flowability of the extrudate is not good, and the processability is poor. On the other hand, in Non-patent literature 3, a mixture containing an amorphous polyester resin is mixed in the presence of THF, and thus a large amount of solvent is required. Furthermore, after the mixture is prepared, 24 hours are required to remove THF and dry it, and there is room for improvement in order to adopt it as an industrial production method.

[0012] The present application is an application that has been made in view of the above-described circumstances, and aims to provide a production method of a crosslinkable polyester composition, which can provide a polyester having a bond exchange type dynamic covalent bond in the future in a state in which the processability is good. Another object of the present application is to provide a cured product (crosslinked polyester composition) having a bond exchange type dynamic covalent bond from the crosslinkable polyester composition having good processability. Another object of the present application is to provide a method of producing the cured product (crosslinked polyester composition) from the crosslinkable polyester composition having good processability. Another object of the present application is to provide a molded body containing the crosslinkable polyester composition having good processability.

[0013]

[0014] The present application is as described below.

[0015] [1] A production method of a crosslinkable polyester composition, comprising: a step of kneading a multifunctional epoxy compound having a plurality of epoxy groups and a transesterification catalyst with a copolyester in a heated and molten state.

[0016] ​​[2] The method for producing a cross-linkable polyester composition according to [1], wherein a step of forming into a prescribed shape is included after the kneading.

[0017] [3] The method for producing a cross-linkable polyester composition according to [1] or [2], wherein the copolymer polyester is an amorphous polyester.

[0018] [4] The method for producing a cross-linkable polyester composition according to any one of [1] to [3], wherein the copolymer polyester contains a first unit composed of terephthalic acid ethylene glycol ester or terephthalic acid butylene glycol ester, and further contains at least one of the components of the following group as an acid component and / or an alcohol component.

[0019] acid component: terephthalic acid, isophthalic acid, sebacic acid

[0020] alcohol component: ethylene glycol, 2,2-dimethyl-l,3-propanediol, 1,4-butanediol

[0021] [5] The method for producing a cross-linkable polyester composition according to any one of [1] to [4], wherein the transesterification catalyst is a catalyst not containing a hydroxyl group.

[0022] [6] The method for producing a cross-linkable polyester composition according to any one of [1] to [5], wherein the kneading is performed at a temperature of 120°C or less than the glass transition temperature (Tg) of the copolymer polyester.

[0023] [7] The method for producing a cross-linkable polyester composition according to any one of [1] to [6], wherein the kneading is performed in a solvent-free state.

[0024] [8] The method for producing a cross-linkable polyester composition according to any one of [1] to [7], wherein the kneading is performed using a twin-screw kneading extruder.

[0025] [9] The method for producing a cross-linkable polyester composition according to [8], wherein a formed body containing the cross-linkable polyester composition in a sheet or film shape is extruded from the twin-screw kneading extruder.

[0026]

[10] A method for producing a cross-linkable polyester composition, which produces a cross-linkable polyester composition by the method according to any one of [1] to [9], and then heats the cross-linkable polyester composition to cross-link it.

[0027]

[11] The method for producing a cross-linkable polyester composition according to

[10] , wherein the cross-linking of the cross-linkable polyester composition is performed by heating at a temperature greater than the kneading temperature.

[0028]

[12] The production method of the cross-linkable polyester composition according to

[10] or

[11] , wherein the cross-linking of the cross-linkable polyester composition is performed by heating at a temperature of 120°C to 250°C for 1 hour or more.

[0029]

[13] A shaped body containing a cross-linkable polyester composition, which contains a copolyester, a multifunctional epoxy compound having a plurality of epoxy groups, and a transesterification catalyst, and has a gel fraction of less than 30%, the shaped body being in a rod shape, a filament shape, a granular shape, or a flake shape.

[0030]

[14] A shaped body containing a cross-linkable polyester composition, which contains a copolyester, a multifunctional epoxy compound having a plurality of epoxy groups, and a transesterification catalyst, and has a gel fraction of less than 30%, the shaped body being in a sheet shape or a film shape having a thickness of 20 μm or more.

[0031]

[15] The shaped body containing a cross-linkable polyester composition according to

[13] or

[14] , wherein the gel fraction after heating at a temperature of 120°C to 250°C for 3 hours is 30% or more.

[0032]

Effects of Invention

[0033] According to the present application, since a copolyester is kneaded with a multifunctional epoxy compound having a plurality of epoxy groups and a transesterification catalyst, the kneaded product can have a dynamic covalent bond of the exchangeable bond type in the future. Also, since the kneaded product is in a non-cross-linked state (i.e., a state having cross-linkability) when it is heated and kneaded, it is possible to make the processability good. When a cross-linkable polyester composition is produced by such a method, a dynamic covalent bond of the exchangeable bond type can be introduced by heating later, so it is possible to easily provide a cross-linked polyester having a dynamic covalent bond of the exchangeable bond type. When the cross-linkable polyester is cross-linked by a dynamic covalent bond of the exchangeable bond type, even after cross-linking, a bond exchange reaction occurs further by heating, so it is possible to perform re-shaping. BRIEF DESCRIPTION OF DRAWINGS

[0034]

Figure 1A

[0035]

Figure 1B

[0036]

Figure 1C

[0037]

Figure 2A

[0038]

Figure 2B

[0039]

Figure 2C

[0040]

Figure 2D

[0041]

Figure 3

[0042]

Figure 4

[0043]

Figure 5A

[0044]

Figure 5B

[0045] The method for manufacturing a crosslinked polyester composition according to embodiments of the present invention is characterized by including a step of compounding a polyfunctional epoxy compound having multiple epoxy groups and an ester exchange catalyst with a copolyester in a heated molten state. In this specification, a crosslinked polyester composition refers to a composition containing polyester before crosslinking, possessing crosslinking properties, and containing polyester that has undergone crosslinking through heating via an epoxy ring-opening reaction or a bond exchange reaction. Furthermore, a substance that crosslinks polyesters by heating a crosslinked polyester composition is also called a crosslinked polyester composition.

[0046] (Copolyester)

[0047] The copolyester used in the embodiments of the present invention can be an aliphatic polyester, an aromatic polyester, or a combination of aliphatic polyester and aromatic polyester.

[0048] Copolyesters can be prepared, for example, by polycondensing an acid component, an alcohol component, and a dicarboxylic acid containing a nucleophilic reactive group (e.g., a thiol group), and then reacting the nucleophilic reactive group of the dicarboxylic acid with an unsaturated carboxylic acid; or by polycondensing an acid component, an alcohol component, and an unsaturated polycarboxylic acid or its anhydride, and then reacting the unsaturated group of the unsaturated polycarboxylic acid with a carboxylic acid having a nucleophilic reactive group.

