Process for producing a crosslinkable polyester composition

Abstract

Provided is a method for producing a crosslinkable polyester composition, with which a polyester able to contain bond exchange type dynamic covalent bonds in the future can be provided in a condition having favorable workability in a simple manner. Also provided is a cured product having bond exchange type dynamic covalent bonds from the crosslinkable polyester composition having favorable workability. Also provided is a method for producing the cured product from the crosslinkable polyester composition having favorable workability. Also provided is a molded body containing the crosslinkable polyester composition having favorable workability.　The method for producing a crosslinkable polyester composition includes a step for kneading a copolyester in a heated molten state with a polyfunctional epoxy compound having a plurality of epoxy groups and a transesterification catalyst. The molded body contains a crosslinkable polyester composition which contains: a copolyester; a polyfunctional epoxy compound having a plurality of epoxy groups; and a transesterification catalyst. The crosslinkable polyester composition has a gel fraction of less than 30%, and is in the form of a rod, a yarn, a granule or flake.

Description

Technical Field

[0001] The present invention relates to a method for producing a crosslinkable polyester composition, a method for producing a crosslinked polyester composition, and a molded article containing the crosslinkable polyester composition.

Background Art

[0002] Polyester is a polycondensate synthesized by dehydrative condensation of a polyvalent carboxylic acid and a polyalcohol, and examples thereof include polymers produced from terephthalic acid or its ester-forming derivative and ethylene glycol. Polyester is excellent in terms of versatility and practicality, and is suitably used, for example, as a material for films, sheets, fibers, bottles, etc. Polyester is expected to be applied to various uses in the future due to its excellent mechanical properties, weather resistance, and chemical resistance, and examples thereof include industrial part uses such as electrical insulation uses, solar cell uses, and tire cords.

[0003] Such polyesters are also used as crosslinked polyesters by crosslinking polyesters with a crosslinking agent. Conventional crosslinked polyesters could not be reshaped because the polyesters were crosslinked by covalent bonds. In recent years, however, crosslinked polyesters in which polyesters are crosslinked by bond-exchange type dynamic covalent bonds have attracted attention. The crosslinked polyester crosslinked by bond-exchange type dynamic covalent bonds undergoes a bond-exchange reaction by further heating, enabling reshaping.

[0004] As an example of the production of a crosslinked polyester crosslinked by a combination-exchange type dynamic covalent bond, for example, Non-Patent Document 1 describes that polyethylene terephthalate (PET), diglycidyl ether of bisphenol A, and 2,2-bis(hydroxymethyl)-2,2’,2’’-nitrilotriethanol (BIS-TRIS) are heated at 240 to 270 °C using a twin-screw extruder, melted, kneaded to produce pellets, and the obtained pellets are post-cured at 205 °C for 10 hours under vacuum. Further, Non-Patent Document 2 describes that polybutylene terephthalate (PBT), diglycidyl ether of bisphenol A, and zinc acetylacetonate hydrate are heated at 270 °C using a twin-screw extruder, melted, kneaded, and the obtained melt is injected into a 200 °C mold in the shape of a test piece and held. On the other hand, the present inventors disclosed in Non-Patent Document 3 a method for producing a binding exchangeable resin film with 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]-7-undecene in the presence of THF, removing THF by casting and vacuum drying, and then heating the solid at 200 °C for 24 hours.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] Since both polyethylene terephthalate described in Non-Patent Document 1 and polybutylene terephthalate described in Non-Patent Document 2 have crystallinity, the temperature when heating, melting, and kneading using a twin-screw extruder becomes high, and they were already crosslinked at the time of extrusion from the twin-screw extruder. Therefore, the extrudate had poor fluidity and inferior processability. On the other hand, in Non-Patent Document 3, since a mixture containing an amorphous polyester resin is mixed in the presence of THF, a large amount of solvent is required. Further, since it takes about 24 hours to remove THF and dry the mixture after the preparation of the mixture, there is room for improvement in order to adopt it as an industrial manufacturing method.

[0007] The present invention has been made paying attention to the above circumstances, and its object is to provide a method for producing a crosslinkable polyester composition that can easily provide a polyester that may have a bond exchange type dynamic covalent bond in the future in a state with good processability. Another object of the present invention is to provide a cured product (crosslinked polyester composition) having a bond exchange type dynamic covalent bond from the crosslinkable polyester composition with good processability. Another object of the present invention is to provide a method for producing the cured product (crosslinked polyester composition) from the crosslinkable polyester composition with good processability. Another object of the present invention is to provide a molded body containing the crosslinkable polyester composition with good processability.

Means for Solving the Problems

[0008] The present invention is as follows. [1] A method for producing a crosslinkable polyester composition, comprising a step of kneading a copolymer polyester in a heat-melted state with a polyfunctional epoxy compound having a plurality of epoxy groups and a transesterification catalyst. [2] The method for producing a crosslinkable polyester composition according to [1], comprising a step of molding into a predetermined shape after the kneading. [3] The method for producing a crosslinkable polyester composition according to [1] or [2], wherein the copolyester is an amorphous polyester. [4] The method for producing a crosslinkable polyester composition according to any one of [1] to [3], wherein the copolyester contains a first unit composed of ethylene terephthalate or butylene terephthalate, and further contains at least one component from the following groups 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 crosslinkable polyester composition according to any one of [1] to [4], wherein the transesterification catalyst is a catalyst that does not contain a hydroxyl group. [6] The method for producing a crosslinkable polyester composition according to any one of [1] to [5], wherein the kneading is performed at a temperature of the glass transition temperature (Tg) of the copolyester + 120°C or lower. [7] The method for producing a crosslinkable polyester composition according to any one of [1] to [6], wherein the kneading is performed in a solvent-free state. [8] The method for producing a crosslinkable polyester composition according to any one of [1] to [7], wherein the kneading is performed using a twin-screw kneading extruder. [9] The method for producing a crosslinkable polyester composition according to [8], wherein a molded article containing a sheet-like or film-like crosslinkable polyester composition is extruded from the twin-screw kneading extruder.

[10] The method for producing a crosslinked polyester composition, which comprises producing a crosslinkable polyester composition by the method according to any one of [1] to [9], and then heating and crosslinking the crosslinkable polyester composition.

[11] The method for producing a crosslinked polyester composition according to

[10] , wherein the crosslinking of the crosslinkable polyester composition is performed by heating at a temperature exceeding the temperature at which the kneading is performed.

[12] The method for producing a crosslinked polyester composition according to

[10] or

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

[13] A molded article comprising a crosslinkable polyester composition containing a copolyester, a polyfunctional epoxy compound having a plurality of epoxy groups, and a transesterification catalyst, having a gel fraction of less than 30%, and being rod-shaped, filamentous, granular or flaky.

[14] A molded article comprising a crosslinkable polyester composition containing a copolyester, a polyfunctional epoxy compound having a plurality of epoxy groups, and a transesterification catalyst, having a gel fraction of less than 30%, and being in the form of a sheet or film with a film thickness of 20 μm or more.

[15] A molded article comprising the crosslinkable 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.

