Polyester resin and its manufacturing method, and molded body and its manufacturing method

Abstract

This polyester resin is a first copolymer obtained by polymerizing an acid component containing 50 mol% or more of an aromatic dicarboxylic acid component and 2-50 mol% of a dimer acid component with respect to the total amount of the acid component, and an alcohol component containing 50 mol% or more of a 1,4-butanediol component with respect to the total amount of the alcohol component. Tetrahydrofuran generated when the first copolymer is heated for one hour at 150°C is 1 μg or less per gram of the first copolymer. The acid component is preferably composed of a terephthalic acid component and a dimer acid component, or a 2,6-naphthalenedicarboxylic acid component and a dimer acid component.

Description

Related Applications

[0001] This application claims priority from Japanese Patent Application No. 2023-140521, filed on August 30, 2023, and incorporates all of the contents of that Japanese application by reference. [Technical Field]

[0002] The present disclosure relates to a polyester resin and a method for producing the same, as well as a molded article and a method for producing the same. [Background technology]

[0003] Polybutylene terephthalate (sometimes referred to as "PBT" in this disclosure) and polybutylene naphthalate (sometimes referred to as "PBN" in this disclosure) are used in a variety of applications, such as electrical and electronic equipment components, automotive components, and packaging materials.

[0004] When PBT and PBN are produced, tetrahydrofuran (sometimes referred to as "THF" in this disclosure) remains as a by-product in the produced resin. The remaining THF is released as outgassing. The released THF outgassing can adversely affect the processing of electrical and electronic equipment components, reduce the durability of automotive components, and contaminate packaged items. Furthermore, THF outgassing can also be harmful to the health of workers.

[0005] In the automobile interior trim described in Patent Document 1, a copolymer of ethene and (2-ethyl)hexyl acrylate is mixed with PBT to reduce the amount of THF outgassing.

[0006] In Patent Document 2, a biaxially stretched film containing modified PBT, which is obtained by copolymerizing PBT with polytetramethylene glycol, and polyethylene terephthalate is used to reduce the amount of THF outgassing. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2022-543761 [Patent Document 2] International Publication No. 2011 / 162198 Summary of the Invention [Problem to be solved by the invention]

[0008] The THF content in PBT cannot be reduced by the method described in Patent Document 1. The modified PBT described in Patent Document 2 generates 220 μg / g or more of THF outgassing, and the reduction in the THF content is insufficient.

[0009] Therefore, there is a demand for polyester resins with a reduced THF content. [Means for solving the problem]

[0010] According to a first aspect of the present disclosure, an alcohol component including 50 mol% or more of a 2,6-naphthalenedicarboxylic acid component and 2 mol% to 50 mol% of a dimer acid component relative to the total amount of the acid component, and 50 mol% or more of a 1,4-butanediol component relative to the total amount of the alcohol component, was polymerized First Copolymer is A polyester resin is provided, wherein the amount of tetrahydrofuran generated per gram of the first copolymer when the first copolymer is heated at 150°C for 1 hour is 1 μg or less.

[0011] According to a second aspect of the present disclosure, Pertaining to the first perspective A first step of preparing a first copolymer and subjecting the first copolymer to a pressure of 4,000 Pa or less. under, 66℃ or higher Upper part Below the melting point of copolymer 1 Temperature in Canada and a second step of heat treating.

[0012] According to a third aspect of the present disclosure, there is provided a molded article containing the polyester resin according to the first aspect.

[0013] According to a fourth aspect of the present disclosure, there is provided a molded article comprising 5 to 70% by mass of the polyester resin according to the first aspect and 30 to 95% by mass of a second copolymer, the second copolymer being 1,4-butanediol. component and polytetramethylene glycol component The polyester resin contains, as an alcohol component, at least one selected from the group consisting of: When a molded product is heated at 150°C for 1 hour, the amount of tetrahydrofuran generated is 50µg or less per 1g of the molded product.

[0014] According to a fifth aspect of the present disclosure, Pertaining to the first aspect A first step of preparing a first copolymer and subjecting the first copolymer to a pressure of 4,000 Pa or less. under, 66℃ or higher Upper part Below the melting point of copolymer 1 Temperature in Canada The method for producing a molded article includes a second step of heat-treating the mixture, and a third step of molding the mixture of 5% to 95% by mass of the first copolymer and 5% to 95% by mass of the second copolymer. The second copolymer is 1,4-butanediol. component and polytetramethylene glycol component The polyester resin contains at least one alcohol component selected from the group consisting of: [Effects of the Invention]

[0015] The polyester resin of the present disclosure has a low residual THF content. Therefore, the amount of THF outgassing to which workers are exposed when using the polyester resin of the present disclosure can be reduced. Furthermore, deterioration in the quality of applied products due to the generation of THF outgassing from the polyester resin can be suppressed. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a flowchart illustrating a method for producing a polyester resin according to the present disclosure. [Figure 2] FIG. 2 is a flowchart showing a method for producing a molded article according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0017] According to a preferred embodiment of the first aspect, when the first copolymer that has not been subjected to a heat treatment at 50°C or higher is heated at 150°C for 1 hour, tetrahydrofuran is generated in an amount of 1 μg or less per 1 g of the copolymer.

[0018] According to a preferred embodiment of the first aspect, when the first copolymer is heated at 150° C. for 1 hour, the amount of tetrahydrofuran generated is 0.5 μg or less per 1 g of the copolymer.

[0019] According to a preferred embodiment of the first aspect, the acid component is 60 mol% to 90 mol% of the total amount of acid components 2,6-naphthalenedicarboxylic acid component and 10mol% to 40mol% Dimer acid component Includes. The alcohol content , 80 mol% or more of the total amount of alcohol components 1,4-butanediol component Includes.

[0020] According to a preferred embodiment of the first aspect, the dimer acid component has at least one carbon atom selected from the group consisting of 44 and 36 carbon atoms.

[0021] According to a preferred embodiment of the second aspect, the heat treatment is carried out for 6 to 100 hours.

[0022] According to a preferred embodiment of the second aspect, the second step is carried out before the first copolymer is heat-treated to 50° C. or higher.

[0023] According to a preferred embodiment of the second aspect, The first copolymerThe first copolymer is obtained by polymerizing an acid containing 60 mol% to 90 mol% of 2,6-naphthalenedicarboxylic acid and 10 mol% to 40 mol% of dimer acid relative to the total amount of acids, and an alcohol containing 80 mol% or more of 1,4-butanediol relative to the total amount of alcohols.