[0049] As the acid component, a dicarboxylic acid is preferably used as the main component (for example, relative to 100 molar parts of the acid component, the dicarboxylic acid is preferably 60 molar parts or more, more preferably 80 molar parts or more). Examples of dicarboxylic acids that can be used include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic 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 fumaric acid, maleic acid, and terpene-maleic acid adducts. One or more of these dicarboxylic acids may be used. As the acid component, at least one selected from aromatic dicarboxylic acids and aliphatic dicarboxylic acids is preferred. As the acid component, for example, tricarboxylic acids or tetracarboxylic acids such as trimellitic acid, pyromellitic acid, and 3,3',4,4'-benzophenone tetracarboxylic acid can be used. It is preferable to supply the tricarboxylic acid or tetracarboxylic acid as an anhydride to the polycondensation reaction.

[0050] As the alcohol component, for example, aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-l,3-propanediol, 2,2-dimethyl-l,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 3-methyl-l,5-pentanediol, 2,4-diethyl-l,5-pentanediol, 1,6-hexanediol, 3-methyl-l,6-hexanediol, 4-methyl-l,7-heptanediol, 2-methyl-l,8-octanediol, 4-methyl-l,8-octanediol, 4-propyl-l,8-octanediol, 1,9-nonanediol, and the like; polyether glycols such as diethylene glycol, triethylene glycol, and the like; polyalkylene glycols such as polyethylene glycol, polytetramethylene glycol, and the like; alicyclic polyols such as 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecane glycols, hydrogenated bisphenols, and the like; glycol-modified aromatic dicarboxylic acids such as 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, and the like; alkylene oxide-adducts of phenols such as ethylene oxide-adducts of bisphenol A, propylene oxide-adducts of bisphenol A, and the like; and the like can be used. One of these can be used as the alcohol component, or two or more of these can be used. As the alcohol component, an aliphatic diol is preferred.

[0051] The copolymerized polyester is, for example, preferably one that contains a first unit composed of ethylene terephthalate or butylene terephthalate, and further contains at least one of the components of the following group as an acid component and / or an alcohol component.

[0052] Acid component: terephthalic acid, isophthalic acid, sebacic acid

[0053] Alcohol component: ethylene glycol, 2,2-dimethyl-l,3-propanediol, 1,4-butanediol

[0054] As the dicarboxylic acid containing a nucleophilic reaction group, for example, a dicarboxylic acid containing a mercapto group as the nucleophilic reaction group can be used, and a fatty acid dicarboxylic acid having a mercapto group with a carbon number of about 4 to 10, such as thiomalic acid, is preferably used.

[0055] As the unsaturated carboxylic acid that reacts with the nucleophilic reaction group of the dicarboxylic acid, for example, an aliphatic α,β-unsaturated monocarboxylic acid with a carbon number of about 3 to 10, such as acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, and the like can be used.

[0056] As the unsaturated polycarboxylic acid, for example, an aliphatic α,β-unsaturated dicarboxylic acid with a carbon number of about 4 to 10, such as maleic acid, fumaric acid, and the like can be used.

[0057] As the carboxylic acid having a nucleophilic reaction group with the unsaturated group of the unsaturated polycarboxylic acid, for example, a fatty acid having a thiol group, such as mercaptoacetic acid, mercapto propionic acid, and the like, having 2 to 10 carbon atoms can be used.

[0058] The number average molecular weight (Mn) of the copolyester is, for example, preferably 6,000 to 50,000. By making the number average molecular weight (Mn) of the copolyester 6,000 or more, heat resistance can be improved. The number average molecular weight (Mn) is more preferably 6,500 or more, and further preferably 7,000 or more. However, when the number average molecular weight (Mn) of the copolyester is too large, the viscosity becomes high and the copolyester becomes difficult to flow, and kneading becomes difficult. Therefore, the number average molecular weight (Mn) is preferably 50,000 or less, more preferably 40,000 or less, further preferably 28,000 or less, and particularly preferably 25,000 or less. That is, the number average molecular weight (Mn) of the copolyester is, for example, more preferably 6,500 to 40,000, further preferably 7,000 to 28,000, and particularly preferably 7,000 to 25,000.

[0059] The acid value of the copolyester is, for example, preferably 0.1 to 5 mgKOH / g, more preferably 0.3 to 3 mgKOH / g, and further preferably 0.5 to 2.0 mgKOH / g. The larger the acid value, the more crosslinking points increase, and the higher the heat resistance.

[0060] The glass transition temperature (Tg) of the copolyester is, for example, preferably -15 to 130°C. By making the glass transition temperature (Tg) of the copolyester 130°C or less, the flowability of the crosslinkable polyester composition becomes good. Therefore, the heating temperature at the time of kneading the copolyester with the multifunctional epoxy compound having a plurality of epoxy groups and the ester exchange catalyst can be easily reduced, and although the polyester easily crosslinks, crosslinking thereof can be suppressed, and the flowability of the kneaded product can be easily improved. The glass transition temperature (Tg) of the copolyester is more preferably 100°C or less, and further preferably 80°C or less. The lower limit of the glass transition temperature (Tg) of the copolyester is not particularly limited, and from the viewpoint of the mechanical properties after curing, for example, the glass transition temperature (Tg) is preferably -15°C or more, more preferably 1°C or more, and further preferably 3°C or more. That is, the glass transition temperature (Tg) of the copolyester is more preferably 1 to 100°C, and further preferably 3 to 80°C.

[0061] The copolyester is preferably an amorphous polyester. Amorphous means a polyester having no clear melting point. By using an amorphous polyester, the heating temperature at the time of kneading the copolyester with the multifunctional epoxy compound having a plurality of epoxy groups and the ester exchange catalyst can be easily reduced.

[0062] (Multifunctional epoxy compound)

[0063] The polyfunctional epoxy compound having a plurality of epoxy groups used in the embodiments of the present application refers to an epoxy compound having 2 or more epoxy groups in the molecule. The number of functional groups (epoxy groups) contained in the polyfunctional epoxy compound can be 3 or more, or 4 or more, and more preferably 4 or more. The upper limit of the number of epoxy groups is not particularly limited, and for example, can be 6 or less, or 5 or less. That is, the number of functional groups (epoxy groups) contained in the polyfunctional epoxy compound is preferably 2 to 6, more preferably 3 to 5, and further preferably 4 to 5.

[0064] As the polyfunctional epoxy compound, for example, bisphenol A diglycidyl ether (hereinafter sometimes referred to as DGEBA), 4,4'-methylenebis(N,N-diglycidylaniline), or the like can be used. Bisphenol A diglycidyl ether is a difunctional epoxy compound having 2 epoxy groups in the molecule. 4,4'-Methylenebis(N,N-diglycidylaniline) is a tetrafunctional epoxy compound having 4 epoxy groups in the molecule. The polyfunctional epoxy compound can be used singly or in combination of two or more.