Advantages of the Invention

[0009] According to the present invention, since the copolyester is kneaded with a polyfunctional epoxy compound having a plurality of epoxy groups and a transesterification catalyst, the kneaded product can potentially have bond exchange type dynamic covalent bonds in the future. Moreover, since this kneaded product is in a non-crosslinked state (i.e., a state having crosslinkability) while being heat-kneaded, the processability can be improved. By producing a crosslinkable polyester composition in such a manner, a crosslinked polyester having bond exchange type dynamic covalent bonds can be easily provided since a bond exchange type dynamic covalent bond can be introduced by heating thereafter. When the crosslinkable polyester is crosslinked by bond exchange type dynamic covalent bonds, a bond exchange reaction occurs by further heating even after crosslinking, enabling re-molding processing.

Brief Description of the Drawings

[0010]

Figure 1A

Figure 1B

Figure 1C

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Figure 2B

Figure 2C

Figure 2D

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Figure 5A

Figure 5B

Mode for Carrying Out the Invention

[0011] The manufacturing method of the crosslinkable polyester composition according to an embodiment of the present invention is characterized by including a step of kneading a polycondensation polyester in a heat-melted state with a polyfunctional epoxy compound having a plurality of epoxy groups and a transesterification catalyst. In this specification, the crosslinkable polyester composition refers to a composition containing a polyester before crosslinking, having crosslinkability, and including a polyester in which crosslinking occurs through an epoxy ring-opening reaction or a bond exchange reaction by heating. Further, a composition obtained by heating the crosslinkable polyester composition to crosslink the polyesters is called a crosslinked polyester composition.

[0012] (Copolymerized polyester) The copolymerized polyester used in the embodiment of the present invention may be an aliphatic polyester, an aromatic polyester, or a combination of an aliphatic polyester and an aromatic polyester.

[0013] The copolymerized polyester can be prepared, for example, by polycondensing a dicarboxylic acid containing an acid component, an alcohol component, and a nucleophilic reaction group (e.g., a thiol group), and then reacting the nucleophilic reaction group of the dicarboxylic acid with an unsaturated carboxylic acid, or by polycondensing an acid component, an alcohol component, and an unsaturated polyvalent carboxylic acid or its anhydride, and then reacting the unsaturated group of the unsaturated polyvalent carboxylic acid with a carboxylic acid having a nucleophilic reaction group.

[0014] As the acid component, it is preferable to use dicarboxylic acid as the main component (for example, preferably 60 mol parts or more, more preferably 80 mol parts or more of dicarboxylic acid based on 100 mol parts of the acid component). Examples of the dicarboxylic acid include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, 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, dimer acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, tetrahydrophthalic acid, hexahydroisophthalic acid, 1,2-cyclohexenedicarboxylic acid; unsaturated group-containing dicarboxylic acids such as fumaric acid, maleic acid, terpene-maleic acid adduct; etc. may be used. The dicarboxylic acid may be used alone or in combination of two or more. As the acid component, it is preferable to use at least one selected from the group consisting of aromatic dicarboxylic acids and aliphatic dicarboxylic acids. As the acid component, for example, tricarboxylic acids such as trimellitic acid, pyromellitic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, and tetracarboxylic acids may be used. The tricarboxylic acid and tetracarboxylic acid are preferably subjected to a polycondensation reaction as an acid anhydride.

[0015] Examples of the alcohol component include aliphatic glycols such as ethylene glycol, 1,2 - propylene glycol, 1,3 - propanediol, 2 - methyl - 1,3 - propanediol, 2,2 - dimethyl - 1,3 - propanediol, 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, 3 - methyl - 1,6 - hexanediol, 4 - methyl - 1,7 - heptanediol, 2 - methyl - 1,8 - octanediol, 4 - methyl - 1,8 - octanediol, 4 - propyl - 1,8 - octanediol, 1,9 - nonanediol; polyether glycols such as diethylene glycol and triethylene glycol; polyalkylene glycols such as polyethylene glycol and polytetramethylene glycol; alicyclic polyols such as 1,4 - cyclohexanediol, 1,2 - cyclohexanedimethanol, 1,3 - cyclohexanedimethanol, 1,4 - cyclohexanedimethanol, tricyclodecane glycols, and hydrogenated bisphenols; glycol modified products of 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 orthophthalic acid, and propylene glycol modified orthophthalic acid; alkylene oxide adducts of phenols such as ethylene oxide adduct of bisphenol A and propylene oxide adduct of bisphenol A; etc. The alcohol component may be used singly or in combination of two or more. As the alcohol component, it is preferable to use aliphatic glycols.

[0016] The copolyester preferably contains, for example, a first unit composed of ethylene terephthalate or butylene terephthalate, and further contains at least one component selected from the following groups as an acid component and / or an alcohol component. Acid components: terephthalic acid, isophthalic acid, sebacic acid Alcohol components: ethylene glycol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol

[0017] As the dicarboxylic acid containing a nucleophilic reactive group, for example, a dicarboxylic acid containing a thiol group as a nucleophilic reactive group may be used, and it is preferable to use an aliphatic dicarboxylic acid having 4 to 10 carbon atoms and having a thiol group such as thiomalic acid.

[0018] As the unsaturated carboxylic acid that reacts with the nucleophilic reactive group of the dicarboxylic acid, for example, an aliphatic α,β-unsaturated monocarboxylic acid having 3 to 10 carbon atoms such as acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, etc. may be used.

[0019] As the unsaturated polycarboxylic acid, for example, an aliphatic α,β-unsaturated dicarboxylic acid having 4 to 10 carbon atoms such as maleic acid, fumaric acid, etc. may be used.

[0020] As the carboxylic acid having a nucleophilic reactive group that reacts with the unsaturated group of the unsaturated polycarboxylic acid, for example, an aliphatic monocarboxylic acid having 2 to 10 carbon atoms and having a thiol group such as thioglycolic acid, mercaptopropionic acid, etc. may be used.

[0021] The number average molecular weight (Mn) of the copolyester is preferably, for example, from 6,000 to 50,000. By having the number average molecular weight (Mn) of the copolyester be 6,000 or more, the heat resistance can be improved. The number average molecular weight (Mn) is more preferably 6,500 or more, and even more preferably 7,000 or more. However, if the number average molecular weight (Mn) of the copolyester becomes too large, the viscosity becomes high and it becomes difficult to flow and difficult to knead. Therefore, the number average molecular weight (Mn) is preferably 50,000 or less, more preferably 40,000 or less, even more preferably 28,000 or less, and particularly preferably 25,000 or less. That is, the number average molecular weight (Mn) of the copolyester is more preferably, for example, from 6,500 to 40,000, even more preferably from 7,000 to 28,000, and particularly preferably from 7,000 to 25,000.

[0022] The acid value of the copolyester is preferably, for example, from 0.1 to 5 mgKOH / g, more preferably from 0.3 to 3 mgKOH / g, and even more preferably from 0.5 to 2.0 mgKOH / g. The greater the acid value, the more crosslinking points increase and the heat resistance improves.