[0024] According to a preferred embodiment of the second aspect, a dimer Acid The number of carbon atoms is at least one selected from the group consisting of 44 and 36.

[0025] According to a preferred embodiment of the fourth aspect, the second copolymer is The second copolymer Tetrahydrofuran generated when heated at 150°C for 1 hour Second Copolymer It is 150μg to 600μg per gram.

[0026] According to a preferred embodiment of the fourth aspect, the molded article has at least one shape selected from the group consisting of a sheet shape, a film shape, and a container shape.

[0027] According to preferred embodiments of the third and fourth aspects, there is provided a member for an electric / electronic device, which includes the molded article of the third and fourth aspects.

[0028] According to preferred embodiments of the third and fourth aspects, there are provided automobile members including the molded articles of the third and fourth aspects.

[0029] According to preferred embodiments of the third and fourth aspects, there is provided a packaging material including the molded article of the third and fourth aspects.

[0030] According to a preferred embodiment of the fifth aspect, in the third step, the mixture is formed into at least one shape selected from the group consisting of a sheet shape, a film shape, and a container shape.

[0031] In the present specification and claims, each acid component and each alcohol component may also include its derivatives. For example, an acid component may also include a derivative of the acid component (e.g., an ester).

[0032] A polyester resin according to a first embodiment of the present disclosure will be described. The polyester resin referred to in the present disclosure also includes molded articles thereof (for example, polyester films, containers, packaging, etc.). In the present disclosure, the polymer may also include copolymers composed of two or more types of monomer components, and cross-linked polymers (crosspolymers).

[0033] The polyester resin of the present disclosure can be in various forms, such as pellets, sheets, films, containers, and packaging.

[0034] The pellets are produced by cutting the strand-shaped polyester resin into particles. 100 The mass per piece can be, for example, 2 g to 3 g.

[0035] In this disclosure, a sheet refers to a molded product having a shape that is thinner than the dimensions in other directions. In this disclosure, a film refers to a molded product having an extremely thin shape obtained by subjecting a sheet to a heat-stretching process.

[0036] Hereinafter, the total amount of a component may refer to the total number of moles of the monomers on which the component is based.

[0037] The polyester resin according to the first embodiment is a first copolymer obtained by polymerizing (A) an acid component and (B) an alcohol component, and has PBT or PBN as its main structure.

[0038] In the present disclosure, the (A) acid component may include a polycarboxylic acid component, which is a compound having multiple carboxy groups and / or a derivative thereof, and the (B) alcohol component may include a polyol component, which is a compound having multiple hydroxy groups (a polyhydroxy compound) and / or a derivative thereof.

[0039] [(A) Acid component] The (A) acid component includes an aromatic dicarboxylic acid component and a dimer acid component. Examples of aromatic dicarboxylic acid components include terephthalic acid components, isophthalic acid components, 2,5-furandicarboxylic acid, 2,4-furandicarboxylic acid, 1,4-naphthalenedicarboxylic acid components, 2,6-naphthalenedicarboxylic acid components, 4,4'-diphenyldicarboxylic acid components, 9,9-bis(2-carboxyethyl)fluorene components, etc. Among these, terephthalic acid components and 2,6-naphthalenedicarboxylic acid components are particularly preferred.

[0040] The aromatic dicarboxylic acid component can be, for example, 50 mol% or more, 55 mol% or more, 60 mol% or more, 65 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more relative to the total amount of component (A). If the aromatic dicarboxylic acid component is less than 50 mol%, the properties of the resulting polyester resin will be lost. The aromatic dicarboxylic acid component can be, for example, 98 mol% or less, 95 mol% or less, 92 mol% or less, 90 mol% or less, 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, or 65 mol% or less relative to the total amount of component (A).

[0041] Dimer acid is a dicarboxylic acid compound obtained by dimerizing unsaturated fatty acids having 10 to 30 carbon atoms. The dimer acid is at least one selected from the group consisting of dimeric dicarboxylic acids having 36 and 44 carbon atoms obtained by dimerizing unsaturated fatty acids having 18 carbon atoms, such as oleic acid and linoleic acid, and unsaturated fatty acids having 22 carbon atoms, such as erucic acid, and their ester-forming derivatives. Dimer acids in which the unsaturated double bonds remaining after dimerization are saturated by hydrogenation are called hydrogenated dimer acids. Hydrogenated dimer acids are preferred in terms of reaction stability, flexibility, impact resistance, and the like. Dimer acids are typically obtained as a mixture of compounds having a linear branched structure, an alicyclic structure, and the like. The contents of these compounds vary depending on the production process, but are not particularly limited. Among these, dimer acids having 44 carbon atoms are preferred because they can significantly reduce the amount of THF outgassing.

[0042] The dimer acid component may be, for example, 2 mol% or more, 5 mol% or more, 8 mol% or more, 10 mol% or more, 15 mol% or more, 20 mol% or more, 25 mol% or more, 30 mol% or more, or 35 mol% or more relative to the total amount of component (A). If the dimer acid component is less than 2 mol%, the amount of THF outgassing from the polyester resin will be large. The dimer acid component is preferably 50 mol% or less relative to the total amount of component (A). The dimer acid component may be, for example, 45 mol% or less, 40 mol% or less, 35 mol% or less, 30 mol% or less, 25 mol% or less, 20 mol% or less, 15 mol% or less, 10 mol% or less, or 5 mol% or less relative to the total amount of component (A). If the dimer acid component exceeds 50 mol%, the heat resistance of the polyester resin will be reduced.

[0043] The (A) acid component may contain an acid component other than an aromatic dicarboxylic acid component and a dimer acid component, as long as the essential properties of the polyester resin of the present disclosure are not altered. Examples of other acid components include aliphatic dicarboxylic acid components such as succinic acid, glutaric acid, adipic acid, pyremic acid, suberic acid, azelaic acid, and sebacic acid; and alicyclic dicarboxylic acid components such as 1,2-, 1,3-, and 1,4-cyclohexanedicarboxylic acid and 1,4-, 1,5-, 2,6-, and 2,7-decahydronaphthalenedicarboxylic acid. These acid components may be used alone or in combination of two or more.

[0044] In the acid component of the first copolymer, the total amount of the aromatic dicarboxylic acid component and the dimer acid component can be 100 mol % relative to the total amount of the component (A).

[0045] [(B) Alcohol component] (B) The alcohol component includes a 1,4-butanediol component.