[0065] The compounding amount of the polyfunctional epoxy compound is, for example, preferably 5 parts by mass or more, more preferably 8 parts by mass or more, and further preferably 10 parts by mass or more, and is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and further preferably 15 parts by mass or less, with respect to 100 parts by mass of the copolymerized polyester. When a plurality of polyfunctional epoxy compounds is used, the total amount is meant. That is, the compounding amount of the polyfunctional epoxy compound is preferably 5 parts by mass to 20 parts by mass, more preferably 8 parts by mass to 18 parts by mass, and further preferably 10 parts by mass to 15 parts by mass, with respect to 100 parts by mass of the copolymerized polyester.

[0066] (Ester exchange catalyst)

[0067] As the ester exchange catalyst used in the embodiments of the present application, a basic catalyst, an acid catalyst, or an inorganic salt catalyst (Lewis acid catalyst) can be used. As the basic catalyst, for example, 1,8-diazabicyclo[5.4.0]-7-undecene (hereinafter sometimes referred to as DBU), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (hereinafter sometimes referred to as TBD), 1-methylimidazole, or the like can be used. As the acid catalyst, for example, p-toluenesulfonic acid or the like can be used. As the inorganic salt catalyst, for example, zinc acetate, tin(II) 2-ethylhexanoate, or the like can be used. The ester exchange catalyst can be used singly or in combination of two or more.

[0068] The compounding amount of the transesterification catalyst is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and further preferably 8 parts by mass or less, relative to 100 parts by mass of the copolymer polyester. The lower limit of the compounding amount of the transesterification catalyst is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 3 parts by mass or more, relative to 100 parts by mass of the copolymer polyester. When a plurality of transesterification catalysts are used, the total amount is meant. That is, the compounding amount of the transesterification catalyst is preferably 1 part by mass to 20 parts by mass, more preferably 2 parts by mass to 10 parts by mass, and further preferably 3 parts by mass to 8 parts by mass, relative to 100 parts by mass of the copolymer polyester.

[0069] The transesterification catalyst is preferably a catalyst that does not contain a hydroxyl group. By using a catalyst that does not contain a hydroxyl group, alcoholysis is less likely to occur, and the gel fraction of the crosslinked polyester composition can be increased.

[0070] The kneading is performed in a state in which the copolymer polyester is heated and molten. By kneading the copolymer polyester in a heated and molten state with the multifunctional epoxy compound having a plurality of epoxy groups and the transesterification catalyst, the carboxyl groups contained in the copolymer polyester react with the epoxy groups contained in the multifunctional epoxy compound, and a crosslinkable polyester composition is obtained. Furthermore, when decomposition of the polyester occurs in the kneading, the carboxyl groups or the hydroxyl groups generated at both ends of the decomposed chain react with the epoxy groups, and thus high-molecular-weightization is achieved. The obtained crosslinkable polyester composition is a composition containing a crosslinkable polyester that can have a bond exchange type dynamic covalent bond in the future, and has good processability.

[0071] The kneading is preferably performed, for example, at a temperature of 120°C or lower than the glass transition temperature (Tg) of the copolymer polyester. By performing the kneading in this temperature range, crosslinking of the copolymer polyester during the kneading can be prevented. The kneading is more preferably performed at a temperature of 120°C or lower than the glass transition temperature (Tg) of the copolymer polyester and 250°C or lower.

[0072] The kneading time is not particularly limited, and is preferably 2 minutes or more, for example. By kneading for 2 minutes or more, uniform kneading can be achieved. The kneading time is more preferably 3 minutes or more. However, when the kneading time is prolonged, the productivity deteriorates. Therefore, the upper limit of the kneading time is preferably 1 hour or less, for example. The kneading time is more preferably 30 minutes or less, and further preferably 15 minutes or less. That is, the kneading time is preferably 2 minutes to 1 hour, more preferably 3 minutes to 30 minutes, and further preferably 3 minutes to 15 minutes.

[0073] The kneading is preferably performed, for example, in a non-active gas atmosphere. As the non-active gas, nitrogen, for example, can be used.

[0074] The kneading is preferably performed in a solvent-free state. By performing the kneading in a solvent-free state, it is not necessary to remove the solvent from the cross-linkable polyester composition obtained by the kneading (i.e., it is not necessary to dry the cross-linkable polyester composition), and thus the cross-linkable polyester composition can be produced in a short time and can be produced industrially.

[0075] The number average molecular weight (Mn) of the cross-linkable polyester composition obtained by the kneading is, for example, preferably 6,000 to 50,000. By making the number average molecular weight (Mn) of the cross-linkable polyester composition 6,000 or greater, the heat resistance can be improved. The number average molecular weight (Mn) is more preferably 6,500 or greater, and further preferably 7,000 or greater. However, when the number average molecular weight (Mn) of the cross-linkable polyester composition is too large, the viscosity becomes high and the flowability becomes poor, and the kneading becomes difficult. Therefore, the number average molecular weight (Mn) is preferably 50,000 or less, more preferably 40,000 or less, further preferably 28,000 or less, and particularly preferably 25,000 or less. That is, the number average molecular weight (Mn) of the cross-linkable polyester composition is more preferably 6,500 to 40,000, further preferably 7,000 to 28,000, and particularly preferably 7,000 to 25,000.

[0076] The molecular weight distribution of the cross-linkable polyester composition is, for example, preferably 1.5 to 3. The molecular weight distribution can be calculated based on the weight average molecular weight (Mw) and the number average molecular weight (Mn) by the following formula.

[0077] Molecular weight distribution = Mw / Mn

[0078] The molecular weight distribution of the cross-linkable polyester composition is more preferably 1.8 or greater. However, when the molecular weight distribution of the cross-linkable polyester composition is too large, the deviation in the chain length increases, and thus the deviation in the strength of the cross-linkable polyester composition easily occurs. The molecular weight distribution of the cross-linkable polyester composition is more preferably 2.8 or less. That is, the molecular weight distribution of the cross-linkable polyester composition is more preferably 1.8 to 2.8.

[0079] The production method of the cross-linkable polyester composition according to the embodiment of the present application can further include, after the kneading, a step of forming the cross-linkable polyester composition into a predetermined shape such as a film shape, a sheet shape, a pellet shape, a flake shape, a rod shape, a wire shape, or the like.

[0080] The kneading is, for example, preferably performed using an extrusion molding machine, and more preferably using a twin-screw kneading extruder. When a twin-screw kneading extruder is used, a molded body containing the cross-linkable polyester composition in a pellet shape, a flake shape, a rod shape, a wire shape, a sheet shape, or a film shape is preferably extruded from the twin-screw kneading extruder. The molded body containing the cross-linkable polyester composition in a sheet shape or a film shape can be used, for example, as an adhesive sheet or an adhesive film. By sandwiching the molded body containing the cross-linkable polyester composition in a sheet shape or a film shape between substrates (adherend) to be adhered and heating, a bond exchange reaction occurs, and the substrates can be adhered to each other.