[0023] The glass transition point (Tg) of the copolyester is preferably, for example, from -15 to 130°C. By having the glass transition point (Tg) of the copolyester be 130°C or less, the fluidity of the crosslinkable polyester composition becomes good. Therefore, when kneading the copolyester with a polyfunctional epoxy compound having a plurality of epoxy groups and a transesterification catalyst, it becomes easier to lower the heating temperature, and although the polyester is liable to crosslink, the crosslinking can be suppressed and it becomes easier to increase the fluidity of the kneaded product. The glass transition point (Tg) of the copolyester is more preferably 100°C or less, and even more preferably 80°C or less. The lower limit of the glass transition point (Tg) of the copolyester is not particularly limited, but from the viewpoint of the mechanical properties after curing, for example, -15°C or more is preferable, more preferably 1°C or more, and even more preferably 3°C or more. That is, the glass transition point (Tg) of the copolyester is more preferably from 1 to 100°C, and even more preferably from 3 to 80°C.

[0024] The copolyester is preferably an amorphous polyester. Amorphous refers to a polyester that does not have a distinct melting point. By using an amorphous polyester, it becomes easier to lower the heating temperature when kneading the copolyester with a polyfunctional epoxy compound having a plurality of epoxy groups and a transesterification catalyst.

[0025] (Polyfunctional epoxy compound) The polyfunctional epoxy compound having a plurality of epoxy groups used in the embodiments of the present invention refers to an epoxy compound containing two or more epoxy groups in the molecule. The number of functional groups (epoxy groups) contained in the polyfunctional epoxy compound may be 3 or more, or may be 4 or more, and more preferably 4 or more. The upper limit of the number of epoxy groups is not particularly limited, but for example, it may be 6 or less, or may be 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 even more preferably 4 to 5.

[0026] As the polyfunctional epoxy compound, for example, bisphenol A diglycidyl ether (hereinafter sometimes referred to as DGEBA), 4,4'-methylenebis(N,N-diglycidylaniline), etc. can be used. Bisphenol A diglycidyl ether is a bifunctional epoxy compound containing two epoxy groups in the molecule. 4,4'-methylenebis(N,N-diglycidylaniline) is a tetrafunctional epoxy compound containing four epoxy groups in the molecule. The polyfunctional epoxy compound may be used alone or in combination of two or more of these.

[0027] The blending amount of the polyfunctional epoxy compound is preferably, for example, 5 parts by mass or more, more preferably 8 parts by mass or more, still more preferably 10 parts by mass or more, and preferably 20 parts by mass or less, more preferably 18 parts by mass or less, still more preferably 15 parts by mass or less, based on 100 parts by mass of the copolymerized polyester. When a plurality of types of polyfunctional epoxy compounds are used, it refers to the total amount. That is, the blending 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, still more preferably 10 parts by mass to 15 parts by mass, based on 100 parts by mass of the copolymerized polyester.

[0028] (Transesterification catalyst) As the transesterification catalyst used in the embodiments of the present invention, a basic catalyst, an acid catalyst, or an inorganic salt catalyst (Lewis acid catalyst) may be used. As the basic catalyst, for example, 1,8-Diazabicyclo[5.4.0]-7-undecene (1,8-diazabicyclo[5.4.0]-7-undecene. Hereinafter, it may be referred to as DBU.), 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (1,5,7-triazabicyclo[4.4.0]deca-5-ene. Hereinafter, it may be referred to as TBD.), 1-Methylimidazole, etc. may be used. As the acid catalyst, for example, p-Toluenesulfonic Acid, etc. may be used. As the inorganic salt catalyst, for example, zinc acetate, Tin(II) 2-Ethylhexanoate, etc. may be used. The transesterification catalyst may be used alone or in combination of two or more of these.

[0029] The blending amount of the transesterification catalyst is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and still more preferably 8 parts by mass or less with respect to 100 parts by mass of the copolyester. The lower limit of the blending amount of the transesterification catalyst is preferably, for example, 1 part by mass or more, more preferably 2 parts by mass or more, and still more preferably 3 parts by mass or more with respect to 100 parts by mass of the copolyester. When a plurality of types of transesterification catalysts are used, the total amount is meant. That is, the blending amount of the transesterification catalyst is preferably 1 to 20 parts by mass, more preferably 2 to 10 parts by mass, and still more preferably 3 to 8 parts by mass with respect to 100 parts by mass of the copolyester.

[0030] 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.

[0031] Kneading is performed in a state where the copolyester is heated and melted. By kneading the copolyester in a heated and melted state, a polyfunctional epoxy compound having a plurality of epoxy groups, and a transesterification catalyst, the carboxyl group contained in the copolyester reacts with the epoxy group contained in the polyfunctional epoxy compound, and a crosslinkable polyester composition is obtained. When the polyester is decomposed during kneading, the carboxyl group and hydroxyl group generated at both ends of the decomposed chain react with the epoxy group to increase the molecular weight. The obtained crosslinkable polyester composition is a composition containing a crosslinkable polyester that may have a bond exchange type dynamic covalent bond in the future, and has good processability.

[0032] Kneading is preferably performed, for example, at a temperature of the glass transition temperature (Tg) of the copolyester + 120 °C or lower. Kneading in this temperature range can prevent the copolyester from crosslinking during kneading. Kneading is more preferably performed at a temperature of the glass transition temperature (Tg) of the copolyester + 120 °C or lower and at a temperature of 250 °C or lower.

[0033] The kneading time is not particularly limited, but for example, 2 minutes or more is preferred. By kneading for 2 minutes or more, uniform kneading can be achieved. The kneading time is more preferably 3 minutes or more. However, if the kneading time is too long, productivity deteriorates. Therefore, the upper limit of the kneading time is preferably, for example, 1 hour or less. The kneading time is more preferably 30 minutes or less, and even more 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 even more preferably 3 minutes to 15 minutes.

[0034] Kneading is preferably carried out, for example, in an inert gas atmosphere. As the inert gas, for example, nitrogen gas may be used.

[0035] Kneading is preferably carried out in a solvent-free state. By carrying out kneading in a solvent-free state, there is no need to remove the solvent from the crosslinkable polyester composition obtained by kneading (that is, there is no need to dry the crosslinkable polyester composition), so it can be manufactured in a short time and industrial production becomes possible.

[0036] The number average molecular weight (Mn) of the crosslinkable polyester composition obtained by kneading is preferably, for example, 6000 to 50000. By the number average molecular weight (Mn) of the crosslinkable polyester composition being 6000 or more, the heat resistance can be improved. The number average molecular weight (Mn) is more preferably 6500 or more, and even more preferably 7000 or more. However, if the number average molecular weight (Mn) of the crosslinkable polyester composition becomes too large, the viscosity increases and it becomes difficult to flow and difficult to knead. Therefore, the number average molecular weight (Mn) is preferably 50000 or less, more preferably 40000 or less, even more preferably 28000 or less, and particularly preferably 25000 or less. That is, the number average molecular weight (Mn) of the crosslinkable polyester composition is more preferably 6500 to 40000, even more preferably 7000 to 28000, and particularly preferably 7000 to 25000.