[0046] The amount of 1,4-butanediol component relative to the total amount of component (B) is: 50 mol% or more, It is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more. The 1,4-butanediol component may be 95 mol% or less, 90 mol% or less, or 85 mol% or less, based on the total amount of component (B). The 1,4-butanediol component may be 100 mol% based on the total amount of component (B). The 1,4-butanediol component may be 50 If it is less than mol%, PBT or PBN The properties of the

[0047] The (B) alcohol component may contain components other than the 1,4-butanediol component, provided that the essential properties of the polyester resin of the present disclosure are not altered. Examples of other alcohol components include ethylene glycol, 1,4-cyclohexanedimethanol, propylene glycol, hexanediol, octanediol, decanediol, ethylene oxide-added bisphenol A, ethylene oxide-added bisphenol S, and trimethylolpropane. These alcohol components may be used alone or in combination of two or more.

[0048] The polyester resin of the present disclosure may contain known additives to the extent that the essential properties of the polyester resin of the present disclosure are not altered. Examples of additives that can be used include polymerization catalysts, antistatic agents, UV absorbers, heat stabilizers, light stabilizers, release agents, antioxidants, lubricants, plasticizers, pigments, and dyes.

[0049] The amount of THF outgassing from the polyester resin according to the first embodiment is 1 μg or less (1 ppm or less) per gram of polyester resin when the polyester resin is heated at 150°C for 1 hour in a state where it has not been subjected to a melting treatment after production, for example, in the form of pellets, preferably 0.8 μg or less, more preferably 0.5 μg or less, even more preferably 0.4 μg or less, particularly preferably 0.3 μg or less, even more particularly preferably 0.2 μg or less, and even more particularly preferably 0.1 μg or less.

[0050] The amount of THF outgassing from the polyester resin according to the first embodiment is measured in a molded state, for example, in the form of a sheet molded by extruding and melting pellets, or in the form of a film obtained by heat-stretching the sheet. In a positive mannerFor example, when heated at 150°C for 1 hour, the amount of THF outgassing from the molded article can be reduced to 0.2 μg or less (0.2 ppm or less), preferably 0.1 μg or less (0.1 ppm or less), and more preferably below the detection limit, per gram of the molded article.

[0051] The amount of THF outgassing generated from the polyester resin of the present disclosure can be measured, for example, by a headspace method.

[0052] The polyester resin of the present disclosure has a reduced amount of THF outgassing. This can suppress environmental pollution and reduce adverse effects on the health of workers. In addition, when the polyester of the present disclosure is used in a product, the amount of THF outgassing is reduced. Outgassing This can prevent quality degradation.

[0053] For example, when the polyester resin of the present disclosure is used as a release agent in semiconductor manufacturing, the amount of THF outgassing is small, and therefore the adhesion between the base film and the release layer can be improved. Outgassing Furthermore, the interference with the soldering process caused by THF can be reduced. Outgassing It is also possible to reduce the adverse effects on the quality of the semiconductor itself caused by the above.

[0054] The polyester resin of the present disclosure exhibits little bleed-out, excellent stability over time, and moldability, and therefore can be used in a wide range of molding materials, such as electrical and electronic equipment components, automotive components, and packaging materials.

[0055] The polyester resin of the present disclosure has excellent transparency and flexibility, as well as high heat resistance.

[0056] The polyester resin according to the first embodiment can be mixed with other polyester resins and used as a modifier for reducing the amount of THF outgassing. For example, as shown in the third and fourth embodiments described later, a polyester resin containing THF can be mixed with the polyester resin according to the first embodiment. The mixture is molded By producing a molded body using this method, the amount of THF outgassing from the molded body was reduced. reduction It is possible.

[0057] In the polyester resin of the present disclosure, the molecular structure, crystalline structure, etc. may be unknown, and it may be impossible or impractical to directly identify the polyester resin of the present disclosure by its composition, structure, properties, etc. In such cases, it should be permitted to identify the polyester resin of the present disclosure by its manufacturing method.

[0058] As a second embodiment of the present disclosure, a method for producing a polyester resin according to the first embodiment will be described. Fig. 1 shows a flowchart of the method for producing a polyester resin according to the second embodiment.

[0059] The method for producing a polyester resin according to the second embodiment includes the steps of: First Copolymer A first step (S11) of preparing the First Copolymer of Pressurize under reduced pressure A second step (S12) of heat treatment may be included.

[0060] In the first step, prepare First Copolymer The polyester resin may be a commercially available product having the composition shown in the first embodiment. The first copolymer ( Polyester resin ) A method for producing the above will be described.

[0061] The first step is a step of polymerizing a monomer. That is, it is a step of polycondensing an acid and an alcohol. The polymerization in the first step is not particularly limited, and can be carried out by a known polymerization method using a known catalyst. The method for producing the polyester resin before the second step may be either a method of direct esterification using an unsubstituted polycarboxylic acid as a starting material, or a method of carrying out an ester exchange reaction using an esterified product such as dimethyl ester as a starting material. In the case of direct esterification, the temperature at which the polymerization reaction is carried out becomes high, which can lead to decomposition of 1,4-butanediol and the formation of THF. Outgassing In order to obtain a sufficient reaction rate when producing the polyester resin before the second step, it is desirable to carry out the transesterification reaction under normal pressure using a known catalyst in the first step, and then to carry out the polycondensation reaction under reduced pressure using a known catalyst in the second step.

[0062] The acid and alcohol used as raw materials for the polyester resin may be the same as those described above. The amounts of the acid and alcohol used may be appropriately determined depending on the content of the acid component and alcohol component.

[0063] The transesterification reaction can be carried out, for example, by charging each compound used as a polymerization raw material and various other copolymerization components used as necessary into a reaction vessel equipped with a heater, a stirrer, and a distillation tube, adding a reaction catalyst, and raising the temperature while stirring under an inert gas atmosphere at normal pressure, and distilling off by-products such as methanol produced by the reaction. The reaction temperature can be 150°C to 230°C, preferably 160°C to 220°C. The reaction time can be about 3 to 7 hours.

[0064] At least one catalyst for the transesterification reaction of the kindIt is desirable to use a metal compound. Preferred metal elements include sodium, potassium, calcium, titanium, lithium, magnesium, manganese, zinc, tin, and cobalt. Among these, titanium compounds are preferred because they have high reactivity and produce a good color tone for the resulting resin. The amount of transesterification catalyst used is 5 ppm to 1,000 ppm based on the polyester resin produced. is preferred , 10 ppm to 100 ppm is more preferred.