[0081] The material of the substrate (adherend) is not particularly limited, and for example, wood, glass, resin, metal, or a composite thereof can be used. The form of the substrate is not particularly limited, and for example, a film, a sheet, a foil, or a plate can be used. As the substrate, for example, a resin film, a metal foil, a metal plate, or the like can be used. As the resin film, for example, a polyimide film, a polyester film, a PET film, or the like can be used. As the metal foil, for example, a copper foil, a silver foil, a gold foil, or the like can be used. As the metal plate, for example, an aluminum plate, a stainless steel plate, a steel plate, an iron plate, or the like can be used. The shaped body containing the cross-linkable polyester composition can be used as an adhesive between the same or different substrates, and for example, can be used as an adhesive between resin films, between metal foils, or between a resin film and a metal foil.

[0082] Another embodiment of the present application relates to a shaped body containing a cross-linkable polyester composition, which contains a copolymerized polyester, a polyfunctional epoxy compound having a plurality of epoxy groups, and an ester exchange catalyst, and has a gel fraction of less than 30%, and is in the form of a rod, a filament, a particle, or a flake. By making the gel fraction of the shaped body containing the cross-linkable polyester composition less than 30%, the processability is excellent.

[0083] Another embodiment of the present application relates to a shaped body containing a cross-linkable polyester composition, which contains a copolymerized polyester, a polyfunctional epoxy compound having a plurality of epoxy groups, and an ester exchange catalyst, and has a gel fraction of less than 30%, and is in the form of a sheet or a film having a thickness of 20 μm or more. By making the gel fraction of the shaped body containing the cross-linkable polyester composition less than 30%, the processability is excellent. The thickness of the shaped body containing the cross-linkable polyester composition can be 20 μm to 3 mm, 0.1 mm to 2 mm, or 0.5 mm to 1.5 mm. The shaped body containing the cross-linkable polyester composition is a sheet or a film, and for example, can be used as an adhesive sheet or an adhesive film. By sandwiching the shaped body containing the cross-linkable polyester composition and being in the form of a sheet or a film between substrates (adherends) to be adhered and heating, cross-linking occurs via an epoxy ring-opening reaction or a bond exchange reaction, and the substrates can be adhered. As the substrates, the above-described substrates can be used.

[0084] The gel fraction of the shaped body containing the cross-linkable polyester composition is preferably 30% or more by heating at a temperature of 120°C to 250°C for 3 hours, more preferably 40% or more by heating at a temperature of 120°C to 250°C for 6 hours, and further preferably 50% or more by heating at a temperature of 120°C to 250°C for 12 hours.

[0085] The cross-linked polyester composition of the present embodiment is obtained by heating the cross-linkable polyester composition. The cross-linkable polyester composition is cross-linked by heating, and the cross-linked polyester composition (cured product) obtained by cross-linking the cross-linkable polyester composition is subjected to a bond exchange reaction by further heating, and can be subjected to reforming processing.

[0086] Next, a method for producing the cross-linked polyester composition according to another embodiment of the present invention will be described. The cross-linked polyester composition according to the present embodiment is a cured product of the cross-linkable polyester composition described above, and can be produced by cross-linking the cross-linkable polyester composition by heating. That is, the method for producing the cross-linked polyester composition has the gist including the following steps: a step of kneading a multifunctional epoxy compound having a plurality of epoxy groups and an ester exchange catalyst with a copolymer polyester in a heated molten state, and a step of cross-linking the cross-linkable polyester composition obtained by the above step by heating.

[0087] When producing the cross-linked polyester composition, the cross-linkable polyester composition is preferably heated at a temperature higher than the kneading temperature at which the cross-linkable polyester composition is produced, and specifically, is preferably heated at a temperature of 120°C to 250°C. The heating temperature is more preferably 130°C or higher, further preferably 140°C or higher, more preferably 240°C or lower, and further preferably 230°C or lower. That is, the heating temperature is more preferably 130°C to 240°C, and further preferably 140°C to 230°C. The time for heating is not particularly limited as long as the cross-linking sufficiently proceeds, but is, for example, about 10 minutes to about 10 hours, and can be shorter or longer than this. The heating time can be 1 hour or more, or 1 hour to 10 hours.

[0088] The cross-linked polyester composition has reforming properties, and after being deformed into a prescribed shape, is subjected to reforming by heating in the deformed state to cause a bond exchange reaction, and maintains the prescribed shape even after cooling. The heating temperature can be, for example, 120°C to 250°C, 130°C to 240°C, or 140°C to 230°C.

[0089] The crosslinked polyester composition is excellent in formability, extrusion formability, and the like, and is useful as a molding material, for example. The crosslinked polyester composition is also useful as a material for 3D printing or a material for a network structure, for example. The network structure is a structure in which linear bodies composed of the crosslinked polyester composition are fused at the intersections of the linear bodies to form a network. The shape of the linear bodies is not particularly limited, and the linear bodies can be solid or hollow, and the cross-sectional shape of the linear bodies can be circular or irregular.

[0090] The crosslinked polyester composition is also useful as an adhesive sheet or an adhesive film, for example. When used as an adhesive sheet or an adhesive film, the crosslinked polyester composition is sandwiched between substrates (adherends) to be adhered and heated, and the epoxy ring-opening reaction or the bond exchange reaction occurs, and thus the substrates are adhered to each other. As the substrates, the above-described substrates can be used.

[0091] This application claims the benefit of priority of Japanese Patent Application No. 2023-115347 filed on July 13, 2023. For the purpose of reference, the entire contents of the specification of the above-mentioned Japanese Patent Application No. 2023-115347 are hereby incorporated by reference in the present application.

[0092]

EXAMPLES

[0093] The present application is described in more detail below by citing examples, but the present application is not limited by the following examples, and modifications can be made within the scope of the above and below-described main points, and these are included in the technical scope of the present application. In the following, “parts” means “mass parts”.

[0094] A multifunctional epoxy compound having a plurality of epoxy groups and a transesterification catalyst are kneaded in a copolymerized polyester in a heated molten state to produce a crosslinkable polyester composition.

[0095] A copolymerized polyester A1 or a copolymerized polyester A2 manufactured by Toyo Rikki Co., Ltd. was used as a copolymerized polyester, which was sufficiently dried in advance. The copolymerized polyester A1 and the copolymerized polyester A2 were prepared according to the following procedure.

[0096] (Copolymerized Polyester A1)

[0097] A reaction vessel equipped with a stirrer, a thermometer, and a condenser for distillation was charged with 50 moles of terephthalic acid, 20 moles of isophthalic acid, 30 moles of sebacic acid, 58 moles of ethylene glycol, 42 moles of 2,2-dimethyl-l,3-propanediol, and 0.2 moles of tetrabutyl titanate, and the temperature was slowly raised to 250°C while removing water distilled out of the system, to thereby perform esterification. After completion of the esterification, the temperature was raised to 250°C while slowly reducing the pressure to 10 mmHg and simultaneously performing initial polymerization under reduced pressure, and further performing post-polymerization under a pressure of 1 mmHg or less until a predetermined torque was reached, to thereby obtain copolymerized polyester Al. The composition of the copolymerized polyester Al is shown in Table 1 below.