[0037] The molecular weight distribution of the crosslinkable polyester composition is preferably, for example, 1.5 to 3. The molecular weight distribution can be calculated by the following formula based on the weight average molecular weight (Mw) and the number average molecular weight (Mn). Molecular weight distribution = Mw / Mn

[0038] The molecular weight distribution of the crosslinkable polyester composition is more preferably 1.8 or more. However, if the molecular weight distribution of the crosslinkable polyester composition becomes too large, the variation in chain length becomes large, so the variation in the strength of the crosslinkable polyester composition is likely to occur. The molecular weight distribution of the crosslinkable polyester composition is more preferably 2.8 or less. That is, the molecular weight distribution of the crosslinkable polyester composition is more preferably 1.8 to 2.8.

[0039] The method for producing a crosslinkable polyester composition according to an embodiment of the present invention may further include a step of forming into a predetermined shape such as a film shape, a sheet shape, a granular shape, a flake shape, a rod shape, a filament shape, etc. after kneading.

[0040] For kneading, it is preferable to use, for example, an extrusion molding machine, and more preferably a twin-screw kneading extruder. When using a twin-screw kneading extruder, it is preferable to extrude a molded body containing a crosslinkable polyester composition in a granular, flake, rod, filament, sheet or film shape from the twin-screw kneading extruder. The molded body containing the crosslinkable polyester composition in a sheet or film shape may be used, for example, as an adhesive sheet or an adhesive film. By sandwiching the molded body containing the crosslinkable polyester composition in a sheet or film shape between substrates (adherend members) to be adhered and heating, a transesterification reaction occurs, and the substrates can be adhered to each other.

[0041] The material of the base material (adherend) is not particularly limited and may be, for example, wood, glass, resin, metal, or a composite material thereof. The form of the base material is not particularly limited and may be, for example, film-like, sheet-like, foil-like, or plate-like. As the base material, for example, a resin film, a metal foil, a metal plate, etc. may be used. As the resin film, for example, a polyimide film, a polyester film, a PET film, etc. may be used. As the metal foil, for example, a copper foil, a silver foil, a gold foil, etc. may be used. As the metal plate, for example, an aluminum plate, a stainless steel plate, a steel plate, an iron plate, etc. may be used. The molded article containing the crosslinkable polyester composition may be used as an adhesive between the same or different types of base materials described above. For example, it may be used as an adhesive between resin films, between metal foils, or between a resin film and a metal foil.

[0042] The molded article containing the crosslinkable polyester composition according to another embodiment of the present invention contains a copolyester, a polyfunctional epoxy compound having a plurality of epoxy groups, and a transesterification catalyst, and is characterized in that the gel fraction is less than 30% and it is rod-shaped, thread-shaped, granular, or flaky. The molded article containing the crosslinkable polyester composition has excellent processability due to the gel fraction being less than 30%.

[0043] The molded article containing the crosslinkable polyester composition according to another embodiment of the present invention includes a copolyester, a polyfunctional epoxy compound having a plurality of epoxy groups, and a transesterification catalyst, and is characterized in that the gel fraction is less than 30% and the film thickness is 20 μm or more and is in the form of a sheet or a film. The molded article containing the crosslinkable polyester composition has excellent processability due to the gel fraction being less than 30%. The film thickness of the molded article containing the crosslinkable polyester composition may be 20 μm to 3 mm, may be 0.1 mm to 2 mm, or may be 0.5 mm to 1.5 mm. The molded article containing the crosslinkable polyester composition and being in the form of a sheet or a film may be used, for example, as an adhesive sheet or an adhesive film. By sandwiching between substrates (adherends) to which a molded article in the form of a sheet or a film containing the crosslinkable polyester composition is to be adhered and heating, crosslinking occurs through an epoxy ring-opening reaction or a bond exchange reaction, and the substrates can be adhered to each other. As the substrate, those described above may be used.

[0044] The gel fraction of the molded article containing the crosslinkable polyester composition preferably becomes 30% or more by heating at a temperature of 120°C to 250°C for 3 hours, more preferably becomes 40% or more by heating at a temperature of 120°C to 250°C for 6 hours, and even more preferably becomes 50% or more by heating at a temperature of 120°C to 250°C for 12 hours.

[0045] A molded article containing a crosslinkable polyester composition according to an embodiment of the present invention has good processability. By heating the molded article containing this crosslinkable polyester composition at a temperature exceeding the kneading temperature during the production of the crosslinkable polyester composition, specifically at a temperature of 120°C (especially above 120°C) to 250°C for 3 hours, a cured product (crosslinked polyester composition) with a gel fraction of 30% or more can be obtained. By heating the molded article containing the crosslinkable polyester composition, the polyesters contained in this crosslinkable polyester composition are crosslinked by an epoxy ring-opening reaction or a bond-exchange type dynamic covalent bond, and a cured product (crosslinked polyester composition) is obtained. The crosslinked polyester composition (cured product) obtained by crosslinking the crosslinkable polyester composition can undergo a bond-exchange reaction by further heating, enabling reshaping processing.

[0046] Next, a method for producing a crosslinked polyester composition according to another embodiment of the present invention will be described. The crosslinked polyester composition according to an embodiment of the present invention is a cured product of the above-described crosslinkable polyester composition and can be produced by heating and crosslinking the crosslinkable polyester composition. That is, the method for producing a crosslinked polyester composition has the gist in that it includes a step of kneading a copolyester in a heat-melted state with a polyfunctional epoxy compound having a plurality of epoxy groups and a transesterification catalyst, and a step of heating and crosslinking the crosslinkable polyester composition obtained through the above step.

[0047] When producing a crosslinked polyester composition, it is preferable to heat the crosslinkable polyester composition at a temperature exceeding the kneading temperature during the production of the crosslinkable polyester composition. Specifically, it is preferably heated at a temperature of 120°C to 250°C. The heating temperature is more preferably 130°C or higher, still more preferably 140°C or higher, and more preferably 240°C or lower, still more preferably 230°C or lower. That is, the heating temperature is more preferably 130°C to 240°C, and still more preferably 140°C to 230°C. The time for heating may be any time as long as the crosslinking proceeds sufficiently and is not uniformly determined. For example, it is about 10 minutes to about 10 hours, and it may be shorter or longer than this. The heating time may be 1 hour or more, or may be 1 hour to 10 hours.

[0048] The crosslinked polyester composition has reprocessability. After being deformed into a predetermined shape, a bond exchange reaction occurs by heating in the deformed state, and it is reformed and retains the predetermined shape even when cooled. The heating temperature may be, for example, 120°C to 250°C, 130°C to 240°C, or 140°C to 230°C.

[0049] Since the crosslinked polyester composition has good molding processability and extrusion moldability, it may be used, for example, as a molding material. The crosslinked polyester composition may be used, for example, as a material for a 3D printer or a material for a network structure. The network structure is a structure in which linear bodies made of a crosslinked polyester composition are fused at the intersections of the linear bodies to form a network. The shape of the linear body is not particularly limited, and the inside of the linear body may be either solid or hollow, and the cross-sectional shape of the linear body may be either circular or irregular.

[0050] The crosslinked polyester composition may be used, for example, as an adhesive sheet or an adhesive film. When used as an adhesive sheet or an adhesive film, it is sandwiched between substrates (adherend members) to which the crosslinked polyester composition is to be adhered, and an epoxy ring-opening reaction or a bond exchange reaction occurs by heating, enabling the substrates to be adhered to each other. As the substrate, those described above may be used.