[0065] After the transesterification reaction is complete, it is desirable to add a phosphorus compound in an amount equal to or greater than the transesterification catalyst to further advance the esterification reaction. For example, it is desirable to carry out a transesterification reaction using an ester compound of terephthalic acid and 1,4-butanediol, and then add erucic acid together with the phosphorus compound to advance the esterification reaction, thereby producing a polyester resin. Examples of phosphorus compounds include phosphoric acid, phosphorous acid, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trimethyl phosphite, triethyl phosphite, and tributyl phosphite. Of these, trimethyl phosphate is particularly preferred. The addition rate of the phosphorus compound can be 5 ppm to 1,000 ppm, preferably 20 ppm to 100 ppm, based on the polyester resin produced.

[0066] Following the transesterification reaction, a polycondensation reaction can be further carried out until the desired molecular weight is achieved. The polycondensation reaction can be carried out, for example, by adding a polymerization catalyst to a reaction vessel containing the product obtained after the transesterification reaction, and then gradually increasing the temperature and reducing the pressure inside the reaction vessel. The pressure inside the vessel can be reduced from atmospheric pressure to 0.4 kPa or less, preferably 0.2 kPa or less. The temperature inside the vessel is increased from 220°C to 230°C, and finally to 220°C to 240°C, preferably 228°C to 235°C. After reaching a predetermined torque, the reaction product can be extruded from the bottom of the vessel and recovered. Typically, the reaction product is extruded into water in the form of a strand, cooled, and cut to obtain a pelletized polyester resin.

[0067] At least one catalyst for the polycondensation reaction of the kind It is desirable to use a metal compound. Preferred metal elements include titanium, germanium, antimony, aluminum, etc. Among these, titanium compounds and germanium compounds are particularly preferred when producing optical resins, as they are highly reactive and the resulting resins have excellent transparency and color tone. Titanium compounds are particularly reactive and cheaper than germanium compounds. Furthermore, titanium is not classified as a heavy metal, so titanium compounds can reduce environmental impact. The addition rate of the polymerization catalyst is 30 ppm to 1,000 ppm relative to the polyester resin to be produced. is preferred , 50ppm~500ppm is more preferred.

[0068] The polyester resin of the present disclosure may be appropriately blended with various additives, such as antioxidants, heat stabilizers, lubricants, antistatic agents, plasticizers, UV absorbers, and pigments, depending on the application and molding purpose. These additives may be blended in either the polymerization reaction step or the processing and molding step. Examples of antioxidants include hindered phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. Hindered phenol-based antioxidants are particularly preferred, with a preferred content of approximately 100 ppm to 5,000 ppm. When forming a melt-extrusion film, metal salts, such as magnesium acetate, calcium acetate, and magnesium chloride, may be added to stabilize the electrostatic adhesion of the cooling roll.

[0069] After the polycondensation reaction, a solid-state polymerization reaction may be carried out, which can increase the intrinsic viscosity of the polyester resin.

[0070] Next, in the second step, the polyester resin obtained in the first step is heated under reduced pressure. Canada Heat treat.

[0071] Canada The pressure during the heat treatment is preferably 4,000 Pa or less, more preferably 3,000 Pa or less, even more preferably 2,000 Pa or less, even more preferably 1,000 Pa or less, particularly preferably 500 Pa or less, more particularly preferably 400 Pa or less, even more particularly preferably 300 Pa or less, most preferably 200 Pa or less, and even most preferably 100 Pa or less.

[0072] Canada The temperature of the heat treatment is preferably 66°C or higher, and more preferably 70°C or higher. Canada The temperature of the heat treatment can be 80°C or higher, 90°C or higher, 100°C or higher, or 110°C or higher. Canada The temperature of the heat treatment is preferably equal to or lower than the melting point of the polyester resin, and more preferably equal to or lower than 150°C. Canada The heat treatment temperature The obtained polyester resin Above the melting point ,polyester This will cause the resin to fuse together.

[0073] Canada The heat treatment time can be, for example, 6 hours or more, 10 hours or more, 20 hours or more, 30 hours or more, 40 hours or more, or 50 hours or more. Canada The heat treatment time can be, for example, 100 hours or less, 90 hours or less, 80 hours or less, 70 hours or less, 60 hours or less, 50 hours or less, 40 hours or less, 30 hours or less, or 20 hours or less.

[0074] In the second step Canada When the heat treatment temperature is less than 100°C, Canada The heat treatment time is 20 hours or more, preferably 30 hours or more, more preferably 40 hours or more, and even more preferably 50 hours or more. Canada When the heat treatment temperature is 100°C or higher, Canada The heat treatment time is 6 hours or more, preferably 8 hours or more, and more preferably 10 hours or more.

[0075] In the second step, the polyester resin in the form of pellets obtained in the first step is Canada It can be heat treated, or it can be made into a molded product such as a film. Canada It is also possible to perform a heat treatment. The second step is preferably carried out in the form of pellets, following the first step. By performing a heat treatment at an early stage, the operator can but THF Outgassing This reduces the risk of exposure to THF Outgassing Furthermore, the polyester resin of the present disclosure can be treated with THF, such as polypropylene or polycarbonate, to suppress the decrease in mechanical strength and hydrolysis of the polyester resin due to the above-mentioned reaction. Outgassing When blended with a resin having low resistance to oxidative stress, the adverse effects on the blended resin can be reduced.

[0076] The method for producing the polyester film of the present disclosure will be described.

[0077] The polyester film of the present disclosure can be produced according to a general polyester film production method. For example, a polyester resin is melted, and the non-oriented polyester is extruded into a sheet. The non-oriented polyester is stretched in the running direction at a temperature equal to or higher than the glass transition temperature by utilizing a roll speed difference, and then stretched in the width direction using a tenter and heat-treated. The thickness of the non-oriented polyester before stretching can be set taking into account the desired final polyester film thickness, stretching ratio, retardation of the resulting polyester film, etc.

[0078] According to the method for producing a polyester resin according to the second embodiment, a polyester resin with a low THF outgassing amount during molding can be produced. In particular, the THF content in the polyester resin can be reduced before molding. This reduces the THF content of the polyester resin according to the present disclosure for workers who handle the polyester resin. Outgassing Furthermore, the adverse effects of THF on products to which the polyester resin of the present disclosure is applied can be reduced. Outgassing This can reduce the adverse effects of

[0079] A molded article according to a third embodiment of the present disclosure will be described.