[0098] (Copolymerized polyester A2)

[0099] A reaction vessel equipped with a stirrer, a thermometer, and a condenser for distillation was charged with 50 moles of terephthalic acid, 20 moles of isophthalic acid, 30 moles of sebacic acid, 58 moles of ethylene glycol, 42 moles of 2,2-dimethyl-l,3-propanediol, and 0.2 moles of tetrabutyl titanate, and the temperature was slowly raised to 250°C while removing water distilled out of the system, to thereby perform esterification. After completion of the esterification, the temperature was raised to 250°C while slowly reducing the pressure to 10 mmHg and simultaneously performing initial polymerization under reduced pressure, and further performing post-polymerization under a pressure of 1 mmHg or less until a predetermined torque was reached, to thereby obtain copolymerized polyester Al. The composition of the copolymerized polyester Al is shown in Table 1 below.

[0100] The copolymerized polyester Al and the copolymerized polyester A2 do not have a cross-linking functional group in the side chain and are linear amorphous polyesters.

[0101] Then, the acid value (mgKOH / g) and the glass transition temperature (°C) of the copolymerized polyester Al and the copolymerized polyester A2 were measured according to the following procedures and are shown in Table 1 below.

[0102] (Acid value)

[0103] The copolymerized polyester 0.2 g was dissolved in chloroform 20 ml, and phenothalin as an indicator was added to the solution, which was titrated with a 0.1 N potassium hydroxide ethanol solution. The acid value (mgKOH / g) was calculated from the amount of the neutralized potassium hydroxide (mgKOH) per 1 g of the copolymerized polyester.

[0104] (Glass transition temperature)

[0105] The glass transition temperature (Tg) was determined using a DSC7020 (HITACHI HighTech) at a temperature change rate of 10°C / min in the range of -50°C to 200°C in an N2 atmosphere.

[0106] [Table 1]

[0107]

[0108] Further, the number average molecular weight (Mn) was measured according to the following procedure for the copolyesters Al, A2.

[0109] (Number average molecular weight (Mn)

[0110] The copolyester was dissolved in dimethylformamide (DMF) so that the concentration became about 0.5 mass%, and the material filtered with a polytetrafluoroethylene membrane filter having a pore size of 0.5 μm was set as a sample for measurement. DMF to which LiBr (0.05 mass%) was added was set as a mobile phase, and the number average molecular weight (Mn) was measured by gel permeation chromatography with a differential refractometer as a detector. The flow rate was set to 0.5 mL / minute, and the column temperature was set to 40°C. The chromatographic column used was KF-803, KF-804L, or KF-805L manufactured by Showa Denko. The standard material (molecular weight standard) used was monodisperse polymethyl methacrylate. Low molecular compounds (oligomers, etc.) having a number average molecular weight (Mn) of less than 1000 were not counted and were omitted.

[0111] The number average molecular weight (Mn) of the copolyester Al was 27267, and the weight average molecular weight (Mw) was 50559, and the number average molecular weight (Mn) of the copolyester A2 was 23604, and the weight average molecular weight (Mw) was 44018.

[0112] As the multifunctional epoxy compound having a plurality of epoxy groups, 4,4'-methylenebis(N,N-diglycidyl aniline) or bisphenol A diglycidyl ether was used. 4,4'-Methylenebis(N,N-diglycidyl aniline) is a tetrafunctional epoxy compound having four epoxy groups. Bisphenol A diglycidyl ether (DGEBA) is a bifunctional epoxy compound having two epoxy groups.

[0113] As the transesterification catalyst, diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), or zinc acetate was used. Diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and zinc acetate are all catalysts that do not contain a hydroxyl group.

[0114] (Example 1)

[0115] A cross-linkable polyester composition was produced by mixing 100 parts of the copolymer polyester Al in a heated molten state with 10 parts of 4,4'-methylenebis(N,N-diglycidylaniline) and 2.5 parts of DBU. The mixing was performed using a twin-screw kneader [Haake (trademark) MiniLab] manufactured by Thermo Fisher Scientific in a solvent-free state. The mixing was performed for 5 minutes in a nitrogen atmosphere at a temperature of 120°C and a rotation speed of 50 rpm. The resulting cross-linkable polyester composition was designated as cross-linkable polyester composition 1.

[0116] (Example 2)

[0117] A cross-linkable polyester composition was produced under the same conditions as in Example 1, except that 4,4'-methylenebis(N,N-diglycidylaniline) in Example 1 was changed to 20 parts. The resulting cross-linkable polyester composition was designated as cross-linkable polyester composition 2.

[0118] (Comparative Example 1)

[0119] A cross-linkable polyester composition was produced under the same conditions as in Example 1, except that 4,4'-methylenebis(N,N-diglycidylaniline) in Example 1 was not used. The resulting cross-linkable polyester composition was designated as comparative cross-linkable polyester composition 1.

[0120] (Comparative Example 2)

[0121] A cross-linkable polyester composition was produced under the same conditions as in Example 1, except that 4,4'-methylenebis(N,N-diglycidylaniline) in Example 1 was not used and DBU was changed to 5 parts. The resulting cross-linkable polyester composition was designated as comparative cross-linkable polyester composition 2.

[0122] (Comparative Example 3)

[0123] A cross-linkable polyester composition was produced under the same conditions as in Example 1, except that DBU in Example 1 was not used. The resulting cross-linkable polyester composition was designated as comparative cross-linkable polyester composition 3.

[0124] (Example 3)

[0125] A cross-linkable polyester composition was produced under the same conditions as in Example 1, except that 100 parts of the copolymer polyester A2 was used instead of 100 parts of the copolymer polyester Al in Example 1. The resulting cross-linkable polyester composition was designated as cross-linkable polyester composition 3.

[0126] (Example 4)

[0127] A cross-linkable polyester composition was produced under the same conditions as in Example 1 except that 2.5 parts of zinc acetate was used instead of 2.5 parts of DBU in Example 1. The cross-linkable polyester composition thus obtained is hereinafter referred to as cross-linkable polyester composition 4.

[0128] (Comparative Example 4)

[0129] A cross-linkable polyester composition was produced under the same conditions as in Example 1 except that 100 parts of polybutylene terephthalate (PBT) was used instead of 100 parts of copolymerized polyester Al in Example 1 and the kneading temperature was changed to 270°C. The polybutylene terephthalate is a crystalline polyester. The cross-linkable polyester composition thus obtained is hereinafter referred to as comparative cross-linkable polyester composition 4.

[0130] (Comparative Example 5)

[0131] A cross-linkable polyester composition was produced under the same conditions as in Example 1 except that 100 parts of polybutylene terephthalate (PBT) was used instead of 100 parts of copolymerized polyester Al in Example 1, 1 part of DGEBA was used instead of 10 parts of 4,4'-methylenebis(N,N-diglycidyl aniline), and the kneading temperature was changed to 270°C. The cross-linkable polyester composition thus obtained is hereinafter referred to as comparative cross-linkable polyester composition 5.