[0051] This application claims the benefit of priority based on Japanese Patent Application No. 2023-115347 filed on July 13, 2023. The entire contents of the specification of the above Japanese Patent Application No. 2023-115347 are incorporated herein by reference for reference purposes.

Example

[0052] Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, and it is of course possible to make modifications within the scope that conforms to the above and following gists and implement them, and all of them are included in the technical scope of the present invention. Hereinafter, "parts" represents "parts by mass".

[0053] A crosslinkable polyester composition was produced by kneading a polyfunctional epoxy compound having a plurality of epoxy groups and a transesterification catalyst into a copolymer polyester in a heat-melted state.

[0054] As the copolymer polyester, copolymer polyester A1 or copolymer polyester A2 manufactured by Toyobo Co., Ltd., which had been sufficiently dried in advance, was used. Copolymer polyester A1 and copolymer polyester A2 were prepared by the following procedure.

[0055] (Copolymer polyester A1) In a reaction vessel equipped with a stirrer, a thermometer, and a distillation condenser, 50 mol of terephthalic acid, 20 mol of isophthalic acid, 30 mol of sebacic acid, 58 mol of ethylene glycol, 42 mol of 2,2-dimethyl-1,3-propanediol, and 0.2 mol of tetrabutyl titanate were charged, and the temperature was gradually raised to 250°C, and an esterification reaction was carried out while removing the water distilled out of the system. After the completion of the esterification reaction, vacuum initial polymerization was carried out while gradually reducing the pressure to 10 mmHg, and the temperature was raised to 250°C, and then post-polymerization was carried out at 1 mmHg or less until a predetermined torque was obtained to obtain copolymer polyester A1. The composition of copolymer polyester A1 is shown in Table 1 below.

[0056] (Copolymer polyester A2) Into a reaction vessel equipped with a stirrer, a thermometer, and a distillation cooler, 50 moles of terephthalic acid, 50 moles of isophthalic acid, 50 moles of ethylene glycol, 50 moles of 2,2-dimethyl-1,3-propanediol, and 0.2 moles of tetrabutyl titanate were charged. The temperature was gradually raised to 250 °C, and an esterification reaction was carried out while removing the water distilled out of the system. After the completion of the esterification reaction, initial polymerization was carried out while gradually reducing the pressure to 10 mmHg and raising the temperature to 250 °C. Further, post-polymerization was carried out at 1 mmHg or less until a predetermined torque was obtained to obtain a copolymer polyester A2. The composition of the copolymer polyester A2 is shown in Table 1 below.

[0057] The copolymer polyesters A1 and A2 do not have crosslinkable functional groups in the side chains and are linear amorphous polyesters.

[0058] Next, for the copolymer polyesters A1 and A2, the acid value (mgKOH / g) and the glass transition temperature (°C) were measured by the following procedure and shown in Table 1 below. (Acid value) 0.2 g of the copolymer polyester was dissolved in 20 ml of chloroform, phenolphthalein as an indicator was added to this solution, and neutralization titration was carried out with a 0.1 N potassium hydroxide ethanol solution. From the titration amount, the number of mg of potassium hydroxide consumed for neutralization (mgKOH) was converted to the amount per 1 g of the copolymer polyester to calculate the acid value (mgKOH / g). (Glass transition temperature) Using DSC7020 (manufactured by HITACHI HighTech), in the range from -50 °C to 200 °C, under a nitrogen gas atmosphere, the heat flow rate was measured at a temperature change rate of 10 °C / min to determine the glass transition temperature (Tg).

[0059]

Table 1

[0060] Also, for the copolymer polyesters A1 and A2, the number average molecular weight (Mn) was measured by the following procedure. (Number average molecular weight (Mn) The copolyester was dissolved in dimethylformamide (DMF) to a concentration of about 0.5% by mass and filtered through a polytetrafluoroethylene membrane filter with a pore size of 0.5 μm to obtain a measurement sample. Gel permeation chromatography using DMF added with LiBr (0.05% by mass) as the mobile phase and a differential refractometer as the detector was used to measure the number average molecular weight (Mn). The flow rate was 0.5 mL / min and the column temperature was 40°C. Columns KF-803, KF-804L, and KF-805L manufactured by Showa Denko were used. Monodisperse polymethyl methacrylate was used as the standard substance (molecular weight standard). Low molecular weight compounds (oligomers, etc.) with a number average molecular weight (Mn) of less than 1000 were omitted without counting.

[0061] The number average molecular weight (Mn) of copolyester A1 was 27267 and the weight average molecular weight (Mw) was 50559. The number average molecular weight (Mn) of copolyester A2 was 23604 and the weight average molecular weight (Mw) was 44018.

[0062] As the polyfunctional epoxy compound having a plurality of epoxy groups, 4,4'-methylenebis(N,N-diglycidylaniline) or bisphenol A diglycidyl ether was used. 4,4'-methylenebis(N,N-diglycidylaniline) is a tetrafunctional epoxy compound having four epoxy groups. Bisphenol A diglycidyl ether (DGEBA) is a bifunctional epoxy compound having two epoxy groups.

[0063] As the transesterification catalyst, 1,8-Diazabicyclo[5.4.0]-7-undecene (DBU), 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD), or zinc acetate was used. 1,8-Diazabicyclo[5.4.0]-7-undecene, 1,5,7-Triazabicyclo[4.4.0]dec-5-ene, and zinc acetate are all catalysts that do not contain a hydroxyl group.

[0064] (Example 1) 100 parts of the copolyester A1 was heated and melted, and 10 parts of 4,4'-methylenebis(N,N-diglycidylaniline) and 2.5 parts of DBU were kneaded to produce a crosslinkable polyester composition. For the kneading, a twin-screw kneader [Haake (trademark) MiniLab] manufactured by Thermo Fisher Scientific was used, and it was carried out in a solvent-free state. The kneading conditions were at a temperature of 120 °C, a rotation speed of 50 rpm, for 5 minutes, and in a nitrogen gas atmosphere. The obtained crosslinkable polyester composition is hereinafter referred to as crosslinkable polyester composition 1.

[0065] (Example 2) In Example 1, a crosslinkable polyester composition was produced under the same conditions as in Example 1, except that 4,4'-methylenebis(N,N-diglycidylaniline) was changed to 20 parts. The obtained crosslinkable polyester composition is hereinafter referred to as crosslinkable polyester composition 2.

[0066] (Comparative Example 1) In Example 1, a crosslinkable polyester composition was produced under the same conditions as in Example 1, except that 4,4'-methylenebis(N,N-diglycidylaniline) was not used. The obtained crosslinkable polyester composition is hereinafter referred to as comparative crosslinkable polyester composition 1.

[0067] (Comparative Example 2) In Example 1, a crosslinkable polyester composition was produced under the same conditions as in Example 1, except that 4,4'-methylenebis(N,N-diglycidylaniline) was not used and DBU was changed to 5 parts. The obtained crosslinkable polyester composition is hereinafter referred to as comparative crosslinkable polyester composition 2.