[0080] The molded article according to the third embodiment of the present disclosure is a molded article containing a first copolymer, which is the polyester resin according to the first embodiment, and a second copolymer. The molded article can have at least one shape selected from the group consisting of a sheet shape, a film shape, and a container shape.

[0081] The above description is applicable to the polyester resin according to the first embodiment.

[0082] The second copolymer comprises (C) an acid component and (D) an alcohol component. have It is a polyester resin. Component (D) is 1,4-butanediol. component and polytetramethylene glycol component The composition includes at least one selected from the group consisting of:

[0083] In the present disclosure, the (C) acid component may include a polycarboxylic acid component, which is a compound having multiple carboxy groups and / or a derivative thereof, and the (D) alcohol component may include a polyol component, which is a compound having multiple hydroxy groups (a polyhydroxy compound) and / or a derivative thereof.

[0084] [(C) Acid component] The (C) acid component includes at least one selected from the group consisting of a terephthalic acid component and a 2,6-naphthalenedicarboxylic acid component.

[0085] When the terephthalic acid component is the main component of component (C), the terephthalic acid component can be, for example, 50 mol% or more, 55 mol% or more, 60 mol% or more, 65 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more relative to the total amount of component (C). If the terephthalic acid component is less than 50 mol%, the polybutylene terephthalate will be difficult to obtain. To The properties will be lost. The amount of the terephthalic acid component can be, for example, 98 mol% or less, 95 mol% or less, 92 mol% or less, 90 mol% or less, 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, or 65 mol% or less relative to the total amount of component (C). Component (C) can be 100 mol% of the terephthalic acid component.

[0086] When 2,6-naphthalenedicarboxylic acid is the main component of component (C), the 2,6-naphthalenedicarboxylic acid component can be, for example, 50 mol% or more, 55 mol% or more, 60 mol% or more, 65 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more relative to the total amount of component (C). If the 2,6-naphthalenedicarboxylic acid component is less than 50 mol%, the properties of polybutylene naphthalate are lost. The naphthalenedicarboxylic acid component can be, for example, 98 mol% or less, 95 mol% or less, 92 mol% or less, 90 mol% or less, 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, or 65 mol% or less relative to the total amount of component (C). Component (C) can be 100 mol% 2,6-naphthalenedicarboxylic acid component.

[0087] The acid component (C) may contain an acid component other than a terephthalic acid component and a 2,6-naphthalenedicarboxylic acid component, as long as the essential properties of the polyester resin of the present disclosure are not altered. Examples of other acid components include aromatic dicarboxylic acid components such as isophthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, and 9,9-bis(2-carboxyethyl)fluorene; aliphatic dicarboxylic acid components such as succinic acid, glutaric acid, adipic acid, pyremic acid, suberic acid, azelaic acid, and sebacic acid; and alicyclic dicarboxylic acid components such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,4-decahydronaphthalenedicarboxylic acid, 1,5-decahydronaphthalenedicarboxylic acid, 2,6-decahydronaphthalenedicarboxylic acid, and 2,7-decahydronaphthalenedicarboxylic acid. These acid components may be used alone or in combination.

[0088] (C) The acid component is at least one of a terephthalic acid component and a 2,6-naphthalenedicarboxylic acid component, Other Acids The total amount can be 100 mol %.

[0089] [(D) Alcohol component] The (D) alcohol component includes at least one selected from the group consisting of a 1,4-butanediol component and a polytetramethylene glycol component.

[0090] The 1,4-butanediol component is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more, based on the total amount of component (D). The 1,4-butanediol component can be 95 mol% or less, 90 mol% or less, or 85 mol% or less, based on the total amount of component (D). The 1,4-butanediol component can be 100 mol% based on the total amount of component (D). If the 1,4-butanediol component is less than 80 mol%, the properties of PBT or PBN will be lost.

[0091] The polytetramethylene glycol component may be 5 mol% or more, 10 mol% or more, or 15 mol% or more, based on the total amount of component (D).The polytetramethylene glycol component may be 30 mol% or less, 25 mol% or less, 20 mol% or less, 15 mol% or less, or 10 mol% or less, based on the total amount of component (D).

[0092] When component (D) contains a polytetramethylene glycol component, the remaining component (D) is 1,4-butanediol. Ingredients and It is possible.

[0093] The (D) alcohol component may contain alcohol components other than a 1,4-butanediol component and a polytetramethylene glycol component, as long as the essential properties of the polyester resin of the present disclosure are not altered. Examples of other alcohol components include an ethylene glycol component, a 1,4-cyclohexanedimethanol component, a propylene glycol component, a hexanediol component, an octanediol component, a decanediol component, an ethylene oxide-added bisphenol A component, an ethylene oxide-added bisphenol S component, and a trimethylolpropane component. These other alcohol components may be used alone or in combination of two or more.

[0094] Examples of the second copolymer include polybutylene terephthalate, polybutylene naphthalate, polybutylene terephthalate copolymerized with isophthalic acid, polybutylene terephthalate copolymerized with polytetramethylene glycol, and polyethylene terephthalate copolymerized with polytetramethylene glycol.

[0095] The amount of THF outgassing from the second copolymer is The second copolymer ( Polyester resin ) After manufacturing, the temperature will be above 50°C. Canada Before being subjected to heat treatment and before being mixed with the first copolymer, e.g. , the second copolymer In the pellet state, Second Copolymer The amount of THF outgassing from the second copolymer can be 100 μg or more, or 200 μg or more, per 1 g of the copolymer. The second copolymer ( Polyester resin ) After manufacturing, the temperature will be above 50°C. Canada Before being subjected to heat treatment and before being mixed with the first copolymer, e.g. , the second copolymer In the pellet state, Second Copolymer Per 1g, it can be 3,000μg or less or 2,000μg or less. The second copolymer is The second copolymer Tetrahydrofuran generated when heated at 150°C for 1 hour Second Copolymer 1It is preferable that the amount is 150 μg to 600 μg per g.

[0096] In the molded article according to the third embodiment, the content of the first copolymer may be 5% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, or 50% by mass or more, relative to the mass of the molded article according to the third embodiment. The content of the first copolymer may be 70% by mass or less, 60% by mass or less, 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, or 10% by mass or less, relative to the mass of the molded article according to the third embodiment.