[0132] (Example 5)

[0133] A cross-linkable polyester composition was produced under the same conditions as in Example 1 except that 10 parts of DGEBA was used instead of 10 parts of 4,4'-methylenebis(N,N-diglycidyl aniline) in Example 1. The cross-linkable polyester composition thus obtained is hereinafter referred to as cross-linkable polyester composition 5.

[0134] The compositions (parts) of the cross-linkable polyester compositions 1 to 5 obtained in Examples 1 to 5 and the comparative cross-linkable polyester compositions 1 to 5 obtained in Comparative Examples 1 to 5 are shown in Table 2 below.

[0135] [Table 2-1]

[0136]

[0137] [Table 2-2]

[0138]

[0139] Then, for the cross-linkable polyester compositions and the comparative cross-linkable polyester compositions, GPC chromatograms were measured and number average molecular weights (Mn) and molecular weight distributions (Mw / Mn) were calculated according to the following procedures.

[0140] [Number-average molecular weight (Mn) and molecular weight distribution (Mw / Mn)]

[0141] GPC chromatograms of crosslinked polyester compositions were determined using size exclusion chromatography. A solution of dimethylformamide dissolved in the crosslinked polyester composition at a concentration of approximately 0.2% by mass was used as the sample. Dimethylformamide containing 0.05% by mass lithium bromide was used as the mobile phase. A Shimadzu RID-20A detector and a Shimadzu LC-20AD pump system were used to determine the GPC chromatograms, and the number-average molecular weight (Mn) and weight-average molecular weight (Mw) were calculated. The flow rate was set to 1.0 mL / min, and the column temperature was set to 40 °C. Shodex K-803, K-804, and K-805 columns were used. Polymethyl methacrylate (PMMA) was used as the standard. The molecular weight distribution (Mw / Mn) was calculated based on the number-average molecular weight (Mn) and weight-average molecular weight (Mw). The results are shown in Table 2 above. In Table 2, "-" indicates that the GPC chromatogram was not determined.

[0142] The GPC chromatograms for the determination of crosslinked polyester compositions 1 and 2 are shown in [the original text]. Figure 1A .like Figure 1A Curve E1 represents the result for crosslinked polyester composition 1, and curve E2 represents the result for crosslinked polyester composition 2. The GPC chromatograms comparing the determinations of crosslinked polyester compositions 1 and 2 are shown below. Figure 1B . Figure 1B Curve CE1 represents the results of comparing crosslinked polyester composition 1, and curve CE2 represents the results of comparing crosslinked polyester composition 2. The GPC chromatogram for comparing crosslinked polyester composition 3 is shown below. Figure 1C . Figure 1C The curve CE3 shown represents the results of comparing cross-linked polyester composition 3. Figures 1A-1C The GPC chromatogram for the determination of copolyester A1 is also shown in the image. Figures 1A-1C Curve A1 shown represents the result of copolyester A1. Figures 1A-1C In the diagram, the horizontal axis represents the elution time (minutes), and the vertical axis represents the differential refractive index.

[0143] according to Figure 1A The results of Examples 1 and 2 show that the elution times of crosslinked polyester compositions 1 and 2 are longer than those of copolyester A1, resulting in a lower molecular weight. Furthermore, the elution times of crosslinked polyester compositions 1 and 2 also appear to be shorter than those of copolyester A1, thus generating components with slightly increased molecular weights through compounding. Based on these results, it is known that a 4,4'-methylenebis(N,N-diglycidylaniline) component is present, which reacts with the decomposed polyester. Figure 1BFrom the results of Comparative Example 1 and Comparative Example 2, it was found that Comparative Cross-linkable Polyester Compositions 1 and 2 were eluted for a longer time than Copolymerized Polyester Al and were lower in molecular weight. From this result, it was found that DBU initiated decomposition of the main chain of the polyester during kneading. From the results of Comparative Example 2, it was found that the decomposition of 4,4'-methylenebis(N,N-diglycidylaniline) during kneading and the reaction with the epoxy group did not occur. Figure 1C From the results of Comparative Example 3, it was found that Comparative Cross-linkable Polyester Composition 3 did not show a large change in molecular characteristics compared to Copolymerized Polyester Al. From this result, it was found that the decomposition of 4,4'-methylenebis(N,N-diglycidylaniline) during kneading and the reaction with the epoxy group did not occur.

[0144] Next, the adhesiveness of Cross-linkable Polyester Compositions 3 and 4 was evaluated. Cross-linkable Polyester Compositions 3 and 4 were sandwiched with TEFLON (registered trademark) sheets, and pressed for 2 minutes at 180°C and 2 MPa using a hot press to make sheet shapes. Two aluminum sheets were prepared as substrates, and Cross-linkable Polyester Compositions 3 and 4 were sandwiched with the two aluminum sheets, and pressed for 5 minutes at 180°C and 2 MPa using a hot press, and the material heated for 3 hours in an oven at 180°C was set as Test Piece a. Two polyethylene terephthalate films (PET films) were prepared as substrates, and Cross-linkable Polyester Compositions 3 and 4 were sandwiched with the two PET films, and pressed for 5 minutes at 180°C and 2 MPa using a hot press, and the material heated for 3 hours in an oven at 180°C was set as Test Piece b. After the heated Test Pieces a and b were left to cool to room temperature, the substrates were touched by hand, and the adhesiveness was evaluated.

[0145] The results of the evaluation were that Cross-linkable Polyester Composition 3 was adhered in either case of the aluminum sheet and the PET film. Cross-linkable Polyester Composition 4 was adhered in either case of the aluminum sheet and the PET film.

[0146] Next, the change in viscoelasticity when Cross-linkable Polyester Compositions or Comparative Cross-linkable Polyester Compositions were heated was measured, and the cross-linking reaction was investigated. Specifically, Cross-linkable Polyester Compositions or Comparative Cross-linkable Polyester Compositions were heated, and isothermal time-division viscoelasticity measurement was performed according to the following procedure.

[0147] [Isothermal time-division viscoelasticity measurement]

[0148] Cross-linkable Polyester Compositions or Comparative Cross-linkable Polyester Compositions were heated for 3 hours at 180°C, and isothermal time-division viscoelasticity measurement was performed. In the isothermal time-division viscoelasticity measurement, the change in storage modulus (G') and the change in loss modulus (G'') with respect to the heating time were measured. MCR102 manufactured by Anton paar was used as the measurement device. A disposable aluminum jig with a diameter of 8 mm was used as the jig. The shape of the test piece was set to a diameter of 8 mm and a thickness of about 0.5 mm. The measurement was performed in a nitrogen atmosphere.

[0149] The isothermal time-slice viscoelasticity diagram measured for the cross-linkable polyester composition 1 is shown in Figure 2A The isothermal time-slice viscoelasticity diagram measured for the cross-linkable polyester composition 2 is shown in Figure 2B The isothermal time-slice viscoelasticity diagram measured for the comparative cross-linkable polyester composition 1 is shown in Figure 2A The isothermal time-slice viscoelasticity diagram measured for the comparative cross-linkable polyester composition 3 is shown in Figure 2B . Figure 2C In the above diagrams, the horizontal axis represents time (sec), and the vertical axis represents the storage modulus (G') or the loss modulus (G").