[0068] (Comparative Example 3) In Example 1, a crosslinkable polyester composition was produced under the same conditions as in Example 1, except that DBU was not used. The obtained crosslinkable polyester composition is hereinafter referred to as comparative crosslinkable polyester composition 3.

[0069] (Example 3) In Example 1, a crosslinkable polyester composition was produced under the same conditions as in Example 1, except that 100 parts of copolymer polyester A2 was used instead of 100 parts of copolymer polyester A1. The obtained crosslinkable polyester composition is hereinafter referred to as crosslinkable polyester composition 3.

[0070] (Example 4) In Example 1, a crosslinkable 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. The obtained crosslinkable polyester composition is hereinafter referred to as crosslinkable polyester composition 4.

[0071] (Comparative Example 4) In Example 1, a crosslinkable 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 copolymer polyester A1 and the kneading temperature was changed to 270°C. Polybutylene terephthalate is a crystalline polyester. The obtained crosslinkable polyester composition is hereinafter referred to as comparative crosslinkable polyester composition 4.

[0072] (Comparative Example 5) In Example 1, a crosslinkable 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 copolymer polyester A1, 1 part of DGEBA was used instead of 10 parts of 4,4'-methylenebis(N,N-diglycidylaniline), and the kneading temperature was changed to 270°C. The obtained crosslinkable polyester composition is hereinafter referred to as comparative crosslinkable polyester composition 5.

[0073] (Example 5) In Example 1, a crosslinkable 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-diglycidylaniline). The obtained crosslinkable polyester composition is hereinafter referred to as crosslinkable polyester composition 5.

[0074] The compositions (parts) of the crosslinkable polyester compositions 1 to 5 obtained in Examples 1 to 5 and the comparative crosslinkable polyester compositions 1 to 5 obtained in Comparative Examples 1 to 5 are shown in Table 2 below.

[0075] [Table 2-1] [Table 2-2]

[0076] Next, for the crosslinkable polyester composition and the comparative crosslinkable polyester composition, the GPC chromatogram was measured according to the following procedure, and the number average molecular weight (Mn) and the molecular weight distribution (Mw / Mn) were determined.

[0077] [Number average molecular weight (Mn) and molecular weight distribution (Mw / Mn)] Using size exclusion chromatography, the GPC chromatogram of the crosslinkable polyester composition was measured. A sample prepared by dissolving the crosslinkable polyester composition in dimethylformamide so that the concentration was about 0.2% by mass was used as the measurement sample. Dimethylformamide containing 0.05% by mass of lithium bromide was used as the mobile phase, RID-20A manufactured by Shimadzu Corporation (SHIMADZU) was used as the detector, and LC-20AD manufactured by Shimadzu Corporation (SHIMADZU) was used as the pump system to measure the GPC chromatogram, and the number average molecular weight (Mn) and the weight average molecular weight (Mw) were determined. The flow rate was 1.0 mL / min and the column temperature was 40°C. Columns K-803, K-804, and K-805 manufactured by Shodex were used. Poly(methyl methacrylate) was used as the standard substance (molecular weight standard). Based on the number average molecular weight (Mn) and the weight average molecular weight (Mw), the molecular weight distribution (Mw / Mn) was calculated. The results are shown in Table 2 above. In Table 2, "-" indicates that the GPC chromatogram was not measured.

[0078] The GPC chromatograms measured for the crosslinkable polyester compositions 1 and 2 are shown in Fig. 1A. The curve E1 shown in Fig. 1A indicates the result of the crosslinkable polyester composition 1, and the curve E2 indicates the result of the crosslinkable polyester composition 2. The GPC chromatograms measured for the comparative crosslinkable polyester compositions 1 and 2 are shown in Fig. 1B. The curve CE1 shown in Fig. 1B indicates the result of the comparative crosslinkable polyester composition 1, and the curve CE2 indicates the result of the comparative crosslinkable polyester composition 2. The GPC chromatogram measured for the comparative crosslinkable polyester composition 3 is shown in Fig. 1C. The curve CE3 shown in Fig. 1C indicates the result of the comparative crosslinkable polyester composition 3. In Figs. 1A to 1C, the GPC chromatogram measured for the copolyester A1 is also shown. The curve A1 shown in Figs. 1A to 1C indicates the result of the copolyester A1. In Figs. 1A to 1C, the horizontal axis represents the elution time (minutes), and the vertical axis represents the differential refractive index.

[0079] According to the results of Example 1 and Example 2 shown in Fig. 1A, it can be seen that the crosslinkable polyester compositions 1 and 2 have a longer elution time than the copolyester A1, indicating that they have been depolymerized. Also, since the elution curves of the crosslinkable polyester compositions 1 and 2 appear on the shorter time side than that of the copolyester A1, it can be seen that components with a slightly increased molecular weight were also generated by kneading. According to this result, it can be seen that there is a 4,4'-methylenebis(N,N-diglycidylaniline) component that reacts with the decomposed polyester. According to the results of Comparative Example 1 and Comparative Example 2 shown in Fig. 1B, it can be seen that the comparative crosslinkable polyester compositions 1 and 2 have a longer elution time than the copolyester A1, indicating that they have been depolymerized. According to this result, it became clear that DBU induces the decomposition of the main chain of the polyester during kneading. According to the result of Comparative Example 3 shown in Fig. 1C, no significant change in the molecular characteristics was observed for the comparative crosslinkable polyester composition 3 compared to the copolyester A1. According to this result, it became clear that the decomposition of 4,4'-methylenebis(N,N-diglycidylaniline) was not observed during kneading, and no reaction with the epoxy group occurred.

[0080] Next, the adhesiveness of the crosslinkable polyester compositions 3 and 4 was evaluated. The crosslinkable polyester compositions 3 and 4 were sandwiched between Teflon (registered trademark) sheets and pressed at 180 °C and 2 MPa for 2 minutes using a heat press machine to form sheet shapes. Two aluminum pieces were prepared as substrates, and the crosslinkable polyester compositions 3 and 4 were sandwiched between the two aluminum pieces and pressed at 180 °C and 2 MPa for 5 minutes using a heat press machine, and then heated in an oven at 180 °C for 3 hours to obtain test piece a. Two polyethylene terephthalate films (PET films) were prepared as substrates, and the crosslinkable polyester compositions 3 and 4 were sandwiched between the two PET films and pressed at 180 °C and 2 MPa for 5 minutes using a heat press machine, and then heated in an oven at 180 °C for 3 hours to obtain test piece b. After allowing the heated test pieces a and b to cool to room temperature, they were touched by hand to evaluate whether the substrates were adhered.

[0081] As a result of the evaluation, when the crosslinkable polyester composition 3 was used, it was adhered to both the aluminum piece and the PET film. When the crosslinkable polyester composition 4 was used, it was adhered to both the aluminum piece and the PET film.

[0082] Next, the viscoelasticity change when the crosslinkable polyester composition or the comparative crosslinkable polyester composition was heated was measured to conduct a crosslinking reaction investigation. Specifically, the crosslinkable polyester composition or the comparative crosslinkable polyester composition was heated, and isothermal and time-resolved viscoelasticity measurements were performed according to the following procedure.