[0097] In the molded article according to the third embodiment, the second copolymer may be present in an amount of 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more relative to the mass of the molded article according to the third embodiment. The second copolymer may be present in an amount of 95% by mass or less, 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or more relative to the mass of the molded article according to the third embodiment.

[0098] In the molded article according to the third embodiment, the total amount of the first copolymer and the second copolymer can be 100% by mass.

[0099] The amount of THF outgassing from the molded body according to the third embodiment is: Molded body When heated at 150°C for 1 hour, 1g of molded product Win , 50 μg or less (50 ppm or less), preferably 40 μg or less, more preferably 30 μg or less, even more preferably 20 μg or less, particularly preferably 10 μg or less, even more particularly preferably 5 μg or less, and most preferably below the detection limit.

[0100] The molded article according to the third embodiment may contain known additives to the extent that they do not change the essential properties of the molded article according to the third embodiment. Examples of additives that can be used include polymerization catalysts, antistatic agents, ultraviolet absorbers, heat stabilizers, light stabilizers, mold release agents, antioxidants, lubricants, plasticizers, pigments, and dyes.

[0101] The molded article according to the third embodiment exhibits reduced THF outgassing even when a second copolymer containing a large amount of THF is mixed in. When a second copolymer containing at least one selected from the group consisting of 1,4-butanediol and polytetramethylene glycol is produced by a conventional method, it contains by-produced THF. However, when the first copolymer and the second copolymer are mixed and molded, the THF can be removed during molding. This reduces the amount of THF outgassing from the molded article according to the third embodiment.

[0102] The molded article according to the third embodiment can be used, for example, as a member for electric / electronic devices, a member for automobiles, or a packaging material.

[0103] Examples of electrical and electronic equipment components include release films used in the production of various electrical and electronic equipment components; protective films used in various electrical and electronic equipment components; and various electrical and electronic equipment molded products such as switches, touch panels, sensors, and connectors.

[0104] Examples of automotive parts include interior parts such as instrument panels, consoles, door trims, headrests, tool boxes, luggage boxes, and sun visors; exterior parts such as bumpers, rear spoilers, front lids, and fenders; decorative films for interior and exterior parts; and protective films for interior and exterior parts.

[0105] Examples of packaging materials include various packaging films for container packaging, food packaging, pharmaceutical packaging, industrial chemical packaging, precision electronic component packaging, and agricultural chemical packaging.

[0106] As a fourth embodiment of the present disclosure, a method for manufacturing a molded product according to the third embodiment will be described. A method for producing a molded article according to a fourth embodiment of the present disclosure includes: a mixture of an acid component containing 50 mol% or more of an aromatic dicarboxylic acid component and 2 mol% to 50 mol% of a dimer acid component relative to the total amount of the acid component; and an alcohol component containing 50 mol% or more of a 1,4-butanediol component relative to the total amount of the alcohol component. 、 a first step of preparing a first copolymer in which The first copolymer is subjected to a pressure of 4,000 Pa or less. under, 66℃ or higher Upper front the melting point of the first copolymer or less Temperature in Canada a second step of heat treating; and a third step of molding a mixture of 5% to 95% by mass of the first copolymer and 5% to 95% by mass of the second copolymer.

[0107] The first step and the second step are the same as the first step and the second step in the method for producing a polyester resin according to the second embodiment. The second copolymer is 1,4-butanediol component and polytetramethylene glycol component The polyester resin contains at least one alcohol component selected from the group consisting of:

[0108] The molding method used in the third step may be a known molding method such as injection molding, blow molding, extrusion molding, lamination, etc. The molded product may have at least one shape selected from the group consisting of a sheet shape, a film shape, and a container shape.

[0109] When the molded body obtained in the third step is heated at 150° C. for 1 hour, the amount of tetrahydrofuran generated is preferably 50 μg or less per 1 g of the molded body. The second copolymer is The second copolymerTetrahydrofuran generated when heated at 150°C for 1 hour Second Copolymer It is preferable that the amount is 150 μg to 600 μg per 1 g.

[0110] FIG. 2 shows a flowchart of the method for producing a molded body according to the fourth embodiment.

[0111] The method for producing a molded article according to the fourth embodiment includes a step (S21) of preparing a first copolymer; A step (S22) of heat-treating the first copolymer under reduced pressure; The method for producing a molded article according to the fourth embodiment can include a step (S23) of preparing a second copolymer and a step (S24) of mixing the first copolymer and the second copolymer. a first copolymer, The order of steps S21 to S23 does not matter.

[0112] The method for producing the polyester resin according to the second embodiment is used as the method for producing the first copolymer.

[0113] The second copolymer can be produced by a known production method depending on the composition, or the second copolymer may be a commercially available product.

[0114] The method may include a step of producing a molded article by heating and melting the mixture of the first copolymer and the second copolymer at a temperature of, for example, 200° C. or higher, or 220° C. or higher. Examples of the molded article include a sheet, a film, a container, and the like.

[0115] According to the method for producing a molded article according to the fourth embodiment, even if the second copolymer contains THF, the THF can be removed during molding of the mixture with the first copolymer, making it possible to produce a molded article with a low THF outgassing even when the base polyester resin has a high THF content. [Example]

[0116] Examples of the polyester resin of the present disclosure, its production method, and the molded body and its production method will be described below with reference to examples. However, the polyester resin of the present disclosure, its production method, and the molded body and its production method are not limited to the following examples. The analysis of the polyester resin composition by NMR was performed by the following method.

[0117] <Analysis Method of Polyester Resin Composition by NMR> Using a FT-NMR apparatus (DPX400 type) manufactured by Bruker Biospin, the polyester resin was dissolved in deuterated chloroform, mixed with tetramethylsilane as a standard, and the proton NMR spectrum was measured. The resin composition was calculated from the NMR spectrum.

[0118] [Test Examples 1 to 10] In Test Examples 1 to 10, Acid and Dimethyl terephthalate at 100 mol% or a mixture of dimethyl terephthalate and dimer acid (Pripol 1004, manufactured by Croda), which is a dimer of C22 erucic acid, or dimer acid (Pripol 1009, manufactured by Croda), which is a dimer of C18 unsaturated fatty acid, in a total amount of 100 mol%, and alcohol Ru and A mixture containing 100 mol% of 1,4-butanediol was charged into a reactor equipped with a stirrer, a rectification column, and a methanol distillation condenser. After dissolving the mixture in a solvent at 190 °C, 35 ppm of tetra-n-butoxytitanium was added, and the temperature was raised from 190 °C to 225 °C over 3 hours, and a transesterification reaction was carried out while distilling the generated methanol out of the system. After the transesterification reaction was completed, the temperature was gradually raised from 225 °C to 235 °C over 60 minutes, and the pressure was gradually reduced from atmospheric pressure to 0.2 kPa to terminate the reaction at a predetermined viscosity. Then, it was extruded into cooling water and pelletized using a strand cutter. Tables 1 and 2 show the charged compositions of each test example and the polyester resin compositions analyzed by NMR. The intrinsic viscosity of the obtained polymer was 0.65 to 2.0 dl / g.