[0150] In the measurement in which the temperature and the frequency are set constant, the progress of the cross-linking reaction upon heating can be tracked based on the storage modulus (G') and the loss modulus (G"). In a temperature much higher than the glass transition temperature of the cross-linkable polyester composition, G" > G' when the cross-linking is insufficient, but upon the progress of the cross-linking by heating, G' rises, and after a certain period of time, G' = G" is reached. The time at which G' = G" is reached can be simply determined as the gelation time, and the time scale of the progress of the cross-linking under a certain temperature condition can be evaluated. Further, upon a certain heating time, G" < G' is reached, which can be regarded as a state in which the cross-linking is sufficiently progressed in the range.

[0151] As is clear from Figure 2D , the G' of the cross-linkable polyester composition 1 rose significantly with the passage of time, and the gelation point at which G' = G" was reached was about 100 seconds from the start of heating. This result indicates that the decomposition of the chain of the copolymerized polyester Al and the reaction with 4,4'-methylenebis(N,N-diglycidylaniline) proceeded, and a network structure was formed. It is considered that in this system, the hydroxyl group and the carboxylic acid group generated by the decomposition reacted with 4,4'-methylenebis(N,N-diglycidylaniline), an epoxy ring-opening reaction occurred, and further, the network grew gradually by the bond exchange reaction between the hydroxyl group generated based on the epoxy ring-opening reaction and the chain of the copolymerized polyester Al.

[0152] As is clear from Figure 2C , the G' of the cross-linkable polyester composition 2 rose with the passage of time, and the gelation point at which G' = G" was reached was about 1000 seconds from the start of heating. This result indicates that the decomposition of the chain of the copolymerized polyester Al and the reaction with 4,4'-methylenebis(N,N-diglycidylaniline) proceeded, and a network structure was formed. It is considered that in this system, the hydroxyl group and the carboxylic acid group generated by the decomposition reacted with 4,4'-methylenebis(N,N-diglycidylaniline), an epoxy ring-opening reaction occurred, and further, the network grew gradually by the bond exchange reaction between the hydroxyl group generated based on the epoxy ring-opening reaction and the chain of the copolymerized polyester Al.

[0153] As is clear fromFigure 2D and Figure 3 As a result, it was found that the compounding amount of 4, 4'-methylenebis (N, N-diglycidyl aniline) had an influence on the gelation time. It was considered that by setting the compounding amount of 4, 4'-methylenebis (N, N-diglycidyl aniline) to 10 parts, the gelation was performed in a short time. In addition, the value of the storage modulus (G') of the cross-linkable polyester composition 1 was 0.81 MPa and the value of the storage modulus (G') of the cross-linkable polyester composition 2 was 0.013 MPa when heated at 180°C for 3 hours.

[0154] As a result, it was found that the compounding amount of 4, 4'-methylenebis (N, N-diglycidyl aniline) had an influence on the cross-linking density of the cross-linked polyester composition. It was considered that by setting the compounding amount of 4, 4'-methylenebis (N, N-diglycidyl aniline) to 10 parts, the cross-linking density was increased.

[0155] According to Figure 3 Even if time passed, the value of the loss modulus (G") of the comparative cross-linkable polyester composition 1 was substantially constant, but the value of the storage modulus (G') decreased as time passed. The comparative cross-linkable polyester composition 1 was an example in which the multifunctional epoxy compound having a plurality of epoxy groups was not contained, and it was shown that the polyester was slowly decomposed during the heating process by the action of DBU.

[0156] According to Figure 3 Even if time passed, the value of the loss modulus (G") of the comparative cross-linkable polyester composition 3 was substantially constant, but the value of the storage modulus (G') decreased as time passed. The comparative cross-linkable polyester composition 3 was an example in which the ester exchange catalyst was not contained, and it was found that the molecular weight of the polyester was slowly increased during the heating process by the reaction of the copolymer polyester Al and 4, 4'-methylenebis (N, N-diglycidyl aniline).

[0157] As Figure 3 and Figure 4 It was found that the gelation point at which G' = G" was not detected, and it was considered that the cross-linking reaction was not performed even when heated at 180°C.

[0158] Then, the cross-linkable polyester composition or the comparative cross-linkable polyester composition was heated, and the gel fraction of the obtained sample (cross-linked polyester composition) was measured.

[0159] [Measurement of Gel Fraction]

[0160] Crosslinked polyester compositions 1 and 2 were heated at 180°C to prepare a sample (crosslinked polyester composition). The heating time was set to 3 hours, 6 hours, 12 hours, or 24 hours. The obtained sample was immersed in a solvent (tetrahydrofuran) for 24 hours, and the solvent exchange step was repeated 3 times. After the 3 times, the sample was removed, vacuum dried, and the dry weight (m) was measured. d ). Compared with the initial weight before heating (m) i In comparison, the gel fraction (f) is calculated based on the following formula. gel ).

[0161] f gel (%) = m d / m i ×100

[0162] In addition, crosslinked polyester compositions 3-5 and comparative crosslinked polyester compositions 4 and 5 were heated at 180°C, and the gel fraction of the resulting samples (crosslinked polyester compositions) was calculated. The heating time was set to 3 hours, 6 hours, or 12 hours. For comparative crosslinked polyester compositions 4 and 5, samples were prepared under the same conditions as above, except that hexafluoroisopropanol (HFIP) was used instead of tetrahydrofuran as the solvent for impregnating the heated samples, and the gel fraction was calculated.

[0163] The calculated gel fractions are shown in Table 2. In Table 2, the results of determining the gel fraction of the crosslinked polyester composition itself before heating are also shown in the column for heating time 0 hours. Furthermore, for the example using DBU as the transesterification catalyst, since DBU is a distillate component, the gel fraction is calculated from the initial weight (m³). i Remove the weight of DBU from the equation.

[0164] The gel fractions calculated for samples 1 and 2 (crosslinked polyester compositions 1 and 2) made from crosslinked polyester compositions 1 and 2 are shown below. Figure 4 . Figure 4 In the diagram, the horizontal axis represents heating time (time), and the vertical axis represents gel fraction (%). Figure 4 In the diagram, ● (black dot) indicates the result of sample 1 obtained by heating cross-linked polyester composition 1, and ▲ (black triangle) indicates the result of sample 2 obtained by heating cross-linked polyester composition 2.