[0083] [Isothermal and Time-Resolved Viscoelasticity Measurement] The crosslinkable polyester composition or the comparative crosslinkable polyester composition was heated at 180 °C for 3 hours, and isothermal and time-resolved viscoelasticity measurements were performed. In the isothermal and time-resolved viscoelasticity measurement, the change in the storage modulus (G') and the change in the loss modulus (G'') with respect to the heating time were measured. As the measuring device, MCR102 manufactured by Anton paar was used. As the jig, an aluminum disposable jig with a diameter of 8 mm was used. The shape of the test piece was a diameter of 8 mm and a thickness of about 0.5 mm. The measurement was performed in a nitrogen gas atmosphere.

[0084] The isothermal time-resolved viscoelastic spectra measured for the crosslinkable polyester composition 1 are shown in Fig. 2A. The isothermal time-resolved viscoelastic spectra measured for the crosslinkable polyester composition 2 are shown in Fig. 2B. The isothermal time-resolved viscoelastic spectra measured for the comparative crosslinkable polyester composition 1 are shown in Fig. 2C. The isothermal time-resolved viscoelastic spectra measured for the comparative crosslinkable polyester composition 3 are shown in Fig. 2D. In Figs. 2A to 2D, the horizontal axis indicates time (seconds), and the vertical axis indicates the storage modulus (G’) or the loss modulus (G’’).

[0085] In the measurement with constant temperature and frequency, based on the storage modulus (G’) and the loss modulus (G’’), the progress of the crosslinking reaction during heating can be traced. At a temperature sufficiently higher than the glass transition temperature of the crosslinkable polyester composition, when the crosslinking is insufficient, G’’ > G’, but as the crosslinking progresses upon heating, G’ increases, and after a certain period of time, G’ = G’’. The time when G’ = G’’ can be simply defined as the gelation time, and the time scale of the crosslinking progress under certain temperature conditions can be evaluated. When the heating time further elapses, G’’ < G’, and in this region, it can be regarded that the crosslinking has proceeded sufficiently.

[0086] As is clear from Fig. 2A, for the crosslinkable polyester composition 1, G’ increased significantly with the passage of time, and reached the gelation point where G’ = G’’ about 100 seconds after the start of heating. This result indicates that the decomposition of the copolymer polyester A1 chain and the reaction with 4,4’-methylenebis(N,N-diglycidylaniline) proceeded, and a network structure was formed. In this system, it is considered that the hydroxyl groups and carboxylic acid groups generated by the decomposition react with 4,4’-methylenebis(N,N-diglycidylaniline), causing an epoxy ring-opening reaction, and further, a bond exchange reaction occurs between the hydroxyl groups generated by the epoxy ring-opening reaction and the copolymer polyester A1 chain, resulting in the growth of the network.

[0087] As is apparent from Fig. 2B, in the crosslinkable polyester composition 2, G' increased with the passage of time and reached the gelation point where G' = G'' at about 1000 seconds from the start of heating. This result indicates that the chains of the copolyester A1 decomposed and reacted with 4,4'-methylenebis(N,N-diglycidylaniline), forming a network structure. In this system, it is considered that the hydroxyl groups and carboxylic acid groups generated by the decomposition react with 4,4'-methylenebis(N,N-diglycidylaniline), causing an epoxy ring-opening reaction, and further, a network grows by a bond exchange reaction between the hydroxyl groups generated by the epoxy ring-opening reaction and the chains of the copolyester A1.

[0088] From the results of Fig. 2A and Fig. 2B, it can be seen that the compounding amount of 4,4'-methylenebis(N,N-diglycidylaniline) affects the gelation progress time. It is considered that gelation progresses in a short time by setting the compounding amount of 4,4'-methylenebis(N,N-diglycidylaniline) to 10 parts. Also, at the time of heating at 180°C for 3 hours, the value of the storage elastic modulus (G') in the crosslinkable polyester composition 1 was 0.81 MPa, and the value of the storage elastic modulus (G') in the crosslinkable polyester composition 2 was 0.013 MPa.

[0089] As is clear from these results, it can be seen that the compounding amount of 4,4'-methylenebis(N,N-diglycidylaniline) affects the crosslink density of the crosslinked polyester composition. It is considered that the crosslink density increases by setting the compounding amount of 4,4'-methylenebis(N,N-diglycidylaniline) to 10 parts.

[0090] According to Fig. 2C, in the comparative crosslinkable polyester composition 1, the value of the loss elastic modulus (G'') remained almost constant over time, but the value of the storage elastic modulus (G') decreased over time. The comparative crosslinkable polyester composition 1 is an example that does not contain a polyfunctional epoxy compound having a plurality of epoxy groups, indicating that the polyester is slowly decomposing during heating by the action of DBU.

[0091] According to FIG. 2D, in the comparative crosslinkable polyester composition 3, the value of the loss modulus (G'') remained almost constant over time, while the value of the storage modulus (G') increased with time. The comparative crosslinkable polyester composition 3 is an example that does not contain a transesterification catalyst, and it was found that the molecular weight of the polyester increased gradually during heating by the reaction of the copolyester A1 and 4,4'-methylenebis(N,N-diglycidylaniline).

[0092] As is clear from FIGS. 2C and 2D, the gelation point where G' = G'' was not detected, and it is considered that the crosslinking reaction did not proceed even when heated at 180°C.

[0093] Next, the crosslinkable polyester composition or the comparative crosslinkable polyester composition was heated, and the gel fraction of the obtained sample (crosslinked polyester composition) was measured.

[0094] [Measurement of Gel Fraction] The crosslinkable polyester compositions 1 and 2 were heated at 180°C to produce samples (crosslinked polyester compositions). The heating time was 3 hours, 6 hours, 12 hours, or 24 hours. After the obtained samples were immersed in a solvent (tetrahydrofuran) for 24 hours, the procedure of exchanging the solvent was repeated 3 times. After 3 times, the samples were taken out, vacuum dried, and then the dry weight (m d ) was measured. Compared with the initial weight (m i ) before heating, the gel fraction (f gel ) was calculated based on the following formula. f gel (%) = m d / m i × 100

[0095] Also, the crosslinkable polyester compositions 3 to 5 and the comparative crosslinkable polyester compositions 4 and 5 were heated at 180°C, and the gel fraction of the obtained samples (crosslinked polyester compositions) was calculated. The heating time was 3 hours, 6 hours, or 12 hours. For the comparative crosslinkable 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 in which the samples obtained by heating were immersed, and the gel fraction was calculated.

[0096] The calculated gel fractions are shown in Table 2. In Table 2, the results of measuring the gel fraction of the crosslinkable polyester composition itself before heating are also shown in the column for a heating time of 0 hours. For the example using DBU as the transesterification catalyst, since DBU is an outflow component, the weight of DBU was excluded from the initial weight (m i )).

[0097] The gel fractions calculated for Samples 1 and 2 (crosslinked polyester compositions 1 and 2) produced from the crosslinkable polyester compositions 1 and 2 are shown in Figure 3. In Figure 3, the horizontal axis represents the heating time (hours), and the vertical axis represents the gel fraction (%). In Figure 3, ● (black circle) indicates the result of Sample 1 obtained by heating the crosslinkable polyester composition 1, and ▲ (black triangle) indicates the result of Sample 2 obtained by heating the crosslinkable polyester composition 2.