[0119] [Test Examples 11 to 13] In Test Examples 11 to 13, a polyester resin obtained by copolymerizing polybutylene terephthalate with polytetramethylene glycol was prepared. The manufacturing method was the same as that in Test Examples 1 to 10, except for the different compositions. Table 3 shows the charged compositions of each test example and the polyester resin compositions analyzed by NMR.

[0120] [Test Examples 14 to 21] In Test Examples 14 to 21, Acid and except that a total of 100 mol% of dimethyl 2,6-naphthalenedicarboxylate and dimer acid (manufactured by Croda, Pripol 1004), which is a dimer of erucic acid C22, was used, the manufacturing method was the same as that in Test Examples 1 to 10. Table 4 shows the charged compositions of each test example and the polyester resin compositions analyzed by NMR.

[0121] Next, the obtained pellets were heat-treated under the conditions shown in Tables 1 to 4. The heating in Test Example 6 was carried out under atmospheric pressure in a nitrogen atmosphere. The melting point of the polyester resin before the heat treatment was measured as follows. Also, the amount of THF outgas generated was measured as follows, and the reduction rate of the amount of THF outgas generated was calculated as follows.

[0122] <Measurement of Melting Point> Using 10 mg of the polyester resin, the melting point Tm was determined from the DSC curve measured at a heating rate of 10 °C / min using a scanning differential calorimeter DSC (DSC7 manufactured by Perkin Elmer).

[0123] <Measurement of the Amount of THF Outgas Generated and Calculation of the Reduction Rate of the Amount of THF Outgas Generated> The amount of THF outgassing was measured for polyester resin before and after heat treatment. The heat-treated polyester resin was not the same polyester resin for which the amount of THF outgassing was measured before heat treatment, but rather the same polyester resin lot as before heat treatment. The polyester resin was freeze-pulverized to a 30-50 mesh powder, 20 mg of which was sealed in a 25 ml vial, and kept at 150 °C for 1 hour. The amount of THF outgassing was measured by headspace gas chromatography using a Shimadzu Corporation GC-14A gas chromatograph. The detection limit for THF outgassing was 0.1 μg (0.1 ppm) per gram of polyester resin.

[0124] The reduction rate of the amount of THF outgassing was calculated using the following formula. Reduction rate of THF outgassing amount (%) = {(THF outgassing amount before heat treatment - THF outgassing amount after heat treatment) / THF outgassing amount before heat treatment} × 100

[0125] The abbreviations used in Tables 1 to 5 are as follows: TPA: Terephthalic acid component DA(C44): Dimer acid component with 44 carbon atoms DA(C36): Dimer acid component with 36 carbon atoms NDCA: 2,6-naphthalenedicarboxylic acid component BD: 1,4-butanediol component PTMG: Polytetramethylene glycol component

[0126] [Table 1]

[0127] [Table 2]

[0128] [Table 3]

[0129] [Table 4]

[0130] From the results of Tables 1 to 4, in Test Example 1, in which neither dimer acid nor polytetramethylene glycol was used as a monomer, the reduction in the amount of THF outgassing was small. Also, in Test Examples 11 to 13, in which polytetramethylene glycol was used as a monomer, the reduction in the amount of THF outgassing was small. On the other hand, in Test Examples 2 to 10, in which dimer acid was used as a monomer, the amount of THF outgassing was significantly reduced. In particular, by heating under reduced pressure, the amount of THF outgassing was reduced to nearly the detection limit. In Test Example 6, in which heat treatment was performed under atmospheric pressure, the heating time was 10 times that of Test Example 3, but the amount of THF outgassing could not be reduced to the same extent as in Test Example 3. In Test Examples 4 and 5, the amount of THF outgassing was reduced even at a heating temperature of 70°C. The amount of THF outgassing was reduced more with a dimer acid having 44 carbon atoms than with a dimer acid having 36 carbon atoms. Furthermore, in Test Examples 15 to 21, in which 2,6-naphthalenedicarboxylic acid and dimer acid were used as monomers, the amount of THF outgassing was significantly reduced. 2 THF outgassing amount is the same as in 10. could be significantly reduced.

[0131] [Test Examples 22-25] The polyester resins in pellet form of Test Examples 3 and 8 were heat treated and then molded into a 100 mm thick sheet, and the amount of THF outgassing was measured. The molding method into the sheet was performed using a T-die extruder, which is a common method for manufacturing polyester sheets. Molding temperatures shown in Table 5 The mixture was melt-extruded at 20°C and wound around a cast roll whose temperature was controlled to 20°C to obtain a sheet-like molded product. The amount of THF outgassing was measured in accordance with the method of Test Example 1- 21 In Table 5, "not detectable" means that the level is below the detection limit. Ruko Indicates that.

[0132] [Table 5] From the results in Table 5, regardless of the molding temperature, no THF outgassing could be confirmed from the polyester resin in film form.

[0133] [Test Examples 26-47] The copolymers of Test Examples 2, 3, 7, 8, and 11 to 13 after heat treatment (referred to as "first copolymer" in Table 6) and the polybutylene terephthalate of Test Example 1 after heat treatment (referred to as "second copolymer" in Table 5) were mixed and molded into sheets. The amount of THF outgassing was measured for the molded sheets. No heat treatment at 50°C or higher was performed after molding before measurement. Table 6 shows the mixing ratio (mass ratio) of the first copolymer to the second copolymer and the amount of THF outgassing.

[0134] For sheet molding, the first copolymer and the second copolymer were mixed in the mass ratio shown in Table 6, melt-extruded at 250°C using a T-die extruder, which is a common method for producing polyester sheets, and wound around a cast roll whose temperature was controlled at 20°C to obtain a sheet-like molded product. In test examples in which the two copolymers were not mixed, sheets were similarly formed using a single copolymer.