[0165] Depend on Figure 5AIt was found that the crosslinked polyester composition 1 having a high gel fraction of 85 to 90% was obtained by heating the crosslinkable polyester composition 1 at 180°C for 3 hours. However, even if the heating time was extended to more than 3 hours, the gel fraction of the crosslinked polyester composition 1 did not change greatly. The crosslinked polyester composition 2 having a gel fraction of about 30% was obtained by heating the crosslinkable polyester composition 2 at 180°C for 3 hours. The gel fraction of the crosslinked polyester composition 2 was about 30%, and it was found that the crosslinking proceeded more slowly compared to Example 1. This result was consistent with the results of the viscoelasticity measurement described above. In the crosslinkable polyester composition 2, the gel fraction of the crosslinked polyester composition 2 increased by extending the heating time, but even if the heating was performed for 24 hours, the gel fraction of the crosslinked polyester composition 2 was about 55%. From this result, it was found that the compounding amount of 4,4'-methylenebis(N,N-diglycidyl aniline) was an important factor related to the progress of crosslinking of the crosslinkable polyester composition, and affected the gel fraction of the crosslinked polyester composition. By setting the compounding amount of 4,4'-methylenebis(N,N-diglycidyl aniline) to 10 parts, the gel fraction of the crosslinked polyester composition increased.

[0166] Then, regarding the crosslinkable polyester composition 1, except that the heating temperature was set to 120°C, 140°C, or 160°C instead of 180°C and the heating time was set to 3 hours, the sample (crosslinked polyester composition) was produced under the same conditions as described above, and the gel fraction was measured. The measured gel fraction is shown in Table 3.

[0167] [Table 3]

[0168]

[0169] From Tables 2 and 3, it was found that the crosslinkable polyester composition 1 obtained in Example 1 was heated at 180°C for 3 hours to obtain a crosslinked polyester composition having a gel fraction of 85 to 90%. In contrast, when the heating temperature was lowered, the gel fraction of the crosslinked polyester composition decreased.

[0170] Then, the crosslinkable polyester composition 1 was heated and crosslinked, and the crosslinking exchange property of the obtained sample (crosslinked polyester composition) was evaluated. The crosslinking exchange property was evaluated based on the results of the stress relaxation measurement and the results of the reshaping test.

[0171] [Stress relaxation measurement]

[0172] In the stress relaxation measurement, MCR102 manufactured by Anton paar was used as a measurement device. A disposable aluminum jig with a diameter of 8 mm was used as a jig. A test piece was prepared using a sample (crosslinked polyester composition) obtained by heating crosslinkable polyester composition 1 at 180°C for 3 hours. The shape of the test piece was set to a diameter of 8 mm and a thickness of about 0.5 mm. The measurement temperature was set to 170°C, 180°C, 190°C, or 200°C. The measurement was performed in a nitrogen atmosphere. The stress relaxation profile of the measurement is shown in Figure 5B . ​ In the graph, the horizontal axis represents time (sec), and the vertical axis represents stress (σ / σ0) normalized with the initial stress (σ0). ​ The curves shown from the left represent the results of the measurement at 190°C, 180°C, 170°C, and 160°C, respectively.

[0173] As is clear from ​ , significant stress relaxation was observed, and from this result, it was confirmed that bond exchange was performed via a bond exchange reaction at a high temperature.

[0174] [Reformation Test]

[0175] In the reformation test, a test piece (film thickness: 1 mm) in a long strip shape was cut out from a sample (crosslinked polyester composition) obtained by heating crosslinkable polyester composition 1 at 180°C for 3 hours, and the test piece was wound around a glass tube as shown in ​ , and both ends thereof were fixed with a tape, and the test piece was fixed to a spatula. The test piece fixed to the spatula was heated at 180°C in an oven for 1 hour. After the heating for 1 hour, the test piece was left to cool to room temperature, and when the tape was removed, the test piece was fixed in a curved shape as shown in ​ . Even when the test piece fixed in the curved shape was heated using a dryer, it did not return to the original flat shape. It is considered that the sample was reformed because the elasticity disappeared due to the activation of the bond exchange at a high temperature of 180°C, and the new mesh structure was fixed after being left to cool.

[0176] It is considered that, from the above results, by heating the sample (crosslinked polyester composition) at 180°C, it was confirmed that the bond exchange property was introduced while forming a crosslinked structure, and the material conversion from the crosslinkable polyester composition was achieved.

Claims

1. A method for producing a cross-linkable polyester composition, comprising: a step of kneading a polyfunctional epoxy compound having a plurality of epoxy groups and a transesterification catalyst with a copolymerized polyester in a heated molten state.

2. The method for producing a cross-linkable polyester composition according to claim 1, wherein comprises: a step of forming into a prescribed shape after the kneading.

3. The method for producing a cross-linkable polyester composition according to claim 1, wherein, The copolymerized polyester is an amorphous polyester.

4. The method for producing a cross-linkable polyester composition according to claim 1, wherein, The copolymerized polyester contains a first unit composed of an ethylene terephthalate or a butylene terephthalate, and further contains at least one of the components of the following group as an acid component and / or an alcohol component, acid component: terephthalic acid, isophthalic acid, sebacic acid; alcohol component: ethylene glycol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol.

5. The method for producing a cross-linkable polyester composition according to claim 1, wherein, The transesterification catalyst is a catalyst not containing a hydroxyl group.

6. The method for producing the cross-linkable polyester composition according to claim 1, wherein, The kneading is performed at a temperature of 120°C or lower than the glass transition temperature Tg of the copolymerized polyester.

7. The method for producing the cross-linkable polyester composition according to claim 1, wherein, The kneading is performed in a solvent-free state.

8. The method for producing the cross-linkable polyester composition according to claim 1, wherein, The kneading is performed using a twin-screw kneading extruder.

9. The method for producing a cross-linkable polyester composition according to claim 8, wherein, a formed body containing the cross-linkable polyester composition in a sheet or film shape is extruded from the twin-screw kneading extruder.

10. A method for producing a cross-linkable polyester composition, the cross-linkable polyester composition is produced by the method of claim 1, and then the cross-linkable polyester composition is heated to cross-link.

11. The method for producing a cross-linkable polyester composition according to claim 10, wherein The cross-linking of the cross-linkable polyester composition is performed by heating at a temperature higher than the kneading temperature.

12. The method for producing a cross-linkable polyester composition according to claim 10, wherein, The cross-linking of the cross-linkable polyester composition is performed by heating at a temperature of 120°C to 250°C for 1 hour or more.

13. A formed body containing a cross-linkable polyester composition, which contains a copolymerized polyester, a polyfunctional epoxy compound having a plurality of epoxy groups, and a transesterification catalyst, the formed body having a gel fraction of less than 30%, and the formed body being in a rod shape, a filament shape, a granular shape, or a flake shape.

14. A formed body containing a cross-linkable polyester composition, which contains a copolymerized polyester, a polyfunctional epoxy compound having a plurality of epoxy groups, and a transesterification catalyst, the formed body having a gel fraction of less than 30%, and the formed body being in a sheet or film shape having a thickness of 20 μm or more.

15. The shaped body containing a crosslinkable polyester composition according to claim 13 or 14, wherein, The gel fraction after heating at a temperature of 120°C to 250°C for 3 hours is 30% or more.

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