[0098] As is clear from Fig. 3, by heating the crosslinkable polyester composition 1 at 180°C for 3 hours, a crosslinked polyester composition 1 showing a high gel fraction of 85 - 90% was obtained. However, even when the heating time was made longer than 3 hours, the gel fraction of the obtained crosslinked polyester composition 1 did not change significantly. By heating the crosslinkable polyester composition 2 at 180°C for 3 hours, a crosslinked polyester composition 2 with a gel fraction of about 30% was obtained. The gel fraction of the crosslinked polyester composition 2 remained at about 30%, and it was found that the progress of crosslinking was slow compared with Example 1. This result is consistent with the result of the viscoelasticity measurement described above. In the case of the crosslinkable polyester composition 2, the gel fraction of the crosslinked polyester composition 2 increased by increasing the heating time, but even when heated for 24 hours, the gel fraction of the crosslinked polyester composition 2 remained at about 55%. From this result, the blending amount of 4,4'-methylenebis(N,N-diglycidylaniline) is an important factor regarding the progress of crosslinking of the crosslinkable polyester composition, affects the gel fraction of the crosslinked polyester composition, and it was found that the gel fraction of the crosslinked polyester composition increases by setting the blending amount of 4,4'-methylenebis(N,N-diglycidylaniline) to 10 parts.

[0099] Next, for the crosslinkable polyester composition 1, samples (crosslinked polyester compositions) were prepared under the same conditions as above except that the heating temperature was set to 120°C, 140°C, or 160°C instead of 180°C and the heating time was 3 hours, and the gel fraction was measured. The measured gel fractions are shown in Table 3.

[0100]

Table 3

[0101] As is clear from Tables 2 and 3, for the crosslinkable polyester composition 1 obtained in Example 1, a crosslinked polyester composition with a gel fraction of 85 - 90% was obtained by heating at 180°C for 3 hours, whereas it was found that the gel fraction of the crosslinked polyester composition decreased when the heating temperature was lowered.

[0102] Next, the crosslinkable polyester composition 1 was heated and crosslinked, and the bond exchange characteristics of the obtained sample (crosslinked polyester composition) were evaluated. The bond exchange characteristics were evaluated based on the results of stress relaxation measurement and the remolding test.

[0103] [Stress Relaxation Measurement] For the stress relaxation measurement, an MCR102 manufactured by Anton paar was used as the measuring device. As the jig, an aluminum disposable jig with a diameter of 8 mm was used. A test piece was prepared using the sample (crosslinked polyester composition) obtained by heating the crosslinkable polyester composition 1 at 180 °C for 3 hours. The shape of the test piece was such that the diameter was 8 mm and the thickness was about 0.5 mm. The measurement temperature was 170 °C, 180 °C, 190 °C, or 200 °C. The measurement was carried out in a nitrogen gas atmosphere. The measured stress relaxation spectrum is shown in Figure 4. In Figure 4, the horizontal axis represents time (seconds), and the vertical axis represents the stress (σ / σ0) normalized by the initial stress (σ0). The curves shown in Figure 4 indicate the results measured at 190 °C, 180 °C, 170 °C, and 160 °C in order from the left.

[0104] As is clear from Figure 4, significant stress relaxation was observed, and from this result, the progress of bond exchange via the bond exchange reaction at high temperatures was confirmed.

[0105] [Remolding Test] In the remolding test, a planar test piece (film thickness 1 mm) cut out in a strip shape from the sample (crosslinked polyester composition) obtained by heating the crosslinkable polyester composition 1 at 180 °C for 3 hours was wound around a glass tube as shown in Figure 5A, both ends were taped, and fixed to a spatula. The test piece fixed to the spatula was heated in an oven at 180 °C for 1 hour. After heating for 1 hour and cooling to room temperature and removing the tape, the test piece was fixed in a curved shape as shown in Figure 5B. The test piece fixed in a curved shape did not return to its original planar shape even when warmed with a dryer. It is considered that the sample was remolded because the bond exchange was activated at a high temperature of 180 °C, the elasticity disappeared, and a new network structure was fixed after cooling.

[0106] From the above results, it is considered that by heating the sample (crosslinked polyester composition) at 180°C, the formation of a crosslinked structure and the introduction of bond exchange characteristics were confirmed, and the material conversion from the crosslinkable polyester composition was achieved.

Claims

1. A method for producing a crosslinkable polyester composition, comprising a step of kneading a copolyester in a heat-melted state with a polyfunctional epoxy compound having a plurality of epoxy groups and a transesterification catalyst, wherein the copolyester is an amorphous polyester, and the kneading is carried out at a temperature of the glass transition temperature (Tg) of the copolyester + 120°C or lower. A method for producing a crosslinkable polyester composition.

2. The method for producing a crosslinkable polyester composition according to claim 1, further comprising a step of molding into a predetermined shape after the kneading.

3. The method for producing a crosslinkable polyester composition according to claim 1, wherein the copolyester contains a first unit composed of ethylene terephthalate or butylene terephthalate, and further contains at least one component from the following groups 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

4. The method for producing a crosslinkable polyester composition according to claim 1, wherein the transesterification catalyst is a catalyst that does not contain a hydroxyl group.

5. The method for producing a crosslinkable polyester composition according to claim 1, wherein the kneading is carried out in a solvent-free state.

6. The method for producing a crosslinkable polyester composition according to claim 1, wherein the kneading is carried out using a twin-screw kneading extruder.

7. The method for producing a crosslinkable polyester composition according to claim 6, wherein a molded body containing a sheet-like or film-like crosslinkable polyester composition is extruded from the twin-screw kneading extruder.

8. A method for producing a crosslinked polyester composition, comprising producing a crosslinkable polyester composition by the method according to claim 1, and then heating and crosslinking the crosslinkable polyester composition.

9. The method for producing a crosslinked polyester composition according to claim 8, wherein the crosslinking of the crosslinkable polyester composition is carried out by heating at a temperature exceeding the temperature of the kneading.

10. The method for producing a crosslinked polyester composition according to claim 8, wherein the crosslinking of the crosslinkable polyester composition is carried out by heating at a temperature of 120°C to 250°C for 1 hour or more.

11. A molded body comprising a crosslinkable polyester composition containing a copolyester, a polyfunctional epoxy compound having a plurality of epoxy groups, and a transesterification catalyst, The copolyester is an amorphous polyester, the gel fraction of the molded article is less than 30%, and the shape of the molded article is rod-shaped, filamentous, granular, or flaky. A molded article.

12. A molded article comprising a crosslinkable polyester composition containing a copolyester, a polyfunctional epoxy compound having a plurality of epoxy groups, and a transesterification catalyst, wherein the copolyester is an amorphous polyester, the gel fraction of the molded article is less than 30%, and the shape of the molded article is sheet-like or film-like with a film thickness of 20 μm or more. A molded article.

13. The molded article is a molded article comprising the crosslinkable polyester composition according to claim 11 or 12, 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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