[0135] [Table 6]

[0136] From the results in Table 6, in Test Example 26, the amount of THF outgassing could not be reduced when polybutylene terephthalate was used alone, even when it was made into a sheet. In Test Examples 39 to 47, the amount of THF outgassing remained high even when a mixture of a polyester resin containing a polytetramethylene glycol component and polybutylene terephthalate was used. On the other hand, in Test Examples 27 to 38, the amount of THF outgassing was high when a dimer acid componentWhen polyester resin containing THF was formed into a sheet, the amount of THF outgassing could be significantly reduced. Amount of outgassing was able to reduce.

[0137] [Test Examples 48-63] The copolymers of Test Examples 15 to 21 after heat treatment (referred to as "first copolymer" in Table 7) and the polybutylene naphthalate of Test Example 14 after heat treatment (referred to as "second copolymer" in Table 7) were mixed and molded into sheets. The amount of THF outgassing was measured for the molded sheets. No heat treatment at 50°C or higher was performed after molding before measurement. Table 7 shows the mixing ratio (mass ratio) of the first copolymer to the second copolymer and the amount of THF outgassing.

[0138] [Table 7]

[0139] From the results in Table 7, in Test Example 48, the amount of THF outgassing could not be reduced when polybutylene naphthalate was used alone, even when it was made into a sheet. component When polyester resin containing THF was formed into a sheet, the amount of THF outgassing could be significantly reduced. Amount of outgassing was able to reduce.

[0140] The polyester resin and its manufacturing method of the present disclosure have been described based on the above embodiments and examples, but are not limited to the above embodiments and examples, and can include various modifications, changes, and improvements to each disclosed element (including elements described in the claims, specification, and drawings) within the scope of the present invention and based on the basic technical idea of ​​the present invention. Furthermore, various combinations, substitutions, and selections of each disclosed element are possible within the scope of the claims of the present invention.

[0141] Further objects, purposes and modes (including modifications) of the present invention will become apparent from the entire disclosure of the present invention including the claims.

[0142] With respect to numerical ranges set forth herein, unless otherwise specified, any numerical value or range falling within that range should be construed as being specifically set forth herein.

[0143] Some or all of the above embodiments may be described as, but are not limited to, the following supplementary notes. Each supplementary note may be combined with each claim in the claims. [Appendix 1] A method of use in which the polyester resin according to the first embodiment is added to a polyester resin containing at least one alcohol component selected from the group consisting of 1,4-butanediol and polytetramethylene glycol. [Industrial Applicability]

[0144] The polyester resin and its manufacturing method, as well as the molded article and its manufacturing method of the present disclosure, can be applied to various molded articles, and can be particularly suitably applied to components for electric and electronic devices, components for automobiles, packaging materials, and the like.

Claims

1. a first copolymer obtained by polymerizing an acid component containing 50 mol% or more of a 2,6-naphthalenedicarboxylic acid component and 2 mol% to 50 mol% of a dimer acid component relative to the total amount of the acid component, and an alcohol component containing 50 mol% or more of a 1,4-butanediol component relative to the total amount of the alcohol component; A polyester resin, wherein the amount of tetrahydrofuran generated when the first copolymer is heated at 150°C for 1 hour is 1 µg or less per 1 g of the first copolymer.

2. 2. The polyester resin according to claim 1, wherein the amount of tetrahydrofuran generated when the first copolymer is heated at 150°C for 1 hour is 0.5 μg or less per 1 g of the first copolymer.

3. the acid component contains 60 mol % to 90 mol % of a 2,6-naphthalenedicarboxylic acid component and 10 mol % to 40 mol % of a dimer acid component, based on the total amount of the acid component; 2. The polyester resin according to claim 1, wherein the alcohol component contains 80 mol % or more of a 1,4-butanediol component based on the total amount of the alcohol component.

4. The polyester resin according to claim 1 , wherein the dimer acid component has at least one carbon atom selected from the group consisting of 44 and 36 carbon atoms.

5. a first step of preparing a first copolymer according to any one of claims 1 to 4; a second step of heat-treating the first copolymer under a pressure of 4,000 Pa or less at a temperature of 66°C or more and the melting point of the first copolymer or less.

6. The method for producing a polyester resin according to claim 5, wherein the heat treatment is carried out for 6 to 100 hours.

7. The method for producing a polyester resin according to claim 5 , wherein the second step is carried out before the first copolymer is heat-treated to 50° C. or higher.

8. A method for producing a polyester resin as described in claim 5, wherein the first copolymer is a first copolymer obtained by polymerizing an acid containing 60 mol% to 90 mol% of 2,6-naphthalenedicarboxylic acid and 10 mol% to 40 mol% of dimer acid relative to the total amount of acid, and an alcohol containing 80 mol% or more of 1,4-butanediol relative to the total amount of alcohol.

9. The method for producing a polyester resin according to claim 8 , wherein the dimer acid has at least one carbon atom selected from the group consisting of 44 and 36.

10. A molded article comprising the polyester resin according to any one of claims 1 to 4.

11. 5% by mass to 70% by mass of the polyester resin according to any one of claims 1 to 4; 30% to 95% by weight of a second copolymer, the second copolymer is a polyester resin containing at least one alcohol component selected from the group consisting of a 1,4-butanediol component and a polytetramethylene glycol component; A molded body, wherein the amount of tetrahydrofuran generated when the molded body is heated at 150°C for 1 hour is 50 µg or less per 1 g of the molded body.

12. The molded article according to claim 11, wherein the amount of tetrahydrofuran generated from the second copolymer when the second copolymer is heated at 150°C for 1 hour is 150 μg to 600 μg per 1 g of the second copolymer.

13. The molded article according to claim 11, which has at least one shape selected from the group consisting of a sheet shape, a film shape, and a container shape.

14. A member for electric / electronic devices, an automobile part, or a packaging material, comprising the molded article according to claim 10.

15. A member for electric / electronic devices, an automobile part, or a packaging material, comprising the molded article according to claim 11.

16. a first step of preparing a first copolymer according to any one of claims 1 to 4; a second step of heat-treating the first copolymer at a temperature of 66°C or higher and a melting point of the first copolymer under a pressure of 4,000 Pa or lower; a third step of molding a mixture of 5% to 95% by weight of the first copolymer and 5% to 95% by weight of the second copolymer; The method for producing a molded article, wherein the second copolymer is a polyester resin containing at least one alcohol component selected from the group consisting of a 1,4-butanediol component and a polytetramethylene glycol component.

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